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 string Server that this instance is currently connected to */
  51         protected $server;
  52         /** @var string User that this instance is currently connected under the name of */
  53         protected $user;
  54         /** @var string Password used to establish the current connection */
  55         protected $password;
  56         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  57         protected $tableAliases = [];
  58         /** @var string[] Map of (index alias => index) */
  59         protected $indexAliases = [];
  60         /** @var bool Whether this PHP instance is for a CLI script */
  61         protected $cliMode;
  62         /** @var string Agent name for query profiling */
  63         protected $agent;
  64         /** @var int Bitfield of class DBO_* constants */
  65         protected $flags;
  66         /** @var array LoadBalancer tracking information */
  67         protected $lbInfo = [];
  68         /** @var array|bool Variables use for schema element placeholders */
  69         protected $schemaVars = false;
  70         /** @var array Parameters used by initConnection() to establish a connection */
  71         protected $connectionParams = [];
  72         /** @var array SQL variables values to use for all new connections */
  73         protected $connectionVariables = [];
  74         /** @var string Current SQL query delimiter */
  75         protected $delimiter = ';';
  76         /** @var string|bool|null Stashed value of html_errors INI setting */
  77         protected $htmlErrors;
  78         /** @var int Row batch size to use for emulated INSERT SELECT queries */
  79         protected $nonNativeInsertSelectBatchSize = 10000;
  80
  81         /** @var BagOStuff APC cache */
  82         protected $srvCache;
  83         /** @var LoggerInterface */
  84         protected $connLogger;
  85         /** @var LoggerInterface */
  86         protected $queryLogger;
  87         /** @var callable Error logging callback */
  88         protected $errorLogger;
  89         /** @var callable Deprecation logging callback */
  90         protected $deprecationLogger;
  91         /** @var callable|null */
  92         protected $profiler;
  93         /** @var TransactionProfiler */
  94         protected $trxProfiler;
  95         /** @var DatabaseDomain */
  96         protected $currentDomain;
  97         /** @var object|resource|null Database connection */
  98         protected $conn;
  99
 100         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 101         private $lazyMasterHandle;
 102
 103         /** @var array Map of (name => 1) for locks obtained via lock() */
 104         protected $sessionNamedLocks = [];
 105         /** @var array Map of (table name => 1) for TEMPORARY tables */
 106         protected $sessionTempTables = [];
 107
 108         /** @var string ID of the active transaction or the empty string otherwise */
 109         protected $trxShortId = '';
 110         /** @var int Transaction status */
 111         protected $trxStatus = self::STATUS_TRX_NONE;
 112         /** @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR */
 113         protected $trxStatusCause;
 114         /** @var array|null Error details of the last statement-only rollback */
 115         private $trxStatusIgnoredCause;
 116         /** @var float|null UNIX timestamp at the time of BEGIN for the last transaction */
 117         private $trxTimestamp = null;
 118         /** @var float Replication lag estimate at the time of BEGIN for the last transaction */
 119         private $trxReplicaLag = null;
 120         /** @var string Name of the function that start the last transaction */
 121         private $trxFname = null;
 122         /** @var bool Whether possible write queries were done in the last transaction started */
 123         private $trxDoneWrites = false;
 124         /** @var bool Whether the current transaction was started implicitly due to DBO_TRX */
 125         private $trxAutomatic = false;
 126         /** @var int Counter for atomic savepoint identifiers (reset with each transaction) */
 127         private $trxAtomicCounter = 0;
 128         /** @var array List of (name, unique ID, savepoint ID) for each active atomic section level */
 129         private $trxAtomicLevels = [];
 130         /** @var bool Whether the current transaction was started implicitly by startAtomic() */
 131         private $trxAutomaticAtomic = false;
 132         /** @var string[] Write query callers of the current transaction */
 133         private $trxWriteCallers = [];
 134         /** @var float Seconds spent in write queries for the current transaction */
 135         private $trxWriteDuration = 0.0;
 136         /** @var int Number of write queries for the current transaction */
 137         private $trxWriteQueryCount = 0;
 138         /** @var int Number of rows affected by write queries for the current transaction */
 139         private $trxWriteAffectedRows = 0;
 140         /** @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries */
 141         private $trxWriteAdjDuration = 0.0;
 142         /** @var int Number of write queries counted in trxWriteAdjDuration */
 143         private $trxWriteAdjQueryCount = 0;
 144         /** @var array[] List of (callable, method name, atomic section id) */
 145         private $trxIdleCallbacks = [];
 146         /** @var array[] List of (callable, method name, atomic section id) */
 147         private $trxPreCommitCallbacks = [];
 148         /** @var array[] List of (callable, method name, atomic section id) */
 149         private $trxEndCallbacks = [];
 150         /** @var array[] List of (callable, method name, atomic section id) */
 151         private $trxSectionCancelCallbacks = [];
 152         /** @var callable[] Map of (name => callable) */
 153         private $trxRecurringCallbacks = [];
 154         /** @var bool Whether to suppress triggering of transaction end callbacks */
 155         private $trxEndCallbacksSuppressed = false;
 156
 157         /** @var int[] Prior flags member variable values */
 158         private $priorFlags = [];
 159
 160         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 161         protected $affectedRowCount;
 162
 163         /** @var float UNIX timestamp */
 164         private $lastPing = 0.0;
 165         /** @var string The last SQL query attempted */
 166         private $lastQuery = '';
 167         /** @var float|bool UNIX timestamp of last write query */
 168         private $lastWriteTime = false;
 169         /** @var string|bool */
 170         private $lastPhpError = false;
 171         /** @var float Query rount trip time estimate */
 172         private $lastRoundTripEstimate = 0.0;
 173
 174         /** @var string Lock granularity is on the level of the entire database */
 175         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
 176         /** @var string The SCHEMA keyword refers to a grouping of tables in a database */
 177         const ATTR_SCHEMAS_AS_TABLE_GROUPS = 'supports-schemas';
 178
 179         /** @var int New Database instance will not be connected yet when returned */
 180         const NEW_UNCONNECTED = 0;
 181         /** @var int New Database instance will already be connected when returned */
 182         const NEW_CONNECTED = 1;
 183
 184         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 185         const STATUS_TRX_ERROR = 1;
 186         /** @var int Transaction is active and in a normal state */
 187         const STATUS_TRX_OK = 2;
 188         /** @var int No transaction is active */
 189         const STATUS_TRX_NONE = 3;
 190
 191         /** @var string Idiom used when a cancelable atomic section started the transaction */
 192         private static $NOT_APPLICABLE = 'n/a';
 193         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 194         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 195
 196         /** @var int Writes to this temporary table do not affect lastDoneWrites() */
 197         private static $TEMP_NORMAL = 1;
 198         /** @var int Writes to this temporary table effect lastDoneWrites() */
 199         private static $TEMP_PSEUDO_PERMANENT = 2;
 200
 201         /** @var int Number of times to re-try an operation in case of deadlock */
 202         private static $DEADLOCK_TRIES = 4;
 203         /** @var int Minimum time to wait before retry, in microseconds */
 204         private static $DEADLOCK_DELAY_MIN = 500000;
 205         /** @var int Maximum time to wait before retry */
 206         private static $DEADLOCK_DELAY_MAX = 1500000;
 207
 208         /** @var int How long before it is worth doing a dummy query to test the connection */
 209         private static $PING_TTL = 1.0;
 210         /** @var string Dummy SQL query */
 211         private static $PING_QUERY = 'SELECT 1 AS ping';
 212
 213         /** @var float Guess of how many seconds it takes to replicate a small insert */
 214         private static $TINY_WRITE_SEC = 0.010;
 215         /** @var float Consider a write slow if it took more than this many seconds */
 216         private static $SLOW_WRITE_SEC = 0.500;
 217         /** @var float Assume an insert of this many rows or less should be fast to replicate */
 218         private static $SMALL_WRITE_ROWS = 100;
 219
 220         /**
 221          * @note exceptions for missing libraries/drivers should be thrown in initConnection()
 222          * @param array $params Parameters passed from Database::factory()
 223          */
 224         protected function __construct( array $params ) {
 225                 foreach ( [ 'host', 'user', 'password', 'dbname', 'schema', 'tablePrefix' ] as $name ) {
 226                         $this->connectionParams[$name] = $params[$name];
 227                 }
 228
 229                 $this->cliMode = $params['cliMode'];
 230                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 231                 $this->agent = str_replace( '/', '-', $params['agent'] );
 232
 233                 $this->flags = $params['flags'];
 234                 if ( $this->flags & self::DBO_DEFAULT ) {
 235                         if ( $this->cliMode ) {
 236                                 $this->flags &= ~self::DBO_TRX;
 237                         } else {
 238                                 $this->flags |= self::DBO_TRX;
 239                         }
 240                 }
 241                 // Disregard deprecated DBO_IGNORE flag (T189999)
 242                 $this->flags &= ~self::DBO_IGNORE;
 243
 244                 $this->connectionVariables = $params['variables'];
 245
 246                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 247
 248                 $this->profiler = is_callable( $params['profiler'] ) ? $params['profiler'] : null;
 249                 $this->trxProfiler = $params['trxProfiler'];
 250                 $this->connLogger = $params['connLogger'];
 251                 $this->queryLogger = $params['queryLogger'];
 252                 $this->errorLogger = $params['errorLogger'];
 253                 $this->deprecationLogger = $params['deprecationLogger'];
 254
 255                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 256                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 257                 }
 258
 259                 // Set initial dummy domain until open() sets the final DB/prefix
 260                 $this->currentDomain = new DatabaseDomain(
 261                         $params['dbname'] != '' ? $params['dbname'] : null,
 262                         $params['schema'] != '' ? $params['schema'] : null,
 263                         $params['tablePrefix']
 264                 );
 265         }
 266
 267         /**
 268          * Initialize the connection to the database over the wire (or to local files)
 269          *
 270          * @throws LogicException
 271          * @throws InvalidArgumentException
 272          * @throws DBConnectionError
 273          * @since 1.31
 274          */
 275         final public function initConnection() {
 276                 if ( $this->isOpen() ) {
 277                         throw new LogicException( __METHOD__ . ': already connected' );
 278                 }
 279                 // Establish the connection
 280                 $this->doInitConnection();
 281         }
 282
 283         /**
 284          * Actually connect to the database over the wire (or to local files)
 285          *
 286          * @throws InvalidArgumentException
 287          * @throws DBConnectionError
 288          * @since 1.31
 289          */
 290         protected function doInitConnection() {
 291                 if ( strlen( $this->connectionParams['user'] ) ) {
 292                         $this->open(
 293                                 $this->connectionParams['host'],
 294                                 $this->connectionParams['user'],
 295                                 $this->connectionParams['password'],
 296                                 $this->connectionParams['dbname'],
 297                                 $this->connectionParams['schema'],
 298                                 $this->connectionParams['tablePrefix']
 299                         );
 300                 } else {
 301                         throw new InvalidArgumentException( "No database user provided" );
 302                 }
 303         }
 304
 305         /**
 306          * Open a new connection to the database (closing any existing one)
 307          *
 308          * @param string|null $server Database server host
 309          * @param string|null $user Database user name
 310          * @param string|null $password Database user password
 311          * @param string|null $dbName Database name
 312          * @param string|null $schema Database schema name
 313          * @param string $tablePrefix Table prefix
 314          * @throws DBConnectionError
 315          */
 316         abstract protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix );
 317
 318         /**
 319          * Construct a Database subclass instance given a database type and parameters
 320          *
 321          * This also connects to the database immediately upon object construction
 322          *
 323          * @param string $type A possible DB type (sqlite, mysql, postgres,...)
 324          * @param array $params Parameter map with keys:
 325          *   - host : The hostname of the DB server
 326          *   - user : The name of the database user the client operates under
 327          *   - password : The password for the database user
 328          *   - dbname : The name of the database to use where queries do not specify one.
 329          *      The database must exist or an error might be thrown. Setting this to the empty string
 330          *      will avoid any such errors and make the handle have no implicit database scope. This is
 331          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 332          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 333          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 334          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 335          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 336          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 337          *      recognized in queries. This can be used in place of schemas for handle site farms.
 338          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 339          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 340          *      flag in place UNLESS this this database simply acts as a key/value store.
 341          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 342          *      'mysqli' driver; the old one 'mysql' has been removed.
 343          *   - variables: Optional map of session variables to set after connecting. This can be
 344          *      used to adjust lock timeouts or encoding modes and the like.
 345          *   - connLogger: Optional PSR-3 logger interface instance.
 346          *   - queryLogger: Optional PSR-3 logger interface instance.
 347          *   - profiler : Optional callback that takes a section name argument and returns
 348          *      a ScopedCallback instance that ends the profile section in its destructor.
 349          *      These will be called in query(), using a simplified version of the SQL that
 350          *      also includes the agent as a SQL comment.
 351          *   - trxProfiler: Optional TransactionProfiler instance.
 352          *   - errorLogger: Optional callback that takes an Exception and logs it.
 353          *   - deprecationLogger: Optional callback that takes a string and logs it.
 354          *   - cliMode: Whether to consider the execution context that of a CLI script.
 355          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 356          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 357          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 358          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 359          * @return Database|null If the database driver or extension cannot be found
 360          * @throws InvalidArgumentException If the database driver or extension cannot be found
 361          * @since 1.18
 362          */
 363         final public static function factory( $type, $params = [], $connect = self::NEW_CONNECTED ) {
 364                 $class = self::getClass( $type, $params['driver'] ?? null );
 365
 366                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 367                         $params += [
 368                                 'host' => null,
 369                                 'user' => null,
 370                                 'password' => null,
 371                                 'dbname' => null,
 372                                 'schema' => null,
 373                                 'tablePrefix' => '',
 374                                 'flags' => 0,
 375                                 'variables' => [],
 376                                 'cliMode' => ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' ),
 377                                 'agent' => basename( $_SERVER['SCRIPT_NAME'] ) . '@' . gethostname()
 378                         ];
 379
 380                         $normalizedParams = [
 381                                 // Configuration
 382                                 'host' => strlen( $params['host'] ) ? $params['host'] : null,
 383                                 'user' => strlen( $params['user'] ) ? $params['user'] : null,
 384                                 'password' => is_string( $params['password'] ) ? $params['password'] : null,
 385                                 'dbname' => strlen( $params['dbname'] ) ? $params['dbname'] : null,
 386                                 'schema' => strlen( $params['schema'] ) ? $params['schema'] : null,
 387                                 'tablePrefix' => (string)$params['tablePrefix'],
 388                                 'flags' => (int)$params['flags'],
 389                                 'variables' => $params['variables'],
 390                                 'cliMode' => (bool)$params['cliMode'],
 391                                 'agent' => (string)$params['agent'],
 392                                 // Objects and callbacks
 393                                 'profiler' => $params['profiler'] ?? null,
 394                                 'trxProfiler' => $params['trxProfiler'] ?? new TransactionProfiler(),
 395                                 'connLogger' => $params['connLogger'] ?? new NullLogger(),
 396                                 'queryLogger' => $params['queryLogger'] ?? new NullLogger(),
 397                                 'errorLogger' => $params['errorLogger'] ?? function ( Exception $e ) {
 398                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 399                                 },
 400                                 'deprecationLogger' => $params['deprecationLogger'] ?? function ( $msg ) {
 401                                         trigger_error( $msg, E_USER_DEPRECATED );
 402                                 }
 403                         ] + $params;
 404
 405                         /** @var Database $conn */
 406                         $conn = new $class( $normalizedParams );
 407                         if ( $connect === self::NEW_CONNECTED ) {
 408                                 $conn->initConnection();
 409                         }
 410                 } else {
 411                         $conn = null;
 412                 }
 413
 414                 return $conn;
 415         }
 416
 417         /**
 418          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 419          * @param string|null $driver Optional name of a specific DB client driver
 420          * @return array Map of (Database::ATTR_* constant => value) for all such constants
 421          * @throws InvalidArgumentException
 422          * @since 1.31
 423          */
 424         final public static function attributesFromType( $dbType, $driver = null ) {
 425                 static $defaults = [
 426                         self::ATTR_DB_LEVEL_LOCKING => false,
 427                         self::ATTR_SCHEMAS_AS_TABLE_GROUPS => false
 428                 ];
 429
 430                 $class = self::getClass( $dbType, $driver );
 431
 432                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 433         }
 434
 435         /**
 436          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 437          * @param string|null $driver Optional name of a specific DB client driver
 438          * @return string Database subclass name to use
 439          * @throws InvalidArgumentException
 440          */
 441         private static function getClass( $dbType, $driver = null ) {
 442                 // For database types with built-in support, the below maps type to IDatabase
 443                 // implementations. For types with multipe driver implementations (PHP extensions),
 444                 // an array can be used, keyed by extension name. In case of an array, the
 445                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 446                 // we auto-detect the first available driver. For types without built-in support,
 447                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 448                 static $builtinTypes = [
 449                         'mssql' => DatabaseMssql::class,
 450                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 451                         'sqlite' => DatabaseSqlite::class,
 452                         'postgres' => DatabasePostgres::class,
 453                 ];
 454
 455                 $dbType = strtolower( $dbType );
 456                 $class = false;
 457
 458                 if ( isset( $builtinTypes[$dbType] ) ) {
 459                         $possibleDrivers = $builtinTypes[$dbType];
 460                         if ( is_string( $possibleDrivers ) ) {
 461                                 $class = $possibleDrivers;
 462                         } elseif ( (string)$driver !== '' ) {
 463                                 if ( !isset( $possibleDrivers[$driver] ) ) {
 464                                         throw new InvalidArgumentException( __METHOD__ .
 465                                                 " type '$dbType' does not support driver '{$driver}'" );
 466                                 }
 467
 468                                 $class = $possibleDrivers[$driver];
 469                         } else {
 470                                 foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 471                                         if ( extension_loaded( $posDriver ) ) {
 472                                                 $class = $possibleClass;
 473                                                 break;
 474                                         }
 475                                 }
 476                         }
 477                 } else {
 478                         $class = 'Database' . ucfirst( $dbType );
 479                 }
 480
 481                 if ( $class === false ) {
 482                         throw new InvalidArgumentException( __METHOD__ .
 483                                 " no viable database extension found for type '$dbType'" );
 484                 }
 485
 486                 return $class;
 487         }
 488
 489         /**
 490          * @return array Map of (Database::ATTR_* constant => value
 491          * @since 1.31
 492          */
 493         protected static function getAttributes() {
 494                 return [];
 495         }
 496
 497         /**
 498          * Set the PSR-3 logger interface to use for query logging. (The logger
 499          * interfaces for connection logging and error logging can be set with the
 500          * constructor.)
