includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Psr\Log\NullLogger;
  31 use Wikimedia\ScopedCallback;
  32 use Wikimedia\Timestamp\ConvertibleTimestamp;
  33 use Wikimedia\AtEase\AtEase;
  34 use BagOStuff;
  35 use HashBagOStuff;
  36 use LogicException;
  37 use InvalidArgumentException;
  38 use UnexpectedValueException;
  39 use Exception;
  40 use RuntimeException;
  41 use Throwable;
  42
  43 /**
  44  * Relational database abstraction object
  45  *
  46  * @ingroup Database
  47  * @since 1.28
  48  */
  49 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  50         /** @var BagOStuff APC cache */
  51         protected $srvCache;
  52         /** @var LoggerInterface */
  53         protected $connLogger;
  54         /** @var LoggerInterface */
  55         protected $queryLogger;
  56         /** @var callable Error logging callback */
  57         protected $errorLogger;
  58         /** @var callable Deprecation logging callback */
  59         protected $deprecationLogger;
  60         /** @var callable|null */
  61         protected $profiler;
  62         /** @var TransactionProfiler */
  63         protected $trxProfiler;
  64
  65         /** @var DatabaseDomain */
  66         protected $currentDomain;
  67
  68         /** @var object|resource|null Database connection */
  69         protected $conn;
  70
  71         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
  72         private $lazyMasterHandle;
  73
  74         /** @var string Server that this instance is currently connected to */
  75         protected $server;
  76         /** @var string User that this instance is currently connected under the name of */
  77         protected $user;
  78         /** @var string Password used to establish the current connection */
  79         protected $password;
  80         /** @var bool Whether this PHP instance is for a CLI script */
  81         protected $cliMode;
  82         /** @var string Agent name for query profiling */
  83         protected $agent;
  84         /** @var array Parameters used by initConnection() to establish a connection */
  85         protected $connectionParams;
  86         /** @var string[]|int[]|float[] SQL variables values to use for all new connections */
  87         protected $connectionVariables;
  88         /** @var int Row batch size to use for emulated INSERT SELECT queries */
  89         protected $nonNativeInsertSelectBatchSize;
  90
  91         /** @var int Current bit field of class DBO_* constants */
  92         protected $flags;
  93         /** @var array Current LoadBalancer tracking information */
  94         protected $lbInfo = [];
  95         /** @var string Current SQL query delimiter */
  96         protected $delimiter = ';';
  97         /** @var array[] Current map of (table => (dbname, schema, prefix) map) */
  98         protected $tableAliases = [];
  99         /** @var string[] Current map of (index alias => index) */
 100         protected $indexAliases = [];
 101         /** @var array|null Current variables use for schema element placeholders */
 102         protected $schemaVars;
 103
 104         /** @var string|bool|null Stashed value of html_errors INI setting */
 105         private $htmlErrors;
 106         /** @var int[] Prior flags member variable values */
 107         private $priorFlags = [];
 108
 109         /** @var array Map of (name => 1) for locks obtained via lock() */
 110         protected $sessionNamedLocks = [];
 111         /** @var array Map of (table name => 1) for TEMPORARY tables */
 112         protected $sessionTempTables = [];
 113
 114         /** @var string ID of the active transaction or the empty string otherwise */
 115         private $trxShortId = '';
 116         /** @var int Transaction status */
 117         private $trxStatus = self::STATUS_TRX_NONE;
 118         /** @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR */
 119         private $trxStatusCause;
 120         /** @var array|null Error details of the last statement-only rollback */
 121         private $trxStatusIgnoredCause;
 122         /** @var float|null UNIX timestamp at the time of BEGIN for the last transaction */
 123         private $trxTimestamp = null;
 124         /** @var float Replication lag estimate at the time of BEGIN for the last transaction */
 125         private $trxReplicaLag = null;
 126         /** @var string Name of the function that start the last transaction */
 127         private $trxFname = null;
 128         /** @var bool Whether possible write queries were done in the last transaction started */
 129         private $trxDoneWrites = false;
 130         /** @var bool Whether the current transaction was started implicitly due to DBO_TRX */
 131         private $trxAutomatic = false;
 132         /** @var int Counter for atomic savepoint identifiers (reset with each transaction) */
 133         private $trxAtomicCounter = 0;
 134         /** @var array List of (name, unique ID, savepoint ID) for each active atomic section level */
 135         private $trxAtomicLevels = [];
 136         /** @var bool Whether the current transaction was started implicitly by startAtomic() */
 137         private $trxAutomaticAtomic = false;
 138         /** @var string[] Write query callers of the current transaction */
 139         private $trxWriteCallers = [];
 140         /** @var float Seconds spent in write queries for the current transaction */
 141         private $trxWriteDuration = 0.0;
 142         /** @var int Number of write queries for the current transaction */
 143         private $trxWriteQueryCount = 0;
 144         /** @var int Number of rows affected by write queries for the current transaction */
 145         private $trxWriteAffectedRows = 0;
 146         /** @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries */
 147         private $trxWriteAdjDuration = 0.0;
 148         /** @var int Number of write queries counted in trxWriteAdjDuration */
 149         private $trxWriteAdjQueryCount = 0;
 150         /** @var array[] List of (callable, method name, atomic section id) */
 151         private $trxIdleCallbacks = [];
 152         /** @var array[] List of (callable, method name, atomic section id) */
 153         private $trxPreCommitCallbacks = [];
 154         /** @var array[] List of (callable, method name, atomic section id) */
 155         private $trxEndCallbacks = [];
 156         /** @var array[] List of (callable, method name, atomic section id) */
 157         private $trxSectionCancelCallbacks = [];
 158         /** @var callable[] Map of (name => callable) */
 159         private $trxRecurringCallbacks = [];
 160         /** @var bool Whether to suppress triggering of transaction end callbacks */
 161         private $trxEndCallbacksSuppressed = false;
 162
 163         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 164         protected $affectedRowCount;
 165
 166         /** @var float UNIX timestamp */
 167         private $lastPing = 0.0;
 168         /** @var string The last SQL query attempted */
 169         private $lastQuery = '';
 170         /** @var float|bool UNIX timestamp of last write query */
 171         private $lastWriteTime = false;
 172         /** @var string|bool */
 173         private $lastPhpError = false;
 174         /** @var float Query rount trip time estimate */
 175         private $lastRoundTripEstimate = 0.0;
 176
 177         /** @var string Whether the database is a file on disk */
 178         const ATTR_DB_IS_FILE = 'db-is-file';
 179         /** @var string Lock granularity is on the level of the entire database */
 180         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
 181         /** @var string The SCHEMA keyword refers to a grouping of tables in a database */
 182         const ATTR_SCHEMAS_AS_TABLE_GROUPS = 'supports-schemas';
 183
 184         /** @var int New Database instance will not be connected yet when returned */
 185         const NEW_UNCONNECTED = 0;
 186         /** @var int New Database instance will already be connected when returned */
 187         const NEW_CONNECTED = 1;
 188
 189         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 190         const STATUS_TRX_ERROR = 1;
 191         /** @var int Transaction is active and in a normal state */
 192         const STATUS_TRX_OK = 2;
 193         /** @var int No transaction is active */
 194         const STATUS_TRX_NONE = 3;
 195
 196         /** @var string Idiom used when a cancelable atomic section started the transaction */
 197         private static $NOT_APPLICABLE = 'n/a';
 198         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 199         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 200
 201         /** @var int Writes to this temporary table do not affect lastDoneWrites() */
 202         private static $TEMP_NORMAL = 1;
 203         /** @var int Writes to this temporary table effect lastDoneWrites() */
 204         private static $TEMP_PSEUDO_PERMANENT = 2;
 205
 206         /** @var int Number of times to re-try an operation in case of deadlock */
 207         private static $DEADLOCK_TRIES = 4;
 208         /** @var int Minimum time to wait before retry, in microseconds */
 209         private static $DEADLOCK_DELAY_MIN = 500000;
 210         /** @var int Maximum time to wait before retry */
 211         private static $DEADLOCK_DELAY_MAX = 1500000;
 212
 213         /** @var int How long before it is worth doing a dummy query to test the connection */
 214         private static $PING_TTL = 1.0;
 215         /** @var string Dummy SQL query */
 216         private static $PING_QUERY = 'SELECT 1 AS ping';
 217
 218         /** @var float Guess of how many seconds it takes to replicate a small insert */
 219         private static $TINY_WRITE_SEC = 0.010;
 220         /** @var float Consider a write slow if it took more than this many seconds */
 221         private static $SLOW_WRITE_SEC = 0.500;
 222         /** @var float Assume an insert of this many rows or less should be fast to replicate */
 223         private static $SMALL_WRITE_ROWS = 100;
 224
 225         /** @var string[] List of DBO_* flags that can be changed after connection */
 226         protected static $MUTABLE_FLAGS = [
 227                 'DBO_DEBUG',
 228                 'DBO_NOBUFFER',
 229                 'DBO_TRX',
 230                 'DBO_DDLMODE',
 231         ];
 232         /** @var int Bit field of all DBO_* flags that can be changed after connection */
 233         protected static $DBO_MUTABLE = (
 234                 self::DBO_DEBUG | self::DBO_NOBUFFER | self::DBO_TRX | self::DBO_DDLMODE
 235         );
 236
 237         /**
 238          * @note exceptions for missing libraries/drivers should be thrown in initConnection()
 239          * @param array $params Parameters passed from Database::factory()
 240          */
 241         public function __construct( array $params ) {
 242                 $this->connectionParams = [];
 243                 foreach ( [ 'host', 'user', 'password', 'dbname', 'schema', 'tablePrefix' ] as $name ) {
 244                         $this->connectionParams[$name] = $params[$name];
 245                 }
 246                 $this->connectionVariables = $params['variables'] ?? [];
 247                 $this->cliMode = $params['cliMode'];
 248                 $this->agent = $params['agent'];
 249                 $this->flags = $params['flags'];
 250                 $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'] ?? 10000;
 251
 252                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 253                 $this->profiler = is_callable( $params['profiler'] ) ? $params['profiler'] : null;
 254                 $this->trxProfiler = $params['trxProfiler'];
 255                 $this->connLogger = $params['connLogger'];
 256                 $this->queryLogger = $params['queryLogger'];
 257                 $this->errorLogger = $params['errorLogger'];
 258                 $this->deprecationLogger = $params['deprecationLogger'];
 259
 260                 // Set initial dummy domain until open() sets the final DB/prefix
 261                 $this->currentDomain = new DatabaseDomain(
 262                         $params['dbname'] != '' ? $params['dbname'] : null,
 263                         $params['schema'] != '' ? $params['schema'] : null,
 264                         $params['tablePrefix']
 265                 );
 266         }
 267
 268         /**
 269          * Initialize the connection to the database over the wire (or to local files)
 270          *
 271          * @throws LogicException
 272          * @throws InvalidArgumentException
 273          * @throws DBConnectionError
 274          * @since 1.31
 275          */
 276         final public function initConnection() {
 277                 if ( $this->isOpen() ) {
 278                         throw new LogicException( __METHOD__ . ': already connected' );
 279                 }
 280                 // Establish the connection
 281                 $this->doInitConnection();
 282         }
 283
 284         /**
 285          * Actually connect to the database over the wire (or to local files)
 286          *
 287          * @throws DBConnectionError
 288          * @since 1.31
 289          */
 290         protected function doInitConnection() {
 291                 $this->open(
 292                         $this->connectionParams['host'],
 293                         $this->connectionParams['user'],
 294                         $this->connectionParams['password'],
 295                         $this->connectionParams['dbname'],
 296                         $this->connectionParams['schema'],
 297                         $this->connectionParams['tablePrefix']
 298                 );
 299         }
 300
 301         /**
 302          * Open a new connection to the database (closing any existing one)
 303          *
 304          * @param string|null $server Database server host
 305          * @param string|null $user Database user name
 306          * @param string|null $password Database user password
 307          * @param string|null $dbName Database name
 308          * @param string|null $schema Database schema name
 309          * @param string $tablePrefix Table prefix
 310          * @throws DBConnectionError
 311          */
 312         abstract protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix );
 313
 314         /**
 315          * Construct a Database subclass instance given a database type and parameters
 316          *
 317          * This also connects to the database immediately upon object construction
 318          *
 319          * @param string $type A possible DB type (sqlite, mysql, postgres,...)
 320          * @param array $params Parameter map with keys:
 321          *   - host : The hostname of the DB server
 322          *   - user : The name of the database user the client operates under
 323          *   - password : The password for the database user
 324          *   - dbname : The name of the database to use where queries do not specify one.
 325          *      The database must exist or an error might be thrown. Setting this to the empty string
 326          *      will avoid any such errors and make the handle have no implicit database scope. This is
 327          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 328          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 329          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 330          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 331          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 332          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 333          *      recognized in queries. This can be used in place of schemas for handle site farms.
 334          *   - flags : Optional bit field of DBO_* constants that define connection, protocol,
 335          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 336          *      flag in place UNLESS this this database simply acts as a key/value store.
 337          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 338          *      'mysqli' driver; the old one 'mysql' has been removed.
 339          *   - variables: Optional map of session variables to set after connecting. This can be
 340          *      used to adjust lock timeouts or encoding modes and the like.
 341          *   - connLogger: Optional PSR-3 logger interface instance.
 342          *   - queryLogger: Optional PSR-3 logger interface instance.
 343          *   - profiler : Optional callback that takes a section name argument and returns
 344          *      a ScopedCallback instance that ends the profile section in its destructor.
 345          *      These will be called in query(), using a simplified version of the SQL that
 346          *      also includes the agent as a SQL comment.
 347          *   - trxProfiler: Optional TransactionProfiler instance.
 348          *   - errorLogger: Optional callback that takes an Exception and logs it.
 349          *   - deprecationLogger: Optional callback that takes a string and logs it.
 350          *   - cliMode: Whether to consider the execution context that of a CLI script.
 351          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 352          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 353          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 354          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 355          * @return Database|null If the database driver or extension cannot be found
 356          * @throws InvalidArgumentException If the database driver or extension cannot be found
 357          * @since 1.18
 358          */
 359         final public static function factory( $type, $params = [], $connect = self::NEW_CONNECTED ) {
 360                 $class = self::getClass( $type, $params['driver'] ?? null );
 361
 362                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 363                         $params += [
 364                                 'host' => null,
 365                                 'user' => null,
 366                                 'password' => null,
 367                                 'dbname' => null,
 368                                 'schema' => null,
 369                                 'tablePrefix' => '',
 370                                 'flags' => 0,
 371                                 'variables' => [],
 372                                 'cliMode' => ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' ),
 373                                 'agent' => basename( $_SERVER['SCRIPT_NAME'] ) . '@' . gethostname()
 374                         ];
 375
 376                         $normalizedParams = [
 377                                 // Configuration
 378                                 'host' => strlen( $params['host'] ) ? $params['host'] : null,
 379                                 'user' => strlen( $params['user'] ) ? $params['user'] : null,
 380                                 'password' => is_string( $params['password'] ) ? $params['password'] : null,
 381                                 'dbname' => strlen( $params['dbname'] ) ? $params['dbname'] : null,
 382                                 'schema' => strlen( $params['schema'] ) ? $params['schema'] : null,
 383                                 'tablePrefix' => (string)$params['tablePrefix'],
 384                                 'flags' => (int)$params['flags'],
 385                                 'variables' => $params['variables'],
 386                                 'cliMode' => (bool)$params['cliMode'],
 387                                 'agent' => (string)$params['agent'],
 388                                 // Objects and callbacks
 389                                 'srvCache' => $params['srvCache'] ?? new HashBagOStuff(),
 390                                 'profiler' => $params['profiler'] ?? null,
 391                                 'trxProfiler' => $params['trxProfiler'] ?? new TransactionProfiler(),
 392                                 'connLogger' => $params['connLogger'] ?? new NullLogger(),
 393                                 'queryLogger' => $params['queryLogger'] ?? new NullLogger(),
 394                                 'errorLogger' => $params['errorLogger'] ?? function ( Exception $e ) {
 395                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 396                                 },
 397                                 'deprecationLogger' => $params['deprecationLogger'] ?? function ( $msg ) {
 398                                         trigger_error( $msg, E_USER_DEPRECATED );
 399                                 }
 400                         ] + $params;
 401
 402                         /** @var Database $conn */
 403                         $conn = new $class( $normalizedParams );
 404                         if ( $connect === self::NEW_CONNECTED ) {
 405                                 $conn->initConnection();
 406                         }
 407                 } else {
 408                         $conn = null;
 409                 }
 410
 411                 return $conn;
 412         }
 413
 414         /**
 415          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 416          * @param string|null $driver Optional name of a specific DB client driver
 417          * @return array Map of (Database::ATTR_* constant => value) for all such constants
 418          * @throws InvalidArgumentException
 419          * @since 1.31
 420          */
 421         final public static function attributesFromType( $dbType, $driver = null ) {
 422                 static $defaults = [
 423                         self::ATTR_DB_IS_FILE => false,
 424                         self::ATTR_DB_LEVEL_LOCKING => false,
 425                         self::ATTR_SCHEMAS_AS_TABLE_GROUPS => false
 426                 ];
 427
 428                 $class = self::getClass( $dbType, $driver );
 429
 430                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 431         }
 432
 433         /**
 434          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 435          * @param string|null $driver Optional name of a specific DB client driver
 436          * @return string Database subclass name to use
 437          * @throws InvalidArgumentException
 438          */
 439         private static function getClass( $dbType, $driver = null ) {
 440                 // For database types with built-in support, the below maps type to IDatabase
 441                 // implementations. For types with multipe driver implementations (PHP extensions),
 442                 // an array can be used, keyed by extension name. In case of an array, the
 443                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 444                 // we auto-detect the first available driver. For types without built-in support,
 445                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 446                 static $builtinTypes = [
 447                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 448                         'sqlite' => DatabaseSqlite::class,
 449                         'postgres' => DatabasePostgres::class,
 450                 ];
 451
 452                 $dbType = strtolower( $dbType );
 453                 $class = false;
 454
 455                 if ( isset( $builtinTypes[$dbType] ) ) {
 456                         $possibleDrivers = $builtinTypes[$dbType];
 457                         if ( is_string( $possibleDrivers ) ) {
 458                                 $class = $possibleDrivers;
 459                         } elseif ( (string)$driver !== '' ) {
 460                                 if ( !isset( $possibleDrivers[$driver] ) ) {
 461                                         throw new InvalidArgumentException( __METHOD__ .
 462                                                 " type '$dbType' does not support driver '{$driver}'" );
 463                                 }
 464
 465                                 $class = $possibleDrivers[$driver];
 466                         } else {
 467                                 foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 468                                         if ( extension_loaded( $posDriver ) ) {
 469                                                 $class = $possibleClass;
 470                                                 break;
 471                                         }
 472                                 }
 473                         }
 474                 } else {
 475                         $class = 'Database' . ucfirst( $dbType );
 476                 }
 477
 478                 if ( $class === false ) {
 479                         throw new InvalidArgumentException( __METHOD__ .
 480                                 " no viable database extension found for type '$dbType'" );
 481                 }
 482
 483                 return $class;
 484         }
 485
 486         /**
 487          * @return array Map of (Database::ATTR_* constant => value)
 488          * @since 1.31
 489          */
 490         protected static function getAttributes() {
 491                 return [];
 492         }
 493
 494         /**
 495          * Set the PSR-3 logger interface to use for query logging. (The logger
 496          * interfaces for connection logging and error logging can be set with the
 497          * constructor.)
