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
  42 /**
  43  * Relational database abstraction object
  44  *
  45  * @ingroup Database
  46  * @since 1.28
  47  */
  48 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  49         /** Number of times to re-try an operation in case of deadlock */
  50         const DEADLOCK_TRIES = 4;
  51         /** Minimum time to wait before retry, in microseconds */
  52         const DEADLOCK_DELAY_MIN = 500000;
  53         /** Maximum time to wait before retry */
  54         const DEADLOCK_DELAY_MAX = 1500000;
  55
  56         /** How long before it is worth doing a dummy query to test the connection */
  57         const PING_TTL = 1.0;
  58         const PING_QUERY = 'SELECT 1 AS ping';
  59
  60         const TINY_WRITE_SEC = 0.010;
  61         const SLOW_WRITE_SEC = 0.500;
  62         const SMALL_WRITE_ROWS = 100;
  63
  64         /** @var string Whether lock granularity is on the level of the entire database */
  65         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
  66
  67         /** @var int New Database instance will not be connected yet when returned */
  68         const NEW_UNCONNECTED = 0;
  69         /** @var int New Database instance will already be connected when returned */
  70         const NEW_CONNECTED = 1;
  71
  72         /** @var string SQL query */
  73         protected $lastQuery = '';
  74         /** @var float|bool UNIX timestamp of last write query */
  75         protected $lastWriteTime = false;
  76         /** @var string|bool */
  77         protected $phpError = false;
  78         /** @var string Server that this instance is currently connected to */
  79         protected $server;
  80         /** @var string User that this instance is currently connected under the name of */
  81         protected $user;
  82         /** @var string Password used to establish the current connection */
  83         protected $password;
  84         /** @var string Database that this instance is currently connected to */
  85         protected $dbName;
  86         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  87         protected $tableAliases = [];
  88         /** @var string[] Map of (index alias => index) */
  89         protected $indexAliases = [];
  90         /** @var bool Whether this PHP instance is for a CLI script */
  91         protected $cliMode;
  92         /** @var string Agent name for query profiling */
  93         protected $agent;
  94         /** @var array Parameters used by initConnection() to establish a connection */
  95         protected $connectionParams = [];
  96         /** @var BagOStuff APC cache */
  97         protected $srvCache;
  98         /** @var LoggerInterface */
  99         protected $connLogger;
 100         /** @var LoggerInterface */
 101         protected $queryLogger;
 102         /** @var callback Error logging callback */
 103         protected $errorLogger;
 104         /** @var callback Deprecation logging callback */
 105         protected $deprecationLogger;
 106
 107         /** @var resource|null Database connection */
 108         protected $conn = null;
 109         /** @var bool */
 110         protected $opened = false;
 111
 112         /** @var array[] List of (callable, method name, atomic section id) */
 113         protected $trxIdleCallbacks = [];
 114         /** @var array[] List of (callable, method name, atomic section id) */
 115         protected $trxPreCommitCallbacks = [];
 116         /** @var array[] List of (callable, method name, atomic section id) */
 117         protected $trxEndCallbacks = [];
 118         /** @var callable[] Map of (name => callable) */
 119         protected $trxRecurringCallbacks = [];
 120         /** @var bool Whether to suppress triggering of transaction end callbacks */
 121         protected $trxEndCallbacksSuppressed = false;
 122
 123         /** @var string */
 124         protected $tablePrefix = '';
 125         /** @var string */
 126         protected $schema = '';
 127         /** @var int */
 128         protected $flags;
 129         /** @var array */
 130         protected $lbInfo = [];
 131         /** @var array|bool */
 132         protected $schemaVars = false;
 133         /** @var array */
 134         protected $sessionVars = [];
 135         /** @var array|null */
 136         protected $preparedArgs;
 137         /** @var string|bool|null Stashed value of html_errors INI setting */
 138         protected $htmlErrors;
 139         /** @var string */
 140         protected $delimiter = ';';
 141         /** @var DatabaseDomain */
 142         protected $currentDomain;
 143         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 144         protected $affectedRowCount;
 145
 146         /**
 147          * @var int Transaction status
 148          */
 149         protected $trxStatus = self::STATUS_TRX_NONE;
 150         /**
 151          * @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR
 152          */
 153         protected $trxStatusCause;
 154         /**
 155          * @var array|null If wasKnownStatementRollbackError() prevented trxStatus from being set,
 156          *  the relevant details are stored here.
 157          */
 158         protected $trxStatusIgnoredCause;
 159         /**
 160          * Either 1 if a transaction is active or 0 otherwise.
 161          * The other Trx fields may not be meaningfull if this is 0.
 162          *
 163          * @var int
 164          */
 165         protected $trxLevel = 0;
 166         /**
 167          * Either a short hexidecimal string if a transaction is active or ""
 168          *
 169          * @var string
 170          * @see Database::trxLevel
 171          */
 172         protected $trxShortId = '';
 173         /**
 174          * The UNIX time that the transaction started. Callers can assume that if
 175          * snapshot isolation is used, then the data is *at least* up to date to that
 176          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 177          *
 178          * @var float|null
 179          * @see Database::trxLevel
 180          */
 181         private $trxTimestamp = null;
 182         /** @var float Lag estimate at the time of BEGIN */
 183         private $trxReplicaLag = null;
 184         /**
 185          * Remembers the function name given for starting the most recent transaction via begin().
 186          * Used to provide additional context for error reporting.
 187          *
 188          * @var string
 189          * @see Database::trxLevel
 190          */
 191         private $trxFname = null;
 192         /**
 193          * Record if possible write queries were done in the last transaction started
 194          *
 195          * @var bool
 196          * @see Database::trxLevel
 197          */
 198         private $trxDoneWrites = false;
 199         /**
 200          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 201          *
 202          * @var bool
 203          * @see Database::trxLevel
 204          */
 205         private $trxAutomatic = false;
 206         /**
 207          * Counter for atomic savepoint identifiers. Reset when a new transaction begins.