 501          *
 502          * @param LoggerInterface $logger
 503          */
 504         public function setLogger( LoggerInterface $logger ) {
 505                 $this->queryLogger = $logger;
 506         }
 507
 508         public function getServerInfo() {
 509                 return $this->getServerVersion();
 510         }
 511
 512         public function bufferResults( $buffer = null ) {
 513                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 514                 if ( $buffer !== null ) {
 515                         $buffer
 516                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 517                                 : $this->setFlag( self::DBO_NOBUFFER );
 518                 }
 519
 520                 return $res;
 521         }
 522
 523         final public function trxLevel() {
 524                 return ( $this->trxShortId != '' ) ? 1 : 0;
 525         }
 526
 527         public function trxTimestamp() {
 528                 return $this->trxLevel() ? $this->trxTimestamp : null;
 529         }
 530
 531         /**
 532          * @return int One of the STATUS_TRX_* class constants
 533          * @since 1.31
 534          */
 535         public function trxStatus() {
 536                 return $this->trxStatus;
 537         }
 538
 539         public function tablePrefix( $prefix = null ) {
 540                 $old = $this->currentDomain->getTablePrefix();
 541                 if ( $prefix !== null ) {
 542                         $this->currentDomain = new DatabaseDomain(
 543                                 $this->currentDomain->getDatabase(),
 544                                 $this->currentDomain->getSchema(),
 545                                 $prefix
 546                         );
 547                 }
 548
 549                 return $old;
 550         }
 551
 552         public function dbSchema( $schema = null ) {
 553                 if ( strlen( $schema ) && $this->getDBname() === null ) {
 554                         throw new DBUnexpectedError( $this, "Cannot set schema to '$schema'; no database set" );
 555                 }
 556
 557                 $old = $this->currentDomain->getSchema();
 558                 if ( $schema !== null ) {
 559                         $this->currentDomain = new DatabaseDomain(
 560                                 $this->currentDomain->getDatabase(),
 561                                 // DatabaseDomain uses null for unspecified schemas
 562                                 strlen( $schema ) ? $schema : null,
 563                                 $this->currentDomain->getTablePrefix()
 564                         );
 565                 }
 566
 567                 return (string)$old;
 568         }
 569
 570         /**
 571          * @return string Schema to use to qualify relations in queries
 572          */
 573         protected function relationSchemaQualifier() {
 574                 return $this->dbSchema();
 575         }
 576
 577         public function getLBInfo( $name = null ) {
 578                 if ( is_null( $name ) ) {
 579                         return $this->lbInfo;
 580                 }
 581
 582                 if ( array_key_exists( $name, $this->lbInfo ) ) {
 583                         return $this->lbInfo[$name];
 584                 }
 585
 586                 return null;
 587         }
 588
 589         public function setLBInfo( $name, $value = null ) {
 590                 if ( is_null( $value ) ) {
 591                         $this->lbInfo = $name;
 592                 } else {
 593                         $this->lbInfo[$name] = $value;
 594                 }
 595         }
 596
 597         public function setLazyMasterHandle( IDatabase $conn ) {
 598                 $this->lazyMasterHandle = $conn;
 599         }
 600
 601         /**
 602          * @return IDatabase|null
 603          * @see setLazyMasterHandle()
 604          * @since 1.27
 605          */
 606         protected function getLazyMasterHandle() {
 607                 return $this->lazyMasterHandle;
 608         }
 609
 610         public function implicitGroupby() {
 611                 return true;
 612         }
 613
 614         public function implicitOrderby() {
 615                 return true;
 616         }
 617
 618         public function lastQuery() {
 619                 return $this->lastQuery;
 620         }
 621
 622         public function doneWrites() {
 623                 return (bool)$this->lastWriteTime;
 624         }
 625
 626         public function lastDoneWrites() {
 627                 return $this->lastWriteTime ?: false;
 628         }
 629
 630         public function writesPending() {
 631                 return $this->trxLevel() && $this->trxDoneWrites;
 632         }
 633
 634         public function writesOrCallbacksPending() {
 635                 return $this->trxLevel() && (
 636                         $this->trxDoneWrites ||
 637                         $this->trxIdleCallbacks ||
 638                         $this->trxPreCommitCallbacks ||
 639                         $this->trxEndCallbacks ||
 640                         $this->trxSectionCancelCallbacks
 641                 );
 642         }
 643
 644         public function preCommitCallbacksPending() {
 645                 return $this->trxLevel() && $this->trxPreCommitCallbacks;
 646         }
 647
 648         /**
 649          * @return string|null
 650          */
 651         final protected function getTransactionRoundId() {
 652                 // If transaction round participation is enabled, see if one is active
 653                 if ( $this->getFlag( self::DBO_TRX ) ) {
 654                         $id = $this->getLBInfo( 'trxRoundId' );
 655
 656                         return is_string( $id ) ? $id : null;
 657                 }
 658
 659                 return null;
 660         }
 661
 662         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 663                 if ( !$this->trxLevel() ) {
 664                         return false;
 665                 } elseif ( !$this->trxDoneWrites ) {
 666                         return 0.0;
 667                 }
 668
 669                 switch ( $type ) {
 670                         case self::ESTIMATE_DB_APPLY:
 671                                 return $this->pingAndCalculateLastTrxApplyTime();
 672                         default: // everything
 673                                 return $this->trxWriteDuration;
 674                 }
 675         }
 676
 677         /**
 678          * @return float Time to apply writes to replicas based on trxWrite* fields
 679          */
 680         private function pingAndCalculateLastTrxApplyTime() {
 681                 $this->ping( $rtt );
 682
 683                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 684                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 685                 // For omitted queries, make them count as something at least
 686                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 687                 $applyTime += self::$TINY_WRITE_SEC * $omitted;
 688
 689                 return $applyTime;
 690         }
 691
 692         public function pendingWriteCallers() {
 693                 return $this->trxLevel() ? $this->trxWriteCallers : [];
 694         }
 695
 696         public function pendingWriteRowsAffected() {
 697                 return $this->trxWriteAffectedRows;
 698         }
 699
 700         /**
 701          * List the methods that have write queries or callbacks for the current transaction
 702          *
 703          * This method should not be used outside of Database/LoadBalancer
 704          *
 705          * @return string[]
 706          * @since 1.32
 707          */
 708         public function pendingWriteAndCallbackCallers() {
 709                 $fnames = $this->pendingWriteCallers();
 710                 foreach ( [
 711                         $this->trxIdleCallbacks,
 712                         $this->trxPreCommitCallbacks,
 713                         $this->trxEndCallbacks,
 714                         $this->trxSectionCancelCallbacks
 715                 ] as $callbacks ) {
 716                         foreach ( $callbacks as $callback ) {
 717                                 $fnames[] = $callback[1];
 718                         }
 719                 }
 720
 721                 return $fnames;
 722         }
 723
 724         /**
 725          * @return string
 726          */
 727         private function flatAtomicSectionList() {
 728                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 729                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 730                 } );
 731         }
 732
 733         public function isOpen() {
 734                 return (bool)$this->conn;
 735         }
 736
 737         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 738                 if ( ( $flag & self::DBO_IGNORE ) ) {
 739                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed" );
 740                 }
 741
 742                 if ( $remember === self::REMEMBER_PRIOR ) {
 743                         array_push( $this->priorFlags, $this->flags );
 744                 }
 745                 $this->flags |= $flag;
 746         }
 747
 748         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 749                 if ( ( $flag & self::DBO_IGNORE ) ) {
 750                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed" );
 751                 }
 752
 753                 if ( $remember === self::REMEMBER_PRIOR ) {
 754                         array_push( $this->priorFlags, $this->flags );
 755                 }
 756                 $this->flags &= ~$flag;
 757         }
 758
 759         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 760                 if ( !$this->priorFlags ) {
 761                         return;
 762                 }
 763
 764                 if ( $state === self::RESTORE_INITIAL ) {
 765                         $this->flags = reset( $this->priorFlags );
 766                         $this->priorFlags = [];
 767                 } else {
 768                         $this->flags = array_pop( $this->priorFlags );
 769                 }
 770         }
 771
 772         public function getFlag( $flag ) {
 773                 return (bool)( $this->flags & $flag );
 774         }
 775
 776         /**
 777          * @param string $name Class field name
 778          * @return mixed
 779          * @deprecated Since 1.28
 780          */
 781         public function getProperty( $name ) {
 782                 return $this->$name;
 783         }
 784
 785         public function getDomainID() {
 786                 return $this->currentDomain->getId();
 787         }
 788
 789         final public function getWikiID() {
 790                 return $this->getDomainID();
 791         }
 792
 793         /**
 794          * Get information about an index into an object
 795          * @param string $table Table name
 796          * @param string $index Index name
 797          * @param string $fname Calling function name
 798          * @return mixed Database-specific index description class or false if the index does not exist
 799          */
 800         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 801
 802         /**
 803          * Wrapper for addslashes()
 804          *
 805          * @param string $s String to be slashed.
 806          * @return string Slashed string.
 807          */
 808         abstract function strencode( $s );
 809
 810         /**
 811          * Set a custom error handler for logging errors during database connection
 812          */
 813         protected function installErrorHandler() {
 814                 $this->lastPhpError = false;
 815                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 816                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 817         }
 818
 819         /**
 820          * Restore the previous error handler and return the last PHP error for this DB
 821          *
 822          * @return bool|string
 823          */
 824         protected function restoreErrorHandler() {
 825                 restore_error_handler();
 826                 if ( $this->htmlErrors !== false ) {
 827                         ini_set( 'html_errors', $this->htmlErrors );
 828                 }
 829
 830                 return $this->getLastPHPError();
 831         }
 832
 833         /**
 834          * @return string|bool Last PHP error for this DB (typically connection errors)
 835          */
 836         protected function getLastPHPError() {
 837                 if ( $this->lastPhpError ) {
 838                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->lastPhpError );
 839                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 840
 841                         return $error;
 842                 }
 843
 844                 return false;
 845         }
 846
 847         /**
 848          * Error handler for logging errors during database connection
 849          * This method should not be used outside of Database classes
 850          *
 851          * @param int $errno
 852          * @param string $errstr
 853          */
 854         public function connectionErrorLogger( $errno, $errstr ) {
 855                 $this->lastPhpError = $errstr;
 856         }
 857
 858         /**
 859          * Create a log context to pass to PSR-3 logger functions.
 860          *
 861          * @param array $extras Additional data to add to context
 862          * @return array
 863          */
 864         protected function getLogContext( array $extras = [] ) {
 865                 return array_merge(
 866                         [
 867                                 'db_server' => $this->server,
 868                                 'db_name' => $this->getDBname(),
 869                                 'db_user' => $this->user,
 870                         ],
 871                         $extras
 872                 );
 873         }
 874
 875         final public function close() {
 876                 $exception = null; // error to throw after disconnecting
 877
 878                 $wasOpen = (bool)$this->conn;
 879                 // This should mostly do nothing if the connection is already closed
 880                 if ( $this->conn ) {
 881                         // Roll back any dangling transaction first
 882                         if ( $this->trxLevel() ) {
 883                                 if ( $this->trxAtomicLevels ) {
 884                                         // Cannot let incomplete atomic sections be committed
 885                                         $levels = $this->flatAtomicSectionList();
 886                                         $exception = new DBUnexpectedError(
 887                                                 $this,
 888                                                 __METHOD__ . ": atomic sections $levels are still open"
 889                                         );
 890                                 } elseif ( $this->trxAutomatic ) {
 891                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 892                                         // (empty ones we can silently roll back)
 893                                         if ( $this->writesOrCallbacksPending() ) {
 894                                                 $exception = new DBUnexpectedError(
 895                                                         $this,
 896                                                         __METHOD__ .
 897                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)"
 898                                                 );
 899                                         }
 900                                 } else {
 901                                         // Manual transactions should have been committed or rolled
 902                                         // back, even if empty.
 903                                         $exception = new DBUnexpectedError(
 904                                                 $this,
 905                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})"
 906                                         );
 907                                 }
 908
 909                                 if ( $this->trxEndCallbacksSuppressed ) {
 910                                         $exception = $exception ?: new DBUnexpectedError(
 911                                                 $this,
 912                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit'
 913                                         );
 914                                 }
 915
 916                                 // Rollback the changes and run any callbacks as needed
 917                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 918                         }
 919
 920                         // Close the actual connection in the binding handle
 921                         $closed = $this->closeConnection();
 922                 } else {
 923                         $closed = true; // already closed; nothing to do
 924                 }
 925
 926                 $this->conn = false;
 927
 928                 // Throw any unexpected errors after having disconnected
 929                 if ( $exception instanceof Exception ) {
 930                         throw $exception;
 931                 }
 932
 933                 // Note that various subclasses call close() at the start of open(), which itself is
 934                 // called by replaceLostConnection(). In that case, just because onTransactionResolution()
 935                 // callbacks are pending does not mean that an exception should be thrown. Rather, they
 936                 // will be executed after the reconnection step.
 937                 if ( $wasOpen ) {
 938                         // Sanity check that no callbacks are dangling
 939                         $fnames = $this->pendingWriteAndCallbackCallers();
 940                         if ( $fnames ) {
 941                                 throw new RuntimeException(
 942                                         "Transaction callbacks are still pending: " . implode( ', ', $fnames )
 943                                 );
 944                         }
 945                 }
 946
 947                 return $closed;
 948         }
 949
 950         /**
 951          * Make sure there is an open connection handle (alive or not) as a sanity check
 952          *
 953          * This guards against fatal errors to the binding handle not being defined
 954          * in cases where open() was never called or close() was already called
 955          *
 956          * @throws DBUnexpectedError
 957          */
 958         final protected function assertHasConnectionHandle() {
 959                 if ( !$this->isOpen() ) {
 960                         throw new DBUnexpectedError( $this, "DB connection was already closed" );
 961                 }
 962         }
 963
 964         /**
 965          * Make sure that this server is not marked as a replica nor read-only as a sanity check
 966          *
 967          * @throws DBReadOnlyRoleError
 968          * @throws DBReadOnlyError
 969          */
 970         protected function assertIsWritableMaster() {
 971                 if ( $this->getLBInfo( 'replica' ) === true ) {
 972                         throw new DBReadOnlyRoleError(
 973                                 $this,
 974                                 'Write operations are not allowed on replica database connections'
 975                         );
 976                 }
 977                 $reason = $this->getReadOnlyReason();
 978                 if ( $reason !== false ) {
 979                         throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 980                 }
 981         }
 982
 983         /**
 984          * Closes underlying database connection
 985          * @since 1.20
 986          * @return bool Whether connection was closed successfully
 987          */
 988         abstract protected function closeConnection();
 989
 990         /**
 991          * Run a query and return a DBMS-dependent wrapper or boolean
 992          *
 993          * This is meant to handle the basic command of actually sending a query to the
 994          * server via the driver. No implicit transaction, reconnection, nor retry logic
 995          * should happen here. The higher level query() method is designed to handle those
 996          * sorts of concerns. This method should not trigger such higher level methods.
 997          *
 998          * The lastError() and lastErrno() methods should meaningfully reflect what error,
 999          * if any, occured during the last call to this method. Methods like executeQuery(),
1000          * query(), select(), insert(), update(), delete(), and upsert() implement their calls
1001          * to doQuery() such that an immediately subsequent call to lastError()/lastErrno()
1002          * meaningfully reflects any error that occured during that public query method call.
1003          *
1004          * For SELECT queries, this returns either:
1005          *   - a) A driver-specific value/resource, only on success. This can be iterated
1006          *        over by calling fetchObject()/fetchRow() until there are no more rows.
1007          *        Alternatively, the result can be passed to resultObject() to obtain an
1008          *        IResultWrapper instance which can then be iterated over via "foreach".
1009          *   - b) False, on any query failure
1010          *
1011          * For non-SELECT queries, this returns either:
1012          *   - a) A driver-specific value/resource, only on success
1013          *   - b) True, only on success (e.g. no meaningful result other than "OK")
1014          *   - c) False, on any query failure
1015          *
1016          * @param string $sql SQL query
1017          * @return mixed|bool An object, resource, or true on success; false on failure
1018          */
1019         abstract protected function doQuery( $sql );
1020
1021         /**
1022          * Determine whether a query writes to the DB. When in doubt, this returns true.
1023          *
1024          * Main use cases:
1025          *
1026          * - Subsequent web requests should not need to wait for replication from
1027          *   the master position seen by this web request, unless this request made
1028          *   changes to the master. This is handled by ChronologyProtector by checking
1029          *   doneWrites() at the end of the request. doneWrites() returns true if any
1030          *   query set lastWriteTime; which query() does based on isWriteQuery().
1031          *
1032          * - Reject write queries to replica DBs, in query().
1033          *
1034          * @param string $sql
1035          * @return bool
1036          */
1037         protected function isWriteQuery( $sql ) {
1038                 // BEGIN and COMMIT queries are considered read queries here.
1039                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1040                 // treat these as write queries, in that their results have "affected rows"
1041                 // as meta data as from writes, instead of "num rows" as from reads.
1042                 // But, we treat them as read queries because when reading data (from
1043                 // either replica or master) we use transactions to enable repeatable-read
1044                 // snapshots, which ensures we get consistent results from the same snapshot
1045                 // for all queries within a request. Use cases:
1046                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1047                 // - We use this method to reject writes to replicas, but we need to allow
1048                 //   use of transactions on replicas for read snapshots. This is fine given
1049                 //   that transactions by themselves don't make changes, only actual writes
1050                 //   within the transaction matter, which we still detect.
1051                 return !preg_match(
1052                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|USE|\(SELECT)\b/i',
1053                         $sql
1054                 );
1055         }
1056
1057         /**
1058          * @param string $sql
1059          * @return string|null
1060          */
1061         protected function getQueryVerb( $sql ) {
1062                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1063         }
1064
1065         /**
1066          * Determine whether a SQL statement is sensitive to isolation level.
1067          *
1068          * A SQL statement is considered transactable if its result could vary
1069          * depending on the transaction isolation level. Operational commands
1070          * such as 'SET' and 'SHOW' are not considered to be transactable.
1071          *
1072          * Main purpose: Used by query() to decide whether to begin a transaction
1073          * before the current query (in DBO_TRX mode, on by default).
1074          *
1075          * @param string $sql
1076          * @return bool
1077          */
1078         protected function isTransactableQuery( $sql ) {
1079                 return !in_array(
1080                         $this->getQueryVerb( $sql ),
1081                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER', 'USE', 'SHOW' ],
1082                         true
1083                 );
1084         }
1085
1086         /**
1087          * @param string $sql A SQL query
1088          * @param bool $pseudoPermanent Treat any table from CREATE TEMPORARY as pseudo-permanent
1089          * @return array A n-tuple of:
1090          *   - int|null: A self::TEMP_* constant for temp table operations or null otherwise
1091          *   - string|null: The name of the new temporary table $sql creates, or null
1092          *   - string|null: The name of the temporary table that $sql drops, or null
1093          */
1094         protected function getTempWrites( $sql, $pseudoPermanent ) {
1095                 static $qt = '[`"\']?(\w+)[`"\']?'; // quoted table
1096
1097                 if ( preg_match(
1098                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?' . $qt . '/i',
1099                         $sql,
1100                         $matches
1101                 ) ) {
1102                         $type = $pseudoPermanent ? self::$TEMP_PSEUDO_PERMANENT : self::$TEMP_NORMAL;
1103
1104                         return [ $type, $matches[1], null ];
1105                 } elseif ( preg_match(
1106                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1107                         $sql,
1108                         $matches
1109                 ) ) {
1110                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, $matches[1] ];
1111                 } elseif ( preg_match(
1112                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1113                         $sql,
1114                         $matches
1115                 ) ) {
1116                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
1117                 } elseif ( preg_match(
1118                         '/^(?:(?:INSERT|REPLACE)\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+' . $qt . '/i',
1119                         $sql,
1120                         $matches
1121                 ) ) {
1122                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
1123                 }
1124
1125                 return [ null, null, null ];
1126         }
1127
1128         /**
1129          * @param IResultWrapper|bool $ret
1130          * @param int|null $tmpType TEMP_NORMAL or TEMP_PSEUDO_PERMANENT
1131          * @param string|null $tmpNew Name of created temp table
1132          * @param string|null $tmpDel Name of dropped temp table
1133          */
1134         protected function registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel ) {
1135                 if ( $ret !== false ) {
1136                         if ( $tmpNew !== null ) {
1137                                 $this->sessionTempTables[$tmpNew] = $tmpType;
1138                         }
1139                         if ( $tmpDel !== null ) {
1140                                 unset( $this->sessionTempTables[$tmpDel] );
1141                         }
1142                 }
1143         }
1144
1145         public function query( $sql, $fname = __METHOD__, $flags = 0 ) {
1146                 $flags = (int)$flags; // b/c; this field used to be a bool
1147                 // Sanity check that the SQL query is appropriate in the current context and is
1148                 // allowed for an outside caller (e.g. does not break transaction/session tracking).