 498          *
 499          * @param LoggerInterface $logger
 500          */
 501         public function setLogger( LoggerInterface $logger ) {
 502                 $this->queryLogger = $logger;
 503         }
 504
 505         public function getServerInfo() {
 506                 return $this->getServerVersion();
 507         }
 508
 509         /**
 510          * Backwards-compatibility no-op method for disabling query buffering
 511          *
 512          * @param null|bool $buffer Whether to buffer queries (ignored)
 513          * @return bool Whether buffering was already enabled (always true)
 514          * @deprecated Since 1.34 Use query batching; this no longer does anything
 515          */
 516         public function bufferResults( $buffer = null ) {
 517                 return true;
 518         }
 519
 520         final public function trxLevel() {
 521                 return ( $this->trxShortId != '' ) ? 1 : 0;
 522         }
 523
 524         public function trxTimestamp() {
 525                 return $this->trxLevel() ? $this->trxTimestamp : null;
 526         }
 527
 528         /**
 529          * @return int One of the STATUS_TRX_* class constants
 530          * @since 1.31
 531          */
 532         public function trxStatus() {
 533                 return $this->trxStatus;
 534         }
 535
 536         public function tablePrefix( $prefix = null ) {
 537                 $old = $this->currentDomain->getTablePrefix();
 538                 if ( $prefix !== null ) {
 539                         $this->currentDomain = new DatabaseDomain(
 540                                 $this->currentDomain->getDatabase(),
 541                                 $this->currentDomain->getSchema(),
 542                                 $prefix
 543                         );
 544                 }
 545
 546                 return $old;
 547         }
 548
 549         public function dbSchema( $schema = null ) {
 550                 if ( strlen( $schema ) && $this->getDBname() === null ) {
 551                         throw new DBUnexpectedError( $this, "Cannot set schema to '$schema'; no database set" );
 552                 }
 553
 554                 $old = $this->currentDomain->getSchema();
 555                 if ( $schema !== null ) {
 556                         $this->currentDomain = new DatabaseDomain(
 557                                 $this->currentDomain->getDatabase(),
 558                                 // DatabaseDomain uses null for unspecified schemas
 559                                 strlen( $schema ) ? $schema : null,
 560                                 $this->currentDomain->getTablePrefix()
 561                         );
 562                 }
 563
 564                 return (string)$old;
 565         }
 566
 567         /**
 568          * @return string Schema to use to qualify relations in queries
 569          */
 570         protected function relationSchemaQualifier() {
 571                 return $this->dbSchema();
 572         }
 573
 574         public function getLBInfo( $name = null ) {
 575                 if ( is_null( $name ) ) {
 576                         return $this->lbInfo;
 577                 }
 578
 579                 if ( array_key_exists( $name, $this->lbInfo ) ) {
 580                         return $this->lbInfo[$name];
 581                 }
 582
 583                 return null;
 584         }
 585
 586         public function setLBInfo( $nameOrArray, $value = null ) {
 587                 if ( is_array( $nameOrArray ) ) {
 588                         $this->lbInfo = $nameOrArray;
 589                 } elseif ( is_string( $nameOrArray ) ) {
 590                         if ( $value !== null ) {
 591                                 $this->lbInfo[$nameOrArray] = $value;
 592                         } else {
 593                                 unset( $this->lbInfo[$nameOrArray] );
 594                         }
 595                 } else {
 596                         throw new InvalidArgumentException( "Got non-string key" );
 597                 }
 598         }
 599
 600         public function setLazyMasterHandle( IDatabase $conn ) {
 601                 $this->lazyMasterHandle = $conn;
 602         }
 603
 604         /**
 605          * @return IDatabase|null
 606          * @see setLazyMasterHandle()
 607          * @since 1.27
 608          */
 609         protected function getLazyMasterHandle() {
 610                 return $this->lazyMasterHandle;
 611         }
 612
 613         public function implicitOrderby() {
 614                 return true;
 615         }
 616
 617         public function lastQuery() {
 618                 return $this->lastQuery;
 619         }
 620
 621         public function lastDoneWrites() {
 622                 return $this->lastWriteTime ?: false;
 623         }
 624
 625         public function writesPending() {
 626                 return $this->trxLevel() && $this->trxDoneWrites;
 627         }
 628
 629         public function writesOrCallbacksPending() {
 630                 return $this->trxLevel() && (
 631                         $this->trxDoneWrites ||
 632                         $this->trxIdleCallbacks ||
 633                         $this->trxPreCommitCallbacks ||
 634                         $this->trxEndCallbacks ||
 635                         $this->trxSectionCancelCallbacks
 636                 );
 637         }
 638
 639         public function preCommitCallbacksPending() {
 640                 return $this->trxLevel() && $this->trxPreCommitCallbacks;
 641         }
 642
 643         /**
 644          * @return string|null
 645          */
 646         final protected function getTransactionRoundId() {
 647                 // If transaction round participation is enabled, see if one is active
 648                 if ( $this->getFlag( self::DBO_TRX ) ) {
 649                         $id = $this->getLBInfo( 'trxRoundId' );
 650
 651                         return is_string( $id ) ? $id : null;
 652                 }
 653
 654                 return null;
 655         }
 656
 657         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 658                 if ( !$this->trxLevel() ) {
 659                         return false;
 660                 } elseif ( !$this->trxDoneWrites ) {
 661                         return 0.0;
 662                 }
 663
 664                 switch ( $type ) {
 665                         case self::ESTIMATE_DB_APPLY:
 666                                 return $this->pingAndCalculateLastTrxApplyTime();
 667                         default: // everything
 668                                 return $this->trxWriteDuration;
 669                 }
 670         }
 671
 672         /**
 673          * @return float Time to apply writes to replicas based on trxWrite* fields
 674          */
 675         private function pingAndCalculateLastTrxApplyTime() {
 676                 $this->ping( $rtt );
 677
 678                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 679                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 680                 // For omitted queries, make them count as something at least
 681                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 682                 $applyTime += self::$TINY_WRITE_SEC * $omitted;
 683
 684                 return $applyTime;
 685         }
 686
 687         public function pendingWriteCallers() {
 688                 return $this->trxLevel() ? $this->trxWriteCallers : [];
 689         }
 690
 691         public function pendingWriteRowsAffected() {
 692                 return $this->trxWriteAffectedRows;
 693         }
 694
 695         /**
 696          * List the methods that have write queries or callbacks for the current transaction
 697          *
 698          * This method should not be used outside of Database/LoadBalancer
 699          *
 700          * @return string[]
 701          * @since 1.32
 702          */
 703         public function pendingWriteAndCallbackCallers() {
 704                 $fnames = $this->pendingWriteCallers();
 705                 foreach ( [
 706                         $this->trxIdleCallbacks,
 707                         $this->trxPreCommitCallbacks,
 708                         $this->trxEndCallbacks,
 709                         $this->trxSectionCancelCallbacks
 710                 ] as $callbacks ) {
 711                         foreach ( $callbacks as $callback ) {
 712                                 $fnames[] = $callback[1];
 713                         }
 714                 }
 715
 716                 return $fnames;
 717         }
 718
 719         /**
 720          * @return string
 721          */
 722         private function flatAtomicSectionList() {
 723                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 724                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 725                 } );
 726         }
 727
 728         public function isOpen() {
 729                 return (bool)$this->conn;
 730         }
 731
 732         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 733                 if ( $flag & ~static::$DBO_MUTABLE ) {
 734                         throw new DBUnexpectedError(
 735                                 $this,
 736                                 "Got $flag (allowed: " . implode( ', ', static::$MUTABLE_FLAGS ) . ')'
 737                         );
 738                 }
 739
 740                 if ( $remember === self::REMEMBER_PRIOR ) {
 741                         array_push( $this->priorFlags, $this->flags );
 742                 }
 743
 744                 $this->flags |= $flag;
 745         }
 746
 747         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 748                 if ( $flag & ~static::$DBO_MUTABLE ) {
 749                         throw new DBUnexpectedError(
 750                                 $this,
 751                                 "Got $flag (allowed: " . implode( ', ', static::$MUTABLE_FLAGS ) . ')'
 752                         );
 753                 }
 754
 755                 if ( $remember === self::REMEMBER_PRIOR ) {
 756                         array_push( $this->priorFlags, $this->flags );
 757                 }
 758
 759                 $this->flags &= ~$flag;
 760         }
 761
 762         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 763                 if ( !$this->priorFlags ) {
 764                         return;
 765                 }
 766
 767                 if ( $state === self::RESTORE_INITIAL ) {
 768                         $this->flags = reset( $this->priorFlags );
 769                         $this->priorFlags = [];
 770                 } else {
 771                         $this->flags = array_pop( $this->priorFlags );
 772                 }
 773         }
 774
 775         public function getFlag( $flag ) {
 776                 return ( ( $this->flags & $flag ) === $flag );
 777         }
 778
 779         public function getDomainID() {
 780                 return $this->currentDomain->getId();
 781         }
 782
 783         /**
 784          * Get information about an index into an object
 785          * @param string $table Table name
 786          * @param string $index Index name
 787          * @param string $fname Calling function name
 788          * @return mixed Database-specific index description class or false if the index does not exist
 789          */
 790         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 791
 792         /**
 793          * Wrapper for addslashes()
 794          *
 795          * @param string $s String to be slashed.
 796          * @return string Slashed string.
 797          */
 798         abstract function strencode( $s );
 799
 800         /**
 801          * Set a custom error handler for logging errors during database connection
 802          */
 803         protected function installErrorHandler() {
 804                 $this->lastPhpError = false;
 805                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 806                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 807         }
 808
 809         /**
 810          * Restore the previous error handler and return the last PHP error for this DB
 811          *
 812          * @return bool|string
 813          */
 814         protected function restoreErrorHandler() {
 815                 restore_error_handler();
 816                 if ( $this->htmlErrors !== false ) {
 817                         ini_set( 'html_errors', $this->htmlErrors );
 818                 }
 819
 820                 return $this->getLastPHPError();
 821         }
 822
 823         /**
 824          * @return string|bool Last PHP error for this DB (typically connection errors)
 825          */
 826         protected function getLastPHPError() {
 827                 if ( $this->lastPhpError ) {
 828                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->lastPhpError );
 829                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 830
 831                         return $error;
 832                 }
 833
 834                 return false;
 835         }
 836
 837         /**
 838          * Error handler for logging errors during database connection
 839          * This method should not be used outside of Database classes
 840          *
 841          * @param int $errno
 842          * @param string $errstr
 843          */
 844         public function connectionErrorLogger( $errno, $errstr ) {
 845                 $this->lastPhpError = $errstr;
 846         }
 847
 848         /**
 849          * Create a log context to pass to PSR-3 logger functions.
 850          *
 851          * @param array $extras Additional data to add to context
 852          * @return array
 853          */
 854         protected function getLogContext( array $extras = [] ) {
 855                 return array_merge(
 856                         [
 857                                 'db_server' => $this->server,
 858                                 'db_name' => $this->getDBname(),
 859                                 'db_user' => $this->user,
 860                         ],
 861                         $extras
 862                 );
 863         }
 864
 865         final public function close() {
 866                 $exception = null; // error to throw after disconnecting
 867
 868                 $wasOpen = (bool)$this->conn;
 869                 // This should mostly do nothing if the connection is already closed
 870                 if ( $this->conn ) {
 871                         // Roll back any dangling transaction first
 872                         if ( $this->trxLevel() ) {
 873                                 if ( $this->trxAtomicLevels ) {
 874                                         // Cannot let incomplete atomic sections be committed
 875                                         $levels = $this->flatAtomicSectionList();
 876                                         $exception = new DBUnexpectedError(
 877                                                 $this,
 878                                                 __METHOD__ . ": atomic sections $levels are still open"
 879                                         );
 880                                 } elseif ( $this->trxAutomatic ) {
 881                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 882                                         // (empty ones we can silently roll back)
 883                                         if ( $this->writesOrCallbacksPending() ) {
 884                                                 $exception = new DBUnexpectedError(
 885                                                         $this,
 886                                                         __METHOD__ .
 887                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)"
 888                                                 );
 889                                         }
 890                                 } else {
 891                                         // Manual transactions should have been committed or rolled
 892                                         // back, even if empty.
 893                                         $exception = new DBUnexpectedError(
 894                                                 $this,
 895                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})"
 896                                         );
 897                                 }
 898
 899                                 if ( $this->trxEndCallbacksSuppressed ) {
 900                                         $exception = $exception ?: new DBUnexpectedError(
 901                                                 $this,
 902                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit'
 903                                         );
 904                                 }
 905
 906                                 // Rollback the changes and run any callbacks as needed
 907                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 908                         }
 909
 910                         // Close the actual connection in the binding handle
 911                         $closed = $this->closeConnection();
 912                 } else {
 913                         $closed = true; // already closed; nothing to do
 914                 }
 915
 916                 $this->conn = null;
 917
 918                 // Throw any unexpected errors after having disconnected
 919                 if ( $exception instanceof Exception ) {
 920                         throw $exception;
 921                 }
 922
 923                 // Note that various subclasses call close() at the start of open(), which itself is
 924                 // called by replaceLostConnection(). In that case, just because onTransactionResolution()
 925                 // callbacks are pending does not mean that an exception should be thrown. Rather, they
 926                 // will be executed after the reconnection step.
 927                 if ( $wasOpen ) {
 928                         // Sanity check that no callbacks are dangling
 929                         $fnames = $this->pendingWriteAndCallbackCallers();
 930                         if ( $fnames ) {
 931                                 throw new RuntimeException(
 932                                         "Transaction callbacks are still pending: " . implode( ', ', $fnames )
 933                                 );
 934                         }
 935                 }
 936
 937                 return $closed;
 938         }
 939
 940         /**
 941          * Make sure there is an open connection handle (alive or not) as a sanity check
 942          *
 943          * This guards against fatal errors to the binding handle not being defined
 944          * in cases where open() was never called or close() was already called
 945          *
 946          * @throws DBUnexpectedError
 947          */
 948         final protected function assertHasConnectionHandle() {
 949                 if ( !$this->isOpen() ) {
 950                         throw new DBUnexpectedError( $this, "DB connection was already closed" );
 951                 }
 952         }
 953
 954         /**
 955          * Make sure that this server is not marked as a replica nor read-only as a sanity check
 956          *
 957          * @throws DBReadOnlyRoleError
 958          * @throws DBReadOnlyError
 959          */
 960         protected function assertIsWritableMaster() {
 961                 if ( $this->getLBInfo( 'replica' ) ) {
 962                         throw new DBReadOnlyRoleError(
 963                                 $this,
 964                                 'Write operations are not allowed on replica database connections'
 965                         );
 966                 }
 967                 $reason = $this->getReadOnlyReason();
 968                 if ( $reason !== false ) {
 969                         throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 970                 }
 971         }
 972
 973         /**
 974          * Closes underlying database connection
 975          * @since 1.20
 976          * @return bool Whether connection was closed successfully
 977          */
 978         abstract protected function closeConnection();
 979
 980         /**
 981          * Run a query and return a DBMS-dependent wrapper or boolean
 982          *
 983          * This is meant to handle the basic command of actually sending a query to the
 984          * server via the driver. No implicit transaction, reconnection, nor retry logic
 985          * should happen here. The higher level query() method is designed to handle those
 986          * sorts of concerns. This method should not trigger such higher level methods.
 987          *
 988          * The lastError() and lastErrno() methods should meaningfully reflect what error,
 989          * if any, occured during the last call to this method. Methods like executeQuery(),
 990          * query(), select(), insert(), update(), delete(), and upsert() implement their calls
 991          * to doQuery() such that an immediately subsequent call to lastError()/lastErrno()
 992          * meaningfully reflects any error that occured during that public query method call.
 993          *
 994          * For SELECT queries, this returns either:
 995          *   - a) A driver-specific value/resource, only on success. This can be iterated
 996          *        over by calling fetchObject()/fetchRow() until there are no more rows.
 997          *        Alternatively, the result can be passed to resultObject() to obtain an
 998          *        IResultWrapper instance which can then be iterated over via "foreach".
 999          *   - b) False, on any query failure
1000          *
1001          * For non-SELECT queries, this returns either:
1002          *   - a) A driver-specific value/resource, only on success
1003          *   - b) True, only on success (e.g. no meaningful result other than "OK")
1004          *   - c) False, on any query failure
1005          *
1006          * @param string $sql SQL query
1007          * @return mixed|bool An object, resource, or true on success; false on failure
1008          */
1009         abstract protected function doQuery( $sql );
1010
1011         /**
1012          * Determine whether a query writes to the DB. When in doubt, this returns true.
1013          *
1014          * Main use cases:
1015          *
1016          * - Subsequent web requests should not need to wait for replication from
1017          *   the master position seen by this web request, unless this request made
1018          *   changes to the master. This is handled by ChronologyProtector by checking
1019          *   doneWrites() at the end of the request. doneWrites() returns true if any
1020          *   query set lastWriteTime; which query() does based on isWriteQuery().
1021          *
1022          * - Reject write queries to replica DBs, in query().
1023          *
1024          * @param string $sql
1025          * @return bool
1026          */
1027         protected function isWriteQuery( $sql ) {
1028                 // BEGIN and COMMIT queries are considered read queries here.
1029                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1030                 // treat these as write queries, in that their results have "affected rows"
1031                 // as meta data as from writes, instead of "num rows" as from reads.
1032                 // But, we treat them as read queries because when reading data (from
1033                 // either replica or master) we use transactions to enable repeatable-read
1034                 // snapshots, which ensures we get consistent results from the same snapshot
1035                 // for all queries within a request. Use cases:
1036                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1037                 // - We use this method to reject writes to replicas, but we need to allow
1038                 //   use of transactions on replicas for read snapshots. This is fine given
1039                 //   that transactions by themselves don't make changes, only actual writes
1040                 //   within the transaction matter, which we still detect.
1041                 return !preg_match(
1042                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|USE|\(SELECT)\b/i',
1043                         $sql
1044                 );
1045         }
1046
1047         /**
1048          * @param string $sql
1049          * @return string|null
1050          */
1051         protected function getQueryVerb( $sql ) {
1052                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1053         }
1054
1055         /**
1056          * Determine whether a SQL statement is sensitive to isolation level.
1057          *
1058          * A SQL statement is considered transactable if its result could vary
1059          * depending on the transaction isolation level. Operational commands
1060          * such as 'SET' and 'SHOW' are not considered to be transactable.
1061          *
1062          * Main purpose: Used by query() to decide whether to begin a transaction
1063          * before the current query (in DBO_TRX mode, on by default).
1064          *
1065          * @param string $sql
1066          * @return bool
1067          */
1068         protected function isTransactableQuery( $sql ) {
1069                 return !in_array(
1070                         $this->getQueryVerb( $sql ),
1071                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER', 'USE', 'SHOW' ],
1072                         true
1073                 );
1074         }
1075
1076         /**
1077          * @param string $sql A SQL query
1078          * @param bool $pseudoPermanent Treat any table from CREATE TEMPORARY as pseudo-permanent
1079          * @return array A n-tuple of:
1080          *   - int|null: A self::TEMP_* constant for temp table operations or null otherwise
1081          *   - string|null: The name of the new temporary table $sql creates, or null
1082          *   - string|null: The name of the temporary table that $sql drops, or null
1083          */
1084         protected function getTempWrites( $sql, $pseudoPermanent ) {
1085                 static $qt = '[`"\']?(\w+)[`"\']?'; // quoted table
1086
1087                 if ( preg_match(
1088                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?' . $qt . '/i',
1089                         $sql,
1090                         $matches
1091                 ) ) {
1092                         $type = $pseudoPermanent ? self::$TEMP_PSEUDO_PERMANENT : self::$TEMP_NORMAL;
1093
1094                         return [ $type, $matches[1], null ];
1095                 } elseif ( preg_match(
1096                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1097                         $sql,
1098                         $matches
1099                 ) ) {
1100                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, $matches[1] ];
1101                 } elseif ( preg_match(
1102                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1103                         $sql,
1104                         $matches
1105                 ) ) {
1106                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
1107                 } elseif ( preg_match(
1108                         '/^(?:(?:INSERT|REPLACE)\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+' . $qt . '/i',
1109                         $sql,
1110                         $matches
1111                 ) ) {
1112                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
1113                 }
1114
1115                 return [ null, null, null ];
1116         }
1117
1118         /**
1119          * @param IResultWrapper|bool $ret
1120          * @param int|null $tmpType TEMP_NORMAL or TEMP_PSEUDO_PERMANENT
1121          * @param string|null $tmpNew Name of created temp table
1122          * @param string|null $tmpDel Name of dropped temp table
1123          */
1124         protected function registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel ) {
1125                 if ( $ret !== false ) {
1126                         if ( $tmpNew !== null ) {
1127                                 $this->sessionTempTables[$tmpNew] = $tmpType;
1128                         }
1129                         if ( $tmpDel !== null ) {
1130                                 unset( $this->sessionTempTables[$tmpDel] );
1131                         }
1132                 }
1133         }
1134
1135         public function query( $sql, $fname = __METHOD__, $flags = 0 ) {
1136                 $flags = (int)$flags; // b/c; this field used to be a bool
1137                 // Sanity check that the SQL query is appropriate in the current context and is
1138                 // allowed for an outside caller (e.g. does not break transaction/session tracking).