 208          *
 209          * @var int
 210          */
 211         private $trxAtomicCounter = 0;
 212         /**
 213          * Array of levels of atomicity within transactions
 214          *
 215          * @var array List of (name, unique ID, savepoint ID)
 216          */
 217         private $trxAtomicLevels = [];
 218         /**
 219          * Record if the current transaction was started implicitly by Database::startAtomic
 220          *
 221          * @var bool
 222          */
 223         private $trxAutomaticAtomic = false;
 224         /**
 225          * Track the write query callers of the current transaction
 226          *
 227          * @var string[]
 228          */
 229         private $trxWriteCallers = [];
 230         /**
 231          * @var float Seconds spent in write queries for the current transaction
 232          */
 233         private $trxWriteDuration = 0.0;
 234         /**
 235          * @var int Number of write queries for the current transaction
 236          */
 237         private $trxWriteQueryCount = 0;
 238         /**
 239          * @var int Number of rows affected by write queries for the current transaction
 240          */
 241         private $trxWriteAffectedRows = 0;
 242         /**
 243          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 244          */
 245         private $trxWriteAdjDuration = 0.0;
 246         /**
 247          * @var int Number of write queries counted in trxWriteAdjDuration
 248          */
 249         private $trxWriteAdjQueryCount = 0;
 250         /**
 251          * @var float RTT time estimate
 252          */
 253         private $rttEstimate = 0.0;
 254
 255         /** @var array Map of (name => 1) for locks obtained via lock() */
 256         private $namedLocksHeld = [];
 257         /** @var array Map of (table name => 1) for TEMPORARY tables */
 258         protected $sessionTempTables = [];
 259
 260         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 261         private $lazyMasterHandle;
 262
 263         /** @var float UNIX timestamp */
 264         protected $lastPing = 0.0;
 265
 266         /** @var int[] Prior flags member variable values */
 267         private $priorFlags = [];
 268
 269         /** @var object|string Class name or object With profileIn/profileOut methods */
 270         protected $profiler;
 271         /** @var TransactionProfiler */
 272         protected $trxProfiler;
 273
 274         /** @var int */
 275         protected $nonNativeInsertSelectBatchSize = 10000;
 276
 277         /** @var string Idiom used when a cancelable atomic section started the transaction */
 278         private static $NOT_APPLICABLE = 'n/a';
 279         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 280         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 281
 282         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 283         const STATUS_TRX_ERROR = 1;
 284         /** @var int Transaction is active and in a normal state */
 285         const STATUS_TRX_OK = 2;
 286         /** @var int No transaction is active */
 287         const STATUS_TRX_NONE = 3;
 288
 289         /**
 290          * @note: exceptions for missing libraries/drivers should be thrown in initConnection()
 291          * @param array $params Parameters passed from Database::factory()
 292          */
 293         protected function __construct( array $params ) {
 294                 foreach ( [ 'host', 'user', 'password', 'dbname' ] as $name ) {
 295                         $this->connectionParams[$name] = $params[$name];
 296                 }
 297
 298                 $this->schema = $params['schema'];
 299                 $this->tablePrefix = $params['tablePrefix'];
 300
 301                 $this->cliMode = $params['cliMode'];
 302                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 303                 $this->agent = str_replace( '/', '-', $params['agent'] );
 304
 305                 $this->flags = $params['flags'];
 306                 if ( $this->flags & self::DBO_DEFAULT ) {
 307                         if ( $this->cliMode ) {
 308                                 $this->flags &= ~self::DBO_TRX;
 309                         } else {
 310                                 $this->flags |= self::DBO_TRX;
 311                         }
 312                 }
 313                 // Disregard deprecated DBO_IGNORE flag (T189999)
 314                 $this->flags &= ~self::DBO_IGNORE;
 315
 316                 $this->sessionVars = $params['variables'];
 317
 318                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 319
 320                 $this->profiler = $params['profiler'];
 321                 $this->trxProfiler = $params['trxProfiler'];
 322                 $this->connLogger = $params['connLogger'];
 323                 $this->queryLogger = $params['queryLogger'];
 324                 $this->errorLogger = $params['errorLogger'];
 325                 $this->deprecationLogger = $params['deprecationLogger'];
 326
 327                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 328                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 329                 }
 330
 331                 // Set initial dummy domain until open() sets the final DB/prefix
 332                 $this->currentDomain = DatabaseDomain::newUnspecified();
 333         }
 334
 335         /**
 336          * Initialize the connection to the database over the wire (or to local files)
 337          *
 338          * @throws LogicException
 339          * @throws InvalidArgumentException
 340          * @throws DBConnectionError
 341          * @since 1.31
 342          */
 343         final public function initConnection() {
 344                 if ( $this->isOpen() ) {
 345                         throw new LogicException( __METHOD__ . ': already connected.' );
 346                 }
 347                 // Establish the connection
 348                 $this->doInitConnection();
 349                 // Set the domain object after open() sets the relevant fields
 350                 if ( $this->dbName != '' ) {
 351                         // Domains with server scope but a table prefix are not used by IDatabase classes
 352                         $this->currentDomain = new DatabaseDomain( $this->dbName, null, $this->tablePrefix );
 353                 }
 354         }
 355
 356         /**
 357          * Actually connect to the database over the wire (or to local files)
 358          *
 359          * @throws InvalidArgumentException
 360          * @throws DBConnectionError
 361          * @since 1.31
 362          */
 363         protected function doInitConnection() {
 364                 if ( strlen( $this->connectionParams['user'] ) ) {
 365                         $this->open(
 366                                 $this->connectionParams['host'],
 367                                 $this->connectionParams['user'],
 368                                 $this->connectionParams['password'],
 369                                 $this->connectionParams['dbname']
 370                         );
 371                 } else {
 372                         throw new InvalidArgumentException( "No database user provided." );
 373                 }
 374         }
 375
 376         /**
 377          * Construct a Database subclass instance given a database type and parameters
 378          *
 379          * This also connects to the database immediately upon object construction
 380          *
 381          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 382          * @param array $p Parameter map with keys:
 383          *   - host : The hostname of the DB server
 384          *   - user : The name of the database user the client operates under
 385          *   - password : The password for the database user
 386          *   - dbname : The name of the database to use where queries do not specify one.
 387          *      The database must exist or an error might be thrown. Setting this to the empty string
 388          *      will avoid any such errors and make the handle have no implicit database scope. This is
 389          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 390          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 391          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 392          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 393          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 394          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 395          *      recognized in queries. This can be used in place of schemas for handle site farms.
 396          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 397          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 398          *      flag in place UNLESS this this database simply acts as a key/value store.
 399          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 400          *      'mysqli' driver; the old one 'mysql' has been removed.
 401          *   - variables: Optional map of session variables to set after connecting. This can be
 402          *      used to adjust lock timeouts or encoding modes and the like.
 403          *   - connLogger: Optional PSR-3 logger interface instance.