1149                 $this->assertQueryIsCurrentlyAllowed( $sql, $fname );
1150
1151                 // Send the query to the server and fetch any corresponding errors
1152                 list( $ret, $err, $errno, $unignorable ) = $this->executeQuery( $sql, $fname, $flags );
1153                 if ( $ret === false ) {
1154                         $ignoreErrors = $this->hasFlags( $flags, self::QUERY_SILENCE_ERRORS );
1155                         // Throw an error unless both the ignore flag was set and a rollback is not needed
1156                         $this->reportQueryError( $err, $errno, $sql, $fname, $ignoreErrors && !$unignorable );
1157                 }
1158
1159                 return $this->resultObject( $ret );
1160         }
1161
1162         /**
1163          * Execute a query, retrying it if there is a recoverable connection loss
1164          *
1165          * This is similar to query() except:
1166          *   - It does not prevent all non-ROLLBACK queries if there is a corrupted transaction
1167          *   - It does not disallow raw queries that are supposed to use dedicated IDatabase methods
1168          *   - It does not throw exceptions for common error cases
1169          *
1170          * This is meant for internal use with Database subclasses.
1171          *
1172          * @param string $sql Original SQL query
1173          * @param string $fname Name of the calling function
1174          * @param int $flags Bitfield of class QUERY_* constants
1175          * @return array An n-tuple of:
1176          *   - mixed|bool: An object, resource, or true on success; false on failure
1177          *   - string: The result of calling lastError()
1178          *   - int: The result of calling lastErrno()
1179          *   - bool: Whether a rollback is needed to allow future non-rollback queries
1180          * @throws DBUnexpectedError
1181          */
1182         final protected function executeQuery( $sql, $fname, $flags ) {
1183                 $this->assertHasConnectionHandle();
1184
1185                 $priorTransaction = $this->trxLevel();
1186
1187                 if ( $this->isWriteQuery( $sql ) ) {
1188                         // In theory, non-persistent writes are allowed in read-only mode, but due to things
1189                         // like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1190                         $this->assertIsWritableMaster();
1191                         // Do not treat temporary table writes as "meaningful writes" since they are only
1192                         // visible to one session and are not permanent. Profile them as reads. Integration
1193                         // tests can override this behavior via $flags.
1194                         $pseudoPermanent = $this->hasFlags( $flags, self::QUERY_PSEUDO_PERMANENT );
1195                         list( $tmpType, $tmpNew, $tmpDel ) = $this->getTempWrites( $sql, $pseudoPermanent );
1196                         $isPermWrite = ( $tmpType !== self::$TEMP_NORMAL );
1197                         // DBConnRef uses QUERY_REPLICA_ROLE to enforce the replica role for raw SQL queries
1198                         if ( $isPermWrite && $this->hasFlags( $flags, self::QUERY_REPLICA_ROLE ) ) {
1199                                 throw new DBReadOnlyRoleError( $this, "Cannot write; target role is DB_REPLICA" );
1200                         }
1201                 } else {
1202                         // No permanent writes in this query
1203                         $isPermWrite = false;
1204                         // No temporary tables written to either
1205                         list( $tmpType, $tmpNew, $tmpDel ) = [ null, null, null ];
1206                 }
1207
1208                 // Add trace comment to the begin of the sql string, right after the operator.
1209                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1210                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1211
1212                 // Send the query to the server and fetch any corresponding errors.
1213                 // This also doubles as a "ping" to see if the connection was dropped.
1214                 list( $ret, $err, $errno, $recoverableSR, $recoverableCL, $reconnected ) =
1215                         $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1216
1217                 // Check if the query failed due to a recoverable connection loss
1218                 $allowRetry = !$this->hasFlags( $flags, self::QUERY_NO_RETRY );
1219                 if ( $ret === false && $recoverableCL && $reconnected && $allowRetry ) {
1220                         // Silently resend the query to the server since it is safe and possible
1221                         list( $ret, $err, $errno, $recoverableSR, $recoverableCL ) =
1222                                 $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1223                 }
1224
1225                 // Register creation and dropping of temporary tables
1226                 $this->registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel );
1227
1228                 $corruptedTrx = false;
1229
1230                 if ( $ret === false ) {
1231                         if ( $priorTransaction ) {
1232                                 if ( $recoverableSR ) {
1233                                         # We're ignoring an error that caused just the current query to be aborted.
1234                                         # But log the cause so we can log a deprecation notice if a caller actually
1235                                         # does ignore it.
1236                                         $this->trxStatusIgnoredCause = [ $err, $errno, $fname ];
1237                                 } elseif ( !$recoverableCL ) {
1238                                         # Either the query was aborted or all queries after BEGIN where aborted.
1239                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1240                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1241                                         # option is ROLLBACK, since the snapshots would have been released.
1242                                         $corruptedTrx = true; // cannot recover
1243                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1244                                         $this->trxStatusCause =
1245                                                 $this->getQueryExceptionAndLog( $err, $errno, $sql, $fname );
1246                                         $this->trxStatusIgnoredCause = null;
1247                                 }
1248                         }
1249                 }
1250
1251                 return [ $ret, $err, $errno, $corruptedTrx ];
1252         }
1253
1254         /**
1255          * Wrapper for doQuery() that handles DBO_TRX, profiling, logging, affected row count
1256          * tracking, and reconnects (without retry) on query failure due to connection loss
1257          *
1258          * @param string $sql Original SQL query
1259          * @param string $commentedSql SQL query with debugging/trace comment
1260          * @param bool $isPermWrite Whether the query is a (non-temporary table) write
1261          * @param string $fname Name of the calling function
1262          * @param int $flags Bitfield of class QUERY_* constants
1263          * @return array An n-tuple of:
1264          *   - mixed|bool: An object, resource, or true on success; false on failure
1265          *   - string: The result of calling lastError()
1266          *   - int: The result of calling lastErrno()
1267          *       - bool: Whether a statement rollback error occured
1268          *   - bool: Whether a disconnect *both* happened *and* was recoverable
1269          *   - bool: Whether a reconnection attempt was *both* made *and* succeeded
1270          * @throws DBUnexpectedError
1271          */
1272         private function executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags ) {
1273                 $priorWritesPending = $this->writesOrCallbacksPending();
1274
1275                 if ( ( $flags & self::QUERY_IGNORE_DBO_TRX ) == 0 ) {
1276                         $this->beginIfImplied( $sql, $fname );
1277                 }
1278
1279                 // Keep track of whether the transaction has write queries pending
1280                 if ( $isPermWrite ) {
1281                         $this->lastWriteTime = microtime( true );
1282                         if ( $this->trxLevel() && !$this->trxDoneWrites ) {
1283                                 $this->trxDoneWrites = true;
1284                                 $this->trxProfiler->transactionWritingIn(
1285                                         $this->server, $this->getDomainID(), $this->trxShortId );
1286                         }
1287                 }
1288
1289                 $prefix = !is_null( $this->getLBInfo( 'master' ) ) ? 'query-m: ' : 'query: ';
1290                 $generalizedSql = new GeneralizedSql( $sql, $this->trxShortId, $prefix );
1291
1292                 $startTime = microtime( true );
1293                 $ps = $this->profiler
1294                         ? ( $this->profiler )( $generalizedSql->stringify() )
1295                         : null;
1296                 $this->affectedRowCount = null;
1297                 $this->lastQuery = $sql;
1298                 $ret = $this->doQuery( $commentedSql );
1299                 $lastError = $this->lastError();
1300                 $lastErrno = $this->lastErrno();
1301
1302                 $this->affectedRowCount = $this->affectedRows();
1303                 unset( $ps ); // profile out (if set)
1304                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1305
1306                 $recoverableSR = false; // recoverable statement rollback?
1307                 $recoverableCL = false; // recoverable connection loss?
1308                 $reconnected = false; // reconnection both attempted and succeeded?
1309
1310                 if ( $ret !== false ) {
1311                         $this->lastPing = $startTime;
1312                         if ( $isPermWrite && $this->trxLevel() ) {
1313                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1314                                 $this->trxWriteCallers[] = $fname;
1315                         }
1316                 } elseif ( $this->wasConnectionError( $lastErrno ) ) {
1317                         # Check if no meaningful session state was lost
1318                         $recoverableCL = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1319                         # Update session state tracking and try to restore the connection
1320                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1321                 } else {
1322                         # Check if only the last query was rolled back
1323                         $recoverableSR = $this->wasKnownStatementRollbackError();
1324                 }
1325
1326                 if ( $sql === self::$PING_QUERY ) {
1327                         $this->lastRoundTripEstimate = $queryRuntime;
1328                 }
1329
1330                 $this->trxProfiler->recordQueryCompletion(
1331                         $generalizedSql,
1332                         $startTime,
1333                         $isPermWrite,
1334                         $isPermWrite ? $this->affectedRows() : $this->numRows( $ret )
1335                 );
1336
1337                 // Avoid the overhead of logging calls unless debug mode is enabled
1338                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1339                         $this->queryLogger->debug(
1340                                 "{method} [{runtime}s]: $sql",
1341                                 [
1342                                         'method' => $fname,
1343                                         'db_host' => $this->getServer(),
1344                                         'domain' => $this->getDomainID(),
1345                                         'runtime' => round( $queryRuntime, 3 )
1346                                 ]
1347                         );
1348                 }
1349
1350                 return [ $ret, $lastError, $lastErrno, $recoverableSR, $recoverableCL, $reconnected ];
1351         }
1352
1353         /**
1354          * Start an implicit transaction if DBO_TRX is enabled and no transaction is active
1355          *
1356          * @param string $sql
1357          * @param string $fname
1358          */
1359         private function beginIfImplied( $sql, $fname ) {
1360                 if (
1361                         !$this->trxLevel() &&
1362                         $this->getFlag( self::DBO_TRX ) &&
1363                         $this->isTransactableQuery( $sql )
1364                 ) {
1365                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1366                         $this->trxAutomatic = true;
1367                 }
1368         }
1369
1370         /**
1371          * Update the estimated run-time of a query, not counting large row lock times
1372          *
1373          * LoadBalancer can be set to rollback transactions that will create huge replication
1374          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1375          * queries, like inserting a row can take a long time due to row locking. This method
1376          * uses some simple heuristics to discount those cases.
1377          *
1378          * @param string $sql A SQL write query
1379          * @param float $runtime Total runtime, including RTT
1380          * @param int $affected Affected row count
1381          */
1382         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1383                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1384                 $indicativeOfReplicaRuntime = true;
1385                 if ( $runtime > self::$SLOW_WRITE_SEC ) {
1386                         $verb = $this->getQueryVerb( $sql );
1387                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1388                         if ( $verb === 'INSERT' ) {
1389                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS;
1390                         } elseif ( $verb === 'REPLACE' ) {
1391                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS / 2;
1392                         }
1393                 }
1394
1395                 $this->trxWriteDuration += $runtime;
1396                 $this->trxWriteQueryCount += 1;
1397                 $this->trxWriteAffectedRows += $affected;
1398                 if ( $indicativeOfReplicaRuntime ) {
1399                         $this->trxWriteAdjDuration += $runtime;
1400                         $this->trxWriteAdjQueryCount += 1;
1401                 }
1402         }
1403
1404         /**
1405          * Error out if the DB is not in a valid state for a query via query()
1406          *
1407          * @param string $sql
1408          * @param string $fname
1409          * @throws DBTransactionStateError
1410          */
1411         private function assertQueryIsCurrentlyAllowed( $sql, $fname ) {
1412                 $verb = $this->getQueryVerb( $sql );
1413                 if ( $verb === 'USE' ) {
1414                         throw new DBUnexpectedError( $this, "Got USE query; use selectDomain() instead" );
1415                 }
1416
1417                 if ( $verb === 'ROLLBACK' ) { // transaction/savepoint
1418                         return;
1419                 }
1420
1421                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1422                         throw new DBTransactionStateError(
1423                                 $this,
1424                                 "Cannot execute query from $fname while transaction status is ERROR",
1425                                 [],
1426                                 $this->trxStatusCause
1427                         );
1428                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1429                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1430                         call_user_func( $this->deprecationLogger,
1431                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1432                                 "[$iLastErrno] $iLastError"
1433                         );
1434                         $this->trxStatusIgnoredCause = null;
1435                 }
1436         }
1437
1438         public function assertNoOpenTransactions() {
1439                 if ( $this->explicitTrxActive() ) {
1440                         throw new DBTransactionError(
1441                                 $this,
1442                                 "Explicit transaction still active. A caller may have caught an error. "
1443                                 . "Open transactions: " . $this->flatAtomicSectionList()
1444                         );
1445                 }
1446         }
1447
1448         /**
1449          * Determine whether it is safe to retry queries after a database connection is lost
1450          *
1451          * @param string $sql SQL query
1452          * @param bool $priorWritesPending Whether there is a transaction open with
1453          *     possible write queries or transaction pre-commit/idle callbacks
1454          *     waiting on it to finish.
1455          * @return bool True if it is safe to retry the query, false otherwise
1456          */
1457         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1458                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1459                 # Dropped connections also mean that named locks are automatically released.
1460                 # Only allow error suppression in autocommit mode or when the lost transaction
1461                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1462                 if ( $this->sessionNamedLocks ) {
1463                         return false; // possible critical section violation
1464                 } elseif ( $this->sessionTempTables ) {
1465                         return false; // tables might be queried latter
1466                 } elseif ( $sql === 'COMMIT' ) {
1467                         return !$priorWritesPending; // nothing written anyway? (T127428)
1468                 } elseif ( $sql === 'ROLLBACK' ) {
1469                         return true; // transaction lost...which is also what was requested :)
1470                 } elseif ( $this->explicitTrxActive() ) {
1471                         return false; // don't drop atomocity and explicit snapshots
1472                 } elseif ( $priorWritesPending ) {
1473                         return false; // prior writes lost from implicit transaction
1474                 }
1475
1476                 return true;
1477         }
1478
1479         /**
1480          * Clean things up after session (and thus transaction) loss before reconnect
1481          */
1482         private function handleSessionLossPreconnect() {
1483                 // Clean up tracking of session-level things...
1484                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1485                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1486                 $this->sessionTempTables = [];
1487                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1488                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1489                 $this->sessionNamedLocks = [];
1490                 // Session loss implies transaction loss
1491                 $oldTrxShortId = $this->consumeTrxShortId();
1492                 $this->trxAtomicCounter = 0;
1493                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1494                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1495                 // @note: leave trxRecurringCallbacks in place
1496                 if ( $this->trxDoneWrites ) {
1497                         $this->trxProfiler->transactionWritingOut(
1498                                 $this->server,
1499                                 $this->getDomainID(),
1500                                 $oldTrxShortId,
1501                                 $this->pendingWriteQueryDuration( self::ESTIMATE_TOTAL ),
1502                                 $this->trxWriteAffectedRows
1503                         );
1504                 }
1505         }
1506
1507         /**
1508          * Clean things up after session (and thus transaction) loss after reconnect
1509          */
1510         private function handleSessionLossPostconnect() {
1511                 try {
1512                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1513                         // If callback suppression is set then the array will remain unhandled.
1514                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1515                 } catch ( Exception $ex ) {
1516                         // Already logged; move on...
1517                 }
1518                 try {
1519                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1520                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1521                 } catch ( Exception $ex ) {
1522                         // Already logged; move on...
1523                 }
1524         }
1525
1526         /**
1527          * Reset the transaction ID and return the old one
1528          *
1529          * @return string The old transaction ID or the empty string if there wasn't one
1530          */
1531         private function consumeTrxShortId() {
1532                 $old = $this->trxShortId;
1533                 $this->trxShortId = '';
1534
1535                 return $old;
1536         }
1537
1538         /**
1539          * Checks whether the cause of the error is detected to be a timeout.
1540          *
1541          * It returns false by default, and not all engines support detecting this yet.
1542          * If this returns false, it will be treated as a generic query error.
1543          *
1544          * @param string $error Error text
1545          * @param int $errno Error number
1546          * @return bool
1547          */
1548         protected function wasQueryTimeout( $error, $errno ) {
1549                 return false;
1550         }
1551
1552         /**
1553          * Report a query error. Log the error, and if neither the object ignore
1554          * flag nor the $ignoreErrors flag is set, throw a DBQueryError.
1555          *
1556          * @param string $error
1557          * @param int $errno
1558          * @param string $sql
1559          * @param string $fname
1560          * @param bool $ignore
1561          * @throws DBQueryError
1562          */
1563         public function reportQueryError( $error, $errno, $sql, $fname, $ignore = false ) {
1564                 if ( $ignore ) {
1565                         $this->queryLogger->debug( "SQL ERROR (ignored): $error" );
1566                 } else {
1567                         $exception = $this->getQueryExceptionAndLog( $error, $errno, $sql, $fname );
1568
1569                         throw $exception;
1570                 }
1571         }
1572
1573         /**
1574          * @param string $error
1575          * @param string|int $errno
1576          * @param string $sql
1577          * @param string $fname
1578          * @return DBError
1579          */
1580         private function getQueryExceptionAndLog( $error, $errno, $sql, $fname ) {
1581                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1582                 $this->queryLogger->error(
1583                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1584                         $this->getLogContext( [
1585                                 'method' => __METHOD__,
1586                                 'errno' => $errno,
1587                                 'error' => $error,
1588                                 'sql1line' => $sql1line,
1589                                 'fname' => $fname,
1590                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1591                         ] )
1592                 );
1593                 $this->queryLogger->debug( "SQL ERROR: " . $error . "" );
1594                 if ( $this->wasQueryTimeout( $error, $errno ) ) {
1595                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1596                 } elseif ( $this->wasConnectionError( $errno ) ) {
1597                         $e = new DBQueryDisconnectedError( $this, $error, $errno, $sql, $fname );
1598                 } else {
1599                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1600                 }
1601
1602                 return $e;
1603         }
1604
1605         public function freeResult( $res ) {
1606         }
1607
1608         public function selectField(
1609                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1610         ) {
1611                 if ( $var === '*' ) { // sanity
1612                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1613                 }
1614
1615                 if ( !is_array( $options ) ) {
1616                         $options = [ $options ];
1617                 }
1618
1619                 $options['LIMIT'] = 1;
1620
1621                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1622                 if ( $res === false ) {
1623                         throw new DBUnexpectedError( $this, "Got false from select()" );
1624                 }
1625
1626                 $row = $this->fetchRow( $res );
1627                 if ( $row === false ) {
1628                         return false;
1629                 }
1630
1631                 return reset( $row );
1632         }
1633
1634         public function selectFieldValues(
1635                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1636         ) {
1637                 if ( $var === '*' ) { // sanity
1638                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1639                 } elseif ( !is_string( $var ) ) { // sanity
1640                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1641                 }
1642
1643                 if ( !is_array( $options ) ) {
1644                         $options = [ $options ];
1645                 }
1646
1647                 $res = $this->select( $table, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
1648                 if ( $res === false ) {
1649                         throw new DBUnexpectedError( $this, "Got false from select()" );
1650                 }
1651
1652                 $values = [];
1653                 foreach ( $res as $row ) {
1654                         $values[] = $row->value;
1655                 }
1656
1657                 return $values;
1658         }
1659
1660         /**
1661          * Returns an optional USE INDEX clause to go after the table, and a
1662          * string to go at the end of the query.
1663          *
1664          * @param array $options Associative array of options to be turned into
1665          *   an SQL query, valid keys are listed in the function.