1139                 $this->assertQueryIsCurrentlyAllowed( $sql, $fname );
1140
1141                 // Send the query to the server and fetch any corresponding errors
1142                 list( $ret, $err, $errno, $unignorable ) = $this->executeQuery( $sql, $fname, $flags );
1143                 if ( $ret === false ) {
1144                         $ignoreErrors = $this->fieldHasBit( $flags, self::QUERY_SILENCE_ERRORS );
1145                         // Throw an error unless both the ignore flag was set and a rollback is not needed
1146                         $this->reportQueryError( $err, $errno, $sql, $fname, $ignoreErrors && !$unignorable );
1147                 }
1148
1149                 return $this->resultObject( $ret );
1150         }
1151
1152         /**
1153          * Execute a query, retrying it if there is a recoverable connection loss
1154          *
1155          * This is similar to query() except:
1156          *   - It does not prevent all non-ROLLBACK queries if there is a corrupted transaction
1157          *   - It does not disallow raw queries that are supposed to use dedicated IDatabase methods
1158          *   - It does not throw exceptions for common error cases
1159          *
1160          * This is meant for internal use with Database subclasses.
1161          *
1162          * @param string $sql Original SQL query
1163          * @param string $fname Name of the calling function
1164          * @param int $flags Bit field of class QUERY_* constants
1165          * @return array An n-tuple of:
1166          *   - mixed|bool: An object, resource, or true on success; false on failure
1167          *   - string: The result of calling lastError()
1168          *   - int: The result of calling lastErrno()
1169          *   - bool: Whether a rollback is needed to allow future non-rollback queries
1170          * @throws DBUnexpectedError
1171          */
1172         final protected function executeQuery( $sql, $fname, $flags ) {
1173                 $this->assertHasConnectionHandle();
1174
1175                 $priorTransaction = $this->trxLevel();
1176
1177                 if ( $this->isWriteQuery( $sql ) ) {
1178                         // In theory, non-persistent writes are allowed in read-only mode, but due to things
1179                         // like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1180                         $this->assertIsWritableMaster();
1181                         // Do not treat temporary table writes as "meaningful writes" since they are only
1182                         // visible to one session and are not permanent. Profile them as reads. Integration
1183                         // tests can override this behavior via $flags.
1184                         $pseudoPermanent = $this->fieldHasBit( $flags, self::QUERY_PSEUDO_PERMANENT );
1185                         list( $tmpType, $tmpNew, $tmpDel ) = $this->getTempWrites( $sql, $pseudoPermanent );
1186                         $isPermWrite = ( $tmpType !== self::$TEMP_NORMAL );
1187                         // DBConnRef uses QUERY_REPLICA_ROLE to enforce the replica role for raw SQL queries
1188                         if ( $isPermWrite && $this->fieldHasBit( $flags, self::QUERY_REPLICA_ROLE ) ) {
1189                                 throw new DBReadOnlyRoleError( $this, "Cannot write; target role is DB_REPLICA" );
1190                         }
1191                 } else {
1192                         // No permanent writes in this query
1193                         $isPermWrite = false;
1194                         // No temporary tables written to either
1195                         list( $tmpType, $tmpNew, $tmpDel ) = [ null, null, null ];
1196                 }
1197
1198                 // Add trace comment to the begin of the sql string, right after the operator.
1199                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598).
1200                 $encAgent = str_replace( '/', '-', $this->agent );
1201                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $encAgent */ ", $sql, 1 );
1202
1203                 // Send the query to the server and fetch any corresponding errors.
1204                 // This also doubles as a "ping" to see if the connection was dropped.
1205                 list( $ret, $err, $errno, $recoverableSR, $recoverableCL, $reconnected ) =
1206                         $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1207
1208                 // Check if the query failed due to a recoverable connection loss
1209                 $allowRetry = !$this->fieldHasBit( $flags, self::QUERY_NO_RETRY );
1210                 if ( $ret === false && $recoverableCL && $reconnected && $allowRetry ) {
1211                         // Silently resend the query to the server since it is safe and possible
1212                         list( $ret, $err, $errno, $recoverableSR, $recoverableCL ) =
1213                                 $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1214                 }
1215
1216                 // Register creation and dropping of temporary tables
1217                 $this->registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel );
1218
1219                 $corruptedTrx = false;
1220
1221                 if ( $ret === false ) {
1222                         if ( $priorTransaction ) {
1223                                 if ( $recoverableSR ) {
1224                                         # We're ignoring an error that caused just the current query to be aborted.
1225                                         # But log the cause so we can log a deprecation notice if a caller actually
1226                                         # does ignore it.
1227                                         $this->trxStatusIgnoredCause = [ $err, $errno, $fname ];
1228                                 } elseif ( !$recoverableCL ) {
1229                                         # Either the query was aborted or all queries after BEGIN where aborted.
1230                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1231                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1232                                         # option is ROLLBACK, since the snapshots would have been released.
1233                                         $corruptedTrx = true; // cannot recover
1234                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1235                                         $this->trxStatusCause =
1236                                                 $this->getQueryExceptionAndLog( $err, $errno, $sql, $fname );
1237                                         $this->trxStatusIgnoredCause = null;
1238                                 }
1239                         }
1240                 }
1241
1242                 return [ $ret, $err, $errno, $corruptedTrx ];
1243         }
1244
1245         /**
1246          * Wrapper for doQuery() that handles DBO_TRX, profiling, logging, affected row count
1247          * tracking, and reconnects (without retry) on query failure due to connection loss
1248          *
1249          * @param string $sql Original SQL query
1250          * @param string $commentedSql SQL query with debugging/trace comment
1251          * @param bool $isPermWrite Whether the query is a (non-temporary table) write
1252          * @param string $fname Name of the calling function
1253          * @param int $flags Bit field of class QUERY_* constants
1254          * @return array An n-tuple of:
1255          *   - mixed|bool: An object, resource, or true on success; false on failure
1256          *   - string: The result of calling lastError()
1257          *   - int: The result of calling lastErrno()
1258          *       - bool: Whether a statement rollback error occured
1259          *   - bool: Whether a disconnect *both* happened *and* was recoverable
1260          *   - bool: Whether a reconnection attempt was *both* made *and* succeeded
1261          * @throws DBUnexpectedError
1262          */
1263         private function executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags ) {
1264                 $priorWritesPending = $this->writesOrCallbacksPending();
1265
1266                 if ( ( $flags & self::QUERY_IGNORE_DBO_TRX ) == 0 ) {
1267                         $this->beginIfImplied( $sql, $fname );
1268                 }
1269
1270                 // Keep track of whether the transaction has write queries pending
1271                 if ( $isPermWrite ) {
1272                         $this->lastWriteTime = microtime( true );
1273                         if ( $this->trxLevel() && !$this->trxDoneWrites ) {
1274                                 $this->trxDoneWrites = true;
1275                                 $this->trxProfiler->transactionWritingIn(
1276                                         $this->server, $this->getDomainID(), $this->trxShortId );
1277                         }
1278                 }
1279
1280                 $prefix = $this->getLBInfo( 'master' ) ? 'query-m: ' : 'query: ';
1281                 $generalizedSql = new GeneralizedSql( $sql, $this->trxShortId, $prefix );
1282
1283                 $startTime = microtime( true );
1284                 $ps = $this->profiler
1285                         ? ( $this->profiler )( $generalizedSql->stringify() )
1286                         : null;
1287                 $this->affectedRowCount = null;
1288                 $this->lastQuery = $sql;
1289                 $ret = $this->doQuery( $commentedSql );
1290                 $lastError = $this->lastError();
1291                 $lastErrno = $this->lastErrno();
1292
1293                 $this->affectedRowCount = $this->affectedRows();
1294                 unset( $ps ); // profile out (if set)
1295                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1296
1297                 $recoverableSR = false; // recoverable statement rollback?
1298                 $recoverableCL = false; // recoverable connection loss?
1299                 $reconnected = false; // reconnection both attempted and succeeded?
1300
1301                 if ( $ret !== false ) {
1302                         $this->lastPing = $startTime;
1303                         if ( $isPermWrite && $this->trxLevel() ) {
1304                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1305                                 $this->trxWriteCallers[] = $fname;
1306                         }
1307                 } elseif ( $this->wasConnectionError( $lastErrno ) ) {
1308                         # Check if no meaningful session state was lost
1309                         $recoverableCL = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1310                         # Update session state tracking and try to restore the connection
1311                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1312                 } else {
1313                         # Check if only the last query was rolled back
1314                         $recoverableSR = $this->wasKnownStatementRollbackError();
1315                 }
1316
1317                 if ( $sql === self::$PING_QUERY ) {
1318                         $this->lastRoundTripEstimate = $queryRuntime;
1319                 }
1320
1321                 $this->trxProfiler->recordQueryCompletion(
1322                         $generalizedSql,
1323                         $startTime,
1324                         $isPermWrite,
1325                         $isPermWrite ? $this->affectedRows() : $this->numRows( $ret )
1326                 );
1327
1328                 // Avoid the overhead of logging calls unless debug mode is enabled
1329                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1330                         $this->queryLogger->debug(
1331                                 "{method} [{runtime}s] {db_host}: $sql",
1332                                 [
1333                                         'method' => $fname,
1334                                         'db_host' => $this->getServer(),
1335                                         'domain' => $this->getDomainID(),
1336                                         'runtime' => round( $queryRuntime, 3 )
1337                                 ]
1338                         );
1339                 }
1340
1341                 return [ $ret, $lastError, $lastErrno, $recoverableSR, $recoverableCL, $reconnected ];
1342         }
1343
1344         /**
1345          * Start an implicit transaction if DBO_TRX is enabled and no transaction is active
1346          *
1347          * @param string $sql
1348          * @param string $fname
1349          */
1350         private function beginIfImplied( $sql, $fname ) {
1351                 if (
1352                         !$this->trxLevel() &&
1353                         $this->getFlag( self::DBO_TRX ) &&
1354                         $this->isTransactableQuery( $sql )
1355                 ) {
1356                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1357                         $this->trxAutomatic = true;
1358                 }
1359         }
1360
1361         /**
1362          * Update the estimated run-time of a query, not counting large row lock times
1363          *
1364          * LoadBalancer can be set to rollback transactions that will create huge replication
1365          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1366          * queries, like inserting a row can take a long time due to row locking. This method
1367          * uses some simple heuristics to discount those cases.
1368          *
1369          * @param string $sql A SQL write query
1370          * @param float $runtime Total runtime, including RTT
1371          * @param int $affected Affected row count
1372          */
1373         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1374                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1375                 $indicativeOfReplicaRuntime = true;
1376                 if ( $runtime > self::$SLOW_WRITE_SEC ) {
1377                         $verb = $this->getQueryVerb( $sql );
1378                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1379                         if ( $verb === 'INSERT' ) {
1380                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS;
1381                         } elseif ( $verb === 'REPLACE' ) {
1382                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS / 2;
1383                         }
1384                 }
1385
1386                 $this->trxWriteDuration += $runtime;
1387                 $this->trxWriteQueryCount += 1;
1388                 $this->trxWriteAffectedRows += $affected;
1389                 if ( $indicativeOfReplicaRuntime ) {
1390                         $this->trxWriteAdjDuration += $runtime;
1391                         $this->trxWriteAdjQueryCount += 1;
1392                 }
1393         }
1394
1395         /**
1396          * Error out if the DB is not in a valid state for a query via query()
1397          *
1398          * @param string $sql
1399          * @param string $fname
1400          * @throws DBTransactionStateError
1401          */
1402         private function assertQueryIsCurrentlyAllowed( $sql, $fname ) {
1403                 $verb = $this->getQueryVerb( $sql );
1404                 if ( $verb === 'USE' ) {
1405                         throw new DBUnexpectedError( $this, "Got USE query; use selectDomain() instead" );
1406                 }
1407
1408                 if ( $verb === 'ROLLBACK' ) { // transaction/savepoint
1409                         return;
1410                 }
1411
1412                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1413                         throw new DBTransactionStateError(
1414                                 $this,
1415                                 "Cannot execute query from $fname while transaction status is ERROR",
1416                                 [],
1417                                 $this->trxStatusCause
1418                         );
1419                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1420                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1421                         call_user_func( $this->deprecationLogger,
1422                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1423                                 "[$iLastErrno] $iLastError"
1424                         );
1425                         $this->trxStatusIgnoredCause = null;
1426                 }
1427         }
1428
1429         public function assertNoOpenTransactions() {
1430                 if ( $this->explicitTrxActive() ) {
1431                         throw new DBTransactionError(
1432                                 $this,
1433                                 "Explicit transaction still active. A caller may have caught an error. "
1434                                 . "Open transactions: " . $this->flatAtomicSectionList()
1435                         );
1436                 }
1437         }
1438
1439         /**
1440          * Determine whether it is safe to retry queries after a database connection is lost
1441          *
1442          * @param string $sql SQL query
1443          * @param bool $priorWritesPending Whether there is a transaction open with
1444          *     possible write queries or transaction pre-commit/idle callbacks
1445          *     waiting on it to finish.
1446          * @return bool True if it is safe to retry the query, false otherwise
1447          */
1448         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1449                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1450                 # Dropped connections also mean that named locks are automatically released.
1451                 # Only allow error suppression in autocommit mode or when the lost transaction
1452                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1453                 if ( $this->sessionNamedLocks ) {
1454                         return false; // possible critical section violation
1455                 } elseif ( $this->sessionTempTables ) {
1456                         return false; // tables might be queried latter
1457                 } elseif ( $sql === 'COMMIT' ) {
1458                         return !$priorWritesPending; // nothing written anyway? (T127428)
1459                 } elseif ( $sql === 'ROLLBACK' ) {
1460                         return true; // transaction lost...which is also what was requested :)
1461                 } elseif ( $this->explicitTrxActive() ) {
1462                         return false; // don't drop atomocity and explicit snapshots
1463                 } elseif ( $priorWritesPending ) {
1464                         return false; // prior writes lost from implicit transaction
1465                 }
1466
1467                 return true;
1468         }
1469
1470         /**
1471          * Clean things up after session (and thus transaction) loss before reconnect
1472          */
1473         private function handleSessionLossPreconnect() {
1474                 // Clean up tracking of session-level things...
1475                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1476                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1477                 $this->sessionTempTables = [];
1478                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1479                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1480                 $this->sessionNamedLocks = [];
1481                 // Session loss implies transaction loss
1482                 $oldTrxShortId = $this->consumeTrxShortId();
1483                 $this->trxAtomicCounter = 0;
1484                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1485                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1486                 // @note: leave trxRecurringCallbacks in place
1487                 if ( $this->trxDoneWrites ) {
1488                         $this->trxProfiler->transactionWritingOut(
1489                                 $this->server,
1490                                 $this->getDomainID(),
1491                                 $oldTrxShortId,
1492                                 $this->pendingWriteQueryDuration( self::ESTIMATE_TOTAL ),
1493                                 $this->trxWriteAffectedRows
1494                         );
1495                 }
1496         }
1497
1498         /**
1499          * Clean things up after session (and thus transaction) loss after reconnect
1500          */
1501         private function handleSessionLossPostconnect() {
1502                 try {
1503                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1504                         // If callback suppression is set then the array will remain unhandled.
1505                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1506                 } catch ( Exception $ex ) {
1507                         // Already logged; move on...
1508                 }
1509                 try {
1510                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1511                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1512                 } catch ( Exception $ex ) {
1513                         // Already logged; move on...
1514                 }
1515         }
1516
1517         /**
1518          * Reset the transaction ID and return the old one
1519          *
1520          * @return string The old transaction ID or the empty string if there wasn't one
1521          */
1522         private function consumeTrxShortId() {
1523                 $old = $this->trxShortId;
1524                 $this->trxShortId = '';
1525
1526                 return $old;
1527         }
1528
1529         /**
1530          * Checks whether the cause of the error is detected to be a timeout.
1531          *
1532          * It returns false by default, and not all engines support detecting this yet.
1533          * If this returns false, it will be treated as a generic query error.
1534          *
1535          * @param string $error Error text
1536          * @param int $errno Error number
1537          * @return bool
1538          */
1539         protected function wasQueryTimeout( $error, $errno ) {
1540                 return false;
1541         }
1542
1543         /**
1544          * Report a query error. Log the error, and if neither the object ignore
1545          * flag nor the $ignoreErrors flag is set, throw a DBQueryError.
1546          *
1547          * @param string $error
1548          * @param int $errno
1549          * @param string $sql
1550          * @param string $fname
1551          * @param bool $ignore
1552          * @throws DBQueryError
1553          */
1554         public function reportQueryError( $error, $errno, $sql, $fname, $ignore = false ) {
1555                 if ( $ignore ) {
1556                         $this->queryLogger->debug( "SQL ERROR (ignored): $error" );
1557                 } else {
1558                         throw $this->getQueryExceptionAndLog( $error, $errno, $sql, $fname );
1559                 }
1560         }
1561
1562         /**
1563          * @param string $error
1564          * @param string|int $errno
1565          * @param string $sql
1566          * @param string $fname
1567          * @return DBError
1568          */
1569         private function getQueryExceptionAndLog( $error, $errno, $sql, $fname ) {
1570                 $this->queryLogger->error(
1571                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1572                         $this->getLogContext( [
1573                                 'method' => __METHOD__,
1574                                 'errno' => $errno,
1575                                 'error' => $error,
1576                                 'sql1line' => mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 ),
1577                                 'fname' => $fname,
1578                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1579                         ] )
1580                 );
1581
1582                 if ( $this->wasQueryTimeout( $error, $errno ) ) {
1583                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1584                 } elseif ( $this->wasConnectionError( $errno ) ) {
1585                         $e = new DBQueryDisconnectedError( $this, $error, $errno, $sql, $fname );
1586                 } else {
1587                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1588                 }
1589
1590                 return $e;
1591         }
1592
1593         /**
1594          * @param string $error
1595          * @return DBConnectionError
1596          */
1597         final protected function newExceptionAfterConnectError( $error ) {
1598                 // Connection was not fully initialized and is not safe for use
1599                 $this->conn = null;
1600
1601                 $this->connLogger->error(
1602                         "Error connecting to {db_server} as user {db_user}: {error}",
1603                         $this->getLogContext( [
1604                                 'error' => $error,
1605                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1606                         ] )
1607                 );
1608
1609                 return new DBConnectionError( $this, $error );
1610         }
1611
1612         public function freeResult( $res ) {
1613         }
1614
1615         public function selectField(
1616                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1617         ) {
1618                 if ( $var === '*' ) { // sanity
1619                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1620                 }
1621
1622                 if ( !is_array( $options ) ) {
1623                         $options = [ $options ];
1624                 }
1625
1626                 $options['LIMIT'] = 1;
1627
1628                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1629                 if ( $res === false ) {
1630                         throw new DBUnexpectedError( $this, "Got false from select()" );
1631                 }
1632
1633                 $row = $this->fetchRow( $res );
1634                 if ( $row === false ) {
1635                         return false;
1636                 }
1637
1638                 return reset( $row );
1639         }
1640
1641         public function selectFieldValues(
1642                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1643         ) {
1644                 if ( $var === '*' ) { // sanity
1645                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1646                 } elseif ( !is_string( $var ) ) { // sanity
1647                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1648                 }
1649
1650                 if ( !is_array( $options ) ) {
1651                         $options = [ $options ];
1652                 }
1653
1654                 $res = $this->select( $table, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
1655                 if ( $res === false ) {
1656                         throw new DBUnexpectedError( $this, "Got false from select()" );
1657                 }
1658
1659                 $values = [];
1660                 foreach ( $res as $row ) {
1661                         $values[] = $row->value;
1662                 }
1663
1664                 return $values;
1665         }
1666
1667         /**
1668          * Returns an optional USE INDEX clause to go after the table, and a
1669          * string to go at the end of the query.