 404          *   - queryLogger: Optional PSR-3 logger interface instance.
 405          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 406          *      These will be called in query(), using a simplified version of the SQL that also
 407          *      includes the agent as a SQL comment.
 408          *   - trxProfiler: Optional TransactionProfiler instance.
 409          *   - errorLogger: Optional callback that takes an Exception and logs it.
 410          *   - deprecationLogger: Optional callback that takes a string and logs it.
 411          *   - cliMode: Whether to consider the execution context that of a CLI script.
 412          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 413          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 414          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 415          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 416          * @return Database|null If the database driver or extension cannot be found
 417          * @throws InvalidArgumentException If the database driver or extension cannot be found
 418          * @since 1.18
 419          */
 420         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 421                 $class = self::getClass( $dbType, $p['driver'] ?? null );
 422
 423                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 424                         // Resolve some defaults for b/c
 425                         $p['host'] = $p['host'] ?? false;
 426                         $p['user'] = $p['user'] ?? false;
 427                         $p['password'] = $p['password'] ?? false;
 428                         $p['dbname'] = $p['dbname'] ?? false;
 429                         $p['flags'] = $p['flags'] ?? 0;
 430                         $p['variables'] = $p['variables'] ?? [];
 431                         $p['tablePrefix'] = $p['tablePrefix'] ?? '';
 432                         $p['schema'] = $p['schema'] ?? '';
 433                         $p['cliMode'] = $p['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 434                         $p['agent'] = $p['agent'] ?? '';
 435                         if ( !isset( $p['connLogger'] ) ) {
 436                                 $p['connLogger'] = new NullLogger();
 437                         }
 438                         if ( !isset( $p['queryLogger'] ) ) {
 439                                 $p['queryLogger'] = new NullLogger();
 440                         }
 441                         $p['profiler'] = $p['profiler'] ?? null;
 442                         if ( !isset( $p['trxProfiler'] ) ) {
 443                                 $p['trxProfiler'] = new TransactionProfiler();
 444                         }
 445                         if ( !isset( $p['errorLogger'] ) ) {
 446                                 $p['errorLogger'] = function ( Exception $e ) {
 447                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 448                                 };
 449                         }
 450                         if ( !isset( $p['deprecationLogger'] ) ) {
 451                                 $p['deprecationLogger'] = function ( $msg ) {
 452                                         trigger_error( $msg, E_USER_DEPRECATED );
 453                                 };
 454                         }
 455
 456                         /** @var Database $conn */
 457                         $conn = new $class( $p );
 458                         if ( $connect == self::NEW_CONNECTED ) {
 459                                 $conn->initConnection();
 460                         }
 461                 } else {
 462                         $conn = null;
 463                 }
 464
 465                 return $conn;
 466         }
 467
 468         /**
 469          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 470          * @param string|null $driver Optional name of a specific DB client driver
 471          * @return array Map of (Database::ATTRIBUTE_* constant => value) for all such constants
 472          * @throws InvalidArgumentException
 473          * @since 1.31
 474          */
 475         final public static function attributesFromType( $dbType, $driver = null ) {
 476                 static $defaults = [ self::ATTR_DB_LEVEL_LOCKING => false ];
 477
 478                 $class = self::getClass( $dbType, $driver );
 479
 480                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 481         }
 482
 483         /**
 484          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 485          * @param string|null $driver Optional name of a specific DB client driver
 486          * @return string Database subclass name to use
 487          * @throws InvalidArgumentException
 488          */
 489         private static function getClass( $dbType, $driver = null ) {
 490                 // For database types with built-in support, the below maps type to IDatabase
 491                 // implementations. For types with multipe driver implementations (PHP extensions),
 492                 // an array can be used, keyed by extension name. In case of an array, the
 493                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 494                 // we auto-detect the first available driver. For types without built-in support,
 495                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 496                 static $builtinTypes = [
 497                         'mssql' => DatabaseMssql::class,
 498                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 499                         'sqlite' => DatabaseSqlite::class,
 500                         'postgres' => DatabasePostgres::class,
 501                 ];
 502
 503                 $dbType = strtolower( $dbType );
 504                 $class = false;
 505
 506                 if ( isset( $builtinTypes[$dbType] ) ) {
 507                         $possibleDrivers = $builtinTypes[$dbType];
 508                         if ( is_string( $possibleDrivers ) ) {
 509                                 $class = $possibleDrivers;
 510                         } else {
 511                                 if ( (string)$driver !== '' ) {
 512                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 513                                                 throw new InvalidArgumentException( __METHOD__ .
 514                                                         " type '$dbType' does not support driver '{$driver}'" );
 515                                         } else {
 516                                                 $class = $possibleDrivers[$driver];
 517                                         }
 518                                 } else {
 519                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 520                                                 if ( extension_loaded( $posDriver ) ) {
 521                                                         $class = $possibleClass;
 522                                                         break;
 523                                                 }
 524                                         }
 525                                 }
 526                         }
 527                 } else {
 528                         $class = 'Database' . ucfirst( $dbType );
 529                 }
 530
 531                 if ( $class === false ) {
 532                         throw new InvalidArgumentException( __METHOD__ .
 533                                 " no viable database extension found for type '$dbType'" );
 534                 }
 535
 536                 return $class;
 537         }
 538
 539         /**
 540          * @return array Map of (Database::ATTRIBUTE_* constant => value
 541          * @since 1.31
 542          */
 543         protected static function getAttributes() {
 544                 return [];
 545         }
 546
 547         /**
 548          * Set the PSR-3 logger interface to use for query logging. (The logger
 549          * interfaces for connection logging and error logging can be set with the
 550          * constructor.)