1666          * @return array
1667          * @see Database::select()
1668          */
1669         protected function makeSelectOptions( $options ) {
1670                 $preLimitTail = $postLimitTail = '';
1671                 $startOpts = '';
1672
1673                 $noKeyOptions = [];
1674
1675                 foreach ( $options as $key => $option ) {
1676                         if ( is_numeric( $key ) ) {
1677                                 $noKeyOptions[$option] = true;
1678                         }
1679                 }
1680
1681                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1682
1683                 $preLimitTail .= $this->makeOrderBy( $options );
1684
1685                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1686                         $postLimitTail .= ' FOR UPDATE';
1687                 }
1688
1689                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1690                         $postLimitTail .= ' LOCK IN SHARE MODE';
1691                 }
1692
1693                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1694                         $startOpts .= 'DISTINCT';
1695                 }
1696
1697                 # Various MySQL extensions
1698                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1699                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1700                 }
1701
1702                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1703                         $startOpts .= ' HIGH_PRIORITY';
1704                 }
1705
1706                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1707                         $startOpts .= ' SQL_BIG_RESULT';
1708                 }
1709
1710                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1711                         $startOpts .= ' SQL_BUFFER_RESULT';
1712                 }
1713
1714                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1715                         $startOpts .= ' SQL_SMALL_RESULT';
1716                 }
1717
1718                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1719                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1720                 }
1721
1722                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1723                         $startOpts .= ' SQL_CACHE';
1724                 }
1725
1726                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1727                         $startOpts .= ' SQL_NO_CACHE';
1728                 }
1729
1730                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1731                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1732                 } else {
1733                         $useIndex = '';
1734                 }
1735                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1736                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1737                 } else {
1738                         $ignoreIndex = '';
1739                 }
1740
1741                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1742         }
1743
1744         /**
1745          * Returns an optional GROUP BY with an optional HAVING
1746          *
1747          * @param array $options Associative array of options
1748          * @return string
1749          * @see Database::select()
1750          * @since 1.21
1751          */
1752         protected function makeGroupByWithHaving( $options ) {
1753                 $sql = '';
1754                 if ( isset( $options['GROUP BY'] ) ) {
1755                         $gb = is_array( $options['GROUP BY'] )
1756                                 ? implode( ',', $options['GROUP BY'] )
1757                                 : $options['GROUP BY'];
1758                         $sql .= ' GROUP BY ' . $gb;
1759                 }
1760                 if ( isset( $options['HAVING'] ) ) {
1761                         $having = is_array( $options['HAVING'] )
1762                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1763                                 : $options['HAVING'];
1764                         $sql .= ' HAVING ' . $having;
1765                 }
1766
1767                 return $sql;
1768         }
1769
1770         /**
1771          * Returns an optional ORDER BY
1772          *
1773          * @param array $options Associative array of options
1774          * @return string
1775          * @see Database::select()
1776          * @since 1.21
1777          */
1778         protected function makeOrderBy( $options ) {
1779                 if ( isset( $options['ORDER BY'] ) ) {
1780                         $ob = is_array( $options['ORDER BY'] )
1781                                 ? implode( ',', $options['ORDER BY'] )
1782                                 : $options['ORDER BY'];
1783
1784                         return ' ORDER BY ' . $ob;
1785                 }
1786
1787                 return '';
1788         }
1789
1790         public function select(
1791                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1792         ) {
1793                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1794
1795                 return $this->query( $sql, $fname );
1796         }
1797
1798         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1799                 $options = [], $join_conds = []
1800         ) {
1801                 if ( is_array( $vars ) ) {
1802                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1803                 } else {
1804                         $fields = $vars;
1805                 }
1806
1807                 $options = (array)$options;
1808                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1809                         ? $options['USE INDEX']
1810                         : [];
1811                 $ignoreIndexes = (
1812                         isset( $options['IGNORE INDEX'] ) &&
1813                         is_array( $options['IGNORE INDEX'] )
1814                 )
1815                         ? $options['IGNORE INDEX']
1816                         : [];
1817
1818                 if (
1819                         $this->selectOptionsIncludeLocking( $options ) &&
1820                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1821                 ) {
1822                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1823                         // functions. Discourage use of such queries to encourage compatibility.
1824                         call_user_func(
1825                                 $this->deprecationLogger,
1826                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)"
1827                         );
1828                 }
1829
1830                 if ( is_array( $table ) ) {
1831                         $from = ' FROM ' .
1832                                 $this->tableNamesWithIndexClauseOrJOIN(
1833                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1834                 } elseif ( $table != '' ) {
1835                         $from = ' FROM ' .
1836                                 $this->tableNamesWithIndexClauseOrJOIN(
1837                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1838                 } else {
1839                         $from = '';
1840                 }
1841
1842                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1843                         $this->makeSelectOptions( $options );
1844
1845                 if ( is_array( $conds ) ) {
1846                         $conds = $this->makeList( $conds, self::LIST_AND );
1847                 }
1848
1849                 if ( $conds === null || $conds === false ) {
1850                         $this->queryLogger->warning(
1851                                 __METHOD__
1852                                 . ' called from '
1853                                 . $fname
1854                                 . ' with incorrect parameters: $conds must be a string or an array'
1855                         );
1856                         $conds = '';
1857                 }
1858
1859                 if ( $conds === '' || $conds === '*' ) {
1860                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1861                 } elseif ( is_string( $conds ) ) {
1862                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1863                                 "WHERE $conds $preLimitTail";
1864                 } else {
1865                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1866                 }
1867
1868                 if ( isset( $options['LIMIT'] ) ) {
1869                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1870                                 $options['OFFSET'] ?? false );
1871                 }
1872                 $sql = "$sql $postLimitTail";
1873
1874                 if ( isset( $options['EXPLAIN'] ) ) {
1875                         $sql = 'EXPLAIN ' . $sql;
1876                 }
1877
1878                 return $sql;
1879         }
1880
1881         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1882                 $options = [], $join_conds = []
1883         ) {
1884                 $options = (array)$options;
1885                 $options['LIMIT'] = 1;
1886
1887                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1888                 if ( $res === false ) {
1889                         throw new DBUnexpectedError( $this, "Got false from select()" );
1890                 }
1891
1892                 if ( !$this->numRows( $res ) ) {
1893                         return false;
1894                 }
1895
1896                 return $this->fetchObject( $res );
1897         }
1898
1899         public function estimateRowCount(
1900                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1901         ) {
1902                 $conds = $this->normalizeConditions( $conds, $fname );
1903                 $column = $this->extractSingleFieldFromList( $var );
1904                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1905                         $conds[] = "$column IS NOT NULL";
1906                 }
1907
1908                 $res = $this->select(
1909                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1910                 );
1911                 $row = $res ? $this->fetchRow( $res ) : [];
1912
1913                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1914         }
1915
1916         public function selectRowCount(
1917                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1918         ) {
1919                 $conds = $this->normalizeConditions( $conds, $fname );
1920                 $column = $this->extractSingleFieldFromList( $var );
1921                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1922                         $conds[] = "$column IS NOT NULL";
1923                 }
1924
1925                 $res = $this->select(
1926                         [
1927                                 'tmp_count' => $this->buildSelectSubquery(
1928                                         $tables,
1929                                         '1',
1930                                         $conds,
1931                                         $fname,
1932                                         $options,
1933                                         $join_conds
1934                                 )
1935                         ],
1936                         [ 'rowcount' => 'COUNT(*)' ],
1937                         [],
1938                         $fname
1939                 );
1940                 $row = $res ? $this->fetchRow( $res ) : [];
1941
1942                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1943         }
1944
1945         /**
1946          * @param string|array $options
1947          * @return bool
1948          */
1949         private function selectOptionsIncludeLocking( $options ) {
1950                 $options = (array)$options;
1951                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1952                         if ( in_array( $lock, $options, true ) ) {
1953                                 return true;
1954                         }
1955                 }
1956
1957                 return false;
1958         }
1959
1960         /**
1961          * @param array|string $fields
1962          * @param array|string $options
1963          * @return bool
1964          */
1965         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1966                 foreach ( (array)$options as $key => $value ) {
1967                         if ( is_string( $key ) ) {
1968                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1969                                         return true;
1970                                 }
1971                         } elseif ( is_string( $value ) ) {
1972                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1973                                         return true;
1974                                 }
1975                         }
1976                 }
1977
1978                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1979                 foreach ( (array)$fields as $field ) {
1980                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1981                                 return true;
1982                         }
1983                 }
1984
1985                 return false;
1986         }
1987
1988         /**
1989          * @param array|string $conds
1990          * @param string $fname
1991          * @return array
1992          */
1993         final protected function normalizeConditions( $conds, $fname ) {
1994                 if ( $conds === null || $conds === false ) {
1995                         $this->queryLogger->warning(
1996                                 __METHOD__
1997                                 . ' called from '
1998                                 . $fname
1999                                 . ' with incorrect parameters: $conds must be a string or an array'
2000                         );
2001                         $conds = '';
2002                 }
2003
2004                 if ( !is_array( $conds ) ) {
2005                         $conds = ( $conds === '' ) ? [] : [ $conds ];
2006                 }
2007
2008                 return $conds;
2009         }
2010
2011         /**
2012          * @param array|string $var Field parameter in the style of select()
2013          * @return string|null Column name or null; ignores aliases
2014          * @throws DBUnexpectedError Errors out if multiple columns are given
2015          */
2016         final protected function extractSingleFieldFromList( $var ) {
2017                 if ( is_array( $var ) ) {
2018                         if ( !$var ) {
2019                                 $column = null;
2020                         } elseif ( count( $var ) == 1 ) {
2021                                 $column = $var[0] ?? reset( $var );
2022                         } else {
2023                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns' );
2024                         }
2025                 } else {
2026                         $column = $var;
2027                 }
2028
2029                 return $column;
2030         }
2031
2032         public function lockForUpdate(
2033                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
2034         ) {
2035                 if ( !$this->trxLevel() && !$this->getFlag( self::DBO_TRX ) ) {
2036                         throw new DBUnexpectedError(
2037                                 $this,
2038                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
2039                         );
2040                 }
2041
2042                 $options = (array)$options;
2043                 $options[] = 'FOR UPDATE';
2044
2045                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
2046         }
2047
2048         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
2049                 $info = $this->fieldInfo( $table, $field );
2050
2051                 return (bool)$info;
2052         }
2053
2054         public function indexExists( $table, $index, $fname = __METHOD__ ) {
2055                 if ( !$this->tableExists( $table ) ) {
2056                         return null;
2057                 }
2058
2059                 $info = $this->indexInfo( $table, $index, $fname );
2060                 if ( is_null( $info ) ) {
2061                         return null;
2062                 } else {
2063                         return $info !== false;
2064                 }
2065         }
2066
2067         abstract public function tableExists( $table, $fname = __METHOD__ );
2068
2069         public function indexUnique( $table, $index ) {
2070                 $indexInfo = $this->indexInfo( $table, $index );
2071
2072                 if ( !$indexInfo ) {
2073                         return null;
2074                 }
2075
2076                 return !$indexInfo[0]->Non_unique;
2077         }
2078
2079         /**
2080          * Helper for Database::insert().
2081          *
2082          * @param array $options
2083          * @return string
2084          */
2085         protected function makeInsertOptions( $options ) {
2086                 return implode( ' ', $options );
2087         }
2088
2089         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2090                 # No rows to insert, easy just return now
2091                 if ( !count( $a ) ) {
2092                         return true;
2093                 }
2094
2095                 $table = $this->tableName( $table );
2096
2097                 if ( !is_array( $options ) ) {
2098                         $options = [ $options ];
2099                 }
2100
2101                 $options = $this->makeInsertOptions( $options );
2102
2103                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2104                         $multi = true;
2105                         $keys = array_keys( $a[0] );
2106                 } else {
2107                         $multi = false;
2108                         $keys = array_keys( $a );
2109                 }
2110
2111                 $sql = 'INSERT ' . $options .
2112                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2113
2114                 if ( $multi ) {
2115                         $first = true;
2116                         foreach ( $a as $row ) {
2117                                 if ( $first ) {
2118                                         $first = false;
2119                                 } else {
2120                                         $sql .= ',';
2121                                 }
2122                                 $sql .= '(' . $this->makeList( $row ) . ')';
2123                         }
2124                 } else {
2125                         $sql .= '(' . $this->makeList( $a ) . ')';
2126                 }
2127
2128                 $this->query( $sql, $fname );
2129
2130                 return true;
2131         }
2132
2133         /**
2134          * Make UPDATE options array for Database::makeUpdateOptions
2135          *
2136          * @param array $options
2137          * @return array
2138          */
2139         protected function makeUpdateOptionsArray( $options ) {
2140                 if ( !is_array( $options ) ) {
2141                         $options = [ $options ];
2142                 }
2143
2144                 $opts = [];
2145
2146                 if ( in_array( 'IGNORE', $options ) ) {
2147                         $opts[] = 'IGNORE';
2148                 }
2149
2150                 return $opts;
2151         }
2152
2153         /**
2154          * Make UPDATE options for the Database::update function
2155          *
2156          * @param array $options The options passed to Database::update
2157          * @return string
2158          */
2159         protected function makeUpdateOptions( $options ) {
2160                 $opts = $this->makeUpdateOptionsArray( $options );
2161
2162                 return implode( ' ', $opts );
2163         }
2164
2165         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2166                 $table = $this->tableName( $table );
2167                 $opts = $this->makeUpdateOptions( $options );
2168                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2169
2170                 if ( $conds !== [] && $conds !== '*' ) {
2171                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2172                 }
2173
2174                 $this->query( $sql, $fname );
2175
2176                 return true;
2177         }
2178
2179         public function makeList( $a, $mode = self::LIST_COMMA ) {
2180                 if ( !is_array( $a ) ) {
2181                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2182                 }
2183
2184                 $first = true;
2185                 $list = '';
2186
2187                 foreach ( $a as $field => $value ) {
2188                         if ( !$first ) {
2189                                 if ( $mode == self::LIST_AND ) {
2190                                         $list .= ' AND ';
2191                                 } elseif ( $mode == self::LIST_OR ) {
2192                                         $list .= ' OR ';
2193                                 } else {
2194                                         $list .= ',';
2195                                 }
2196                         } else {
2197                                 $first = false;
2198                         }
2199
2200                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2201                                 $list .= "($value)";
2202                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2203                                 $list .= "$value";
2204                         } elseif (
2205                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2206                         ) {
2207                                 // Remove null from array to be handled separately if found
2208                                 $includeNull = false;
2209                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2210                                         $includeNull = true;
2211                                         unset( $value[$nullKey] );
2212                                 }
2213                                 if ( count( $value ) == 0 && !$includeNull ) {
2214                                         throw new InvalidArgumentException(
2215                                                 __METHOD__ . ": empty input for field $field" );
2216                                 } elseif ( count( $value ) == 0 ) {
2217                                         // only check if $field is null
2218                                         $list .= "$field IS NULL";
2219                                 } else {
2220                                         // IN clause contains at least one valid element
2221                                         if ( $includeNull ) {
2222                                                 // Group subconditions to ensure correct precedence
2223                                                 $list .= '(';
2224                                         }
2225                                         if ( count( $value ) == 1 ) {
2226                                                 // Special-case single values, as IN isn't terribly efficient
2227                                                 // Don't necessarily assume the single key is 0; we don't
2228                                                 // enforce linear numeric ordering on other arrays here.
2229                                                 $value = array_values( $value )[0];
2230                                                 $list .= $field . " = " . $this->addQuotes( $value );
2231                                         } else {
2232                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2233                                         }
2234                                         // if null present in array, append IS NULL
2235                                         if ( $includeNull ) {
2236                                                 $list .= " OR $field IS NULL)";
2237                                         }
2238                                 }
2239                         } elseif ( $value === null ) {
2240                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2241                                         $list .= "$field IS ";
2242                                 } elseif ( $mode == self::LIST_SET ) {
2243                                         $list .= "$field = ";
2244                                 }
2245                                 $list .= 'NULL';
2246                         } else {
2247                                 if (
2248                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2249                                 ) {
2250                                         $list .= "$field = ";
2251                                 }
2252                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2253                         }
2254                 }
2255
2256                 return $list;
2257         }
2258
2259         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2260                 $conds = [];
2261
2262                 foreach ( $data as $base => $sub ) {
2263                         if ( count( $sub ) ) {
2264                                 $conds[] = $this->makeList(
2265                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2266                                         self::LIST_AND );
2267                         }
2268                 }
2269
2270                 if ( $conds ) {
2271                         return $this->makeList( $conds, self::LIST_OR );
2272                 } else {
2273                         // Nothing to search for...
2274                         return false;
2275                 }
2276         }
2277
2278         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2279                 return $valuename;
2280         }
2281
2282         public function bitNot( $field ) {
2283                 return "(~$field)";
2284         }
2285
2286         public function bitAnd( $fieldLeft, $fieldRight ) {
2287                 return "($fieldLeft & $fieldRight)";
2288         }
2289
2290         public function bitOr( $fieldLeft, $fieldRight ) {
2291                 return "($fieldLeft | $fieldRight)";
2292         }
2293
2294         public function buildConcat( $stringList ) {
2295                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2296         }
2297
2298         public function buildGroupConcatField(
2299                 $delim, $table, $field, $conds = '', $join_conds = []
2300         ) {
2301                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2302
2303                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2304         }
2305
2306         public function buildSubstring( $input, $startPosition, $length = null ) {
2307                 $this->assertBuildSubstringParams( $startPosition, $length );
2308                 $functionBody = "$input FROM $startPosition";
2309                 if ( $length !== null ) {
2310                         $functionBody .= " FOR $length";
2311                 }
2312                 return 'SUBSTRING(' . $functionBody . ')';
2313         }
2314
2315         /**
2316          * Check type and bounds for parameters to self::buildSubstring()
2317          *
2318          * All supported databases have substring functions that behave the same for
2319          * positive $startPosition and non-negative $length, but behaviors differ when
2320          * given 0 or negative $startPosition or negative $length. The simplest
2321          * solution to that is to just forbid those values.
2322          *
2323          * @param int $startPosition
2324          * @param int|null $length
2325          * @since 1.31
2326          */
2327         protected function assertBuildSubstringParams( $startPosition, $length ) {
2328                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2329                         throw new InvalidArgumentException(
2330                                 '$startPosition must be a positive integer'
2331                         );
2332                 }
2333                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2334                         throw new InvalidArgumentException(
2335                                 '$length must be null or an integer greater than or equal to 0'
2336                         );
2337                 }
2338         }
2339
2340         public function buildStringCast( $field ) {
2341                 // In theory this should work for any standards-compliant
2342                 // SQL implementation, although it may not be the best way to do it.
2343                 return "CAST( $field AS CHARACTER )";
2344         }
2345
2346         public function buildIntegerCast( $field ) {
2347                 return 'CAST( ' . $field . ' AS INTEGER )';
2348         }
2349
2350         public function buildSelectSubquery(
2351                 $table, $vars, $conds = '', $fname = __METHOD__,
2352                 $options = [], $join_conds = []
2353         ) {
2354                 return new Subquery(
2355                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2356                 );
2357         }
2358
2359         public function databasesAreIndependent() {
2360                 return false;
2361         }
2362
2363         final public function selectDB( $db ) {
2364                 $this->selectDomain( new DatabaseDomain(
2365                         $db,
2366                         $this->currentDomain->getSchema(),
2367                         $this->currentDomain->getTablePrefix()
2368                 ) );
2369
2370                 return true;
2371         }
2372
2373         final public function selectDomain( $domain ) {
2374                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2375         }
2376
2377         protected function doSelectDomain( DatabaseDomain $domain ) {
2378                 $this->currentDomain = $domain;
2379         }
2380
2381         public function getDBname() {
2382                 return $this->currentDomain->getDatabase();
2383         }
2384
2385         public function getServer() {
2386                 return $this->server;
2387         }
2388
2389         public function tableName( $name, $format = 'quoted' ) {
2390                 if ( $name instanceof Subquery ) {
2391                         throw new DBUnexpectedError(
2392                                 $this,
2393                                 __METHOD__ . ': got Subquery instance when expecting a string'
2394                         );
2395                 }
2396
2397                 # Skip the entire process when we have a string quoted on both ends.