1670          *
1671          * @param array $options Associative array of options to be turned into
1672          *   an SQL query, valid keys are listed in the function.
1673          * @return array
1674          * @see Database::select()
1675          */
1676         protected function makeSelectOptions( $options ) {
1677                 $preLimitTail = $postLimitTail = '';
1678                 $startOpts = '';
1679
1680                 $noKeyOptions = [];
1681
1682                 foreach ( $options as $key => $option ) {
1683                         if ( is_numeric( $key ) ) {
1684                                 $noKeyOptions[$option] = true;
1685                         }
1686                 }
1687
1688                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1689
1690                 $preLimitTail .= $this->makeOrderBy( $options );
1691
1692                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1693                         $postLimitTail .= ' FOR UPDATE';
1694                 }
1695
1696                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1697                         $postLimitTail .= ' LOCK IN SHARE MODE';
1698                 }
1699
1700                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1701                         $startOpts .= 'DISTINCT';
1702                 }
1703
1704                 # Various MySQL extensions
1705                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1706                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1707                 }
1708
1709                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1710                         $startOpts .= ' SQL_BIG_RESULT';
1711                 }
1712
1713                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1714                         $startOpts .= ' SQL_BUFFER_RESULT';
1715                 }
1716
1717                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1718                         $startOpts .= ' SQL_SMALL_RESULT';
1719                 }
1720
1721                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1722                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1723                 }
1724
1725                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1726                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1727                 } else {
1728                         $useIndex = '';
1729                 }
1730                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1731                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1732                 } else {
1733                         $ignoreIndex = '';
1734                 }
1735
1736                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1737         }
1738
1739         /**
1740          * Returns an optional GROUP BY with an optional HAVING
1741          *
1742          * @param array $options Associative array of options
1743          * @return string
1744          * @see Database::select()
1745          * @since 1.21
1746          */
1747         protected function makeGroupByWithHaving( $options ) {
1748                 $sql = '';
1749                 if ( isset( $options['GROUP BY'] ) ) {
1750                         $gb = is_array( $options['GROUP BY'] )
1751                                 ? implode( ',', $options['GROUP BY'] )
1752                                 : $options['GROUP BY'];
1753                         $sql .= ' GROUP BY ' . $gb;
1754                 }
1755                 if ( isset( $options['HAVING'] ) ) {
1756                         $having = is_array( $options['HAVING'] )
1757                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1758                                 : $options['HAVING'];
1759                         $sql .= ' HAVING ' . $having;
1760                 }
1761
1762                 return $sql;
1763         }
1764
1765         /**
1766          * Returns an optional ORDER BY
1767          *
1768          * @param array $options Associative array of options
1769          * @return string
1770          * @see Database::select()
1771          * @since 1.21
1772          */
1773         protected function makeOrderBy( $options ) {
1774                 if ( isset( $options['ORDER BY'] ) ) {
1775                         $ob = is_array( $options['ORDER BY'] )
1776                                 ? implode( ',', $options['ORDER BY'] )
1777                                 : $options['ORDER BY'];
1778
1779                         return ' ORDER BY ' . $ob;
1780                 }
1781
1782                 return '';
1783         }
1784
1785         public function select(
1786                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1787         ) {
1788                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1789
1790                 return $this->query( $sql, $fname );
1791         }
1792
1793         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1794                 $options = [], $join_conds = []
1795         ) {
1796                 if ( is_array( $vars ) ) {
1797                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1798                 } else {
1799                         $fields = $vars;
1800                 }
1801
1802                 $options = (array)$options;
1803                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1804                         ? $options['USE INDEX']
1805                         : [];
1806                 $ignoreIndexes = (
1807                         isset( $options['IGNORE INDEX'] ) &&
1808                         is_array( $options['IGNORE INDEX'] )
1809                 )
1810                         ? $options['IGNORE INDEX']
1811                         : [];
1812
1813                 if (
1814                         $this->selectOptionsIncludeLocking( $options ) &&
1815                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1816                 ) {
1817                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1818                         // functions. Discourage use of such queries to encourage compatibility.
1819                         call_user_func(
1820                                 $this->deprecationLogger,
1821                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)"
1822                         );
1823                 }
1824
1825                 if ( is_array( $table ) ) {
1826                         $from = ' FROM ' .
1827                                 $this->tableNamesWithIndexClauseOrJOIN(
1828                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1829                 } elseif ( $table != '' ) {
1830                         $from = ' FROM ' .
1831                                 $this->tableNamesWithIndexClauseOrJOIN(
1832                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1833                 } else {
1834                         $from = '';
1835                 }
1836
1837                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1838                         $this->makeSelectOptions( $options );
1839
1840                 if ( is_array( $conds ) ) {
1841                         $conds = $this->makeList( $conds, self::LIST_AND );
1842                 }
1843
1844                 if ( $conds === null || $conds === false ) {
1845                         $this->queryLogger->warning(
1846                                 __METHOD__
1847                                 . ' called from '
1848                                 . $fname
1849                                 . ' with incorrect parameters: $conds must be a string or an array'
1850                         );
1851                         $conds = '';
1852                 }
1853
1854                 if ( $conds === '' || $conds === '*' ) {
1855                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1856                 } elseif ( is_string( $conds ) ) {
1857                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1858                                 "WHERE $conds $preLimitTail";
1859                 } else {
1860                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1861                 }
1862
1863                 if ( isset( $options['LIMIT'] ) ) {
1864                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1865                                 $options['OFFSET'] ?? false );
1866                 }
1867                 $sql = "$sql $postLimitTail";
1868
1869                 if ( isset( $options['EXPLAIN'] ) ) {
1870                         $sql = 'EXPLAIN ' . $sql;
1871                 }
1872
1873                 return $sql;
1874         }
1875
1876         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1877                 $options = [], $join_conds = []
1878         ) {
1879                 $options = (array)$options;
1880                 $options['LIMIT'] = 1;
1881
1882                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1883                 if ( $res === false ) {
1884                         throw new DBUnexpectedError( $this, "Got false from select()" );
1885                 }
1886
1887                 if ( !$this->numRows( $res ) ) {
1888                         return false;
1889                 }
1890
1891                 return $this->fetchObject( $res );
1892         }
1893
1894         public function estimateRowCount(
1895                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1896         ) {
1897                 $conds = $this->normalizeConditions( $conds, $fname );
1898                 $column = $this->extractSingleFieldFromList( $var );
1899                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1900                         $conds[] = "$column IS NOT NULL";
1901                 }
1902
1903                 $res = $this->select(
1904                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1905                 );
1906                 $row = $res ? $this->fetchRow( $res ) : [];
1907
1908                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1909         }
1910
1911         public function selectRowCount(
1912                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1913         ) {
1914                 $conds = $this->normalizeConditions( $conds, $fname );
1915                 $column = $this->extractSingleFieldFromList( $var );
1916                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1917                         $conds[] = "$column IS NOT NULL";
1918                 }
1919
1920                 $res = $this->select(
1921                         [
1922                                 'tmp_count' => $this->buildSelectSubquery(
1923                                         $tables,
1924                                         '1',
1925                                         $conds,
1926                                         $fname,
1927                                         $options,
1928                                         $join_conds
1929                                 )
1930                         ],
1931                         [ 'rowcount' => 'COUNT(*)' ],
1932                         [],
1933                         $fname
1934                 );
1935                 $row = $res ? $this->fetchRow( $res ) : [];
1936
1937                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1938         }
1939
1940         /**
1941          * @param string|array $options
1942          * @return bool
1943          */
1944         private function selectOptionsIncludeLocking( $options ) {
1945                 $options = (array)$options;
1946                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1947                         if ( in_array( $lock, $options, true ) ) {
1948                                 return true;
1949                         }
1950                 }
1951
1952                 return false;
1953         }
1954
1955         /**
1956          * @param array|string $fields
1957          * @param array|string $options
1958          * @return bool
1959          */
1960         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1961                 foreach ( (array)$options as $key => $value ) {
1962                         if ( is_string( $key ) ) {
1963                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1964                                         return true;
1965                                 }
1966                         } elseif ( is_string( $value ) ) {
1967                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1968                                         return true;
1969                                 }
1970                         }
1971                 }
1972
1973                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1974                 foreach ( (array)$fields as $field ) {
1975                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1976                                 return true;
1977                         }
1978                 }
1979
1980                 return false;
1981         }
1982
1983         /**
1984          * @param array|string $conds
1985          * @param string $fname
1986          * @return array
1987          */
1988         final protected function normalizeConditions( $conds, $fname ) {
1989                 if ( $conds === null || $conds === false ) {
1990                         $this->queryLogger->warning(
1991                                 __METHOD__
1992                                 . ' called from '
1993                                 . $fname
1994                                 . ' with incorrect parameters: $conds must be a string or an array'
1995                         );
1996                         $conds = '';
1997                 }
1998
1999                 if ( !is_array( $conds ) ) {
2000                         $conds = ( $conds === '' ) ? [] : [ $conds ];
2001                 }
2002
2003                 return $conds;
2004         }
2005
2006         /**
2007          * @param array|string $var Field parameter in the style of select()
2008          * @return string|null Column name or null; ignores aliases
2009          * @throws DBUnexpectedError Errors out if multiple columns are given
2010          */
2011         final protected function extractSingleFieldFromList( $var ) {
2012                 if ( is_array( $var ) ) {
2013                         if ( !$var ) {
2014                                 $column = null;
2015                         } elseif ( count( $var ) == 1 ) {
2016                                 $column = $var[0] ?? reset( $var );
2017                         } else {
2018                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns' );
2019                         }
2020                 } else {
2021                         $column = $var;
2022                 }
2023
2024                 return $column;
2025         }
2026
2027         public function lockForUpdate(
2028                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
2029         ) {
2030                 if ( !$this->trxLevel() && !$this->getFlag( self::DBO_TRX ) ) {
2031                         throw new DBUnexpectedError(
2032                                 $this,
2033                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
2034                         );
2035                 }
2036
2037                 $options = (array)$options;
2038                 $options[] = 'FOR UPDATE';
2039
2040                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
2041         }
2042
2043         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
2044                 $info = $this->fieldInfo( $table, $field );
2045
2046                 return (bool)$info;
2047         }
2048
2049         public function indexExists( $table, $index, $fname = __METHOD__ ) {
2050                 if ( !$this->tableExists( $table ) ) {
2051                         return null;
2052                 }
2053
2054                 $info = $this->indexInfo( $table, $index, $fname );
2055                 if ( is_null( $info ) ) {
2056                         return null;
2057                 } else {
2058                         return $info !== false;
2059                 }
2060         }
2061
2062         abstract public function tableExists( $table, $fname = __METHOD__ );
2063
2064         public function indexUnique( $table, $index ) {
2065                 $indexInfo = $this->indexInfo( $table, $index );
2066
2067                 if ( !$indexInfo ) {
2068                         return null;
2069                 }
2070
2071                 return !$indexInfo[0]->Non_unique;
2072         }
2073
2074         /**
2075          * Helper for Database::insert().
2076          *
2077          * @param array $options
2078          * @return string
2079          */
2080         protected function makeInsertOptions( $options ) {
2081                 return implode( ' ', $options );
2082         }
2083
2084         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2085                 # No rows to insert, easy just return now
2086                 if ( !count( $a ) ) {
2087                         return true;
2088                 }
2089
2090                 $table = $this->tableName( $table );
2091
2092                 if ( !is_array( $options ) ) {
2093                         $options = [ $options ];
2094                 }
2095
2096                 $options = $this->makeInsertOptions( $options );
2097
2098                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2099                         $multi = true;
2100                         $keys = array_keys( $a[0] );
2101                 } else {
2102                         $multi = false;
2103                         $keys = array_keys( $a );
2104                 }
2105
2106                 $sql = 'INSERT ' . $options .
2107                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2108
2109                 if ( $multi ) {
2110                         $first = true;
2111                         foreach ( $a as $row ) {
2112                                 if ( $first ) {
2113                                         $first = false;
2114                                 } else {
2115                                         $sql .= ',';
2116                                 }
2117                                 $sql .= '(' . $this->makeList( $row ) . ')';
2118                         }
2119                 } else {
2120                         $sql .= '(' . $this->makeList( $a ) . ')';
2121                 }
2122
2123                 $this->query( $sql, $fname );
2124
2125                 return true;
2126         }
2127
2128         /**
2129          * Make UPDATE options array for Database::makeUpdateOptions
2130          *
2131          * @param array $options
2132          * @return array
2133          */
2134         protected function makeUpdateOptionsArray( $options ) {
2135                 if ( !is_array( $options ) ) {
2136                         $options = [ $options ];
2137                 }
2138
2139                 $opts = [];
2140
2141                 if ( in_array( 'IGNORE', $options ) ) {
2142                         $opts[] = 'IGNORE';
2143                 }
2144
2145                 return $opts;
2146         }
2147
2148         /**
2149          * Make UPDATE options for the Database::update function
2150          *
2151          * @param array $options The options passed to Database::update
2152          * @return string
2153          */
2154         protected function makeUpdateOptions( $options ) {
2155                 $opts = $this->makeUpdateOptionsArray( $options );
2156
2157                 return implode( ' ', $opts );
2158         }
2159
2160         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2161                 $table = $this->tableName( $table );
2162                 $opts = $this->makeUpdateOptions( $options );
2163                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2164
2165                 if ( $conds !== [] && $conds !== '*' ) {
2166                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2167                 }
2168
2169                 $this->query( $sql, $fname );
2170
2171                 return true;
2172         }
2173
2174         public function makeList( $a, $mode = self::LIST_COMMA ) {
2175                 if ( !is_array( $a ) ) {
2176                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2177                 }
2178
2179                 $first = true;
2180                 $list = '';
2181
2182                 foreach ( $a as $field => $value ) {
2183                         if ( !$first ) {
2184                                 if ( $mode == self::LIST_AND ) {
2185                                         $list .= ' AND ';
2186                                 } elseif ( $mode == self::LIST_OR ) {
2187                                         $list .= ' OR ';
2188                                 } else {
2189                                         $list .= ',';
2190                                 }
2191                         } else {
2192                                 $first = false;
2193                         }
2194
2195                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2196                                 $list .= "($value)";
2197                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2198                                 $list .= "$value";
2199                         } elseif (
2200                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2201                         ) {
2202                                 // Remove null from array to be handled separately if found
2203                                 $includeNull = false;
2204                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2205                                         $includeNull = true;
2206                                         unset( $value[$nullKey] );
2207                                 }
2208                                 if ( count( $value ) == 0 && !$includeNull ) {
2209                                         throw new InvalidArgumentException(
2210                                                 __METHOD__ . ": empty input for field $field" );
2211                                 } elseif ( count( $value ) == 0 ) {
2212                                         // only check if $field is null
2213                                         $list .= "$field IS NULL";
2214                                 } else {
2215                                         // IN clause contains at least one valid element
2216                                         if ( $includeNull ) {
2217                                                 // Group subconditions to ensure correct precedence
2218                                                 $list .= '(';
2219                                         }
2220                                         if ( count( $value ) == 1 ) {
2221                                                 // Special-case single values, as IN isn't terribly efficient
2222                                                 // Don't necessarily assume the single key is 0; we don't
2223                                                 // enforce linear numeric ordering on other arrays here.
2224                                                 $value = array_values( $value )[0];
2225                                                 $list .= $field . " = " . $this->addQuotes( $value );
2226                                         } else {
2227                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2228                                         }
2229                                         // if null present in array, append IS NULL
2230                                         if ( $includeNull ) {
2231                                                 $list .= " OR $field IS NULL)";
2232                                         }
2233                                 }
2234                         } elseif ( $value === null ) {
2235                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2236                                         $list .= "$field IS ";
2237                                 } elseif ( $mode == self::LIST_SET ) {
2238                                         $list .= "$field = ";
2239                                 }
2240                                 $list .= 'NULL';
2241                         } else {
2242                                 if (
2243                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2244                                 ) {
2245                                         $list .= "$field = ";
2246                                 }
2247                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2248                         }
2249                 }
2250
2251                 return $list;
2252         }
2253
2254         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2255                 $conds = [];
2256
2257                 foreach ( $data as $base => $sub ) {
2258                         if ( count( $sub ) ) {
2259                                 $conds[] = $this->makeList(
2260                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2261                                         self::LIST_AND );
2262                         }
2263                 }
2264
2265                 if ( $conds ) {
2266                         return $this->makeList( $conds, self::LIST_OR );
2267                 } else {
2268                         // Nothing to search for...
2269                         return false;
2270                 }
2271         }
2272
2273         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2274                 return $valuename;
2275         }
2276
2277         public function bitNot( $field ) {
2278                 return "(~$field)";
2279         }
2280
2281         public function bitAnd( $fieldLeft, $fieldRight ) {
2282                 return "($fieldLeft & $fieldRight)";
2283         }
2284
2285         public function bitOr( $fieldLeft, $fieldRight ) {
2286                 return "($fieldLeft | $fieldRight)";
2287         }
2288
2289         public function buildConcat( $stringList ) {
2290                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2291         }
2292
2293         public function buildGroupConcatField(
2294                 $delim, $table, $field, $conds = '', $join_conds = []
2295         ) {
2296                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2297
2298                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2299         }
2300
2301         public function buildSubstring( $input, $startPosition, $length = null ) {
2302                 $this->assertBuildSubstringParams( $startPosition, $length );
2303                 $functionBody = "$input FROM $startPosition";
2304                 if ( $length !== null ) {
2305                         $functionBody .= " FOR $length";
2306                 }
2307                 return 'SUBSTRING(' . $functionBody . ')';
2308         }
2309
2310         /**
2311          * Check type and bounds for parameters to self::buildSubstring()
2312          *
2313          * All supported databases have substring functions that behave the same for
2314          * positive $startPosition and non-negative $length, but behaviors differ when
2315          * given 0 or negative $startPosition or negative $length. The simplest
2316          * solution to that is to just forbid those values.
2317          *
2318          * @param int $startPosition
2319          * @param int|null $length
2320          * @since 1.31
2321          */
2322         protected function assertBuildSubstringParams( $startPosition, $length ) {
2323                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2324                         throw new InvalidArgumentException(
2325                                 '$startPosition must be a positive integer'
2326                         );
2327                 }
2328                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2329                         throw new InvalidArgumentException(
2330                                 '$length must be null or an integer greater than or equal to 0'
2331                         );
2332                 }
2333         }
2334
2335         public function buildStringCast( $field ) {
2336                 // In theory this should work for any standards-compliant
2337                 // SQL implementation, although it may not be the best way to do it.