 551          *
 552          * @param LoggerInterface $logger
 553          */
 554         public function setLogger( LoggerInterface $logger ) {
 555                 $this->queryLogger = $logger;
 556         }
 557
 558         public function getServerInfo() {
 559                 return $this->getServerVersion();
 560         }
 561
 562         public function bufferResults( $buffer = null ) {
 563                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 564                 if ( $buffer !== null ) {
 565                         $buffer
 566                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 567                                 : $this->setFlag( self::DBO_NOBUFFER );
 568                 }
 569
 570                 return $res;
 571         }
 572
 573         public function trxLevel() {
 574                 return $this->trxLevel;
 575         }
 576
 577         public function trxTimestamp() {
 578                 return $this->trxLevel ? $this->trxTimestamp : null;
 579         }
 580
 581         /**
 582          * @return int One of the STATUS_TRX_* class constants
 583          * @since 1.31
 584          */
 585         public function trxStatus() {
 586                 return $this->trxStatus;
 587         }
 588
 589         public function tablePrefix( $prefix = null ) {
 590                 $old = $this->tablePrefix;
 591                 if ( $prefix !== null ) {
 592                         $this->tablePrefix = $prefix;
 593                         $this->currentDomain = ( $this->dbName != '' )
 594                                 ? new DatabaseDomain( $this->dbName, null, $this->tablePrefix )
 595                                 : DatabaseDomain::newUnspecified();
 596                 }
 597
 598                 return $old;
 599         }
 600
 601         public function dbSchema( $schema = null ) {
 602                 $old = $this->schema;
 603                 if ( $schema !== null ) {
 604                         $this->schema = $schema;
 605                 }
 606
 607                 return $old;
 608         }
 609
 610         public function getLBInfo( $name = null ) {
 611                 if ( is_null( $name ) ) {
 612                         return $this->lbInfo;
 613                 } else {
 614                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 615                                 return $this->lbInfo[$name];
 616                         } else {
 617                                 return null;
 618                         }
 619                 }
 620         }
 621
 622         public function setLBInfo( $name, $value = null ) {
 623                 if ( is_null( $value ) ) {
 624                         $this->lbInfo = $name;
 625                 } else {
 626                         $this->lbInfo[$name] = $value;
 627                 }
 628         }
 629
 630         public function setLazyMasterHandle( IDatabase $conn ) {
 631                 $this->lazyMasterHandle = $conn;
 632         }
 633
 634         /**
 635          * @return IDatabase|null
 636          * @see setLazyMasterHandle()
 637          * @since 1.27
 638          */
 639         protected function getLazyMasterHandle() {
 640                 return $this->lazyMasterHandle;
 641         }
 642
 643         public function implicitGroupby() {
 644                 return true;
 645         }
 646
 647         public function implicitOrderby() {
 648                 return true;
 649         }
 650
 651         public function lastQuery() {
 652                 return $this->lastQuery;
 653         }
 654
 655         public function doneWrites() {
 656                 return (bool)$this->lastWriteTime;
 657         }
 658
 659         public function lastDoneWrites() {
 660                 return $this->lastWriteTime ?: false;
 661         }
 662
 663         public function writesPending() {
 664                 return $this->trxLevel && $this->trxDoneWrites;
 665         }
 666
 667         public function writesOrCallbacksPending() {
 668                 return $this->trxLevel && (
 669                         $this->trxDoneWrites ||
 670                         $this->trxIdleCallbacks ||
 671                         $this->trxPreCommitCallbacks ||
 672                         $this->trxEndCallbacks
 673                 );
 674         }
 675
 676         public function preCommitCallbacksPending() {
 677                 return $this->trxLevel && $this->trxPreCommitCallbacks;
 678         }
 679
 680         /**
 681          * @return string|null
 682          */
 683         final protected function getTransactionRoundId() {
 684                 // If transaction round participation is enabled, see if one is active
 685                 if ( $this->getFlag( self::DBO_TRX ) ) {
 686                         $id = $this->getLBInfo( 'trxRoundId' );
 687
 688                         return is_string( $id ) ? $id : null;
 689                 }
 690
 691                 return null;
 692         }
 693
 694         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 695                 if ( !$this->trxLevel ) {
 696                         return false;
 697                 } elseif ( !$this->trxDoneWrites ) {
 698                         return 0.0;
 699                 }
 700
 701                 switch ( $type ) {
 702                         case self::ESTIMATE_DB_APPLY:
 703                                 $this->ping( $rtt );
 704                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 705                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 706                                 // For omitted queries, make them count as something at least
 707                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 708                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 709
 710                                 return $applyTime;
 711                         default: // everything
 712                                 return $this->trxWriteDuration;
 713                 }
 714         }
 715
 716         public function pendingWriteCallers() {
 717                 return $this->trxLevel ? $this->trxWriteCallers : [];
 718         }
 719
 720         public function pendingWriteRowsAffected() {
 721                 return $this->trxWriteAffectedRows;
 722         }
 723
 724         /**
 725          * List the methods that have write queries or callbacks for the current transaction
 726          *
 727          * This method should not be used outside of Database/LoadBalancer
 728          *
 729          * @return string[]
 730          * @since 1.32
 731          */
 732         public function pendingWriteAndCallbackCallers() {
 733                 $fnames = $this->pendingWriteCallers();
 734                 foreach ( [
 735                         $this->trxIdleCallbacks,
 736                         $this->trxPreCommitCallbacks,
 737                         $this->trxEndCallbacks
 738                 ] as $callbacks ) {
 739                         foreach ( $callbacks as $callback ) {
 740                                 $fnames[] = $callback[1];
 741                         }
 742                 }
 743
 744                 return $fnames;
 745         }
 746
 747         /**
 748          * @return string
 749          */
 750         private function flatAtomicSectionList() {
 751                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 752                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 753                 } );
 754         }
 755
 756         public function isOpen() {
 757                 return $this->opened;
 758         }
 759
 760         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 761                 if ( ( $flag & self::DBO_IGNORE ) ) {
 762                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 763                 }
 764
 765                 if ( $remember === self::REMEMBER_PRIOR ) {
 766                         array_push( $this->priorFlags, $this->flags );
 767                 }
 768                 $this->flags |= $flag;
 769         }
 770
 771         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 772                 if ( ( $flag & self::DBO_IGNORE ) ) {
 773                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 774                 }
 775
 776                 if ( $remember === self::REMEMBER_PRIOR ) {
 777                         array_push( $this->priorFlags, $this->flags );
 778                 }
 779                 $this->flags &= ~$flag;
 780         }
 781
 782         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 783                 if ( !$this->priorFlags ) {
 784                         return;
 785                 }
 786
 787                 if ( $state === self::RESTORE_INITIAL ) {
 788                         $this->flags = reset( $this->priorFlags );
 789                         $this->priorFlags = [];
 790                 } else {
 791                         $this->flags = array_pop( $this->priorFlags );
 792                 }
 793         }
 794
 795         public function getFlag( $flag ) {
 796                 return !!( $this->flags & $flag );
 797         }
 798
 799         /**
 800          * @param string $name Class field name
 801          * @return mixed
 802          * @deprecated Since 1.28
 803          */
 804         public function getProperty( $name ) {
 805                 return $this->$name;
 806         }
 807
 808         public function getDomainID() {
 809                 return $this->currentDomain->getId();
 810         }
 811
 812         final public function getWikiID() {
 813                 return $this->getDomainID();
 814         }
 815
 816         /**
 817          * Get information about an index into an object
 818          * @param string $table Table name
 819          * @param string $index Index name
 820          * @param string $fname Calling function name
 821          * @return mixed Database-specific index description class or false if the index does not exist
 822          */
 823         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 824
 825         /**
 826          * Wrapper for addslashes()
 827          *
 828          * @param string $s String to be slashed.
