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