2338                 return "CAST( $field AS CHARACTER )";
2339         }
2340
2341         public function buildIntegerCast( $field ) {
2342                 return 'CAST( ' . $field . ' AS INTEGER )';
2343         }
2344
2345         public function buildSelectSubquery(
2346                 $table, $vars, $conds = '', $fname = __METHOD__,
2347                 $options = [], $join_conds = []
2348         ) {
2349                 return new Subquery(
2350                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2351                 );
2352         }
2353
2354         public function databasesAreIndependent() {
2355                 return false;
2356         }
2357
2358         final public function selectDB( $db ) {
2359                 $this->selectDomain( new DatabaseDomain(
2360                         $db,
2361                         $this->currentDomain->getSchema(),
2362                         $this->currentDomain->getTablePrefix()
2363                 ) );
2364
2365                 return true;
2366         }
2367
2368         final public function selectDomain( $domain ) {
2369                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2370         }
2371
2372         /**
2373          * @param DatabaseDomain $domain
2374          * @throws DBConnectionError
2375          * @throws DBError
2376          * @since 1.32
2377          */
2378         protected function doSelectDomain( DatabaseDomain $domain ) {
2379                 $this->currentDomain = $domain;
2380         }
2381
2382         public function getDBname() {
2383                 return $this->currentDomain->getDatabase();
2384         }
2385
2386         public function getServer() {
2387                 return $this->server;
2388         }
2389
2390         public function tableName( $name, $format = 'quoted' ) {
2391                 if ( $name instanceof Subquery ) {
2392                         throw new DBUnexpectedError(
2393                                 $this,
2394                                 __METHOD__ . ': got Subquery instance when expecting a string'
2395                         );
2396                 }
2397
2398                 # Skip the entire process when we have a string quoted on both ends.
2399                 # Note that we check the end so that we will still quote any use of
2400                 # use of `database`.table. But won't break things if someone wants
2401                 # to query a database table with a dot in the name.
2402                 if ( $this->isQuotedIdentifier( $name ) ) {
2403                         return $name;
2404                 }
2405
2406                 # Lets test for any bits of text that should never show up in a table
2407                 # name. Basically anything like JOIN or ON which are actually part of
2408                 # SQL queries, but may end up inside of the table value to combine
2409                 # sql. Such as how the API is doing.
2410                 # Note that we use a whitespace test rather than a \b test to avoid
2411                 # any remote case where a word like on may be inside of a table name
2412                 # surrounded by symbols which may be considered word breaks.
2413                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2414                         $this->queryLogger->warning(
2415                                 __METHOD__ . ": use of subqueries is not supported this way",
2416                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2417                         );
2418
2419                         return $name;
2420                 }
2421
2422                 # Split database and table into proper variables.
2423                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2424
2425                 # Quote $table and apply the prefix if not quoted.
2426                 # $tableName might be empty if this is called from Database::replaceVars()
2427                 $tableName = "{$prefix}{$table}";
2428                 if ( $format === 'quoted'
2429                         && !$this->isQuotedIdentifier( $tableName )
2430                         && $tableName !== ''
2431                 ) {
2432                         $tableName = $this->addIdentifierQuotes( $tableName );
2433                 }
2434
2435                 # Quote $schema and $database and merge them with the table name if needed
2436                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2437                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2438
2439                 return $tableName;
2440         }
2441
2442         /**
2443          * Get the table components needed for a query given the currently selected database
2444          *
2445          * @param string $name Table name in the form of db.schema.table, db.table, or table
2446          * @return array (DB name or "" for default, schema name, table prefix, table name)
2447          */
2448         protected function qualifiedTableComponents( $name ) {
2449                 # We reverse the explode so that database.table and table both output the correct table.
2450                 $dbDetails = explode( '.', $name, 3 );
2451                 if ( count( $dbDetails ) == 3 ) {
2452                         list( $database, $schema, $table ) = $dbDetails;
2453                         # We don't want any prefix added in this case
2454                         $prefix = '';
2455                 } elseif ( count( $dbDetails ) == 2 ) {
2456                         list( $database, $table ) = $dbDetails;
2457                         # We don't want any prefix added in this case
2458                         $prefix = '';
2459                         # In dbs that support it, $database may actually be the schema
2460                         # but that doesn't affect any of the functionality here
2461                         $schema = '';
2462                 } else {
2463                         list( $table ) = $dbDetails;
2464                         if ( isset( $this->tableAliases[$table] ) ) {
2465                                 $database = $this->tableAliases[$table]['dbname'];
2466                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2467                                         ? $this->tableAliases[$table]['schema']
2468                                         : $this->relationSchemaQualifier();
2469                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2470                                         ? $this->tableAliases[$table]['prefix']
2471                                         : $this->tablePrefix();
2472                         } else {
2473                                 $database = '';
2474                                 $schema = $this->relationSchemaQualifier(); # Default schema
2475                                 $prefix = $this->tablePrefix(); # Default prefix
2476                         }
2477                 }
2478
2479                 return [ $database, $schema, $prefix, $table ];
2480         }
2481
2482         /**
2483          * @param string|null $namespace Database or schema
2484          * @param string $relation Name of table, view, sequence, etc...
2485          * @param string $format One of (raw, quoted)
2486          * @return string Relation name with quoted and merged $namespace as needed
2487          */
2488         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2489                 if ( strlen( $namespace ) ) {
2490                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2491                                 $namespace = $this->addIdentifierQuotes( $namespace );
2492                         }
2493                         $relation = $namespace . '.' . $relation;
2494                 }
2495
2496                 return $relation;
2497         }
2498
2499         public function tableNames() {
2500                 $inArray = func_get_args();
2501                 $retVal = [];
2502
2503                 foreach ( $inArray as $name ) {
2504                         $retVal[$name] = $this->tableName( $name );
2505                 }
2506
2507                 return $retVal;
2508         }
2509
2510         public function tableNamesN() {
2511                 $inArray = func_get_args();
2512                 $retVal = [];
2513
2514                 foreach ( $inArray as $name ) {
2515                         $retVal[] = $this->tableName( $name );
2516                 }
2517
2518                 return $retVal;
2519         }
2520
2521         /**
2522          * Get an aliased table name
2523          *
2524          * This returns strings like "tableName AS newTableName" for aliased tables
2525          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2526          *
2527          * @see Database::tableName()
2528          * @param string|Subquery $table Table name or object with a 'sql' field
2529          * @param string|bool $alias Table alias (optional)
2530          * @return string SQL name for aliased table. Will not alias a table to its own name
2531          */
2532         protected function tableNameWithAlias( $table, $alias = false ) {
2533                 if ( is_string( $table ) ) {
2534                         $quotedTable = $this->tableName( $table );
2535                 } elseif ( $table instanceof Subquery ) {
2536                         $quotedTable = (string)$table;
2537                 } else {
2538                         throw new InvalidArgumentException( "Table must be a string or Subquery" );
2539                 }
2540
2541                 if ( $alias === false || $alias === $table ) {
2542                         if ( $table instanceof Subquery ) {
2543                                 throw new InvalidArgumentException( "Subquery table missing alias" );
2544                         }
2545
2546                         return $quotedTable;
2547                 } else {
2548                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2549                 }
2550         }
2551
2552         /**
2553          * Gets an array of aliased table names
2554          *
2555          * @param array $tables [ [alias] => table ]
2556          * @return string[] See tableNameWithAlias()
2557          */
2558         protected function tableNamesWithAlias( $tables ) {
2559                 $retval = [];
2560                 foreach ( $tables as $alias => $table ) {
2561                         if ( is_numeric( $alias ) ) {
2562                                 $alias = $table;
2563                         }
2564                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2565                 }
2566
2567                 return $retval;
2568         }
2569
2570         /**
2571          * Get an aliased field name
2572          * e.g. fieldName AS newFieldName
2573          *
2574          * @param string $name Field name
2575          * @param string|bool $alias Alias (optional)
2576          * @return string SQL name for aliased field. Will not alias a field to its own name
2577          */
2578         protected function fieldNameWithAlias( $name, $alias = false ) {
2579                 if ( !$alias || (string)$alias === (string)$name ) {
2580                         return $name;
2581                 } else {
2582                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2583                 }
2584         }
2585
2586         /**
2587          * Gets an array of aliased field names
2588          *
2589          * @param array $fields [ [alias] => field ]
2590          * @return string[] See fieldNameWithAlias()
2591          */
2592         protected function fieldNamesWithAlias( $fields ) {
2593                 $retval = [];
2594                 foreach ( $fields as $alias => $field ) {
2595                         if ( is_numeric( $alias ) ) {
2596                                 $alias = $field;
2597                         }
2598                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2599                 }
2600
2601                 return $retval;
2602         }
2603
2604         /**
2605          * Get the aliased table name clause for a FROM clause
2606          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2607          *
2608          * @param array $tables ( [alias] => table )
2609          * @param array $use_index Same as for select()
2610          * @param array $ignore_index Same as for select()
2611          * @param array $join_conds Same as for select()
2612          * @return string
2613          */
2614         protected function tableNamesWithIndexClauseOrJOIN(
2615                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2616         ) {
2617                 $ret = [];
2618                 $retJOIN = [];
2619                 $use_index = (array)$use_index;
2620                 $ignore_index = (array)$ignore_index;
2621                 $join_conds = (array)$join_conds;
2622
2623                 foreach ( $tables as $alias => $table ) {
2624                         if ( !is_string( $alias ) ) {
2625                                 // No alias? Set it equal to the table name
2626                                 $alias = $table;
2627                         }
2628
2629                         if ( is_array( $table ) ) {
2630                                 // A parenthesized group
2631                                 if ( count( $table ) > 1 ) {
2632                                         $joinedTable = '(' .
2633                                                 $this->tableNamesWithIndexClauseOrJOIN(
2634                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2635                                 } else {
2636                                         // Degenerate case
2637                                         $innerTable = reset( $table );
2638                                         $innerAlias = key( $table );
2639                                         $joinedTable = $this->tableNameWithAlias(
2640                                                 $innerTable,
2641                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2642                                         );
2643                                 }
2644                         } else {
2645                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2646                         }
2647
2648                         // Is there a JOIN clause for this table?
2649                         if ( isset( $join_conds[$alias] ) ) {
2650                                 list( $joinType, $conds ) = $join_conds[$alias];
2651                                 $tableClause = $joinType;
2652                                 $tableClause .= ' ' . $joinedTable;
2653                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2654                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2655                                         if ( $use != '' ) {
2656                                                 $tableClause .= ' ' . $use;
2657                                         }
2658                                 }
2659                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2660                                         $ignore = $this->ignoreIndexClause(
2661                                                 implode( ',', (array)$ignore_index[$alias] ) );
2662                                         if ( $ignore != '' ) {
2663                                                 $tableClause .= ' ' . $ignore;
2664                                         }
2665                                 }
2666                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2667                                 if ( $on != '' ) {
2668                                         $tableClause .= ' ON (' . $on . ')';
2669                                 }
2670
2671                                 $retJOIN[] = $tableClause;
2672                         } elseif ( isset( $use_index[$alias] ) ) {
2673                                 // Is there an INDEX clause for this table?
2674                                 $tableClause = $joinedTable;
2675                                 $tableClause .= ' ' . $this->useIndexClause(
2676                                                 implode( ',', (array)$use_index[$alias] )
2677                                         );
2678
2679                                 $ret[] = $tableClause;
2680                         } elseif ( isset( $ignore_index[$alias] ) ) {
2681                                 // Is there an INDEX clause for this table?
2682                                 $tableClause = $joinedTable;
2683                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2684                                                 implode( ',', (array)$ignore_index[$alias] )
2685                                         );
2686
2687                                 $ret[] = $tableClause;
2688                         } else {
2689                                 $tableClause = $joinedTable;
2690
2691                                 $ret[] = $tableClause;
2692                         }
2693                 }
2694
2695                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2696                 $implicitJoins = implode( ',', $ret );
2697                 $explicitJoins = implode( ' ', $retJOIN );
2698
2699                 // Compile our final table clause
2700                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2701         }
2702
2703         /**
2704          * Allows for index remapping in queries where this is not consistent across DBMS
2705          *
2706          * @param string $index
2707          * @return string
2708          */
2709         protected function indexName( $index ) {
2710                 return $this->indexAliases[$index] ?? $index;
2711         }
2712
2713         public function addQuotes( $s ) {
2714                 if ( $s instanceof Blob ) {
2715                         $s = $s->fetch();
2716                 }
2717                 if ( $s === null ) {
2718                         return 'NULL';
2719                 } elseif ( is_bool( $s ) ) {
2720                         return (int)$s;
2721                 } else {
2722                         # This will also quote numeric values. This should be harmless,
2723                         # and protects against weird problems that occur when they really
2724                         # _are_ strings such as article titles and string->number->string
2725                         # conversion is not 1:1.
2726                         return "'" . $this->strencode( $s ) . "'";
2727                 }
2728         }
2729
2730         public function addIdentifierQuotes( $s ) {
2731                 return '"' . str_replace( '"', '""', $s ) . '"';
2732         }
2733
2734         /**
2735          * Returns if the given identifier looks quoted or not according to
2736          * the database convention for quoting identifiers .
2737          *
2738          * @note Do not use this to determine if untrusted input is safe.
2739          *   A malicious user can trick this function.
2740          * @param string $name
2741          * @return bool
2742          */
2743         public function isQuotedIdentifier( $name ) {
2744                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2745         }
2746
2747         /**
2748          * @param string $s
2749          * @param string $escapeChar
2750          * @return string
2751          */
2752         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2753                 return str_replace( [ $escapeChar, '%', '_' ],
2754                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2755                         $s );
2756         }
2757
2758         public function buildLike( $param, ...$params ) {
2759                 if ( is_array( $param ) ) {
2760                         $params = $param;
2761                 } else {
2762                         $params = func_get_args();
2763                 }
2764
2765                 $s = '';
2766
2767                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2768                 // may escape backslashes, creating problems of double escaping. The `
2769                 // character has good cross-DBMS compatibility, avoiding special operators
2770                 // in MS SQL like ^ and %
2771                 $escapeChar = '`';
2772
2773                 foreach ( $params as $value ) {
2774                         if ( $value instanceof LikeMatch ) {
2775                                 $s .= $value->toString();
2776                         } else {
2777                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2778                         }
2779                 }
2780
2781                 return ' LIKE ' .
2782                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2783         }
2784
2785         public function anyChar() {
2786                 return new LikeMatch( '_' );
2787         }
2788
2789         public function anyString() {
2790                 return new LikeMatch( '%' );
2791         }
2792
2793         public function nextSequenceValue( $seqName ) {
2794                 return null;
2795         }
2796
2797         /**
2798          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2799          * is only needed because a) MySQL must be as efficient as possible due to
2800          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2801          * which index to pick. Anyway, other databases might have different
2802          * indexes on a given table. So don't bother overriding this unless you're
2803          * MySQL.
2804          * @param string $index
2805          * @return string
2806          */
2807         public function useIndexClause( $index ) {
2808                 return '';
2809         }
2810
2811         /**
2812          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2813          * is only needed because a) MySQL must be as efficient as possible due to
2814          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2815          * which index to pick. Anyway, other databases might have different
2816          * indexes on a given table. So don't bother overriding this unless you're
2817          * MySQL.
2818          * @param string $index
2819          * @return string
2820          */
2821         public function ignoreIndexClause( $index ) {
2822                 return '';
2823         }
2824
2825         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2826                 if ( count( $rows ) == 0 ) {
2827                         return;
2828                 }
2829
2830                 $uniqueIndexes = (array)$uniqueIndexes;
2831                 // Single row case
2832                 if ( !is_array( reset( $rows ) ) ) {
2833                         $rows = [ $rows ];
2834                 }
2835
2836                 try {
2837                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2838                         $affectedRowCount = 0;
2839                         foreach ( $rows as $row ) {
2840                                 // Delete rows which collide with this one
2841                                 $indexWhereClauses = [];
2842                                 foreach ( $uniqueIndexes as $index ) {
2843                                         $indexColumns = (array)$index;
2844                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2845                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2846                                                 throw new DBUnexpectedError(
2847                                                         $this,
2848                                                         'New record does not provide all values for unique key (' .
2849                                                         implode( ', ', $indexColumns ) . ')'
2850                                                 );
2851                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2852                                                 throw new DBUnexpectedError(
2853                                                         $this,
2854                                                         'New record has a null value for unique key (' .
2855                                                         implode( ', ', $indexColumns ) . ')'
2856                                                 );
2857                                         }
2858                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2859                                 }
2860
2861                                 if ( $indexWhereClauses ) {
2862                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2863                                         $affectedRowCount += $this->affectedRows();
2864                                 }
2865
2866                                 // Now insert the row
2867                                 $this->insert( $table, $row, $fname );
2868                                 $affectedRowCount += $this->affectedRows();
2869                         }
2870                         $this->endAtomic( $fname );
2871                         $this->affectedRowCount = $affectedRowCount;
2872                 } catch ( Exception $e ) {
2873                         $this->cancelAtomic( $fname );
2874                         throw $e;
2875                 }
2876         }
2877
2878         /**
2879          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2880          * statement.
2881          *
2882          * @param string $table Table name
2883          * @param array|string $rows Row(s) to insert
2884          * @param string $fname Caller function name
2885          */
2886         protected function nativeReplace( $table, $rows, $fname ) {
2887                 $table = $this->tableName( $table );
2888
2889                 # Single row case
2890                 if ( !is_array( reset( $rows ) ) ) {
2891                         $rows = [ $rows ];
2892                 }
2893
2894                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2895                 $first = true;
2896
2897                 foreach ( $rows as $row ) {
2898                         if ( $first ) {
2899                                 $first = false;
2900                         } else {
2901                                 $sql .= ',';
2902                         }
2903
2904                         $sql .= '(' . $this->makeList( $row ) . ')';
2905                 }
2906
2907                 $this->query( $sql, $fname );
2908         }
2909
2910         public function upsert( $table, array $rows, $uniqueIndexes, array $set,
2911                 $fname = __METHOD__
2912         ) {
2913                 if ( $rows === [] ) {
2914                         return true; // nothing to do
2915                 }
2916
2917                 $uniqueIndexes = (array)$uniqueIndexes;
2918                 if ( !is_array( reset( $rows ) ) ) {
2919                         $rows = [ $rows ];
2920                 }
2921
2922                 if ( count( $uniqueIndexes ) ) {
2923                         $clauses = []; // list WHERE clauses that each identify a single row
2924                         foreach ( $rows as $row ) {
2925                                 foreach ( $uniqueIndexes as $index ) {
2926                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2927                                         $rowKey = []; // unique key to this row
2928                                         foreach ( $index as $column ) {
2929                                                 $rowKey[$column] = $row[$column];
2930                                         }
2931                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2932                                 }
2933                         }
2934                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2935                 } else {
2936                         $where = false;
2937                 }
2938
2939                 $affectedRowCount = 0;
2940                 try {
2941                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2942                         # Update any existing conflicting row(s)
2943                         if ( $where !== false ) {
2944                                 $this->update( $table, $set, $where, $fname );
2945                                 $affectedRowCount += $this->affectedRows();
2946                         }
2947                         # Now insert any non-conflicting row(s)
2948                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
2949                         $affectedRowCount += $this->affectedRows();
2950                         $this->endAtomic( $fname );
2951                         $this->affectedRowCount = $affectedRowCount;
2952                 } catch ( Exception $e ) {
2953                         $this->cancelAtomic( $fname );
2954                         throw $e;
2955                 }
2956
2957                 return true;
2958         }
2959
2960         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2961                 $fname = __METHOD__
2962         ) {
2963                 if ( !$conds ) {
2964                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2965                 }
2966
2967                 $delTable = $this->tableName( $delTable );
2968                 $joinTable = $this->tableName( $joinTable );
2969                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2970                 if ( $conds != '*' ) {
2971                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2972                 }
2973                 $sql .= ')';
2974
2975                 $this->query( $sql, $fname );
2976         }
2977
2978         public function textFieldSize( $table, $field ) {
2979                 $table = $this->tableName( $table );
2980                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\"";
2981                 $res = $this->query( $sql, __METHOD__ );
2982                 $row = $this->fetchObject( $res );
2983
2984                 $m = [];
2985
2986                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2987                         $size = $m[1];
2988                 } else {
2989                         $size = -1;
2990                 }
2991
2992                 return $size;
2993         }
2994
2995         public function delete( $table, $conds, $fname = __METHOD__ ) {
2996                 if ( !$conds ) {
2997                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2998                 }
2999
3000                 $table = $this->tableName( $table );
3001                 $sql = "DELETE FROM $table";
3002
3003                 if ( $conds != '*' ) {
3004                         if ( is_array( $conds ) ) {
3005                                 $conds = $this->makeList( $conds, self::LIST_AND );
3006                         }
3007                         $sql .= ' WHERE ' . $conds;
3008                 }
3009
3010                 $this->query( $sql, $fname );
3011
3012                 return true;
3013         }
3014
3015         final public function insertSelect(
3016                 $destTable, $srcTable, $varMap, $conds,
3017                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3018         ) {
3019                 static $hints = [ 'NO_AUTO_COLUMNS' ];
3020
3021                 $insertOptions = (array)$insertOptions;
3022                 $selectOptions = (array)$selectOptions;
3023
3024                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
3025                         // For massive migrations with downtime, we don't want to select everything
3026                         // into memory and OOM, so do all this native on the server side if possible.