 829          * @return string Slashed string.
 830          */
 831         abstract function strencode( $s );
 832
 833         /**
 834          * Set a custom error handler for logging errors during database connection
 835          */
 836         protected function installErrorHandler() {
 837                 $this->phpError = false;
 838                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 839                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 840         }
 841
 842         /**
 843          * Restore the previous error handler and return the last PHP error for this DB
 844          *
 845          * @return bool|string
 846          */
 847         protected function restoreErrorHandler() {
 848                 restore_error_handler();
 849                 if ( $this->htmlErrors !== false ) {
 850                         ini_set( 'html_errors', $this->htmlErrors );
 851                 }
 852
 853                 return $this->getLastPHPError();
 854         }
 855
 856         /**
 857          * @return string|bool Last PHP error for this DB (typically connection errors)
 858          */
 859         protected function getLastPHPError() {
 860                 if ( $this->phpError ) {
 861                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 862                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 863
 864                         return $error;
 865                 }
 866
 867                 return false;
 868         }
 869
 870         /**
 871          * Error handler for logging errors during database connection
 872          * This method should not be used outside of Database classes
 873          *
 874          * @param int $errno
 875          * @param string $errstr
 876          */
 877         public function connectionErrorLogger( $errno, $errstr ) {
 878                 $this->phpError = $errstr;
 879         }
 880
 881         /**
 882          * Create a log context to pass to PSR-3 logger functions.
 883          *
 884          * @param array $extras Additional data to add to context
 885          * @return array
 886          */
 887         protected function getLogContext( array $extras = [] ) {
 888                 return array_merge(
 889                         [
 890                                 'db_server' => $this->server,
 891                                 'db_name' => $this->dbName,
 892                                 'db_user' => $this->user,
 893                         ],
 894                         $extras
 895                 );
 896         }
 897
 898         final public function close() {
 899                 $exception = null; // error to throw after disconnecting
 900
 901                 if ( $this->conn ) {
 902                         // Resolve any dangling transaction first
 903                         if ( $this->trxLevel ) {
 904                                 if ( $this->trxAtomicLevels ) {
 905                                         // Cannot let incomplete atomic sections be committed
 906                                         $levels = $this->flatAtomicSectionList();
 907                                         $exception = new DBUnexpectedError(
 908                                                 $this,
 909                                                 __METHOD__ . ": atomic sections $levels are still open."
 910                                         );
 911                                 } elseif ( $this->trxAutomatic ) {
 912                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 913                                         if ( $this->writesOrCallbacksPending() ) {
 914                                                 $exception = new DBUnexpectedError(
 915                                                         $this,
 916                                                         __METHOD__ .
 917                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 918                                                 );
 919                                         }
 920                                 } elseif ( $this->trxLevel ) {
 921                                         // Commit explicit transactions as if this was commit()
 922                                         $this->queryLogger->warning(
 923                                                 __METHOD__ . ": writes or callbacks still pending.",
 924                                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 925                                         );
 926                                 }
 927
 928                                 if ( $this->trxEndCallbacksSuppressed ) {
 929                                         $exception = $exception ?: new DBUnexpectedError(
 930                                                 $this,
 931                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 932                                         );
 933                                 }
 934
 935                                 // Commit or rollback the changes and run any callbacks as needed
 936                                 if ( $this->trxStatus === self::STATUS_TRX_OK && !$exception ) {
 937                                         $this->commit(
 938                                                 __METHOD__,
 939                                                 $this->trxAutomatic ? self::FLUSHING_INTERNAL : self::FLUSHING_ONE
 940                                         );
 941                                 } else {
 942                                         $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 943                                 }
 944                         }
 945
 946                         // Close the actual connection in the binding handle
 947                         $closed = $this->closeConnection();
 948                         $this->conn = false;
 949                 } else {
 950                         $closed = true; // already closed; nothing to do
 951                 }
 952
 953                 $this->opened = false;
 954
 955                 // Throw any unexpected errors after having disconnected
 956                 if ( $exception instanceof Exception ) {
 957                         throw $exception;
 958                 }
 959
 960                 // Sanity check that no callbacks are dangling
 961                 $fnames = $this->pendingWriteAndCallbackCallers();
 962                 if ( $fnames ) {
 963                         throw new RuntimeException(
 964                                 "Transaction callbacks are still pending:\n" . implode( ', ', $fnames )
 965                         );
 966                 }
 967
 968                 return $closed;
 969         }
 970
 971         /**
 972          * Make sure isOpen() returns true as a sanity check
 973          *
 974          * @throws DBUnexpectedError
 975          */
 976         protected function assertOpen() {
 977                 if ( !$this->isOpen() ) {
 978                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 979                 }
 980         }
 981
 982         /**
 983          * Closes underlying database connection
 984          * @since 1.20
 985          * @return bool Whether connection was closed successfully
 986          */
 987         abstract protected function closeConnection();
 988
 989         /**
 990          * @deprecated since 1.32
 991          * @param string $error Fallback message, if none is given by DB
 992          * @throws DBConnectionError
 993          */
 994         public function reportConnectionError( $error = 'Unknown error' ) {
 995                 call_user_func( $this->deprecationLogger, 'Use of ' . __METHOD__ . ' is deprecated.' );
 996                 throw new DBConnectionError( $this, $this->lastError() ?: $error );
 997         }
 998
 999         /**
1000          * Run a query and return a DBMS-dependent wrapper (that has all IResultWrapper methods)
1001          *
1002          * This might return things, such as mysqli_result, that do not formally implement
1003          * IResultWrapper, but nonetheless implement all of its methods correctly
1004          *
1005          * @param string $sql SQL query.
1006          * @return IResultWrapper|bool Iterator to feed to fetchObject/fetchRow; false on failure
1007          */
1008         abstract protected function doQuery( $sql );
1009
1010         /**
1011          * Determine whether a query writes to the DB.