2398                 # Note that we check the end so that we will still quote any use of
2399                 # use of `database`.table. But won't break things if someone wants
2400                 # to query a database table with a dot in the name.
2401                 if ( $this->isQuotedIdentifier( $name ) ) {
2402                         return $name;
2403                 }
2404
2405                 # Lets test for any bits of text that should never show up in a table
2406                 # name. Basically anything like JOIN or ON which are actually part of
2407                 # SQL queries, but may end up inside of the table value to combine
2408                 # sql. Such as how the API is doing.
2409                 # Note that we use a whitespace test rather than a \b test to avoid
2410                 # any remote case where a word like on may be inside of a table name
2411                 # surrounded by symbols which may be considered word breaks.
2412                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2413                         $this->queryLogger->warning(
2414                                 __METHOD__ . ": use of subqueries is not supported this way",
2415                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2416                         );
2417
2418                         return $name;
2419                 }
2420
2421                 # Split database and table into proper variables.
2422                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2423
2424                 # Quote $table and apply the prefix if not quoted.
2425                 # $tableName might be empty if this is called from Database::replaceVars()
2426                 $tableName = "{$prefix}{$table}";
2427                 if ( $format === 'quoted'
2428                         && !$this->isQuotedIdentifier( $tableName )
2429                         && $tableName !== ''
2430                 ) {
2431                         $tableName = $this->addIdentifierQuotes( $tableName );
2432                 }
2433
2434                 # Quote $schema and $database and merge them with the table name if needed
2435                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2436                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2437
2438                 return $tableName;
2439         }
2440
2441         /**
2442          * Get the table components needed for a query given the currently selected database
2443          *
2444          * @param string $name Table name in the form of db.schema.table, db.table, or table
2445          * @return array (DB name or "" for default, schema name, table prefix, table name)
2446          */
2447         protected function qualifiedTableComponents( $name ) {
2448                 # We reverse the explode so that database.table and table both output the correct table.
2449                 $dbDetails = explode( '.', $name, 3 );
2450                 if ( count( $dbDetails ) == 3 ) {
2451                         list( $database, $schema, $table ) = $dbDetails;
2452                         # We don't want any prefix added in this case
2453                         $prefix = '';
2454                 } elseif ( count( $dbDetails ) == 2 ) {
2455                         list( $database, $table ) = $dbDetails;
2456                         # We don't want any prefix added in this case
2457                         $prefix = '';
2458                         # In dbs that support it, $database may actually be the schema
2459                         # but that doesn't affect any of the functionality here
2460                         $schema = '';
2461                 } else {
2462                         list( $table ) = $dbDetails;
2463                         if ( isset( $this->tableAliases[$table] ) ) {
2464                                 $database = $this->tableAliases[$table]['dbname'];
2465                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2466                                         ? $this->tableAliases[$table]['schema']
2467                                         : $this->relationSchemaQualifier();
2468                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2469                                         ? $this->tableAliases[$table]['prefix']
2470                                         : $this->tablePrefix();
2471                         } else {
2472                                 $database = '';
2473                                 $schema = $this->relationSchemaQualifier(); # Default schema
2474                                 $prefix = $this->tablePrefix(); # Default prefix
2475                         }
2476                 }
2477
2478                 return [ $database, $schema, $prefix, $table ];
2479         }
2480
2481         /**
2482          * @param string|null $namespace Database or schema
2483          * @param string $relation Name of table, view, sequence, etc...
2484          * @param string $format One of (raw, quoted)
2485          * @return string Relation name with quoted and merged $namespace as needed
2486          */
2487         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2488                 if ( strlen( $namespace ) ) {
2489                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2490                                 $namespace = $this->addIdentifierQuotes( $namespace );
2491                         }
2492                         $relation = $namespace . '.' . $relation;
2493                 }
2494
2495                 return $relation;
2496         }
2497
2498         public function tableNames() {
2499                 $inArray = func_get_args();
2500                 $retVal = [];
2501
2502                 foreach ( $inArray as $name ) {
2503                         $retVal[$name] = $this->tableName( $name );
2504                 }
2505
2506                 return $retVal;
2507         }
2508
2509         public function tableNamesN() {
2510                 $inArray = func_get_args();
2511                 $retVal = [];
2512
2513                 foreach ( $inArray as $name ) {
2514                         $retVal[] = $this->tableName( $name );
2515                 }
2516
2517                 return $retVal;
2518         }
2519
2520         /**
2521          * Get an aliased table name
2522          *
2523          * This returns strings like "tableName AS newTableName" for aliased tables
2524          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2525          *
2526          * @see Database::tableName()
2527          * @param string|Subquery $table Table name or object with a 'sql' field
2528          * @param string|bool $alias Table alias (optional)
2529          * @return string SQL name for aliased table. Will not alias a table to its own name
2530          */
2531         protected function tableNameWithAlias( $table, $alias = false ) {
2532                 if ( is_string( $table ) ) {
2533                         $quotedTable = $this->tableName( $table );
2534                 } elseif ( $table instanceof Subquery ) {
2535                         $quotedTable = (string)$table;
2536                 } else {
2537                         throw new InvalidArgumentException( "Table must be a string or Subquery" );
2538                 }
2539
2540                 if ( $alias === false || $alias === $table ) {
2541                         if ( $table instanceof Subquery ) {
2542                                 throw new InvalidArgumentException( "Subquery table missing alias" );
2543                         }
2544
2545                         return $quotedTable;
2546                 } else {
2547                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2548                 }
2549         }
2550
2551         /**
2552          * Gets an array of aliased table names
2553          *
2554          * @param array $tables [ [alias] => table ]
2555          * @return string[] See tableNameWithAlias()
2556          */
2557         protected function tableNamesWithAlias( $tables ) {
2558                 $retval = [];
2559                 foreach ( $tables as $alias => $table ) {
2560                         if ( is_numeric( $alias ) ) {
2561                                 $alias = $table;
2562                         }
2563                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2564                 }
2565
2566                 return $retval;
2567         }
2568
2569         /**
2570          * Get an aliased field name
2571          * e.g. fieldName AS newFieldName
2572          *
2573          * @param string $name Field name
2574          * @param string|bool $alias Alias (optional)
2575          * @return string SQL name for aliased field. Will not alias a field to its own name
2576          */
2577         protected function fieldNameWithAlias( $name, $alias = false ) {
2578                 if ( !$alias || (string)$alias === (string)$name ) {
2579                         return $name;
2580                 } else {
2581                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2582                 }
2583         }
2584
2585         /**
2586          * Gets an array of aliased field names
2587          *
2588          * @param array $fields [ [alias] => field ]
2589          * @return string[] See fieldNameWithAlias()
2590          */
2591         protected function fieldNamesWithAlias( $fields ) {
2592                 $retval = [];
2593                 foreach ( $fields as $alias => $field ) {
2594                         if ( is_numeric( $alias ) ) {
2595                                 $alias = $field;
2596                         }
2597                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2598                 }
2599
2600                 return $retval;
2601         }
2602
2603         /**
2604          * Get the aliased table name clause for a FROM clause
2605          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2606          *
2607          * @param array $tables ( [alias] => table )
2608          * @param array $use_index Same as for select()
2609          * @param array $ignore_index Same as for select()
2610          * @param array $join_conds Same as for select()
2611          * @return string
2612          */
2613         protected function tableNamesWithIndexClauseOrJOIN(
2614                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2615         ) {
2616                 $ret = [];
2617                 $retJOIN = [];
2618                 $use_index = (array)$use_index;
2619                 $ignore_index = (array)$ignore_index;
2620                 $join_conds = (array)$join_conds;
2621
2622                 foreach ( $tables as $alias => $table ) {
2623                         if ( !is_string( $alias ) ) {
2624                                 // No alias? Set it equal to the table name
2625                                 $alias = $table;
2626                         }
2627
2628                         if ( is_array( $table ) ) {
2629                                 // A parenthesized group
2630                                 if ( count( $table ) > 1 ) {
2631                                         $joinedTable = '(' .
2632                                                 $this->tableNamesWithIndexClauseOrJOIN(
2633                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2634                                 } else {
2635                                         // Degenerate case
2636                                         $innerTable = reset( $table );
2637                                         $innerAlias = key( $table );
2638                                         $joinedTable = $this->tableNameWithAlias(
2639                                                 $innerTable,
2640                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2641                                         );
2642                                 }
2643                         } else {
2644                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2645                         }
2646
2647                         // Is there a JOIN clause for this table?
2648                         if ( isset( $join_conds[$alias] ) ) {
2649                                 list( $joinType, $conds ) = $join_conds[$alias];
2650                                 $tableClause = $joinType;
2651                                 $tableClause .= ' ' . $joinedTable;
2652                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2653                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2654                                         if ( $use != '' ) {
2655                                                 $tableClause .= ' ' . $use;
2656                                         }
2657                                 }
2658                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2659                                         $ignore = $this->ignoreIndexClause(
2660                                                 implode( ',', (array)$ignore_index[$alias] ) );
2661                                         if ( $ignore != '' ) {
2662                                                 $tableClause .= ' ' . $ignore;
2663                                         }
2664                                 }
2665                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2666                                 if ( $on != '' ) {
2667                                         $tableClause .= ' ON (' . $on . ')';
2668                                 }
2669
2670                                 $retJOIN[] = $tableClause;
2671                         } elseif ( isset( $use_index[$alias] ) ) {
2672                                 // Is there an INDEX clause for this table?
2673                                 $tableClause = $joinedTable;
2674                                 $tableClause .= ' ' . $this->useIndexClause(
2675                                                 implode( ',', (array)$use_index[$alias] )
2676                                         );
2677
2678                                 $ret[] = $tableClause;
2679                         } elseif ( isset( $ignore_index[$alias] ) ) {
2680                                 // Is there an INDEX clause for this table?
2681                                 $tableClause = $joinedTable;
2682                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2683                                                 implode( ',', (array)$ignore_index[$alias] )
2684                                         );
2685
2686                                 $ret[] = $tableClause;
2687                         } else {
2688                                 $tableClause = $joinedTable;
2689
2690                                 $ret[] = $tableClause;
2691                         }
2692                 }
2693
2694                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2695                 $implicitJoins = implode( ',', $ret );
2696                 $explicitJoins = implode( ' ', $retJOIN );
2697
2698                 // Compile our final table clause
2699                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2700         }
2701
2702         /**
2703          * Allows for index remapping in queries where this is not consistent across DBMS
2704          *
2705          * @param string $index
2706          * @return string
2707          */
2708         protected function indexName( $index ) {
2709                 return $this->indexAliases[$index] ?? $index;
2710         }
2711
2712         public function addQuotes( $s ) {
2713                 if ( $s instanceof Blob ) {
2714                         $s = $s->fetch();
2715                 }
2716                 if ( $s === null ) {
2717                         return 'NULL';
2718                 } elseif ( is_bool( $s ) ) {
2719                         return (int)$s;
2720                 } else {
2721                         # This will also quote numeric values. This should be harmless,
2722                         # and protects against weird problems that occur when they really
2723                         # _are_ strings such as article titles and string->number->string
2724                         # conversion is not 1:1.
2725                         return "'" . $this->strencode( $s ) . "'";
2726                 }
2727         }
2728
2729         public function addIdentifierQuotes( $s ) {
2730                 return '"' . str_replace( '"', '""', $s ) . '"';
2731         }
2732
2733         /**
2734          * Returns if the given identifier looks quoted or not according to
2735          * the database convention for quoting identifiers .
2736          *
2737          * @note Do not use this to determine if untrusted input is safe.
2738          *   A malicious user can trick this function.
2739          * @param string $name
2740          * @return bool
2741          */
2742         public function isQuotedIdentifier( $name ) {
2743                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2744         }
2745
2746         /**
2747          * @param string $s
2748          * @param string $escapeChar
2749          * @return string
2750          */
2751         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2752                 return str_replace( [ $escapeChar, '%', '_' ],
2753                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2754                         $s );
2755         }
2756
2757         public function buildLike( $param, ...$params ) {
2758                 if ( is_array( $param ) ) {
2759                         $params = $param;
2760                 } else {
2761                         $params = func_get_args();
2762                 }
2763
2764                 $s = '';
2765
2766                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2767                 // may escape backslashes, creating problems of double escaping. The `
2768                 // character has good cross-DBMS compatibility, avoiding special operators
2769                 // in MS SQL like ^ and %
2770                 $escapeChar = '`';
2771
2772                 foreach ( $params as $value ) {
2773                         if ( $value instanceof LikeMatch ) {
2774                                 $s .= $value->toString();
2775                         } else {
2776                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2777                         }
2778                 }
2779
2780                 return ' LIKE ' .
2781                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2782         }
2783
2784         public function anyChar() {
2785                 return new LikeMatch( '_' );
2786         }
2787
2788         public function anyString() {
2789                 return new LikeMatch( '%' );
2790         }
2791
2792         public function nextSequenceValue( $seqName ) {
2793                 return null;
2794         }
2795
2796         /**
2797          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2798          * is only needed because a) MySQL must be as efficient as possible due to
2799          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2800          * which index to pick. Anyway, other databases might have different
2801          * indexes on a given table. So don't bother overriding this unless you're
2802          * MySQL.
2803          * @param string $index
2804          * @return string
2805          */
2806         public function useIndexClause( $index ) {
2807                 return '';
2808         }
2809
2810         /**
2811          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2812          * is only needed because a) MySQL must be as efficient as possible due to
2813          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2814          * which index to pick. Anyway, other databases might have different
2815          * indexes on a given table. So don't bother overriding this unless you're
2816          * MySQL.
2817          * @param string $index
2818          * @return string
2819          */
2820         public function ignoreIndexClause( $index ) {
2821                 return '';
2822         }
2823
2824         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2825                 if ( count( $rows ) == 0 ) {
2826                         return;
2827                 }
2828
2829                 $uniqueIndexes = (array)$uniqueIndexes;
2830                 // Single row case
2831                 if ( !is_array( reset( $rows ) ) ) {
2832                         $rows = [ $rows ];
2833                 }
2834
2835                 try {
2836                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2837                         $affectedRowCount = 0;
2838                         foreach ( $rows as $row ) {
2839                                 // Delete rows which collide with this one
2840                                 $indexWhereClauses = [];
2841                                 foreach ( $uniqueIndexes as $index ) {
2842                                         $indexColumns = (array)$index;
2843                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2844                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2845                                                 throw new DBUnexpectedError(
2846                                                         $this,
2847                                                         'New record does not provide all values for unique key (' .
2848                                                         implode( ', ', $indexColumns ) . ')'
2849                                                 );
2850                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2851                                                 throw new DBUnexpectedError(
2852                                                         $this,
2853                                                         'New record has a null value for unique key (' .
2854                                                         implode( ', ', $indexColumns ) . ')'
2855                                                 );
2856                                         }
2857                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2858                                 }
2859
2860                                 if ( $indexWhereClauses ) {
2861                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2862                                         $affectedRowCount += $this->affectedRows();
2863                                 }
2864
2865                                 // Now insert the row
2866                                 $this->insert( $table, $row, $fname );
2867                                 $affectedRowCount += $this->affectedRows();
2868                         }
2869                         $this->endAtomic( $fname );
2870                         $this->affectedRowCount = $affectedRowCount;
2871                 } catch ( Exception $e ) {
2872                         $this->cancelAtomic( $fname );
2873                         throw $e;
2874                 }
2875         }
2876
2877         /**
2878          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2879          * statement.
2880          *
2881          * @param string $table Table name
2882          * @param array|string $rows Row(s) to insert
2883          * @param string $fname Caller function name
2884          */
2885         protected function nativeReplace( $table, $rows, $fname ) {
2886                 $table = $this->tableName( $table );
2887
2888                 # Single row case
2889                 if ( !is_array( reset( $rows ) ) ) {
2890                         $rows = [ $rows ];
2891                 }
2892
2893                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2894                 $first = true;
2895
2896                 foreach ( $rows as $row ) {
2897                         if ( $first ) {
2898                                 $first = false;
2899                         } else {
2900                                 $sql .= ',';
2901                         }
2902
2903                         $sql .= '(' . $this->makeList( $row ) . ')';
2904                 }
2905
2906                 $this->query( $sql, $fname );
2907         }
2908
2909         public function upsert( $table, array $rows, $uniqueIndexes, array $set,
2910                 $fname = __METHOD__
2911         ) {
2912                 if ( $rows === [] ) {
2913                         return true; // nothing to do
2914                 }
2915
2916                 $uniqueIndexes = (array)$uniqueIndexes;
2917                 if ( !is_array( reset( $rows ) ) ) {
2918                         $rows = [ $rows ];
2919                 }
2920
2921                 if ( count( $uniqueIndexes ) ) {
2922                         $clauses = []; // list WHERE clauses that each identify a single row
2923                         foreach ( $rows as $row ) {
2924                                 foreach ( $uniqueIndexes as $index ) {
2925                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2926                                         $rowKey = []; // unique key to this row
2927                                         foreach ( $index as $column ) {
2928                                                 $rowKey[$column] = $row[$column];
2929                                         }
2930                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2931                                 }
2932                         }
2933                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2934                 } else {
2935                         $where = false;
2936                 }
2937
2938                 $affectedRowCount = 0;
2939                 try {
2940                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2941                         # Update any existing conflicting row(s)
2942                         if ( $where !== false ) {
2943                                 $this->update( $table, $set, $where, $fname );
2944                                 $affectedRowCount += $this->affectedRows();
2945                         }
2946                         # Now insert any non-conflicting row(s)
2947                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
2948                         $affectedRowCount += $this->affectedRows();
2949                         $this->endAtomic( $fname );
2950                         $this->affectedRowCount = $affectedRowCount;
2951                 } catch ( Exception $e ) {
2952                         $this->cancelAtomic( $fname );
2953                         throw $e;
2954                 }
2955
2956                 return true;
2957         }
2958
2959         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2960                 $fname = __METHOD__
2961         ) {
2962                 if ( !$conds ) {
2963                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2964                 }
2965
2966                 $delTable = $this->tableName( $delTable );
2967                 $joinTable = $this->tableName( $joinTable );
2968                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2969                 if ( $conds != '*' ) {
2970                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2971                 }
2972                 $sql .= ')';
2973
2974                 $this->query( $sql, $fname );
2975         }
2976
2977         public function textFieldSize( $table, $field ) {
2978                 $table = $this->tableName( $table );
2979                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\"";
2980                 $res = $this->query( $sql, __METHOD__ );
2981                 $row = $this->fetchObject( $res );
2982
2983                 $m = [];
2984
2985                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2986                         $size = $m[1];
2987                 } else {
2988                         $size = -1;
2989                 }
2990
2991                 return $size;
2992         }
2993
2994         public function delete( $table, $conds, $fname = __METHOD__ ) {
2995                 if ( !$conds ) {
2996                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2997                 }
2998
2999                 $table = $this->tableName( $table );
3000                 $sql = "DELETE FROM $table";
3001
3002                 if ( $conds != '*' ) {
3003                         if ( is_array( $conds ) ) {
3004                                 $conds = $this->makeList( $conds, self::LIST_AND );
3005                         }
3006                         $sql .= ' WHERE ' . $conds;
3007                 }
3008
3009                 $this->query( $sql, $fname );
3010
3011                 return true;
3012         }
3013
3014         final public function insertSelect(
3015                 $destTable, $srcTable, $varMap, $conds,
3016                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3017         ) {
3018                 static $hints = [ 'NO_AUTO_COLUMNS' ];
3019
3020                 $insertOptions = (array)$insertOptions;
3021                 $selectOptions = (array)$selectOptions;
3022
3023                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
3024                         // For massive migrations with downtime, we don't want to select everything
3025                         // into memory and OOM, so do all this native on the server side if possible.