3027                         $this->nativeInsertSelect(
3028                                 $destTable,
3029                                 $srcTable,
3030                                 $varMap,
3031                                 $conds,
3032                                 $fname,
3033                                 array_diff( $insertOptions, $hints ),
3034                                 $selectOptions,
3035                                 $selectJoinConds
3036                         );
3037                 } else {
3038                         $this->nonNativeInsertSelect(
3039                                 $destTable,
3040                                 $srcTable,
3041                                 $varMap,
3042                                 $conds,
3043                                 $fname,
3044                                 array_diff( $insertOptions, $hints ),
3045                                 $selectOptions,
3046                                 $selectJoinConds
3047                         );
3048                 }
3049
3050                 return true;
3051         }
3052
3053         /**
3054          * @param array $insertOptions INSERT options
3055          * @param array $selectOptions SELECT options
3056          * @return bool Whether an INSERT SELECT with these options will be replication safe
3057          * @since 1.31
3058          */
3059         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3060                 return true;
3061         }
3062
3063         /**
3064          * Implementation of insertSelect() based on select() and insert()
3065          *
3066          * @see IDatabase::insertSelect()
3067          * @since 1.30
3068          * @param string $destTable
3069          * @param string|array $srcTable
3070          * @param array $varMap
3071          * @param array $conds
3072          * @param string $fname
3073          * @param array $insertOptions
3074          * @param array $selectOptions
3075          * @param array $selectJoinConds
3076          */
3077         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3078                 $fname = __METHOD__,
3079                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3080         ) {
3081                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3082                 // on only the master (without needing row-based-replication). It also makes it easy to
3083                 // know how big the INSERT is going to be.
3084                 $fields = [];
3085                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3086                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3087                 }
3088                 $selectOptions[] = 'FOR UPDATE';
3089                 $res = $this->select(
3090                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3091                 );
3092                 if ( !$res ) {
3093                         return;
3094                 }
3095
3096                 try {
3097                         $affectedRowCount = 0;
3098                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3099                         $rows = [];
3100                         $ok = true;
3101                         foreach ( $res as $row ) {
3102                                 $rows[] = (array)$row;
3103
3104                                 // Avoid inserts that are too huge
3105                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3106                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3107                                         if ( !$ok ) {
3108                                                 break;
3109                                         }
3110                                         $affectedRowCount += $this->affectedRows();
3111                                         $rows = [];
3112                                 }
3113                         }
3114                         if ( $rows && $ok ) {
3115                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3116                                 if ( $ok ) {
3117                                         $affectedRowCount += $this->affectedRows();
3118                                 }
3119                         }
3120                         if ( $ok ) {
3121                                 $this->endAtomic( $fname );
3122                                 $this->affectedRowCount = $affectedRowCount;
3123                         } else {
3124                                 $this->cancelAtomic( $fname );
3125                         }
3126                 } catch ( Exception $e ) {
3127                         $this->cancelAtomic( $fname );
3128                         throw $e;
3129                 }
3130         }
3131
3132         /**
3133          * Native server-side implementation of insertSelect() for situations where
3134          * we don't want to select everything into memory
3135          *
3136          * @see IDatabase::insertSelect()
3137          * @param string $destTable
3138          * @param string|array $srcTable
3139          * @param array $varMap
3140          * @param array $conds
3141          * @param string $fname
3142          * @param array $insertOptions
3143          * @param array $selectOptions
3144          * @param array $selectJoinConds
3145          */
3146         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3147                 $fname = __METHOD__,
3148                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3149         ) {
3150                 $destTable = $this->tableName( $destTable );
3151
3152                 if ( !is_array( $insertOptions ) ) {
3153                         $insertOptions = [ $insertOptions ];
3154                 }
3155
3156                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3157
3158                 $selectSql = $this->selectSQLText(
3159                         $srcTable,
3160                         array_values( $varMap ),
3161                         $conds,
3162                         $fname,
3163                         $selectOptions,
3164                         $selectJoinConds
3165                 );
3166
3167                 $sql = "INSERT $insertOptions" .
3168                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3169                         $selectSql;
3170
3171                 $this->query( $sql, $fname );
3172         }
3173
3174         public function limitResult( $sql, $limit, $offset = false ) {
3175                 if ( !is_numeric( $limit ) ) {
3176                         throw new DBUnexpectedError(
3177                                 $this,
3178                                 "Invalid non-numeric limit passed to " . __METHOD__
3179                         );
3180                 }
3181                 // This version works in MySQL and SQLite. It will very likely need to be
3182                 // overridden for most other RDBMS subclasses.
3183                 return "$sql LIMIT "
3184                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3185                         . "{$limit} ";
3186         }
3187
3188         public function unionSupportsOrderAndLimit() {
3189                 return true; // True for almost every DB supported
3190         }
3191
3192         public function unionQueries( $sqls, $all ) {
3193                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3194
3195                 return '(' . implode( $glue, $sqls ) . ')';
3196         }
3197
3198         public function unionConditionPermutations(
3199                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3200                 $options = [], $join_conds = []
3201         ) {
3202                 // First, build the Cartesian product of $permute_conds
3203                 $conds = [ [] ];
3204                 foreach ( $permute_conds as $field => $values ) {
3205                         if ( !$values ) {
3206                                 // Skip empty $values
3207                                 continue;
3208                         }
3209                         $values = array_unique( $values ); // For sanity
3210                         $newConds = [];
3211                         foreach ( $conds as $cond ) {
3212                                 foreach ( $values as $value ) {
3213                                         $cond[$field] = $value;
3214                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3215                                 }
3216                         }
3217                         $conds = $newConds;
3218                 }
3219
3220                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3221
3222                 // If there's just one condition and no subordering, hand off to
3223                 // selectSQLText directly.
3224                 if ( count( $conds ) === 1 &&
3225                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3226                 ) {
3227                         return $this->selectSQLText(
3228                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3229                         );
3230                 }
3231
3232                 // Otherwise, we need to pull out the order and limit to apply after
3233                 // the union. Then build the SQL queries for each set of conditions in
3234                 // $conds. Then union them together (using UNION ALL, because the
3235                 // product *should* already be distinct).
3236                 $orderBy = $this->makeOrderBy( $options );
3237                 $limit = $options['LIMIT'] ?? null;
3238                 $offset = $options['OFFSET'] ?? false;
3239                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3240                 if ( !$this->unionSupportsOrderAndLimit() ) {
3241                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3242                 } else {
3243                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3244                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3245                         }
3246                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3247                                 // We need to increase the limit by the offset rather than
3248                                 // using the offset directly, otherwise it'll skip incorrectly
3249                                 // in the subqueries.
3250                                 $options['LIMIT'] = $limit + $offset;
3251                                 unset( $options['OFFSET'] );
3252                         }
3253                 }
3254
3255                 $sqls = [];
3256                 foreach ( $conds as $cond ) {
3257                         $sqls[] = $this->selectSQLText(
3258                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3259                         );
3260                 }
3261                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3262                 if ( $limit !== null ) {
3263                         $sql = $this->limitResult( $sql, $limit, $offset );
3264                 }
3265
3266                 return $sql;
3267         }
3268
3269         public function conditional( $cond, $trueVal, $falseVal ) {
3270                 if ( is_array( $cond ) ) {
3271                         $cond = $this->makeList( $cond, self::LIST_AND );
3272                 }
3273
3274                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3275         }
3276
3277         public function strreplace( $orig, $old, $new ) {
3278                 return "REPLACE({$orig}, {$old}, {$new})";
3279         }
3280
3281         public function getServerUptime() {
3282                 return 0;
3283         }
3284
3285         public function wasDeadlock() {
3286                 return false;
3287         }
3288
3289         public function wasLockTimeout() {
3290                 return false;
3291         }
3292
3293         public function wasConnectionLoss() {
3294                 return $this->wasConnectionError( $this->lastErrno() );
3295         }
3296
3297         public function wasReadOnlyError() {
3298                 return false;
3299         }
3300
3301         public function wasErrorReissuable() {
3302                 return (
3303                         $this->wasDeadlock() ||
3304                         $this->wasLockTimeout() ||
3305                         $this->wasConnectionLoss()
3306                 );
3307         }
3308
3309         /**
3310          * Do not use this method outside of Database/DBError classes
3311          *
3312          * @param int|string $errno
3313          * @return bool Whether the given query error was a connection drop
3314          */
3315         public function wasConnectionError( $errno ) {
3316                 return false;
3317         }
3318
3319         /**
3320          * @return bool Whether it is known that the last query error only caused statement rollback
3321          * @note This is for backwards compatibility for callers catching DBError exceptions in
3322          *   order to ignore problems like duplicate key errors or foriegn key violations
3323          * @since 1.31
3324          */
3325         protected function wasKnownStatementRollbackError() {
3326                 return false; // don't know; it could have caused a transaction rollback
3327         }
3328
3329         public function deadlockLoop() {
3330                 $args = func_get_args();
3331                 $function = array_shift( $args );
3332                 $tries = self::$DEADLOCK_TRIES;
3333
3334                 $this->begin( __METHOD__ );
3335
3336                 $retVal = null;
3337                 /** @var Exception $e */
3338                 $e = null;
3339                 do {
3340                         try {
3341                                 $retVal = $function( ...$args );
3342                                 break;
3343                         } catch ( DBQueryError $e ) {
3344                                 if ( $this->wasDeadlock() ) {
3345                                         // Retry after a randomized delay
3346                                         usleep( mt_rand( self::$DEADLOCK_DELAY_MIN, self::$DEADLOCK_DELAY_MAX ) );
3347                                 } else {
3348                                         // Throw the error back up
3349                                         throw $e;
3350                                 }
3351                         }
3352                 } while ( --$tries > 0 );
3353
3354                 if ( $tries <= 0 ) {
3355                         // Too many deadlocks; give up
3356                         $this->rollback( __METHOD__ );
3357                         throw $e;
3358                 } else {
3359                         $this->commit( __METHOD__ );
3360
3361                         return $retVal;
3362                 }
3363         }
3364
3365         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3366                 # Real waits are implemented in the subclass.
3367                 return 0;
3368         }
3369
3370         public function getReplicaPos() {
3371                 # Stub
3372                 return false;
3373         }
3374
3375         public function getMasterPos() {
3376                 # Stub
3377                 return false;
3378         }
3379
3380         public function serverIsReadOnly() {
3381                 return false;
3382         }
3383
3384         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3385                 if ( !$this->trxLevel() ) {
3386                         throw new DBUnexpectedError( $this, "No transaction is active" );
3387                 }
3388                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3389         }
3390
3391         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3392                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3393                         // Start an implicit transaction similar to how query() does
3394                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3395                         $this->trxAutomatic = true;
3396                 }
3397
3398                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3399                 if ( !$this->trxLevel() ) {
3400                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3401                 }
3402         }
3403
3404         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3405                 $this->onTransactionCommitOrIdle( $callback, $fname );
3406         }
3407
3408         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3409                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3410                         // Start an implicit transaction similar to how query() does
3411                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3412                         $this->trxAutomatic = true;
3413                 }
3414
3415                 if ( $this->trxLevel() ) {
3416                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3417                 } else {
3418                         // No transaction is active nor will start implicitly, so make one for this callback
3419                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3420                         try {
3421                                 $callback( $this );
3422                                 $this->endAtomic( __METHOD__ );
3423                         } catch ( Exception $e ) {
3424                                 $this->cancelAtomic( __METHOD__ );
3425                                 throw $e;
3426                         }
3427                 }
3428         }
3429
3430         final public function onAtomicSectionCancel( callable $callback, $fname = __METHOD__ ) {
3431                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3432                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3433                 }
3434                 $this->trxSectionCancelCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3435         }
3436
3437         /**
3438          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3439          */
3440         private function currentAtomicSectionId() {
3441                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
3442                         $levelInfo = end( $this->trxAtomicLevels );
3443
3444                         return $levelInfo[1];
3445                 }
3446
3447                 return null;
3448         }
3449
3450         /**
3451          * Hoist callback ownership for callbacks in a section to a parent section.
3452          * All callbacks should have an owner that is present in trxAtomicLevels.
3453          * @param AtomicSectionIdentifier $old
3454          * @param AtomicSectionIdentifier $new
3455          */
3456         private function reassignCallbacksForSection(
3457                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3458         ) {
3459                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3460                         if ( $info[2] === $old ) {
3461                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3462                         }
3463                 }
3464                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3465                         if ( $info[2] === $old ) {
3466                                 $this->trxIdleCallbacks[$key][2] = $new;
3467                         }
3468                 }
3469                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3470                         if ( $info[2] === $old ) {
3471                                 $this->trxEndCallbacks[$key][2] = $new;
3472                         }
3473                 }
3474                 foreach ( $this->trxSectionCancelCallbacks as $key => $info ) {
3475                         if ( $info[2] === $old ) {
3476                                 $this->trxSectionCancelCallbacks[$key][2] = $new;
3477                         }
3478                 }
3479         }
3480
3481         /**
3482          * Update callbacks that were owned by cancelled atomic sections.
3483          *
3484          * Callbacks for "on commit" should never be run if they're owned by a
3485          * section that won't be committed.
3486          *
3487          * Callbacks for "on resolution" need to reflect that the section was
3488          * rolled back, even if the transaction as a whole commits successfully.
3489          *
3490          * Callbacks for "on section cancel" should already have been consumed,
3491          * but errors during the cancellation itself can prevent that while still
3492          * destroying the section. Hoist any such callbacks to the new top section,
3493          * which we assume will itself have to be cancelled or rolled back to
3494          * resolve the error.
3495          *
3496          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3497          * @param AtomicSectionIdentifier|null $newSectionId New top section ID.
3498          * @throws UnexpectedValueException
3499          */
3500         private function modifyCallbacksForCancel(
3501                 array $sectionIds, AtomicSectionIdentifier $newSectionId = null
3502         ) {
3503                 // Cancel the "on commit" callbacks owned by this savepoint
3504                 $this->trxIdleCallbacks = array_filter(
3505                         $this->trxIdleCallbacks,
3506                         function ( $entry ) use ( $sectionIds ) {
3507                                 return !in_array( $entry[2], $sectionIds, true );
3508                         }
3509                 );
3510                 $this->trxPreCommitCallbacks = array_filter(
3511                         $this->trxPreCommitCallbacks,
3512                         function ( $entry ) use ( $sectionIds ) {
3513                                 return !in_array( $entry[2], $sectionIds, true );
3514                         }
3515                 );
3516                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3517                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3518                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3519                                 $callback = $entry[0];
3520                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3521                                         // @phan-suppress-next-line PhanInfiniteRecursion No recursion at all here, phan is confused
3522                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3523                                 };
3524                                 // This "on resolution" callback no longer belongs to a section.
3525                                 $this->trxEndCallbacks[$key][2] = null;
3526                         }
3527                 }
3528                 // Hoist callback ownership for section cancel callbacks to the new top section
3529                 foreach ( $this->trxSectionCancelCallbacks as $key => $entry ) {
3530                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3531                                 $this->trxSectionCancelCallbacks[$key][2] = $newSectionId;
3532                         }
3533                 }
3534         }
3535
3536         final public function setTransactionListener( $name, callable $callback = null ) {
3537                 if ( $callback ) {
3538                         $this->trxRecurringCallbacks[$name] = $callback;
3539                 } else {
3540                         unset( $this->trxRecurringCallbacks[$name] );
3541                 }
3542         }
3543
3544         /**
3545          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3546          *
3547          * This method should not be used outside of Database/LoadBalancer
3548          *
3549          * @param bool $suppress
3550          * @since 1.28
3551          */
3552         final public function setTrxEndCallbackSuppression( $suppress ) {
3553                 $this->trxEndCallbacksSuppressed = $suppress;
3554         }
3555
3556         /**
3557          * Actually consume and run any "on transaction idle/resolution" callbacks.
3558          *
3559          * This method should not be used outside of Database/LoadBalancer
3560          *
3561          * @param int $trigger IDatabase::TRIGGER_* constant
3562          * @return int Number of callbacks attempted
3563          * @since 1.20
3564          * @throws Exception
3565          */
3566         public function runOnTransactionIdleCallbacks( $trigger ) {
3567                 if ( $this->trxLevel() ) { // sanity
3568                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open' );
3569                 }
3570
3571                 if ( $this->trxEndCallbacksSuppressed ) {
3572                         return 0;
3573                 }
3574
3575                 $count = 0;
3576                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3577                 /** @var Exception $e */
3578                 $e = null; // first exception
3579                 do { // callbacks may add callbacks :)
3580                         $callbacks = array_merge(
3581                                 $this->trxIdleCallbacks,
3582                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3583                         );
3584                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3585                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3586
3587                         // Only run trxSectionCancelCallbacks on rollback, not commit.
3588                         // But always consume them.
3589                         if ( $trigger === self::TRIGGER_ROLLBACK ) {
3590                                 $callbacks = array_merge( $callbacks, $this->trxSectionCancelCallbacks );
3591                         }
3592                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3593
3594                         foreach ( $callbacks as $callback ) {
3595                                 ++$count;
3596                                 list( $phpCallback ) = $callback;
3597                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3598                                 try {
3599                                         // @phan-suppress-next-line PhanParamTooManyCallable
3600                                         call_user_func( $phpCallback, $trigger, $this );
3601                                 } catch ( Exception $ex ) {
3602                                         call_user_func( $this->errorLogger, $ex );
3603                                         $e = $e ?: $ex;
3604                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3605                                         // their transactions are ended so other callbacks don't fail
3606                                         if ( $this->trxLevel() ) {
3607                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3608                                         }
3609                                 } finally {
3610                                         if ( $autoTrx ) {
3611                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3612                                         } else {
3613                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3614                                         }
3615                                 }
3616                         }
3617                 } while ( count( $this->trxIdleCallbacks ) );
3618
3619                 if ( $e instanceof Exception ) {
3620                         throw $e; // re-throw any first exception
3621                 }
3622
3623                 return $count;
3624         }
3625
3626         /**
3627          * Actually consume and run any "on transaction pre-commit" callbacks.
3628          *
3629          * This method should not be used outside of Database/LoadBalancer
3630          *
3631          * @since 1.22
3632          * @return int Number of callbacks attempted
3633          * @throws Exception
3634          */
3635         public function runOnTransactionPreCommitCallbacks() {
3636                 $count = 0;
3637
3638                 $e = null; // first exception
3639                 do { // callbacks may add callbacks :)
3640                         $callbacks = $this->trxPreCommitCallbacks;
3641                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3642                         foreach ( $callbacks as $callback ) {
3643                                 try {
3644                                         ++$count;
3645                                         list( $phpCallback ) = $callback;
3646                                         $phpCallback( $this );
3647                                 } catch ( Exception $ex ) {
3648                                         ( $this->errorLogger )( $ex );
3649                                         $e = $e ?: $ex;
3650                                 }
3651                         }
3652                 } while ( count( $this->trxPreCommitCallbacks ) );
3653
3654                 if ( $e instanceof Exception ) {
3655                         throw $e; // re-throw any first exception
3656                 }
3657
3658                 return $count;
3659         }
3660
3661         /**
3662          * Actually run any "atomic section cancel" callbacks.