1012          * Should return true if unsure.
1013          *
1014          * @param string $sql
1015          * @return bool
1016          */
1017         protected function isWriteQuery( $sql ) {
1018                 return !preg_match(
1019                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
1020         }
1021
1022         /**
1023          * @param string $sql
1024          * @return string|null
1025          */
1026         protected function getQueryVerb( $sql ) {
1027                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1028         }
1029
1030         /**
1031          * Determine whether a SQL statement is sensitive to isolation level.
1032          * A SQL statement is considered transactable if its result could vary
1033          * depending on the transaction isolation level. Operational commands
1034          * such as 'SET' and 'SHOW' are not considered to be transactable.
1035          *
1036          * @param string $sql
1037          * @return bool
1038          */
1039         protected function isTransactableQuery( $sql ) {
1040                 return !in_array(
1041                         $this->getQueryVerb( $sql ),
1042                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
1043                         true
1044                 );
1045         }
1046
1047         /**
1048          * @param string $sql A SQL query
1049          * @return bool Whether $sql is SQL for TEMPORARY table operation
1050          */
1051         protected function registerTempTableOperation( $sql ) {
1052                 if ( preg_match(
1053                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1054                         $sql,
1055                         $matches
1056                 ) ) {
1057                         $this->sessionTempTables[$matches[1]] = 1;
1058
1059                         return true;
1060                 } elseif ( preg_match(
1061                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1062                         $sql,
1063                         $matches
1064                 ) ) {
1065                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
1066                         unset( $this->sessionTempTables[$matches[1]] );
1067
1068                         return $isTemp;
1069                 } elseif ( preg_match(
1070                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1071                         $sql,
1072                         $matches
1073                 ) ) {
1074                         return isset( $this->sessionTempTables[$matches[1]] );
1075                 } elseif ( preg_match(
1076                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
1077                         $sql,
1078                         $matches
1079                 ) ) {
1080                         return isset( $this->sessionTempTables[$matches[1]] );
1081                 }
1082
1083                 return false;
1084         }
1085
1086         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1087                 $this->assertTransactionStatus( $sql, $fname );
1088
1089                 # Avoid fatals if close() was called
1090                 $this->assertOpen();
1091
1092                 $priorWritesPending = $this->writesOrCallbacksPending();
1093                 $this->lastQuery = $sql;
1094
1095                 $isWrite = $this->isWriteQuery( $sql );
1096                 if ( $isWrite ) {
1097                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
1098                 } else {
1099                         $isNonTempWrite = false;
1100                 }
1101
1102                 if ( $isWrite ) {
1103                         if ( $this->getLBInfo( 'replica' ) === true ) {
1104                                 throw new DBError(
1105                                         $this,
1106                                         'Write operations are not allowed on replica database connections.'
1107                                 );
1108                         }
1109                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1110                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1111                         $reason = $this->getReadOnlyReason();
1112                         if ( $reason !== false ) {
1113                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1114                         }
1115                         # Set a flag indicating that writes have been done
1116                         $this->lastWriteTime = microtime( true );
1117                 }
1118
1119                 # Add trace comment to the begin of the sql string, right after the operator.
1120                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1121                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1122
1123                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
1124                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
1125                         && $this->isTransactableQuery( $sql )
1126                 ) {
1127                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1128                         $this->trxAutomatic = true;
1129                 }
1130
1131                 # Keep track of whether the transaction has write queries pending
1132                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
1133                         $this->trxDoneWrites = true;
1134                         $this->trxProfiler->transactionWritingIn(
1135                                 $this->server, $this->dbName, $this->trxShortId );
1136                 }
1137
1138                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1139                         $this->queryLogger->debug( "{$this->dbName} {$commentedSql}" );
1140                 }
1141
1142                 # Send the query to the server and fetch any corresponding errors
1143                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1144                 $lastError = $this->lastError();
1145                 $lastErrno = $this->lastErrno();
1146
1147                 # Try reconnecting if the connection was lost
1148                 if ( $ret === false && $this->wasConnectionLoss() ) {
1149                         # Check if any meaningful session state was lost
1150                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1151                         # Update session state tracking and try to restore the connection
1152                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1153                         # Silently resend the query to the server if it is safe and possible
1154                         if ( $reconnected && $recoverable ) {
1155                                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1156                                 $lastError = $this->lastError();
1157                                 $lastErrno = $this->lastErrno();
1158
1159                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1160                                         # Query probably causes disconnects; reconnect and do not re-run it
1161                                         $this->replaceLostConnection( __METHOD__ );
1162                                 }
1163                         }
1164                 }
1165
1166                 if ( $ret === false ) {
1167                         if ( $this->trxLevel ) {
1168                                 if ( $this->wasKnownStatementRollbackError() ) {
1169                                         # We're ignoring an error that caused just the current query to be aborted.
1170                                         # But log the cause so we can log a deprecation notice if a caller actually
1171                                         # does ignore it.
1172                                         $this->trxStatusIgnoredCause = [ $lastError, $lastErrno, $fname ];
1173                                 } else {
1174                                         # Either the query was aborted or all queries after BEGIN where aborted.
1175                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1176                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1177                                         # option is ROLLBACK, since the snapshots would have been released.
1178                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1179                                         $this->trxStatusCause =
1180                                                 $this->makeQueryException( $lastError, $lastErrno, $sql, $fname );
1181                                         $tempIgnore = false; // cannot recover
1182                                         $this->trxStatusIgnoredCause = null;
1183                                 }
1184                         }
1185
1186                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1187                 }
1188
1189                 return $this->resultObject( $ret );
1190         }
1191
1192         /**
1193          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1194          *
1195          * @param string $sql Original SQL query
1196          * @param string $commentedSql SQL query with debugging/trace comment
1197          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1198          * @param string $fname Name of the calling function
1199          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1200          *     object for a successful read query, or false on failure
1201          */
1202         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1203                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1204                 # generalizeSQL() will probably cut down the query to reasonable
1205                 # logging size most of the time. The substr is really just a sanity check.