3026                         $this->nativeInsertSelect(
3027                                 $destTable,
3028                                 $srcTable,
3029                                 $varMap,
3030                                 $conds,
3031                                 $fname,
3032                                 array_diff( $insertOptions, $hints ),
3033                                 $selectOptions,
3034                                 $selectJoinConds
3035                         );
3036                 } else {
3037                         $this->nonNativeInsertSelect(
3038                                 $destTable,
3039                                 $srcTable,
3040                                 $varMap,
3041                                 $conds,
3042                                 $fname,
3043                                 array_diff( $insertOptions, $hints ),
3044                                 $selectOptions,
3045                                 $selectJoinConds
3046                         );
3047                 }
3048
3049                 return true;
3050         }
3051
3052         /**
3053          * @param array $insertOptions INSERT options
3054          * @param array $selectOptions SELECT options
3055          * @return bool Whether an INSERT SELECT with these options will be replication safe
3056          * @since 1.31
3057          */
3058         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3059                 return true;
3060         }
3061
3062         /**
3063          * Implementation of insertSelect() based on select() and insert()
3064          *
3065          * @see IDatabase::insertSelect()
3066          * @since 1.30
3067          * @param string $destTable
3068          * @param string|array $srcTable
3069          * @param array $varMap
3070          * @param array $conds
3071          * @param string $fname
3072          * @param array $insertOptions
3073          * @param array $selectOptions
3074          * @param array $selectJoinConds
3075          */
3076         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3077                 $fname = __METHOD__,
3078                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3079         ) {
3080                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3081                 // on only the master (without needing row-based-replication). It also makes it easy to
3082                 // know how big the INSERT is going to be.
3083                 $fields = [];
3084                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3085                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3086                 }
3087                 $selectOptions[] = 'FOR UPDATE';
3088                 $res = $this->select(
3089                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3090                 );
3091                 if ( !$res ) {
3092                         return;
3093                 }
3094
3095                 try {
3096                         $affectedRowCount = 0;
3097                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3098                         $rows = [];
3099                         $ok = true;
3100                         foreach ( $res as $row ) {
3101                                 $rows[] = (array)$row;
3102
3103                                 // Avoid inserts that are too huge
3104                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3105                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3106                                         if ( !$ok ) {
3107                                                 break;
3108                                         }
3109                                         $affectedRowCount += $this->affectedRows();
3110                                         $rows = [];
3111                                 }
3112                         }
3113                         if ( $rows && $ok ) {
3114                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3115                                 if ( $ok ) {
3116                                         $affectedRowCount += $this->affectedRows();
3117                                 }
3118                         }
3119                         if ( $ok ) {
3120                                 $this->endAtomic( $fname );
3121                                 $this->affectedRowCount = $affectedRowCount;
3122                         } else {
3123                                 $this->cancelAtomic( $fname );
3124                         }
3125                 } catch ( Exception $e ) {
3126                         $this->cancelAtomic( $fname );
3127                         throw $e;
3128                 }
3129         }
3130
3131         /**
3132          * Native server-side implementation of insertSelect() for situations where
3133          * we don't want to select everything into memory
3134          *
3135          * @see IDatabase::insertSelect()
3136          * @param string $destTable
3137          * @param string|array $srcTable
3138          * @param array $varMap
3139          * @param array $conds
3140          * @param string $fname
3141          * @param array $insertOptions
3142          * @param array $selectOptions
3143          * @param array $selectJoinConds
3144          */
3145         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3146                 $fname = __METHOD__,
3147                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3148         ) {
3149                 $destTable = $this->tableName( $destTable );
3150
3151                 if ( !is_array( $insertOptions ) ) {
3152                         $insertOptions = [ $insertOptions ];
3153                 }
3154
3155                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3156
3157                 $selectSql = $this->selectSQLText(
3158                         $srcTable,
3159                         array_values( $varMap ),
3160                         $conds,
3161                         $fname,
3162                         $selectOptions,
3163                         $selectJoinConds
3164                 );
3165
3166                 $sql = "INSERT $insertOptions" .
3167                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3168                         $selectSql;
3169
3170                 $this->query( $sql, $fname );
3171         }
3172
3173         public function limitResult( $sql, $limit, $offset = false ) {
3174                 if ( !is_numeric( $limit ) ) {
3175                         throw new DBUnexpectedError(
3176                                 $this,
3177                                 "Invalid non-numeric limit passed to " . __METHOD__
3178                         );
3179                 }
3180                 // This version works in MySQL and SQLite. It will very likely need to be
3181                 // overridden for most other RDBMS subclasses.
3182                 return "$sql LIMIT "
3183                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3184                         . "{$limit} ";
3185         }
3186
3187         public function unionSupportsOrderAndLimit() {
3188                 return true; // True for almost every DB supported
3189         }
3190
3191         public function unionQueries( $sqls, $all ) {
3192                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3193
3194                 return '(' . implode( $glue, $sqls ) . ')';
3195         }
3196
3197         public function unionConditionPermutations(
3198                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3199                 $options = [], $join_conds = []
3200         ) {
3201                 // First, build the Cartesian product of $permute_conds
3202                 $conds = [ [] ];
3203                 foreach ( $permute_conds as $field => $values ) {
3204                         if ( !$values ) {
3205                                 // Skip empty $values
3206                                 continue;
3207                         }
3208                         $values = array_unique( $values ); // For sanity
3209                         $newConds = [];
3210                         foreach ( $conds as $cond ) {
3211                                 foreach ( $values as $value ) {
3212                                         $cond[$field] = $value;
3213                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3214                                 }
3215                         }
3216                         $conds = $newConds;
3217                 }
3218
3219                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3220
3221                 // If there's just one condition and no subordering, hand off to
3222                 // selectSQLText directly.
3223                 if ( count( $conds ) === 1 &&
3224                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3225                 ) {
3226                         return $this->selectSQLText(
3227                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3228                         );
3229                 }
3230
3231                 // Otherwise, we need to pull out the order and limit to apply after
3232                 // the union. Then build the SQL queries for each set of conditions in
3233                 // $conds. Then union them together (using UNION ALL, because the
3234                 // product *should* already be distinct).
3235                 $orderBy = $this->makeOrderBy( $options );
3236                 $limit = $options['LIMIT'] ?? null;
3237                 $offset = $options['OFFSET'] ?? false;
3238                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3239                 if ( !$this->unionSupportsOrderAndLimit() ) {
3240                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3241                 } else {
3242                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3243                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3244                         }
3245                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3246                                 // We need to increase the limit by the offset rather than
3247                                 // using the offset directly, otherwise it'll skip incorrectly
3248                                 // in the subqueries.
3249                                 $options['LIMIT'] = $limit + $offset;
3250                                 unset( $options['OFFSET'] );
3251                         }
3252                 }
3253
3254                 $sqls = [];
3255                 foreach ( $conds as $cond ) {
3256                         $sqls[] = $this->selectSQLText(
3257                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3258                         );
3259                 }
3260                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3261                 if ( $limit !== null ) {
3262                         $sql = $this->limitResult( $sql, $limit, $offset );
3263                 }
3264
3265                 return $sql;
3266         }
3267
3268         public function conditional( $cond, $trueVal, $falseVal ) {
3269                 if ( is_array( $cond ) ) {
3270                         $cond = $this->makeList( $cond, self::LIST_AND );
3271                 }
3272
3273                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3274         }
3275
3276         public function strreplace( $orig, $old, $new ) {
3277                 return "REPLACE({$orig}, {$old}, {$new})";
3278         }
3279
3280         public function getServerUptime() {
3281                 return 0;
3282         }
3283
3284         public function wasDeadlock() {
3285                 return false;
3286         }
3287
3288         public function wasLockTimeout() {
3289                 return false;
3290         }
3291
3292         public function wasConnectionLoss() {
3293                 return $this->wasConnectionError( $this->lastErrno() );
3294         }
3295
3296         public function wasReadOnlyError() {
3297                 return false;
3298         }
3299
3300         public function wasErrorReissuable() {
3301                 return (
3302                         $this->wasDeadlock() ||
3303                         $this->wasLockTimeout() ||
3304                         $this->wasConnectionLoss()
3305                 );
3306         }
3307
3308         /**
3309          * Do not use this method outside of Database/DBError classes
3310          *
3311          * @param int|string $errno
3312          * @return bool Whether the given query error was a connection drop
3313          */
3314         public function wasConnectionError( $errno ) {
3315                 return false;
3316         }
3317
3318         /**
3319          * @return bool Whether it is known that the last query error only caused statement rollback
3320          * @note This is for backwards compatibility for callers catching DBError exceptions in
3321          *   order to ignore problems like duplicate key errors or foriegn key violations
3322          * @since 1.31
3323          */
3324         protected function wasKnownStatementRollbackError() {
3325                 return false; // don't know; it could have caused a transaction rollback
3326         }
3327
3328         public function deadlockLoop() {
3329                 $args = func_get_args();
3330                 $function = array_shift( $args );
3331                 $tries = self::$DEADLOCK_TRIES;
3332
3333                 $this->begin( __METHOD__ );
3334
3335                 $retVal = null;
3336                 /** @var Exception $e */
3337                 $e = null;
3338                 do {
3339                         try {
3340                                 $retVal = $function( ...$args );
3341                                 break;
3342                         } catch ( DBQueryError $e ) {
3343                                 if ( $this->wasDeadlock() ) {
3344                                         // Retry after a randomized delay
3345                                         usleep( mt_rand( self::$DEADLOCK_DELAY_MIN, self::$DEADLOCK_DELAY_MAX ) );
3346                                 } else {
3347                                         // Throw the error back up
3348                                         throw $e;
3349                                 }
3350                         }
3351                 } while ( --$tries > 0 );
3352
3353                 if ( $tries <= 0 ) {
3354                         // Too many deadlocks; give up
3355                         $this->rollback( __METHOD__ );
3356                         throw $e;
3357                 } else {
3358                         $this->commit( __METHOD__ );
3359
3360                         return $retVal;
3361                 }
3362         }
3363
3364         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3365                 # Real waits are implemented in the subclass.
3366                 return 0;
3367         }
3368
3369         public function getReplicaPos() {
3370                 # Stub
3371                 return false;
3372         }
3373
3374         public function getMasterPos() {
3375                 # Stub
3376                 return false;
3377         }
3378
3379         public function serverIsReadOnly() {
3380                 return false;
3381         }
3382
3383         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3384                 if ( !$this->trxLevel() ) {
3385                         throw new DBUnexpectedError( $this, "No transaction is active" );
3386                 }
3387                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3388         }
3389
3390         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3391                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3392                         // Start an implicit transaction similar to how query() does
3393                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3394                         $this->trxAutomatic = true;
3395                 }
3396
3397                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3398                 if ( !$this->trxLevel() ) {
3399                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3400                 }
3401         }
3402
3403         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3404                 $this->onTransactionCommitOrIdle( $callback, $fname );
3405         }
3406
3407         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3408                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3409                         // Start an implicit transaction similar to how query() does
3410                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3411                         $this->trxAutomatic = true;
3412                 }
3413
3414                 if ( $this->trxLevel() ) {
3415                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3416                 } else {
3417                         // No transaction is active nor will start implicitly, so make one for this callback
3418                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3419                         try {
3420                                 $callback( $this );
3421                                 $this->endAtomic( __METHOD__ );
3422                         } catch ( Exception $e ) {
3423                                 $this->cancelAtomic( __METHOD__ );
3424                                 throw $e;
3425                         }
3426                 }
3427         }
3428
3429         final public function onAtomicSectionCancel( callable $callback, $fname = __METHOD__ ) {
3430                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3431                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3432                 }
3433                 $this->trxSectionCancelCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3434         }
3435
3436         /**
3437          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3438          */
3439         private function currentAtomicSectionId() {
3440                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
3441                         $levelInfo = end( $this->trxAtomicLevels );
3442
3443                         return $levelInfo[1];
3444                 }
3445
3446                 return null;
3447         }
3448
3449         /**
3450          * Hoist callback ownership for callbacks in a section to a parent section.
3451          * All callbacks should have an owner that is present in trxAtomicLevels.
3452          * @param AtomicSectionIdentifier $old
3453          * @param AtomicSectionIdentifier $new
3454          */
3455         private function reassignCallbacksForSection(
3456                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3457         ) {
3458                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3459                         if ( $info[2] === $old ) {
3460                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3461                         }
3462                 }
3463                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3464                         if ( $info[2] === $old ) {
3465                                 $this->trxIdleCallbacks[$key][2] = $new;
3466                         }
3467                 }
3468                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3469                         if ( $info[2] === $old ) {
3470                                 $this->trxEndCallbacks[$key][2] = $new;
3471                         }
3472                 }
3473                 foreach ( $this->trxSectionCancelCallbacks as $key => $info ) {
3474                         if ( $info[2] === $old ) {
3475                                 $this->trxSectionCancelCallbacks[$key][2] = $new;
3476                         }
3477                 }
3478         }
3479
3480         /**
3481          * Update callbacks that were owned by cancelled atomic sections.
3482          *
3483          * Callbacks for "on commit" should never be run if they're owned by a
3484          * section that won't be committed.
3485          *
3486          * Callbacks for "on resolution" need to reflect that the section was
3487          * rolled back, even if the transaction as a whole commits successfully.
3488          *
3489          * Callbacks for "on section cancel" should already have been consumed,
3490          * but errors during the cancellation itself can prevent that while still
3491          * destroying the section. Hoist any such callbacks to the new top section,
3492          * which we assume will itself have to be cancelled or rolled back to
3493          * resolve the error.
3494          *
3495          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3496          * @param AtomicSectionIdentifier|null $newSectionId New top section ID.
3497          * @throws UnexpectedValueException
3498          */
3499         private function modifyCallbacksForCancel(
3500                 array $sectionIds, AtomicSectionIdentifier $newSectionId = null
3501         ) {
3502                 // Cancel the "on commit" callbacks owned by this savepoint
3503                 $this->trxIdleCallbacks = array_filter(
3504                         $this->trxIdleCallbacks,
3505                         function ( $entry ) use ( $sectionIds ) {
3506                                 return !in_array( $entry[2], $sectionIds, true );
3507                         }
3508                 );
3509                 $this->trxPreCommitCallbacks = array_filter(
3510                         $this->trxPreCommitCallbacks,
3511                         function ( $entry ) use ( $sectionIds ) {
3512                                 return !in_array( $entry[2], $sectionIds, true );
3513                         }
3514                 );
3515                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3516                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3517                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3518                                 $callback = $entry[0];
3519                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3520                                         // @phan-suppress-next-line PhanInfiniteRecursion No recursion at all here, phan is confused
3521                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3522                                 };
3523                                 // This "on resolution" callback no longer belongs to a section.
3524                                 $this->trxEndCallbacks[$key][2] = null;
3525                         }
3526                 }
3527                 // Hoist callback ownership for section cancel callbacks to the new top section
3528                 foreach ( $this->trxSectionCancelCallbacks as $key => $entry ) {
3529                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3530                                 $this->trxSectionCancelCallbacks[$key][2] = $newSectionId;
3531                         }
3532                 }
3533         }
3534
3535         final public function setTransactionListener( $name, callable $callback = null ) {
3536                 if ( $callback ) {
3537                         $this->trxRecurringCallbacks[$name] = $callback;
3538                 } else {
3539                         unset( $this->trxRecurringCallbacks[$name] );
3540                 }
3541         }
3542
3543         /**
3544          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3545          *
3546          * This method should not be used outside of Database/LoadBalancer
3547          *
3548          * @param bool $suppress
3549          * @since 1.28
3550          */
3551         final public function setTrxEndCallbackSuppression( $suppress ) {
3552                 $this->trxEndCallbacksSuppressed = $suppress;
3553         }
3554
3555         /**
3556          * Actually consume and run any "on transaction idle/resolution" callbacks.
3557          *
3558          * This method should not be used outside of Database/LoadBalancer
3559          *
3560          * @param int $trigger IDatabase::TRIGGER_* constant
3561          * @return int Number of callbacks attempted
3562          * @since 1.20
3563          * @throws Exception
3564          */
3565         public function runOnTransactionIdleCallbacks( $trigger ) {
3566                 if ( $this->trxLevel() ) { // sanity
3567                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open' );
3568                 }
3569
3570                 if ( $this->trxEndCallbacksSuppressed ) {
3571                         return 0;
3572                 }
3573
3574                 $count = 0;
3575                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3576                 /** @var Exception $e */
3577                 $e = null; // first exception
3578                 do { // callbacks may add callbacks :)
3579                         $callbacks = array_merge(
3580                                 $this->trxIdleCallbacks,
3581                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3582                         );
3583                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3584                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3585
3586                         // Only run trxSectionCancelCallbacks on rollback, not commit.
3587                         // But always consume them.
3588                         if ( $trigger === self::TRIGGER_ROLLBACK ) {
3589                                 $callbacks = array_merge( $callbacks, $this->trxSectionCancelCallbacks );
3590                         }
3591                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3592
3593                         foreach ( $callbacks as $callback ) {
3594                                 ++$count;
3595                                 list( $phpCallback ) = $callback;
3596                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3597                                 try {
3598                                         // @phan-suppress-next-line PhanParamTooManyCallable
3599                                         call_user_func( $phpCallback, $trigger, $this );
3600                                 } catch ( Exception $ex ) {
3601                                         call_user_func( $this->errorLogger, $ex );
3602                                         $e = $e ?: $ex;
3603                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3604                                         // their transactions are ended so other callbacks don't fail
3605                                         if ( $this->trxLevel() ) {
3606                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3607                                         }
3608                                 } finally {
3609                                         if ( $autoTrx ) {
3610                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3611                                         } else {
3612                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3613                                         }
3614                                 }
3615                         }
3616                 } while ( count( $this->trxIdleCallbacks ) );
3617
3618                 if ( $e instanceof Exception ) {
3619                         throw $e; // re-throw any first exception
3620                 }
3621
3622                 return $count;
3623         }
3624
3625         /**
3626          * Actually consume and run any "on transaction pre-commit" callbacks.
3627          *
3628          * This method should not be used outside of Database/LoadBalancer
3629          *
3630          * @since 1.22
3631          * @return int Number of callbacks attempted
3632          * @throws Exception
3633          */
3634         public function runOnTransactionPreCommitCallbacks() {
3635                 $count = 0;
3636
3637                 $e = null; // first exception
3638                 do { // callbacks may add callbacks :)
3639                         $callbacks = $this->trxPreCommitCallbacks;
3640                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3641                         foreach ( $callbacks as $callback ) {
3642                                 try {
3643                                         ++$count;
3644                                         list( $phpCallback ) = $callback;
3645                                         $phpCallback( $this );
3646                                 } catch ( Exception $ex ) {
3647                                         ( $this->errorLogger )( $ex );
3648                                         $e = $e ?: $ex;
3649                                 }
3650                         }
3651                 } while ( count( $this->trxPreCommitCallbacks ) );
3652
3653                 if ( $e instanceof Exception ) {
3654                         throw $e; // re-throw any first exception
3655                 }
3656
3657                 return $count;
3658         }
3659
3660         /**
3661          * Actually run any "atomic section cancel" callbacks.