3663          *
3664          * @param int $trigger IDatabase::TRIGGER_* constant
3665          * @param AtomicSectionIdentifier[]|null $sectionIds Section IDs to cancel,
3666          *  null on transaction rollback
3667          */
3668         private function runOnAtomicSectionCancelCallbacks(
3669                 $trigger, array $sectionIds = null
3670         ) {
3671                 /** @var Exception|Throwable $e */
3672                 $e = null; // first exception
3673
3674                 $notCancelled = [];
3675                 do {
3676                         $callbacks = $this->trxSectionCancelCallbacks;
3677                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3678                         foreach ( $callbacks as $entry ) {
3679                                 if ( $sectionIds === null || in_array( $entry[2], $sectionIds, true ) ) {
3680                                         try {
3681                                                 $entry[0]( $trigger, $this );
3682                                         } catch ( Exception $ex ) {
3683                                                 ( $this->errorLogger )( $ex );
3684                                                 $e = $e ?: $ex;
3685                                         } catch ( Throwable $ex ) {
3686                                                 // @todo: Log?
3687                                                 $e = $e ?: $ex;
3688                                         }
3689                                 } else {
3690                                         $notCancelled[] = $entry;
3691                                 }
3692                         }
3693                 } while ( count( $this->trxSectionCancelCallbacks ) );
3694                 $this->trxSectionCancelCallbacks = $notCancelled;
3695
3696                 if ( $e !== null ) {
3697                         throw $e; // re-throw any first Exception/Throwable
3698                 }
3699         }
3700
3701         /**
3702          * Actually run any "transaction listener" callbacks.
3703          *
3704          * This method should not be used outside of Database/LoadBalancer
3705          *
3706          * @param int $trigger IDatabase::TRIGGER_* constant
3707          * @throws Exception
3708          * @since 1.20
3709          */
3710         public function runTransactionListenerCallbacks( $trigger ) {
3711                 if ( $this->trxEndCallbacksSuppressed ) {
3712                         return;
3713                 }
3714
3715                 /** @var Exception $e */
3716                 $e = null; // first exception
3717
3718                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3719                         try {
3720                                 $phpCallback( $trigger, $this );
3721                         } catch ( Exception $ex ) {
3722                                 ( $this->errorLogger )( $ex );
3723                                 $e = $e ?: $ex;
3724                         }
3725                 }
3726
3727                 if ( $e instanceof Exception ) {
3728                         throw $e; // re-throw any first exception
3729                 }
3730         }
3731
3732         /**
3733          * Create a savepoint
3734          *
3735          * This is used internally to implement atomic sections. It should not be
3736          * used otherwise.
3737          *
3738          * @since 1.31
3739          * @param string $identifier Identifier for the savepoint
3740          * @param string $fname Calling function name
3741          */
3742         protected function doSavepoint( $identifier, $fname ) {
3743                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3744         }
3745
3746         /**
3747          * Release a savepoint
3748          *
3749          * This is used internally to implement atomic sections. It should not be
3750          * used otherwise.
3751          *
3752          * @since 1.31
3753          * @param string $identifier Identifier for the savepoint
3754          * @param string $fname Calling function name
3755          */
3756         protected function doReleaseSavepoint( $identifier, $fname ) {
3757                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3758         }
3759
3760         /**
3761          * Rollback to a savepoint
3762          *
3763          * This is used internally to implement atomic sections. It should not be
3764          * used otherwise.
3765          *
3766          * @since 1.31
3767          * @param string $identifier Identifier for the savepoint
3768          * @param string $fname Calling function name
3769          */
3770         protected function doRollbackToSavepoint( $identifier, $fname ) {
3771                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3772         }
3773
3774         /**
3775          * @param string $fname
3776          * @return string
3777          */
3778         private function nextSavepointId( $fname ) {
3779                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3780                 if ( strlen( $savepointId ) > 30 ) {
3781                         // 30 == Oracle's identifier length limit (pre 12c)
3782                         // With a 22 character prefix, that puts the highest number at 99999999.
3783                         throw new DBUnexpectedError(
3784                                 $this,
3785                                 'There have been an excessively large number of atomic sections in a transaction'
3786                                 . " started by $this->trxFname (at $fname)"
3787                         );
3788                 }
3789
3790                 return $savepointId;
3791         }
3792
3793         final public function startAtomic(
3794                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3795         ) {
3796                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3797
3798                 if ( !$this->trxLevel() ) {
3799                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3800                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3801                         // in all changes being in one transaction to keep requests transactional.
3802                         if ( $this->getFlag( self::DBO_TRX ) ) {
3803                                 // Since writes could happen in between the topmost atomic sections as part
3804                                 // of the transaction, those sections will need savepoints.
3805                                 $savepointId = $this->nextSavepointId( $fname );
3806                                 $this->doSavepoint( $savepointId, $fname );
3807                         } else {
3808                                 $this->trxAutomaticAtomic = true;
3809                         }
3810                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3811                         $savepointId = $this->nextSavepointId( $fname );
3812                         $this->doSavepoint( $savepointId, $fname );
3813                 }
3814
3815                 $sectionId = new AtomicSectionIdentifier;
3816                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3817                 $this->queryLogger->debug( 'startAtomic: entering level ' .
3818                         ( count( $this->trxAtomicLevels ) - 1 ) . " ($fname)" );
3819
3820                 return $sectionId;
3821         }
3822
3823         final public function endAtomic( $fname = __METHOD__ ) {
3824                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3825                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3826                 }
3827
3828                 // Check if the current section matches $fname
3829                 $pos = count( $this->trxAtomicLevels ) - 1;
3830                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3831                 $this->queryLogger->debug( "endAtomic: leaving level $pos ($fname)" );
3832
3833                 if ( $savedFname !== $fname ) {
3834                         throw new DBUnexpectedError(
3835                                 $this,
3836                                 "Invalid atomic section ended (got $fname but expected $savedFname)"
3837                         );
3838                 }
3839
3840                 // Remove the last section (no need to re-index the array)
3841                 array_pop( $this->trxAtomicLevels );
3842
3843                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3844                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3845                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3846                         $this->doReleaseSavepoint( $savepointId, $fname );
3847                 }
3848
3849                 // Hoist callback ownership for callbacks in the section that just ended;
3850                 // all callbacks should have an owner that is present in trxAtomicLevels.
3851                 $currentSectionId = $this->currentAtomicSectionId();
3852                 if ( $currentSectionId ) {
3853                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3854                 }
3855         }
3856
3857         final public function cancelAtomic(
3858                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3859         ) {
3860                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3861                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3862                 }
3863
3864                 $excisedIds = [];
3865                 $newTopSection = $this->currentAtomicSectionId();
3866                 try {
3867                         $excisedFnames = [];
3868                         if ( $sectionId !== null ) {
3869                                 // Find the (last) section with the given $sectionId
3870                                 $pos = -1;
3871                                 foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3872                                         if ( $asId === $sectionId ) {
3873                                                 $pos = $i;
3874                                         }
3875                                 }
3876                                 if ( $pos < 0 ) {
3877                                         throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
3878                                 }
3879                                 // Remove all descendant sections and re-index the array
3880                                 $len = count( $this->trxAtomicLevels );
3881                                 for ( $i = $pos + 1; $i < $len; ++$i ) {
3882                                         $excisedFnames[] = $this->trxAtomicLevels[$i][0];
3883                                         $excisedIds[] = $this->trxAtomicLevels[$i][1];
3884                                 }
3885                                 $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3886                                 $newTopSection = $this->currentAtomicSectionId();
3887                         }
3888
3889                         // Check if the current section matches $fname
3890                         $pos = count( $this->trxAtomicLevels ) - 1;
3891                         list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3892
3893                         if ( $excisedFnames ) {
3894                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
3895                                         "and descendants " . implode( ', ', $excisedFnames ) );
3896                         } else {
3897                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
3898                         }
3899
3900                         if ( $savedFname !== $fname ) {
3901                                 throw new DBUnexpectedError(
3902                                         $this,
3903                                         "Invalid atomic section ended (got $fname but expected $savedFname)"
3904                                 );
3905                         }
3906
3907                         // Remove the last section (no need to re-index the array)
3908                         array_pop( $this->trxAtomicLevels );
3909                         $excisedIds[] = $savedSectionId;
3910                         $newTopSection = $this->currentAtomicSectionId();
3911
3912                         if ( $savepointId !== null ) {
3913                                 // Rollback the transaction to the state just before this atomic section
3914                                 if ( $savepointId === self::$NOT_APPLICABLE ) {
3915                                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
3916                                         // Note: rollback() will run trxSectionCancelCallbacks
3917                                 } else {
3918                                         $this->doRollbackToSavepoint( $savepointId, $fname );
3919                                         $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3920                                         $this->trxStatusIgnoredCause = null;
3921
3922                                         // Run trxSectionCancelCallbacks now.
3923                                         $this->runOnAtomicSectionCancelCallbacks( self::TRIGGER_CANCEL, $excisedIds );
3924                                 }
3925                         } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3926                                 // Put the transaction into an error state if it's not already in one
3927                                 $this->trxStatus = self::STATUS_TRX_ERROR;
3928                                 $this->trxStatusCause = new DBUnexpectedError(
3929                                         $this,
3930                                         "Uncancelable atomic section canceled (got $fname)"
3931                                 );
3932                         }
3933                 } finally {
3934                         // Fix up callbacks owned by the sections that were just cancelled.
3935                         // All callbacks should have an owner that is present in trxAtomicLevels.
3936                         $this->modifyCallbacksForCancel( $excisedIds, $newTopSection );
3937                 }
3938
3939                 $this->affectedRowCount = 0; // for the sake of consistency
3940         }
3941
3942         final public function doAtomicSection(
3943                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3944         ) {
3945                 $sectionId = $this->startAtomic( $fname, $cancelable );
3946                 try {
3947                         $res = $callback( $this, $fname );
3948                 } catch ( Exception $e ) {
3949                         $this->cancelAtomic( $fname, $sectionId );
3950
3951                         throw $e;
3952                 }
3953                 $this->endAtomic( $fname );
3954
3955                 return $res;
3956         }
3957
3958         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3959                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3960                 if ( !in_array( $mode, $modes, true ) ) {
3961                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'" );
3962                 }
3963
3964                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3965                 if ( $this->trxLevel() ) {
3966                         if ( $this->trxAtomicLevels ) {
3967                                 $levels = $this->flatAtomicSectionList();
3968                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open";
3969                                 throw new DBUnexpectedError( $this, $msg );
3970                         } elseif ( !$this->trxAutomatic ) {
3971                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname})";
3972                                 throw new DBUnexpectedError( $this, $msg );
3973                         } else {
3974                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname})";
3975                                 throw new DBUnexpectedError( $this, $msg );
3976                         }
3977                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3978                         $msg = "$fname: Implicit transaction expected (DBO_TRX set)";
3979                         throw new DBUnexpectedError( $this, $msg );
3980                 }
3981
3982                 $this->assertHasConnectionHandle();
3983
3984                 $this->doBegin( $fname );
3985                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3986                 $this->trxStatus = self::STATUS_TRX_OK;
3987                 $this->trxStatusIgnoredCause = null;
3988                 $this->trxAtomicCounter = 0;
3989                 $this->trxTimestamp = microtime( true );
3990                 $this->trxFname = $fname;
3991                 $this->trxDoneWrites = false;
3992                 $this->trxAutomaticAtomic = false;
3993                 $this->trxAtomicLevels = [];
3994                 $this->trxWriteDuration = 0.0;
3995                 $this->trxWriteQueryCount = 0;
3996                 $this->trxWriteAffectedRows = 0;
3997                 $this->trxWriteAdjDuration = 0.0;
3998                 $this->trxWriteAdjQueryCount = 0;
3999                 $this->trxWriteCallers = [];
4000                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
4001                 // Get an estimate of the replication lag before any such queries.
4002                 $this->trxReplicaLag = null; // clear cached value first
4003                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
4004                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
4005                 // caller will think its OK to muck around with the transaction just because startAtomic()
4006                 // has not yet completed (e.g. setting trxAtomicLevels).
4007                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
4008         }
4009
4010         /**
4011          * Issues the BEGIN command to the database server.
4012          *
4013          * @see Database::begin()
4014          * @param string $fname
4015          * @throws DBError
4016          */
4017         protected function doBegin( $fname ) {
4018                 $this->query( 'BEGIN', $fname );
4019         }
4020
4021         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4022                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
4023                 if ( !in_array( $flush, $modes, true ) ) {
4024                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'" );
4025                 }
4026
4027                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
4028                         // There are still atomic sections open; this cannot be ignored
4029                         $levels = $this->flatAtomicSectionList();
4030                         throw new DBUnexpectedError(
4031                                 $this,
4032                                 "$fname: Got COMMIT while atomic sections $levels are still open"
4033                         );
4034                 }
4035
4036                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
4037                         if ( !$this->trxLevel() ) {
4038                                 return; // nothing to do
4039                         } elseif ( !$this->trxAutomatic ) {
4040                                 throw new DBUnexpectedError(
4041                                         $this,
4042                                         "$fname: Flushing an explicit transaction, getting out of sync"
4043                                 );
4044                         }
4045                 } elseif ( !$this->trxLevel() ) {
4046                         $this->queryLogger->error(
4047                                 "$fname: No transaction to commit, something got out of sync" );
4048                         return; // nothing to do
4049                 } elseif ( $this->trxAutomatic ) {
4050                         throw new DBUnexpectedError(
4051                                 $this,
4052                                 "$fname: Expected mass commit of all peer transactions (DBO_TRX set)"
4053                         );
4054                 }
4055
4056                 $this->assertHasConnectionHandle();
4057
4058                 $this->runOnTransactionPreCommitCallbacks();
4059
4060                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
4061                 $this->doCommit( $fname );
4062                 $oldTrxShortId = $this->consumeTrxShortId();
4063                 $this->trxStatus = self::STATUS_TRX_NONE;
4064
4065                 if ( $this->trxDoneWrites ) {
4066                         $this->lastWriteTime = microtime( true );
4067                         $this->trxProfiler->transactionWritingOut(
4068                                 $this->server,
4069                                 $this->getDomainID(),
4070                                 $oldTrxShortId,
4071                                 $writeTime,
4072                                 $this->trxWriteAffectedRows
4073                         );
4074                 }
4075
4076                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4077                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
4078                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
4079                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
4080                 }
4081         }
4082
4083         /**
4084          * Issues the COMMIT command to the database server.
4085          *
4086          * @see Database::commit()
4087          * @param string $fname
4088          * @throws DBError
4089          */
4090         protected function doCommit( $fname ) {
4091                 if ( $this->trxLevel() ) {
4092                         $this->query( 'COMMIT', $fname );
4093                 }
4094         }
4095
4096         final public function rollback( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4097                 $trxActive = $this->trxLevel();
4098
4099                 if ( $flush !== self::FLUSHING_INTERNAL
4100                         && $flush !== self::FLUSHING_ALL_PEERS
4101                         && $this->getFlag( self::DBO_TRX )
4102                 ) {
4103                         throw new DBUnexpectedError(
4104                                 $this,
4105                                 "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)"
4106                         );
4107                 }
4108
4109                 if ( $trxActive ) {
4110                         $this->assertHasConnectionHandle();
4111
4112                         $this->doRollback( $fname );
4113                         $oldTrxShortId = $this->consumeTrxShortId();
4114                         $this->trxStatus = self::STATUS_TRX_NONE;
4115                         $this->trxAtomicLevels = [];
4116                         // Estimate the RTT via a query now that trxStatus is OK
4117                         $writeTime = $this->pingAndCalculateLastTrxApplyTime();
4118
4119                         if ( $this->trxDoneWrites ) {
4120                                 $this->trxProfiler->transactionWritingOut(
4121                                         $this->server,
4122                                         $this->getDomainID(),
4123                                         $oldTrxShortId,
4124                                         $writeTime,
4125                                         $this->trxWriteAffectedRows
4126                                 );
4127                         }
4128                 }
4129
4130                 // Clear any commit-dependant callbacks. They might even be present
4131                 // only due to transaction rounds, with no SQL transaction being active
4132                 $this->trxIdleCallbacks = [];
4133                 $this->trxPreCommitCallbacks = [];
4134
4135                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4136                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
4137                         try {
4138                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
4139                         } catch ( Exception $e ) {
4140                                 // already logged; finish and let LoadBalancer move on during mass-rollback
4141                         }
4142                         try {
4143                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
4144                         } catch ( Exception $e ) {
4145                                 // already logged; let LoadBalancer move on during mass-rollback
4146                         }
4147
4148                         $this->affectedRowCount = 0; // for the sake of consistency
4149                 }
4150         }
4151
4152         /**
4153          * Issues the ROLLBACK command to the database server.
4154          *
4155          * @see Database::rollback()
4156          * @param string $fname
4157          * @throws DBError
4158          */
4159         protected function doRollback( $fname ) {
4160                 if ( $this->trxLevel() ) {
4161                         # Disconnects cause rollback anyway, so ignore those errors
4162                         $ignoreErrors = true;
4163                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
4164                 }
4165         }
4166
4167         public function flushSnapshot( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4168                 if ( $this->explicitTrxActive() ) {
4169                         // Committing this transaction would break callers that assume it is still open
4170                         throw new DBUnexpectedError(
4171                                 $this,
4172                                 "$fname: Cannot flush snapshot; " .
4173                                 "explicit transaction '{$this->trxFname}' is still open"
4174                         );
4175                 } elseif ( $this->writesOrCallbacksPending() ) {
4176                         // This only flushes transactions to clear snapshots, not to write data
4177                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4178                         throw new DBUnexpectedError(
4179                                 $this,
4180                                 "$fname: Cannot flush snapshot; " .
4181                                 "writes from transaction {$this->trxFname} are still pending ($fnames)"
4182                         );
4183                 } elseif (
4184                         $this->trxLevel() &&
4185                         $this->getTransactionRoundId() &&
4186                         $flush !== self::FLUSHING_INTERNAL &&
4187                         $flush !== self::FLUSHING_ALL_PEERS
4188                 ) {
4189                         $this->queryLogger->warning(
4190                                 "$fname: Expected mass snapshot flush of all peer transactions " .
4191                                 "in the explicit transactions round '{$this->getTransactionRoundId()}'",
4192                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
4193                         );
4194                 }
4195
4196                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4197         }
4198
4199         public function explicitTrxActive() {
4200                 return $this->trxLevel() && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4201         }
4202
4203         public function duplicateTableStructure(
4204                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4205         ) {
4206                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4207         }
4208
4209         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4210                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4211         }
4212
4213         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4214                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4215         }
4216
4217         public function timestamp( $ts = 0 ) {
4218                 $t = new ConvertibleTimestamp( $ts );
4219                 // Let errors bubble up to avoid putting garbage in the DB
4220                 return $t->getTimestamp( TS_MW );
4221         }
4222
4223         public function timestampOrNull( $ts = null ) {
4224                 if ( is_null( $ts ) ) {
4225                         return null;
4226                 } else {
4227                         return $this->timestamp( $ts );
4228                 }
4229         }
4230
4231         public function affectedRows() {
4232                 return ( $this->affectedRowCount === null )
4233                         ? $this->fetchAffectedRowCount() // default to driver value
4234                         : $this->affectedRowCount;
4235         }
4236
4237         /**
4238          * @return int Number of retrieved rows according to the driver
4239          */
4240         abstract protected function fetchAffectedRowCount();
4241
4242         /**
4243          * Take a query result and wrap it in an iterable result wrapper if necessary.
4244          * Booleans are passed through as-is to indicate success/failure of write queries.
4245          *
4246          * Once upon a time, Database::query() returned a bare MySQL result
4247          * resource, and it was necessary to call this function to convert it to
4248          * a wrapper. Nowadays, raw database objects are never exposed to external
4249          * callers, so this is unnecessary in external code.