1206                 if ( $isMaster ) {
1207                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1208                 } else {
1209                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1210                 }
1211
1212                 # Include query transaction state
1213                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1214
1215                 $startTime = microtime( true );
1216                 if ( $this->profiler ) {
1217                         $this->profiler->profileIn( $queryProf );
1218                 }
1219                 $this->affectedRowCount = null;
1220                 $ret = $this->doQuery( $commentedSql );
1221                 $this->affectedRowCount = $this->affectedRows();
1222                 if ( $this->profiler ) {
1223                         $this->profiler->profileOut( $queryProf );
1224                 }
1225                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1226
1227                 unset( $queryProfSection ); // profile out (if set)
1228
1229                 if ( $ret !== false ) {
1230                         $this->lastPing = $startTime;
1231                         if ( $isWrite && $this->trxLevel ) {
1232                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1233                                 $this->trxWriteCallers[] = $fname;
1234                         }
1235                 }
1236
1237                 if ( $sql === self::PING_QUERY ) {
1238                         $this->rttEstimate = $queryRuntime;
1239                 }
1240
1241                 $this->trxProfiler->recordQueryCompletion(
1242                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1243                 );
1244                 $this->queryLogger->debug( $sql, [
1245                         'method' => $fname,
1246                         'master' => $isMaster,
1247                         'runtime' => $queryRuntime,
1248                 ] );
1249
1250                 return $ret;
1251         }
1252
1253         /**
1254          * Update the estimated run-time of a query, not counting large row lock times
1255          *
1256          * LoadBalancer can be set to rollback transactions that will create huge replication
1257          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1258          * queries, like inserting a row can take a long time due to row locking. This method
1259          * uses some simple heuristics to discount those cases.
1260          *
1261          * @param string $sql A SQL write query
1262          * @param float $runtime Total runtime, including RTT
1263          * @param int $affected Affected row count
1264          */
1265         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1266                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1267                 $indicativeOfReplicaRuntime = true;
1268                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1269                         $verb = $this->getQueryVerb( $sql );
1270                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1271                         if ( $verb === 'INSERT' ) {
1272                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1273                         } elseif ( $verb === 'REPLACE' ) {
1274                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1275                         }
1276                 }
1277
1278                 $this->trxWriteDuration += $runtime;
1279                 $this->trxWriteQueryCount += 1;
1280                 $this->trxWriteAffectedRows += $affected;
1281                 if ( $indicativeOfReplicaRuntime ) {
1282                         $this->trxWriteAdjDuration += $runtime;
1283                         $this->trxWriteAdjQueryCount += 1;
1284                 }
1285         }
1286
1287         /**
1288          * @param string $sql
1289          * @param string $fname
1290          * @throws DBTransactionStateError
1291          */
1292         private function assertTransactionStatus( $sql, $fname ) {
1293                 if ( $this->getQueryVerb( $sql ) === 'ROLLBACK' ) { // transaction/savepoint
1294                         return;
1295                 }
1296
1297                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1298                         throw new DBTransactionStateError(
1299                                 $this,
1300                                 "Cannot execute query from $fname while transaction status is ERROR.",
1301                                 [],
1302                                 $this->trxStatusCause
1303                         );
1304                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1305                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1306                         call_user_func( $this->deprecationLogger,
1307                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1308                                 "[$iLastErrno] $iLastError"
1309                         );
1310                         $this->trxStatusIgnoredCause = null;
1311                 }
1312         }
1313
1314         /**
1315          * Determine whether or not it is safe to retry queries after a database
1316          * connection is lost
1317          *
1318          * @param string $sql SQL query
1319          * @param bool $priorWritesPending Whether there is a transaction open with
1320          *     possible write queries or transaction pre-commit/idle callbacks
1321          *     waiting on it to finish.
1322          * @return bool True if it is safe to retry the query, false otherwise
1323          */
1324         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1325                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1326                 # Dropped connections also mean that named locks are automatically released.
1327                 # Only allow error suppression in autocommit mode or when the lost transaction
1328                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1329                 if ( $this->namedLocksHeld ) {
1330                         return false; // possible critical section violation
1331                 } elseif ( $this->sessionTempTables ) {
1332                         return false; // tables might be queried latter
1333                 } elseif ( $sql === 'COMMIT' ) {
1334                         return !$priorWritesPending; // nothing written anyway? (T127428)
1335                 } elseif ( $sql === 'ROLLBACK' ) {
1336                         return true; // transaction lost...which is also what was requested :)
1337                 } elseif ( $this->explicitTrxActive() ) {
1338                         return false; // don't drop atomocity and explicit snapshots
1339                 } elseif ( $priorWritesPending ) {
1340                         return false; // prior writes lost from implicit transaction
1341                 }
1342
1343                 return true;
1344         }
1345
1346         /**
1347          * Clean things up after session (and thus transaction) loss
1348          */
1349         private function handleSessionLoss() {
1350                 // Clean up tracking of session-level things...
1351                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1352                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1353                 $this->sessionTempTables = [];
1354                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1355                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1356                 $this->namedLocksHeld = [];
1357                 // Session loss implies transaction loss
1358                 $this->handleTransactionLoss();
1359         }
1360
1361         /**
1362          * Clean things up after transaction loss
1363          */
1364         private function handleTransactionLoss() {
1365                 $this->trxLevel = 0;
1366                 $this->trxAtomicCounter = 0;
1367                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1368                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1369                 try {
1370                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1371                         // If callback suppression is set then the array will remain unhandled.
1372                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1373                 } catch ( Exception $ex ) {
1374                         // Already logged; move on...
1375                 }
1376                 try {
1377                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1378                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1379                 } catch ( Exception $ex ) {
1380                         // Already logged; move on...
1381                 }
1382         }
1383
1384         /**
1385          * Checks whether the cause of the error is detected to be a timeout.
1386          *
1387          * It returns false by default, and not all engines support detecting this yet.
1388          * If this returns false, it will be treated as a generic query error.