3662          *
3663          * @param int $trigger IDatabase::TRIGGER_* constant
3664          * @param AtomicSectionIdentifier[]|null $sectionIds Section IDs to cancel,
3665          *  null on transaction rollback
3666          */
3667         private function runOnAtomicSectionCancelCallbacks(
3668                 $trigger, array $sectionIds = null
3669         ) {
3670                 /** @var Exception|Throwable $e */
3671                 $e = null; // first exception
3672
3673                 $notCancelled = [];
3674                 do {
3675                         $callbacks = $this->trxSectionCancelCallbacks;
3676                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3677                         foreach ( $callbacks as $entry ) {
3678                                 if ( $sectionIds === null || in_array( $entry[2], $sectionIds, true ) ) {
3679                                         try {
3680                                                 $entry[0]( $trigger, $this );
3681                                         } catch ( Exception $ex ) {
3682                                                 ( $this->errorLogger )( $ex );
3683                                                 $e = $e ?: $ex;
3684                                         } catch ( Throwable $ex ) {
3685                                                 // @todo: Log?
3686                                                 $e = $e ?: $ex;
3687                                         }
3688                                 } else {
3689                                         $notCancelled[] = $entry;
3690                                 }
3691                         }
3692                 } while ( count( $this->trxSectionCancelCallbacks ) );
3693                 $this->trxSectionCancelCallbacks = $notCancelled;
3694
3695                 if ( $e !== null ) {
3696                         throw $e; // re-throw any first Exception/Throwable
3697                 }
3698         }
3699
3700         /**
3701          * Actually run any "transaction listener" callbacks.
3702          *
3703          * This method should not be used outside of Database/LoadBalancer
3704          *
3705          * @param int $trigger IDatabase::TRIGGER_* constant
3706          * @throws Exception
3707          * @since 1.20
3708          */
3709         public function runTransactionListenerCallbacks( $trigger ) {
3710                 if ( $this->trxEndCallbacksSuppressed ) {
3711                         return;
3712                 }
3713
3714                 /** @var Exception $e */
3715                 $e = null; // first exception
3716
3717                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3718                         try {
3719                                 $phpCallback( $trigger, $this );
3720                         } catch ( Exception $ex ) {
3721                                 ( $this->errorLogger )( $ex );
3722                                 $e = $e ?: $ex;
3723                         }
3724                 }
3725
3726                 if ( $e instanceof Exception ) {
3727                         throw $e; // re-throw any first exception
3728                 }
3729         }
3730
3731         /**
3732          * Create a savepoint
3733          *
3734          * This is used internally to implement atomic sections. It should not be
3735          * used otherwise.
3736          *
3737          * @since 1.31
3738          * @param string $identifier Identifier for the savepoint
3739          * @param string $fname Calling function name
3740          */
3741         protected function doSavepoint( $identifier, $fname ) {
3742                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3743         }
3744
3745         /**
3746          * Release a savepoint
3747          *
3748          * This is used internally to implement atomic sections. It should not be
3749          * used otherwise.
3750          *
3751          * @since 1.31
3752          * @param string $identifier Identifier for the savepoint
3753          * @param string $fname Calling function name
3754          */
3755         protected function doReleaseSavepoint( $identifier, $fname ) {
3756                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3757         }
3758
3759         /**
3760          * Rollback to a savepoint
3761          *
3762          * This is used internally to implement atomic sections. It should not be
3763          * used otherwise.
3764          *
3765          * @since 1.31
3766          * @param string $identifier Identifier for the savepoint
3767          * @param string $fname Calling function name
3768          */
3769         protected function doRollbackToSavepoint( $identifier, $fname ) {
3770                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3771         }
3772
3773         /**
3774          * @param string $fname
3775          * @return string
3776          */
3777         private function nextSavepointId( $fname ) {
3778                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3779                 if ( strlen( $savepointId ) > 30 ) {
3780                         // 30 == Oracle's identifier length limit (pre 12c)
3781                         // With a 22 character prefix, that puts the highest number at 99999999.
3782                         throw new DBUnexpectedError(
3783                                 $this,
3784                                 'There have been an excessively large number of atomic sections in a transaction'
3785                                 . " started by $this->trxFname (at $fname)"
3786                         );
3787                 }
3788
3789                 return $savepointId;
3790         }
3791
3792         final public function startAtomic(
3793                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3794         ) {
3795                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3796
3797                 if ( !$this->trxLevel() ) {
3798                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3799                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3800                         // in all changes being in one transaction to keep requests transactional.
3801                         if ( $this->getFlag( self::DBO_TRX ) ) {
3802                                 // Since writes could happen in between the topmost atomic sections as part
3803                                 // of the transaction, those sections will need savepoints.
3804                                 $savepointId = $this->nextSavepointId( $fname );
3805                                 $this->doSavepoint( $savepointId, $fname );
3806                         } else {
3807                                 $this->trxAutomaticAtomic = true;
3808                         }
3809                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3810                         $savepointId = $this->nextSavepointId( $fname );
3811                         $this->doSavepoint( $savepointId, $fname );
3812                 }
3813
3814                 $sectionId = new AtomicSectionIdentifier;
3815                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3816                 $this->queryLogger->debug( 'startAtomic: entering level ' .
3817                         ( count( $this->trxAtomicLevels ) - 1 ) . " ($fname)" );
3818
3819                 return $sectionId;
3820         }
3821
3822         final public function endAtomic( $fname = __METHOD__ ) {
3823                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3824                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3825                 }
3826
3827                 // Check if the current section matches $fname
3828                 $pos = count( $this->trxAtomicLevels ) - 1;
3829                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3830                 $this->queryLogger->debug( "endAtomic: leaving level $pos ($fname)" );
3831
3832                 if ( $savedFname !== $fname ) {
3833                         throw new DBUnexpectedError(
3834                                 $this,
3835                                 "Invalid atomic section ended (got $fname but expected $savedFname)"
3836                         );
3837                 }
3838
3839                 // Remove the last section (no need to re-index the array)
3840                 array_pop( $this->trxAtomicLevels );
3841
3842                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3843                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3844                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3845                         $this->doReleaseSavepoint( $savepointId, $fname );
3846                 }
3847
3848                 // Hoist callback ownership for callbacks in the section that just ended;
3849                 // all callbacks should have an owner that is present in trxAtomicLevels.
3850                 $currentSectionId = $this->currentAtomicSectionId();
3851                 if ( $currentSectionId ) {
3852                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3853                 }
3854         }
3855
3856         final public function cancelAtomic(
3857                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3858         ) {
3859                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3860                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3861                 }
3862
3863                 $excisedIds = [];
3864                 $newTopSection = $this->currentAtomicSectionId();
3865                 try {
3866                         $excisedFnames = [];
3867                         if ( $sectionId !== null ) {
3868                                 // Find the (last) section with the given $sectionId
3869                                 $pos = -1;
3870                                 foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3871                                         if ( $asId === $sectionId ) {
3872                                                 $pos = $i;
3873                                         }
3874                                 }
3875                                 if ( $pos < 0 ) {
3876                                         throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
3877                                 }
3878                                 // Remove all descendant sections and re-index the array
3879                                 $len = count( $this->trxAtomicLevels );
3880                                 for ( $i = $pos + 1; $i < $len; ++$i ) {
3881                                         $excisedFnames[] = $this->trxAtomicLevels[$i][0];
3882                                         $excisedIds[] = $this->trxAtomicLevels[$i][1];
3883                                 }
3884                                 $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3885                                 $newTopSection = $this->currentAtomicSectionId();
3886                         }
3887
3888                         // Check if the current section matches $fname
3889                         $pos = count( $this->trxAtomicLevels ) - 1;
3890                         list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3891
3892                         if ( $excisedFnames ) {
3893                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
3894                                         "and descendants " . implode( ', ', $excisedFnames ) );
3895                         } else {
3896                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
3897                         }
3898
3899                         if ( $savedFname !== $fname ) {
3900                                 throw new DBUnexpectedError(
3901                                         $this,
3902                                         "Invalid atomic section ended (got $fname but expected $savedFname)"
3903                                 );
3904                         }
3905
3906                         // Remove the last section (no need to re-index the array)
3907                         array_pop( $this->trxAtomicLevels );
3908                         $excisedIds[] = $savedSectionId;
3909                         $newTopSection = $this->currentAtomicSectionId();
3910
3911                         if ( $savepointId !== null ) {
3912                                 // Rollback the transaction to the state just before this atomic section
3913                                 if ( $savepointId === self::$NOT_APPLICABLE ) {
3914                                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
3915                                         // Note: rollback() will run trxSectionCancelCallbacks
3916                                 } else {
3917                                         $this->doRollbackToSavepoint( $savepointId, $fname );
3918                                         $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3919                                         $this->trxStatusIgnoredCause = null;
3920
3921                                         // Run trxSectionCancelCallbacks now.
3922                                         $this->runOnAtomicSectionCancelCallbacks( self::TRIGGER_CANCEL, $excisedIds );
3923                                 }
3924                         } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3925                                 // Put the transaction into an error state if it's not already in one
3926                                 $this->trxStatus = self::STATUS_TRX_ERROR;
3927                                 $this->trxStatusCause = new DBUnexpectedError(
3928                                         $this,
3929                                         "Uncancelable atomic section canceled (got $fname)"
3930                                 );
3931                         }
3932                 } finally {
3933                         // Fix up callbacks owned by the sections that were just cancelled.
3934                         // All callbacks should have an owner that is present in trxAtomicLevels.
3935                         $this->modifyCallbacksForCancel( $excisedIds, $newTopSection );
3936                 }
3937
3938                 $this->affectedRowCount = 0; // for the sake of consistency
3939         }
3940
3941         final public function doAtomicSection(
3942                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3943         ) {
3944                 $sectionId = $this->startAtomic( $fname, $cancelable );
3945                 try {
3946                         $res = $callback( $this, $fname );
3947                 } catch ( Exception $e ) {
3948                         $this->cancelAtomic( $fname, $sectionId );
3949
3950                         throw $e;
3951                 }
3952                 $this->endAtomic( $fname );
3953
3954                 return $res;
3955         }
3956
3957         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3958                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3959                 if ( !in_array( $mode, $modes, true ) ) {
3960                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'" );
3961                 }
3962
3963                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3964                 if ( $this->trxLevel() ) {
3965                         if ( $this->trxAtomicLevels ) {
3966                                 $levels = $this->flatAtomicSectionList();
3967                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open";
3968                                 throw new DBUnexpectedError( $this, $msg );
3969                         } elseif ( !$this->trxAutomatic ) {
3970                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname})";
3971                                 throw new DBUnexpectedError( $this, $msg );
3972                         } else {
3973                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname})";
3974                                 throw new DBUnexpectedError( $this, $msg );
3975                         }
3976                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3977                         $msg = "$fname: Implicit transaction expected (DBO_TRX set)";
3978                         throw new DBUnexpectedError( $this, $msg );
3979                 }
3980
3981                 $this->assertHasConnectionHandle();
3982
3983                 $this->doBegin( $fname );
3984                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3985                 $this->trxStatus = self::STATUS_TRX_OK;
3986                 $this->trxStatusIgnoredCause = null;
3987                 $this->trxAtomicCounter = 0;
3988                 $this->trxTimestamp = microtime( true );
3989                 $this->trxFname = $fname;
3990                 $this->trxDoneWrites = false;
3991                 $this->trxAutomaticAtomic = false;
3992                 $this->trxAtomicLevels = [];
3993                 $this->trxWriteDuration = 0.0;
3994                 $this->trxWriteQueryCount = 0;
3995                 $this->trxWriteAffectedRows = 0;
3996                 $this->trxWriteAdjDuration = 0.0;
3997                 $this->trxWriteAdjQueryCount = 0;
3998                 $this->trxWriteCallers = [];
3999                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
4000                 // Get an estimate of the replication lag before any such queries.
4001                 $this->trxReplicaLag = null; // clear cached value first
4002                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
4003                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
4004                 // caller will think its OK to muck around with the transaction just because startAtomic()
4005                 // has not yet completed (e.g. setting trxAtomicLevels).
4006                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
4007         }
4008
4009         /**
4010          * Issues the BEGIN command to the database server.
4011          *
4012          * @see Database::begin()
4013          * @param string $fname
4014          * @throws DBError
4015          */
4016         protected function doBegin( $fname ) {
4017                 $this->query( 'BEGIN', $fname );
4018         }
4019
4020         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4021                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
4022                 if ( !in_array( $flush, $modes, true ) ) {
4023                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'" );
4024                 }
4025
4026                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
4027                         // There are still atomic sections open; this cannot be ignored
4028                         $levels = $this->flatAtomicSectionList();
4029                         throw new DBUnexpectedError(
4030                                 $this,
4031                                 "$fname: Got COMMIT while atomic sections $levels are still open"
4032                         );
4033                 }
4034
4035                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
4036                         if ( !$this->trxLevel() ) {
4037                                 return; // nothing to do
4038                         } elseif ( !$this->trxAutomatic ) {
4039                                 throw new DBUnexpectedError(
4040                                         $this,
4041                                         "$fname: Flushing an explicit transaction, getting out of sync"
4042                                 );
4043                         }
4044                 } elseif ( !$this->trxLevel() ) {
4045                         $this->queryLogger->error(
4046                                 "$fname: No transaction to commit, something got out of sync" );
4047                         return; // nothing to do
4048                 } elseif ( $this->trxAutomatic ) {
4049                         throw new DBUnexpectedError(
4050                                 $this,
4051                                 "$fname: Expected mass commit of all peer transactions (DBO_TRX set)"
4052                         );
4053                 }
4054
4055                 $this->assertHasConnectionHandle();
4056
4057                 $this->runOnTransactionPreCommitCallbacks();
4058
4059                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
4060                 $this->doCommit( $fname );
4061                 $oldTrxShortId = $this->consumeTrxShortId();
4062                 $this->trxStatus = self::STATUS_TRX_NONE;
4063
4064                 if ( $this->trxDoneWrites ) {
4065                         $this->lastWriteTime = microtime( true );
4066                         $this->trxProfiler->transactionWritingOut(
4067                                 $this->server,
4068                                 $this->getDomainID(),
4069                                 $oldTrxShortId,
4070                                 $writeTime,
4071                                 $this->trxWriteAffectedRows
4072                         );
4073                 }
4074
4075                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4076                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
4077                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
4078                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
4079                 }
4080         }
4081
4082         /**
4083          * Issues the COMMIT command to the database server.
4084          *
4085          * @see Database::commit()
4086          * @param string $fname
4087          * @throws DBError
4088          */
4089         protected function doCommit( $fname ) {
4090                 if ( $this->trxLevel() ) {
4091                         $this->query( 'COMMIT', $fname );
4092                 }
4093         }
4094
4095         final public function rollback( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4096                 $trxActive = $this->trxLevel();
4097
4098                 if ( $flush !== self::FLUSHING_INTERNAL
4099                         && $flush !== self::FLUSHING_ALL_PEERS
4100                         && $this->getFlag( self::DBO_TRX )
4101                 ) {
4102                         throw new DBUnexpectedError(
4103                                 $this,
4104                                 "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)"
4105                         );
4106                 }
4107
4108                 if ( $trxActive ) {
4109                         $this->assertHasConnectionHandle();
4110
4111                         $this->doRollback( $fname );
4112                         $oldTrxShortId = $this->consumeTrxShortId();
4113                         $this->trxStatus = self::STATUS_TRX_NONE;
4114                         $this->trxAtomicLevels = [];
4115                         // Estimate the RTT via a query now that trxStatus is OK
4116                         $writeTime = $this->pingAndCalculateLastTrxApplyTime();
4117
4118                         if ( $this->trxDoneWrites ) {
4119                                 $this->trxProfiler->transactionWritingOut(
4120                                         $this->server,
4121                                         $this->getDomainID(),
4122                                         $oldTrxShortId,
4123                                         $writeTime,
4124                                         $this->trxWriteAffectedRows
4125                                 );
4126                         }
4127                 }
4128
4129                 // Clear any commit-dependant callbacks. They might even be present
4130                 // only due to transaction rounds, with no SQL transaction being active
4131                 $this->trxIdleCallbacks = [];
4132                 $this->trxPreCommitCallbacks = [];
4133
4134                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4135                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
4136                         try {
4137                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
4138                         } catch ( Exception $e ) {
4139                                 // already logged; finish and let LoadBalancer move on during mass-rollback
4140                         }
4141                         try {
4142                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
4143                         } catch ( Exception $e ) {
4144                                 // already logged; let LoadBalancer move on during mass-rollback
4145                         }
4146
4147                         $this->affectedRowCount = 0; // for the sake of consistency
4148                 }
4149         }
4150
4151         /**
4152          * Issues the ROLLBACK command to the database server.
4153          *
4154          * @see Database::rollback()
4155          * @param string $fname
4156          * @throws DBError
4157          */
4158         protected function doRollback( $fname ) {
4159                 if ( $this->trxLevel() ) {
4160                         # Disconnects cause rollback anyway, so ignore those errors
4161                         $ignoreErrors = true;
4162                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
4163                 }
4164         }
4165
4166         public function flushSnapshot( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4167                 if ( $this->explicitTrxActive() ) {
4168                         // Committing this transaction would break callers that assume it is still open
4169                         throw new DBUnexpectedError(
4170                                 $this,
4171                                 "$fname: Cannot flush snapshot; " .
4172                                 "explicit transaction '{$this->trxFname}' is still open"
4173                         );
4174                 } elseif ( $this->writesOrCallbacksPending() ) {
4175                         // This only flushes transactions to clear snapshots, not to write data
4176                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4177                         throw new DBUnexpectedError(
4178                                 $this,
4179                                 "$fname: Cannot flush snapshot; " .
4180                                 "writes from transaction {$this->trxFname} are still pending ($fnames)"
4181                         );
4182                 } elseif (
4183                         $this->trxLevel() &&
4184                         $this->getTransactionRoundId() &&
4185                         $flush !== self::FLUSHING_INTERNAL &&
4186                         $flush !== self::FLUSHING_ALL_PEERS
4187                 ) {
4188                         $this->queryLogger->warning(
4189                                 "$fname: Expected mass snapshot flush of all peer transactions " .
4190                                 "in the explicit transactions round '{$this->getTransactionRoundId()}'",
4191                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
4192                         );
4193                 }
4194
4195                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4196         }
4197
4198         public function explicitTrxActive() {
4199                 return $this->trxLevel() && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4200         }
4201
4202         public function duplicateTableStructure(
4203                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4204         ) {
4205                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4206         }
4207
4208         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4209                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4210         }
4211
4212         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4213                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4214         }
4215
4216         public function timestamp( $ts = 0 ) {
4217                 $t = new ConvertibleTimestamp( $ts );
4218                 // Let errors bubble up to avoid putting garbage in the DB
4219                 return $t->getTimestamp( TS_MW );
4220         }
4221
4222         public function timestampOrNull( $ts = null ) {
4223                 if ( is_null( $ts ) ) {
4224                         return null;
4225                 } else {
4226                         return $this->timestamp( $ts );
4227                 }
4228         }
4229
4230         public function affectedRows() {
4231                 return ( $this->affectedRowCount === null )
4232                         ? $this->fetchAffectedRowCount() // default to driver value
4233                         : $this->affectedRowCount;
4234         }
4235
4236         /**
4237          * @return int Number of retrieved rows according to the driver
4238          */
4239         abstract protected function fetchAffectedRowCount();
4240
4241         /**
4242          * Take a query result and wrap it in an iterable result wrapper if necessary.
4243          * Booleans are passed through as-is to indicate success/failure of write queries.
4244          *
4245          * Once upon a time, Database::query() returned a bare MySQL result
4246          * resource, and it was necessary to call this function to convert it to
4247          * a wrapper. Nowadays, raw database objects are never exposed to external
4248          * callers, so this is unnecessary in external code.