4250          *
4251          * @param bool|IResultWrapper|resource $result
4252          * @return bool|IResultWrapper
4253          */
4254         protected function resultObject( $result ) {
4255                 if ( !$result ) {
4256                         return false; // failed query
4257                 } elseif ( $result instanceof IResultWrapper ) {
4258                         return $result;
4259                 } elseif ( $result === true ) {
4260                         return $result; // succesful write query
4261                 } else {
4262                         return new ResultWrapper( $this, $result );
4263                 }
4264         }
4265
4266         public function ping( &$rtt = null ) {
4267                 // Avoid hitting the server if it was hit recently
4268                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::$PING_TTL ) {
4269                         if ( !func_num_args() || $this->lastRoundTripEstimate > 0 ) {
4270                                 $rtt = $this->lastRoundTripEstimate;
4271                                 return true; // don't care about $rtt
4272                         }
4273                 }
4274
4275                 // This will reconnect if possible or return false if not
4276                 $flags = self::QUERY_IGNORE_DBO_TRX | self::QUERY_SILENCE_ERRORS;
4277                 $ok = ( $this->query( self::$PING_QUERY, __METHOD__, $flags ) !== false );
4278                 if ( $ok ) {
4279                         $rtt = $this->lastRoundTripEstimate;
4280                 }
4281
4282                 return $ok;
4283         }
4284
4285         /**
4286          * Close any existing (dead) database connection and open a new connection
4287          *
4288          * @param string $fname
4289          * @return bool True if new connection is opened successfully, false if error
4290          */
4291         protected function replaceLostConnection( $fname ) {
4292                 $this->closeConnection();
4293                 $this->conn = null;
4294
4295                 $this->handleSessionLossPreconnect();
4296
4297                 try {
4298                         $this->open(
4299                                 $this->server,
4300                                 $this->user,
4301                                 $this->password,
4302                                 $this->currentDomain->getDatabase(),
4303                                 $this->currentDomain->getSchema(),
4304                                 $this->tablePrefix()
4305                         );
4306                         $this->lastPing = microtime( true );
4307                         $ok = true;
4308
4309                         $this->connLogger->warning(
4310                                 $fname . ': lost connection to {dbserver}; reconnected',
4311                                 [
4312                                         'dbserver' => $this->getServer(),
4313                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4314                                 ]
4315                         );
4316                 } catch ( DBConnectionError $e ) {
4317                         $ok = false;
4318
4319                         $this->connLogger->error(
4320                                 $fname . ': lost connection to {dbserver} permanently',
4321                                 [ 'dbserver' => $this->getServer() ]
4322                         );
4323                 }
4324
4325                 $this->handleSessionLossPostconnect();
4326
4327                 return $ok;
4328         }
4329
4330         public function getSessionLagStatus() {
4331                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4332         }
4333
4334         /**
4335          * Get the replica DB lag when the current transaction started
4336          *
4337          * This is useful when transactions might use snapshot isolation
4338          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4339          * is this lag plus transaction duration. If they don't, it is still
4340          * safe to be pessimistic. This returns null if there is no transaction.
4341          *
4342          * This returns null if the lag status for this transaction was not yet recorded.
4343          *
4344          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4345          * @since 1.27
4346          */
4347         final protected function getRecordedTransactionLagStatus() {
4348                 return ( $this->trxLevel() && $this->trxReplicaLag !== null )
4349                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4350                         : null;
4351         }
4352
4353         /**
4354          * Get a replica DB lag estimate for this server
4355          *
4356          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4357          * @since 1.27
4358          */
4359         protected function getApproximateLagStatus() {
4360                 return [
4361                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4362                         'since' => microtime( true )
4363                 ];
4364         }
4365
4366         /**
4367          * Merge the result of getSessionLagStatus() for several DBs
4368          * using the most pessimistic values to estimate the lag of
4369          * any data derived from them in combination
4370          *
4371          * This is information is useful for caching modules
4372          *
4373          * @see WANObjectCache::set()
4374          * @see WANObjectCache::getWithSetCallback()
4375          *
4376          * @param IDatabase $db1
4377          * @param IDatabase|null $db2 [optional]
4378          * @return array Map of values:
4379          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4380          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4381          *   - pending: whether any of the DBs have uncommitted changes
4382          * @throws DBError
4383          * @since 1.27
4384          */
4385         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4386                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4387                 foreach ( func_get_args() as $db ) {
4388                         /** @var IDatabase $db */
4389                         $status = $db->getSessionLagStatus();
4390                         if ( $status['lag'] === false ) {
4391                                 $res['lag'] = false;
4392                         } elseif ( $res['lag'] !== false ) {
4393                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4394                         }
4395                         $res['since'] = min( $res['since'], $status['since'] );
4396                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4397                 }
4398
4399                 return $res;
4400         }
4401
4402         public function getLag() {
4403                 if ( $this->getLBInfo( 'master' ) ) {
4404                         return 0; // this is the master
4405                 } elseif ( $this->getLBInfo( 'is static' ) ) {
4406                         return 0; // static dataset
4407                 }
4408
4409                 return $this->doGetLag();
4410         }
4411
4412         protected function doGetLag() {
4413                 return 0;
4414         }
4415
4416         public function maxListLen() {
4417                 return 0;
4418         }
4419
4420         public function encodeBlob( $b ) {
4421                 return $b;
4422         }
4423
4424         public function decodeBlob( $b ) {
4425                 if ( $b instanceof Blob ) {
4426                         $b = $b->fetch();
4427                 }
4428                 return $b;
4429         }
4430
4431         public function setSessionOptions( array $options ) {
4432         }
4433
4434         public function sourceFile(
4435                 $filename,
4436                 callable $lineCallback = null,
4437                 callable $resultCallback = null,
4438                 $fname = false,
4439                 callable $inputCallback = null
4440         ) {
4441                 AtEase::suppressWarnings();
4442                 $fp = fopen( $filename, 'r' );
4443                 AtEase::restoreWarnings();
4444
4445                 if ( $fp === false ) {
4446                         throw new RuntimeException( "Could not open \"{$filename}\"" );
4447                 }
4448
4449                 if ( !$fname ) {
4450                         $fname = __METHOD__ . "( $filename )";
4451                 }
4452
4453                 try {
4454                         $error = $this->sourceStream(
4455                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4456                 } catch ( Exception $e ) {
4457                         fclose( $fp );
4458                         throw $e;
4459                 }
4460
4461                 fclose( $fp );
4462
4463                 return $error;
4464         }
4465
4466         public function setSchemaVars( $vars ) {
4467                 $this->schemaVars = is_array( $vars ) ? $vars : null;
4468         }
4469
4470         public function sourceStream(
4471                 $fp,
4472                 callable $lineCallback = null,
4473                 callable $resultCallback = null,
4474                 $fname = __METHOD__,
4475                 callable $inputCallback = null
4476         ) {
4477                 $delimiterReset = new ScopedCallback(
4478                         function ( $delimiter ) {
4479                                 $this->delimiter = $delimiter;
4480                         },
4481                         [ $this->delimiter ]
4482                 );
4483                 $cmd = '';
4484
4485                 while ( !feof( $fp ) ) {
4486                         if ( $lineCallback ) {
4487                                 call_user_func( $lineCallback );
4488                         }
4489
4490                         $line = trim( fgets( $fp ) );
4491
4492                         if ( $line == '' ) {
4493                                 continue;
4494                         }
4495
4496                         if ( $line[0] == '-' && $line[1] == '-' ) {
4497                                 continue;
4498                         }
4499
4500                         if ( $cmd != '' ) {
4501                                 $cmd .= ' ';
4502                         }
4503
4504                         $done = $this->streamStatementEnd( $cmd, $line );
4505
4506                         $cmd .= "$line\n";
4507
4508                         if ( $done || feof( $fp ) ) {
4509                                 $cmd = $this->replaceVars( $cmd );
4510
4511                                 if ( $inputCallback ) {
4512                                         $callbackResult = $inputCallback( $cmd );
4513
4514                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4515                                                 $cmd = $callbackResult;
4516                                         }
4517                                 }
4518
4519                                 if ( $cmd ) {
4520                                         $res = $this->query( $cmd, $fname );
4521
4522                                         if ( $resultCallback ) {
4523                                                 $resultCallback( $res, $this );
4524                                         }
4525
4526                                         if ( $res === false ) {
4527                                                 $err = $this->lastError();
4528
4529                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4530                                         }
4531                                 }
4532                                 $cmd = '';
4533                         }
4534                 }
4535
4536                 ScopedCallback::consume( $delimiterReset );
4537                 return true;
4538         }
4539
4540         /**
4541          * Called by sourceStream() to check if we've reached a statement end
4542          *
4543          * @param string &$sql SQL assembled so far
4544          * @param string &$newLine New line about to be added to $sql
4545          * @return bool Whether $newLine contains end of the statement
4546          */
4547         public function streamStatementEnd( &$sql, &$newLine ) {
4548                 if ( $this->delimiter ) {
4549                         $prev = $newLine;
4550                         $newLine = preg_replace(
4551                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4552                         if ( $newLine != $prev ) {
4553                                 return true;
4554                         }
4555                 }
4556
4557                 return false;
4558         }
4559
4560         /**
4561          * Database independent variable replacement. Replaces a set of variables
4562          * in an SQL statement with their contents as given by $this->getSchemaVars().
4563          *
4564          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4565          *
4566          * - '{$var}' should be used for text and is passed through the database's
4567          *   addQuotes method.
4568          * - `{$var}` should be used for identifiers (e.g. table and database names).
4569          *   It is passed through the database's addIdentifierQuotes method which
4570          *   can be overridden if the database uses something other than backticks.
4571          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4572          *   database's tableName method.
4573          * - / *i* / passes the name that follows through the database's indexName method.
4574          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4575          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4576          *
4577          * @param string $ins SQL statement to replace variables in
4578          * @return string The new SQL statement with variables replaced
4579          */
4580         protected function replaceVars( $ins ) {
4581                 $vars = $this->getSchemaVars();
4582                 return preg_replace_callback(
4583                         '!
4584                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4585                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4586                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4587                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4588                         !x',
4589                         function ( $m ) use ( $vars ) {
4590                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4591                                 // check for both nonexistent keys *and* the empty string.
4592                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4593                                         if ( $m[1] === 'i' ) {
4594                                                 return $this->indexName( $m[2] );
4595                                         } else {
4596                                                 return $this->tableName( $m[2] );
4597                                         }
4598                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4599                                         return $this->addQuotes( $vars[$m[3]] );
4600                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4601                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4602                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4603                                         return $vars[$m[5]];
4604                                 } else {
4605                                         return $m[0];
4606                                 }
4607                         },
4608                         $ins
4609                 );
4610         }
4611
4612         /**
4613          * Get schema variables. If none have been set via setSchemaVars(), then
4614          * use some defaults from the current object.
4615          *
4616          * @return array
4617          */
4618         protected function getSchemaVars() {
4619                 return $this->schemaVars ?? $this->getDefaultSchemaVars();
4620         }
4621
4622         /**
4623          * Get schema variables to use if none have been set via setSchemaVars().
4624          *
4625          * Override this in derived classes to provide variables for tables.sql
4626          * and SQL patch files.
4627          *
4628          * @return array
4629          */
4630         protected function getDefaultSchemaVars() {
4631                 return [];
4632         }
4633
4634         public function lockIsFree( $lockName, $method ) {
4635                 // RDBMs methods for checking named locks may or may not count this thread itself.
4636                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4637                 // the behavior choosen by the interface for this method.
4638                 return !isset( $this->sessionNamedLocks[$lockName] );
4639         }
4640
4641         public function lock( $lockName, $method, $timeout = 5 ) {
4642                 $this->sessionNamedLocks[$lockName] = 1;
4643
4644                 return true;
4645         }
4646
4647         public function unlock( $lockName, $method ) {
4648                 unset( $this->sessionNamedLocks[$lockName] );
4649
4650                 return true;
4651         }
4652
4653         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4654                 if ( $this->writesOrCallbacksPending() ) {
4655                         // This only flushes transactions to clear snapshots, not to write data
4656                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4657                         throw new DBUnexpectedError(
4658                                 $this,
4659                                 "$fname: Cannot flush pre-lock snapshot; " .
4660                                 "writes from transaction {$this->trxFname} are still pending ($fnames)"
4661                         );
4662                 }
4663
4664                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4665                         return null;
4666                 }
4667
4668                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4669                         if ( $this->trxLevel() ) {
4670                                 // There is a good chance an exception was thrown, causing any early return
4671                                 // from the caller. Let any error handler get a chance to issue rollback().
4672                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4673                                 $this->onTransactionResolution(
4674                                         function () use ( $lockKey, $fname ) {
4675                                                 $this->unlock( $lockKey, $fname );
4676                                         },
4677                                         $fname
4678                                 );
4679                         } else {
4680                                 $this->unlock( $lockKey, $fname );
4681                         }
4682                 } );
4683
4684                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4685
4686                 return $unlocker;
4687         }
4688
4689         public function namedLocksEnqueue() {
4690                 return false;
4691         }
4692
4693         public function tableLocksHaveTransactionScope() {
4694                 return true;
4695         }
4696
4697         final public function lockTables( array $read, array $write, $method ) {
4698                 if ( $this->writesOrCallbacksPending() ) {
4699                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending" );
4700                 }
4701
4702                 if ( $this->tableLocksHaveTransactionScope() ) {
4703                         $this->startAtomic( $method );
4704                 }
4705
4706                 return $this->doLockTables( $read, $write, $method );
4707         }
4708
4709         /**
4710          * Helper function for lockTables() that handles the actual table locking
4711          *
4712          * @param array $read Array of tables to lock for read access
4713          * @param array $write Array of tables to lock for write access
4714          * @param string $method Name of caller
4715          * @return true
4716          */
4717         protected function doLockTables( array $read, array $write, $method ) {
4718                 return true;
4719         }
4720
4721         final public function unlockTables( $method ) {
4722                 if ( $this->tableLocksHaveTransactionScope() ) {
4723                         $this->endAtomic( $method );
4724
4725                         return true; // locks released on COMMIT/ROLLBACK
4726                 }
4727
4728                 return $this->doUnlockTables( $method );
4729         }
4730
4731         /**
4732          * Helper function for unlockTables() that handles the actual table unlocking
4733          *
4734          * @param string $method Name of caller
4735          * @return true
4736          */
4737         protected function doUnlockTables( $method ) {
4738                 return true;
4739         }
4740
4741         /**
4742          * Delete a table
4743          * @param string $tableName
4744          * @param string $fName
4745          * @return bool|IResultWrapper
4746          * @since 1.18
4747          */
4748         public function dropTable( $tableName, $fName = __METHOD__ ) {
4749                 if ( !$this->tableExists( $tableName, $fName ) ) {
4750                         return false;
4751                 }
4752                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4753
4754                 return $this->query( $sql, $fName );
4755         }
4756
4757         public function getInfinity() {
4758                 return 'infinity';
4759         }
4760
4761         public function encodeExpiry( $expiry ) {
4762                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4763                         ? $this->getInfinity()
4764                         : $this->timestamp( $expiry );
4765         }
4766
4767         public function decodeExpiry( $expiry, $format = TS_MW ) {
4768                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4769                         return 'infinity';
4770                 }
4771
4772                 return ConvertibleTimestamp::convert( $format, $expiry );
4773         }
4774
4775         public function setBigSelects( $value = true ) {
4776                 // no-op
4777         }
4778
4779         public function isReadOnly() {
4780                 return ( $this->getReadOnlyReason() !== false );
4781         }
4782
4783         /**
4784          * @return string|bool Reason this DB is read-only or false if it is not
4785          */
4786         protected function getReadOnlyReason() {
4787                 $reason = $this->getLBInfo( 'readOnlyReason' );
4788                 if ( is_string( $reason ) ) {
4789                         return $reason;
4790                 } elseif ( $this->getLBInfo( 'replica' ) ) {
4791                         return "Server is configured in the role of a read-only replica database.";
4792                 }
4793
4794                 return false;
4795         }
4796
4797         public function setTableAliases( array $aliases ) {
4798                 $this->tableAliases = $aliases;
4799         }
4800
4801         public function setIndexAliases( array $aliases ) {
4802                 $this->indexAliases = $aliases;
4803         }
4804
4805         /**
4806          * @param int $field
4807          * @param int $flags
4808          * @return bool
4809          * @since 1.34
4810          */
4811         final protected function fieldHasBit( $field, $flags ) {
4812                 return ( ( $field & $flags ) === $flags );
4813         }
4814
4815         /**
4816          * Get the underlying binding connection handle
4817          *
4818          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4819          * This catches broken callers than catch and ignore disconnection exceptions.
4820          * Unlike checking isOpen(), this is safe to call inside of open().
4821          *
4822          * @return mixed
4823          * @throws DBUnexpectedError
4824          * @since 1.26
4825          */
4826         protected function getBindingHandle() {
4827                 if ( !$this->conn ) {
4828                         throw new DBUnexpectedError(
4829                                 $this,
4830                                 'DB connection was already closed or the connection dropped'
4831                         );
4832                 }
4833
4834                 return $this->conn;
4835         }
4836
4837         public function __toString() {
4838                 // spl_object_id is PHP >= 7.2
4839                 $id = function_exists( 'spl_object_id' )
4840                         ? spl_object_id( $this )
4841                         : spl_object_hash( $this );
4842
4843                 $description = $this->getType() . ' object #' . $id;
4844                 if ( is_resource( $this->conn ) ) {
4845                         $description .= ' (' . (string)$this->conn . ')'; // "resource id #<ID>"
4846                 } elseif ( is_object( $this->conn ) ) {
4847                         // spl_object_id is PHP >= 7.2
4848                         $handleId = function_exists( 'spl_object_id' )
4849                                 ? spl_object_id( $this->conn )
4850                                 : spl_object_hash( $this->conn );
4851                         $description .= " (handle id #$handleId)";
4852                 }
4853
4854                 return $description;
4855         }
4856
4857         /**
4858          * Make sure that copies do not share the same client binding handle
4859          * @throws DBConnectionError
4860          */
4861         public function __clone() {
4862                 $this->connLogger->warning(
4863                         "Cloning " . static::class . " is not recommended; forking connection",
4864                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
4865                 );
4866
4867                 if ( $this->isOpen() ) {
4868                         // Open a new connection resource without messing with the old one
4869                         $this->conn = null;
4870                         $this->trxEndCallbacks = []; // don't copy
4871                         $this->trxSectionCancelCallbacks = []; // don't copy
4872                         $this->handleSessionLossPreconnect(); // no trx or locks anymore
4873                         $this->open(
4874                                 $this->server,
4875                                 $this->user,
4876                                 $this->password,
4877                                 $this->currentDomain->getDatabase(),
4878                                 $this->currentDomain->getSchema(),
4879                                 $this->tablePrefix()
4880                         );
4881                         $this->lastPing = microtime( true );
4882                 }
4883         }
4884
4885         /**
4886          * Called by serialize. Throw an exception when DB connection is serialized.
4887          * This causes problems on some database engines because the connection is
4888          * not restored on unserialize.
4889          */
4890         public function __sleep() {
4891                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4892                         'the connection is not restored on wakeup' );
4893         }
4894
4895         /**
4896          * Run a few simple sanity checks and close dangling connections
4897          */
4898         public function __destruct() {
4899                 if ( $this->trxLevel() && $this->trxDoneWrites ) {
4900                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})" );
4901                 }
4902
4903                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4904                 if ( $danglingWriters ) {
4905                         $fnames = implode( ', ', $danglingWriters );
4906                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)" );
4907                 }
4908
4909                 if ( $this->conn ) {
4910                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4911                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4912                         AtEase::suppressWarnings();
4913                         $this->closeConnection();
4914                         AtEase::restoreWarnings();
4915                         $this->conn = null;
4916                 }
4917         }
4918 }
4919
4920 /**
4921  * @deprecated since 1.28
4922  */
4923 class_alias( Database::class, 'DatabaseBase' );
4924
4925 /**
4926  * @deprecated since 1.29
4927  */
4928 class_alias( Database::class, 'Database' );