4249          *
4250          * @param bool|IResultWrapper|resource $result
4251          * @return bool|IResultWrapper
4252          */
4253         protected function resultObject( $result ) {
4254                 if ( !$result ) {
4255                         return false; // failed query
4256                 } elseif ( $result instanceof IResultWrapper ) {
4257                         return $result;
4258                 } elseif ( $result === true ) {
4259                         return $result; // succesful write query
4260                 } else {
4261                         return new ResultWrapper( $this, $result );
4262                 }
4263         }
4264
4265         public function ping( &$rtt = null ) {
4266                 // Avoid hitting the server if it was hit recently
4267                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::$PING_TTL ) {
4268                         if ( !func_num_args() || $this->lastRoundTripEstimate > 0 ) {
4269                                 $rtt = $this->lastRoundTripEstimate;
4270                                 return true; // don't care about $rtt
4271                         }
4272                 }
4273
4274                 // This will reconnect if possible or return false if not
4275                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4276                 $ok = ( $this->query( self::$PING_QUERY, __METHOD__, true ) !== false );
4277                 $this->restoreFlags( self::RESTORE_PRIOR );
4278
4279                 if ( $ok ) {
4280                         $rtt = $this->lastRoundTripEstimate;
4281                 }
4282
4283                 return $ok;
4284         }
4285
4286         /**
4287          * Close any existing (dead) database connection and open a new connection
4288          *
4289          * @param string $fname
4290          * @return bool True if new connection is opened successfully, false if error
4291          */
4292         protected function replaceLostConnection( $fname ) {
4293                 $this->closeConnection();
4294                 $this->conn = false;
4295
4296                 $this->handleSessionLossPreconnect();
4297
4298                 try {
4299                         $this->open(
4300                                 $this->server,
4301                                 $this->user,
4302                                 $this->password,
4303                                 $this->currentDomain->getDatabase(),
4304                                 $this->currentDomain->getSchema(),
4305                                 $this->tablePrefix()
4306                         );
4307                         $this->lastPing = microtime( true );
4308                         $ok = true;
4309
4310                         $this->connLogger->warning(
4311                                 $fname . ': lost connection to {dbserver}; reconnected',
4312                                 [
4313                                         'dbserver' => $this->getServer(),
4314                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4315                                 ]
4316                         );
4317                 } catch ( DBConnectionError $e ) {
4318                         $ok = false;
4319
4320                         $this->connLogger->error(
4321                                 $fname . ': lost connection to {dbserver} permanently',
4322                                 [ 'dbserver' => $this->getServer() ]
4323                         );
4324                 }
4325
4326                 $this->handleSessionLossPostconnect();
4327
4328                 return $ok;
4329         }
4330
4331         public function getSessionLagStatus() {
4332                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4333         }
4334
4335         /**
4336          * Get the replica DB lag when the current transaction started
4337          *
4338          * This is useful when transactions might use snapshot isolation
4339          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4340          * is this lag plus transaction duration. If they don't, it is still
4341          * safe to be pessimistic. This returns null if there is no transaction.
4342          *
4343          * This returns null if the lag status for this transaction was not yet recorded.
4344          *
4345          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4346          * @since 1.27
4347          */
4348         final protected function getRecordedTransactionLagStatus() {
4349                 return ( $this->trxLevel() && $this->trxReplicaLag !== null )
4350                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4351                         : null;
4352         }
4353
4354         /**
4355          * Get a replica DB lag estimate for this server
4356          *
4357          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4358          * @since 1.27
4359          */
4360         protected function getApproximateLagStatus() {
4361                 return [
4362                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4363                         'since' => microtime( true )
4364                 ];
4365         }
4366
4367         /**
4368          * Merge the result of getSessionLagStatus() for several DBs
4369          * using the most pessimistic values to estimate the lag of
4370          * any data derived from them in combination
4371          *
4372          * This is information is useful for caching modules
4373          *
4374          * @see WANObjectCache::set()
4375          * @see WANObjectCache::getWithSetCallback()
4376          *
4377          * @param IDatabase $db1
4378          * @param IDatabase|null $db2 [optional]
4379          * @return array Map of values:
4380          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4381          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4382          *   - pending: whether any of the DBs have uncommitted changes
4383          * @throws DBError
4384          * @since 1.27
4385          */
4386         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4387                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4388                 foreach ( func_get_args() as $db ) {
4389                         /** @var IDatabase $db */
4390                         $status = $db->getSessionLagStatus();
4391                         if ( $status['lag'] === false ) {
4392                                 $res['lag'] = false;
4393                         } elseif ( $res['lag'] !== false ) {
4394                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4395                         }
4396                         $res['since'] = min( $res['since'], $status['since'] );
4397                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4398                 }
4399
4400                 return $res;
4401         }
4402
4403         public function getLag() {
4404                 if ( $this->getLBInfo( 'master' ) ) {
4405                         return 0; // this is the master
4406                 } elseif ( $this->getLBInfo( 'is static' ) ) {
4407                         return 0; // static dataset
4408                 }
4409
4410                 return $this->doGetLag();
4411         }
4412
4413         protected function doGetLag() {
4414                 return 0;
4415         }
4416
4417         public function maxListLen() {
4418                 return 0;
4419         }
4420
4421         public function encodeBlob( $b ) {
4422                 return $b;
4423         }
4424
4425         public function decodeBlob( $b ) {
4426                 if ( $b instanceof Blob ) {
4427                         $b = $b->fetch();
4428                 }
4429                 return $b;
4430         }
4431
4432         public function setSessionOptions( array $options ) {
4433         }
4434
4435         public function sourceFile(
4436                 $filename,
4437                 callable $lineCallback = null,
4438                 callable $resultCallback = null,
4439                 $fname = false,
4440                 callable $inputCallback = null
4441         ) {
4442                 AtEase::suppressWarnings();
4443                 $fp = fopen( $filename, 'r' );
4444                 AtEase::restoreWarnings();
4445
4446                 if ( $fp === false ) {
4447                         throw new RuntimeException( "Could not open \"{$filename}\"" );
4448                 }
4449
4450                 if ( !$fname ) {
4451                         $fname = __METHOD__ . "( $filename )";
4452                 }
4453
4454                 try {
4455                         $error = $this->sourceStream(
4456                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4457                 } catch ( Exception $e ) {
4458                         fclose( $fp );
4459                         throw $e;
4460                 }
4461
4462                 fclose( $fp );
4463
4464                 return $error;
4465         }
4466
4467         public function setSchemaVars( $vars ) {
4468                 $this->schemaVars = $vars;
4469         }
4470
4471         public function sourceStream(
4472                 $fp,
4473                 callable $lineCallback = null,
4474                 callable $resultCallback = null,
4475                 $fname = __METHOD__,
4476                 callable $inputCallback = null
4477         ) {
4478                 $delimiterReset = new ScopedCallback(
4479                         function ( $delimiter ) {
4480                                 $this->delimiter = $delimiter;
4481                         },
4482                         [ $this->delimiter ]
4483                 );
4484                 $cmd = '';
4485
4486                 while ( !feof( $fp ) ) {
4487                         if ( $lineCallback ) {
4488                                 call_user_func( $lineCallback );
4489                         }
4490
4491                         $line = trim( fgets( $fp ) );
4492
4493                         if ( $line == '' ) {
4494                                 continue;
4495                         }
4496
4497                         if ( $line[0] == '-' && $line[1] == '-' ) {
4498                                 continue;
4499                         }
4500
4501                         if ( $cmd != '' ) {
4502                                 $cmd .= ' ';
4503                         }
4504
4505                         $done = $this->streamStatementEnd( $cmd, $line );
4506
4507                         $cmd .= "$line\n";
4508
4509                         if ( $done || feof( $fp ) ) {
4510                                 $cmd = $this->replaceVars( $cmd );
4511
4512                                 if ( $inputCallback ) {
4513                                         $callbackResult = $inputCallback( $cmd );
4514
4515                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4516                                                 $cmd = $callbackResult;
4517                                         }
4518                                 }
4519
4520                                 if ( $cmd ) {
4521                                         $res = $this->query( $cmd, $fname );
4522
4523                                         if ( $resultCallback ) {
4524                                                 $resultCallback( $res, $this );
4525                                         }
4526
4527                                         if ( $res === false ) {
4528                                                 $err = $this->lastError();
4529
4530                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4531                                         }
4532                                 }
4533                                 $cmd = '';
4534                         }
4535                 }
4536
4537                 ScopedCallback::consume( $delimiterReset );
4538                 return true;
4539         }
4540
4541         /**
4542          * Called by sourceStream() to check if we've reached a statement end
4543          *
4544          * @param string &$sql SQL assembled so far
4545          * @param string &$newLine New line about to be added to $sql
4546          * @return bool Whether $newLine contains end of the statement
4547          */
4548         public function streamStatementEnd( &$sql, &$newLine ) {
4549                 if ( $this->delimiter ) {
4550                         $prev = $newLine;
4551                         $newLine = preg_replace(
4552                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4553                         if ( $newLine != $prev ) {
4554                                 return true;
4555                         }
4556                 }
4557
4558                 return false;
4559         }
4560
4561         /**
4562          * Database independent variable replacement. Replaces a set of variables
4563          * in an SQL statement with their contents as given by $this->getSchemaVars().
4564          *
4565          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4566          *
4567          * - '{$var}' should be used for text and is passed through the database's
4568          *   addQuotes method.
4569          * - `{$var}` should be used for identifiers (e.g. table and database names).
4570          *   It is passed through the database's addIdentifierQuotes method which
4571          *   can be overridden if the database uses something other than backticks.
4572          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4573          *   database's tableName method.
4574          * - / *i* / passes the name that follows through the database's indexName method.
4575          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4576          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4577          *
4578          * @param string $ins SQL statement to replace variables in
4579          * @return string The new SQL statement with variables replaced
4580          */
4581         protected function replaceVars( $ins ) {
4582                 $vars = $this->getSchemaVars();
4583                 return preg_replace_callback(
4584                         '!
4585                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4586                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4587                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4588                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4589                         !x',
4590                         function ( $m ) use ( $vars ) {
4591                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4592                                 // check for both nonexistent keys *and* the empty string.
4593                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4594                                         if ( $m[1] === 'i' ) {
4595                                                 return $this->indexName( $m[2] );
4596                                         } else {
4597                                                 return $this->tableName( $m[2] );
4598                                         }
4599                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4600                                         return $this->addQuotes( $vars[$m[3]] );
4601                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4602                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4603                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4604                                         return $vars[$m[5]];
4605                                 } else {
4606                                         return $m[0];
4607                                 }
4608                         },
4609                         $ins
4610                 );
4611         }
4612
4613         /**
4614          * Get schema variables. If none have been set via setSchemaVars(), then
4615          * use some defaults from the current object.
4616          *
4617          * @return array
4618          */
4619         protected function getSchemaVars() {
4620                 if ( $this->schemaVars ) {
4621                         return $this->schemaVars;
4622                 } else {
4623                         return $this->getDefaultSchemaVars();
4624                 }
4625         }
4626
4627         /**
4628          * Get schema variables to use if none have been set via setSchemaVars().
4629          *
4630          * Override this in derived classes to provide variables for tables.sql
4631          * and SQL patch files.
4632          *
4633          * @return array
4634          */
4635         protected function getDefaultSchemaVars() {
4636                 return [];
4637         }
4638
4639         public function lockIsFree( $lockName, $method ) {
4640                 // RDBMs methods for checking named locks may or may not count this thread itself.
4641                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4642                 // the behavior choosen by the interface for this method.
4643                 return !isset( $this->sessionNamedLocks[$lockName] );
4644         }
4645
4646         public function lock( $lockName, $method, $timeout = 5 ) {
4647                 $this->sessionNamedLocks[$lockName] = 1;
4648
4649                 return true;
4650         }
4651
4652         public function unlock( $lockName, $method ) {
4653                 unset( $this->sessionNamedLocks[$lockName] );
4654
4655                 return true;
4656         }
4657
4658         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4659                 if ( $this->writesOrCallbacksPending() ) {
4660                         // This only flushes transactions to clear snapshots, not to write data
4661                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4662                         throw new DBUnexpectedError(
4663                                 $this,
4664                                 "$fname: Cannot flush pre-lock snapshot; " .
4665                                 "writes from transaction {$this->trxFname} are still pending ($fnames)"
4666                         );
4667                 }
4668
4669                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4670                         return null;
4671                 }
4672
4673                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4674                         if ( $this->trxLevel() ) {
4675                                 // There is a good chance an exception was thrown, causing any early return
4676                                 // from the caller. Let any error handler get a chance to issue rollback().
4677                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4678                                 $this->onTransactionResolution(
4679                                         function () use ( $lockKey, $fname ) {
4680                                                 $this->unlock( $lockKey, $fname );
4681                                         },
4682                                         $fname
4683                                 );
4684                         } else {
4685                                 $this->unlock( $lockKey, $fname );
4686                         }
4687                 } );
4688
4689                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4690
4691                 return $unlocker;
4692         }
4693
4694         public function namedLocksEnqueue() {
4695                 return false;
4696         }
4697
4698         public function tableLocksHaveTransactionScope() {
4699                 return true;
4700         }
4701
4702         final public function lockTables( array $read, array $write, $method ) {
4703                 if ( $this->writesOrCallbacksPending() ) {
4704                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending" );
4705                 }
4706
4707                 if ( $this->tableLocksHaveTransactionScope() ) {
4708                         $this->startAtomic( $method );
4709                 }
4710
4711                 return $this->doLockTables( $read, $write, $method );
4712         }
4713
4714         /**
4715          * Helper function for lockTables() that handles the actual table locking
4716          *
4717          * @param array $read Array of tables to lock for read access
4718          * @param array $write Array of tables to lock for write access
4719          * @param string $method Name of caller
4720          * @return true
4721          */
4722         protected function doLockTables( array $read, array $write, $method ) {
4723                 return true;
4724         }
4725
4726         final public function unlockTables( $method ) {
4727                 if ( $this->tableLocksHaveTransactionScope() ) {
4728                         $this->endAtomic( $method );
4729
4730                         return true; // locks released on COMMIT/ROLLBACK
4731                 }
4732
4733                 return $this->doUnlockTables( $method );
4734         }
4735
4736         /**
4737          * Helper function for unlockTables() that handles the actual table unlocking
4738          *
4739          * @param string $method Name of caller
4740          * @return true
4741          */
4742         protected function doUnlockTables( $method ) {
4743                 return true;
4744         }
4745
4746         /**
4747          * Delete a table
4748          * @param string $tableName
4749          * @param string $fName
4750          * @return bool|IResultWrapper
4751          * @since 1.18
4752          */
4753         public function dropTable( $tableName, $fName = __METHOD__ ) {
4754                 if ( !$this->tableExists( $tableName, $fName ) ) {
4755                         return false;
4756                 }
4757                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4758
4759                 return $this->query( $sql, $fName );
4760         }
4761
4762         public function getInfinity() {
4763                 return 'infinity';
4764         }
4765
4766         public function encodeExpiry( $expiry ) {
4767                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4768                         ? $this->getInfinity()
4769                         : $this->timestamp( $expiry );
4770         }
4771
4772         public function decodeExpiry( $expiry, $format = TS_MW ) {
4773                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4774                         return 'infinity';
4775                 }
4776
4777                 return ConvertibleTimestamp::convert( $format, $expiry );
4778         }
4779
4780         public function setBigSelects( $value = true ) {
4781                 // no-op
4782         }
4783
4784         public function isReadOnly() {
4785                 return ( $this->getReadOnlyReason() !== false );
4786         }
4787
4788         /**
4789          * @return string|bool Reason this DB is read-only or false if it is not
4790          */
4791         protected function getReadOnlyReason() {
4792                 $reason = $this->getLBInfo( 'readOnlyReason' );
4793                 if ( is_string( $reason ) ) {
4794                         return $reason;
4795                 } elseif ( $this->getLBInfo( 'replica' ) ) {
4796                         return "Server is configured in the role of a read-only replica database.";
4797                 }
4798
4799                 return false;
4800         }
4801
4802         public function setTableAliases( array $aliases ) {
4803                 $this->tableAliases = $aliases;
4804         }
4805
4806         public function setIndexAliases( array $aliases ) {
4807                 $this->indexAliases = $aliases;
4808         }
4809
4810         /**
4811          * @param int $field
4812          * @param int $flags
4813          * @return bool
4814          */
4815         protected function hasFlags( $field, $flags ) {
4816                 return ( ( $field & $flags ) === $flags );
4817         }
4818
4819         /**
4820          * Get the underlying binding connection handle
4821          *
4822          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4823          * This catches broken callers than catch and ignore disconnection exceptions.
4824          * Unlike checking isOpen(), this is safe to call inside of open().
4825          *
4826          * @return mixed
4827          * @throws DBUnexpectedError
4828          * @since 1.26
4829          */
4830         protected function getBindingHandle() {
4831                 if ( !$this->conn ) {
4832                         throw new DBUnexpectedError(
4833                                 $this,
4834                                 'DB connection was already closed or the connection dropped'
4835                         );
4836                 }
4837
4838                 return $this->conn;
4839         }
4840
4841         public function __toString() {
4842                 // spl_object_id is PHP >= 7.2
4843                 $id = function_exists( 'spl_object_id' )
4844                         ? spl_object_id( $this )
4845                         : spl_object_hash( $this );
4846
4847                 $description = $this->getType() . ' object #' . $id;
4848                 if ( is_resource( $this->conn ) ) {
4849                         $description .= ' (' . (string)$this->conn . ')'; // "resource id #<ID>"
4850                 } elseif ( is_object( $this->conn ) ) {
4851                         // spl_object_id is PHP >= 7.2
4852                         $handleId = function_exists( 'spl_object_id' )
4853                                 ? spl_object_id( $this->conn )
4854                                 : spl_object_hash( $this->conn );
4855                         $description .= " (handle id #$handleId)";
4856                 }
4857
4858                 return $description;
4859         }
4860
4861         /**
4862          * Make sure that copies do not share the same client binding handle
4863          * @throws DBConnectionError
4864          */
4865         public function __clone() {
4866                 $this->connLogger->warning(
4867                         "Cloning " . static::class . " is not recommended; forking connection",
4868                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
4869                 );
4870
4871                 if ( $this->isOpen() ) {
4872                         // Open a new connection resource without messing with the old one
4873                         $this->conn = false;
4874                         $this->trxEndCallbacks = []; // don't copy
4875                         $this->trxSectionCancelCallbacks = []; // don't copy
4876                         $this->handleSessionLossPreconnect(); // no trx or locks anymore
4877                         $this->open(
4878                                 $this->server,
4879                                 $this->user,
4880                                 $this->password,
4881                                 $this->currentDomain->getDatabase(),
4882                                 $this->currentDomain->getSchema(),
4883                                 $this->tablePrefix()
4884                         );
4885                         $this->lastPing = microtime( true );
4886                 }
4887         }
4888
4889         /**
4890          * Called by serialize. Throw an exception when DB connection is serialized.
4891          * This causes problems on some database engines because the connection is
4892          * not restored on unserialize.
4893          */
4894         public function __sleep() {
4895                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4896                         'the connection is not restored on wakeup' );
4897         }
4898
4899         /**
4900          * Run a few simple sanity checks and close dangling connections
4901          */
4902         public function __destruct() {
4903                 if ( $this->trxLevel() && $this->trxDoneWrites ) {
4904                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})" );
4905                 }
4906
4907                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4908                 if ( $danglingWriters ) {
4909                         $fnames = implode( ', ', $danglingWriters );
4910                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)" );
4911                 }
4912
4913                 if ( $this->conn ) {
4914                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4915                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4916                         AtEase::suppressWarnings();
4917                         $this->closeConnection();
4918                         AtEase::restoreWarnings();
4919                         $this->conn = null;
4920                 }
4921         }
4922 }
4923
4924 /**
4925  * @deprecated since 1.28
4926  */
4927 class_alias( Database::class, 'DatabaseBase' );
4928
4929 /**
4930  * @deprecated since 1.29
4931  */
4932 class_alias( Database::class, 'Database' );