1389          *
1390          * @param string $error Error text
1391          * @param int $errno Error number
1392          * @return bool
1393          */
1394         protected function wasQueryTimeout( $error, $errno ) {
1395                 return false;
1396         }
1397
1398         /**
1399          * Report a query error. Log the error, and if neither the object ignore
1400          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1401          *
1402          * @param string $error
1403          * @param int $errno
1404          * @param string $sql
1405          * @param string $fname
1406          * @param bool $tempIgnore
1407          * @throws DBQueryError
1408          */
1409         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1410                 if ( $tempIgnore ) {
1411                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1412                 } else {
1413                         $exception = $this->makeQueryException( $error, $errno, $sql, $fname );
1414
1415                         throw $exception;
1416                 }
1417         }
1418
1419         /**
1420          * @param string $error
1421          * @param string|int $errno
1422          * @param string $sql
1423          * @param string $fname
1424          * @return DBError
1425          */
1426         private function makeQueryException( $error, $errno, $sql, $fname ) {
1427                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1428                 $this->queryLogger->error(
1429                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1430                         $this->getLogContext( [
1431                                 'method' => __METHOD__,
1432                                 'errno' => $errno,
1433                                 'error' => $error,
1434                                 'sql1line' => $sql1line,
1435                                 'fname' => $fname,
1436                         ] )
1437                 );
1438                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1439                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1440                 if ( $wasQueryTimeout ) {
1441                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1442                 } else {
1443                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1444                 }
1445
1446                 return $e;
1447         }
1448
1449         public function freeResult( $res ) {
1450         }
1451
1452         public function selectField(
1453                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1454         ) {
1455                 if ( $var === '*' ) { // sanity
1456                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1457                 }
1458
1459                 if ( !is_array( $options ) ) {
1460                         $options = [ $options ];
1461                 }
1462
1463                 $options['LIMIT'] = 1;
1464
1465                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1466                 if ( $res === false || !$this->numRows( $res ) ) {
1467                         return false;
1468                 }
1469
1470                 $row = $this->fetchRow( $res );
1471
1472                 if ( $row !== false ) {
1473                         return reset( $row );
1474                 } else {
1475                         return false;
1476                 }
1477         }
1478
1479         public function selectFieldValues(
1480                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1481         ) {
1482                 if ( $var === '*' ) { // sanity
1483                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1484                 } elseif ( !is_string( $var ) ) { // sanity
1485                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1486                 }
1487
1488                 if ( !is_array( $options ) ) {
1489                         $options = [ $options ];
1490                 }
1491
1492                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1493                 if ( $res === false ) {
1494                         return false;
1495                 }
1496
1497                 $values = [];
1498                 foreach ( $res as $row ) {
1499                         $values[] = $row->$var;
1500                 }
1501
1502                 return $values;
1503         }
1504
1505         /**
1506          * Returns an optional USE INDEX clause to go after the table, and a
1507          * string to go at the end of the query.
1508          *
1509          * @param array $options Associative array of options to be turned into
1510          *   an SQL query, valid keys are listed in the function.
1511          * @return array
1512          * @see Database::select()
1513          */
1514         protected function makeSelectOptions( $options ) {
1515                 $preLimitTail = $postLimitTail = '';
1516                 $startOpts = '';
1517
1518                 $noKeyOptions = [];
1519
1520                 foreach ( $options as $key => $option ) {
1521                         if ( is_numeric( $key ) ) {
1522                                 $noKeyOptions[$option] = true;
1523                         }
1524                 }
1525
1526                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1527
1528                 $preLimitTail .= $this->makeOrderBy( $options );
1529
1530                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1531                         $postLimitTail .= ' FOR UPDATE';
1532                 }
1533
1534                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1535                         $postLimitTail .= ' LOCK IN SHARE MODE';
1536                 }
1537
1538                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1539                         $startOpts .= 'DISTINCT';
1540                 }
1541
1542                 # Various MySQL extensions
1543                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1544                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1545                 }
1546
1547                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1548                         $startOpts .= ' HIGH_PRIORITY';
1549                 }
1550
1551                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1552                         $startOpts .= ' SQL_BIG_RESULT';
1553                 }
1554
1555                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1556                         $startOpts .= ' SQL_BUFFER_RESULT';
1557                 }
1558
1559                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1560                         $startOpts .= ' SQL_SMALL_RESULT';
1561                 }
1562
1563                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1564                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1565                 }
1566
1567                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1568                         $startOpts .= ' SQL_CACHE';
1569                 }
1570
1571                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1572                         $startOpts .= ' SQL_NO_CACHE';
1573                 }
1574
1575                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1576                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1577                 } else {
1578                         $useIndex = '';
1579                 }
1580                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1581                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1582                 } else {
1583                         $ignoreIndex = '';
1584                 }
1585
1586                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1587         }
1588
1589         /**
1590          * Returns an optional GROUP BY with an optional HAVING
1591          *
1592          * @param array $options Associative array of options
1593          * @return string
1594          * @see Database::select()
1595          * @since 1.21
1596          */
1597         protected function makeGroupByWithHaving( $options ) {
1598                 $sql = '';
1599                 if ( isset( $options['GROUP BY'] ) ) {
1600                         $gb = is_array( $options['GROUP BY'] )
1601                                 ? implode( ',', $options['GROUP BY'] )
1602                                 : $options['GROUP BY'];
1603                         $sql .= ' GROUP BY ' . $gb;
1604                 }
1605                 if ( isset( $options['HAVING'] ) ) {
1606                         $having = is_array( $options['HAVING'] )
1607                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1608                                 : $options['HAVING'];
1609                         $sql .= ' HAVING ' . $having;
1610                 }
1611
1612                 return $sql;
1613         }
1614
1615         /**
1616          * Returns an optional ORDER BY
1617          *
1618          * @param array $options Associative array of options
1619          * @return string
1620          * @see Database::select()
1621          * @since 1.21
1622          */
1623         protected function makeOrderBy( $options ) {
1624                 if ( isset( $options['ORDER BY'] ) ) {
1625                         $ob = is_array( $options['ORDER BY'] )
1626                                 ? implode( ',', $options['ORDER BY'] )
1627                                 : $options['ORDER BY'];
1628
1629                         return ' ORDER BY ' . $ob;
1630                 }
1631
1632                 return '';
1633         }
1634
1635         public function select(
1636                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1637         ) {
1638                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1639
1640                 return $this->query( $sql, $fname );
1641         }
1642
1643         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1644                 $options = [], $join_conds = []
1645         ) {
1646                 if ( is_array( $vars ) ) {
1647                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1648                 } else {
1649                         $fields = $vars;
1650                 }
1651
1652                 $options = (array)$options;
1653                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1654                         ? $options['USE INDEX']
1655                         : [];
1656                 $ignoreIndexes = (
1657                         isset( $options['IGNORE INDEX'] ) &&
1658                         is_array( $options['IGNORE INDEX'] )
1659                 )
1660                         ? $options['IGNORE INDEX']
1661                         : [];
1662
1663                 if (
1664                         $this->selectOptionsIncludeLocking( $options ) &&
1665                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1666                 ) {
1667                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1668                         // functions. Discourage use of such queries to encourage compatibility.
1669                         call_user_func(
1670                                 $this->deprecationLogger,
1671                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1672                         );
1673                 }
1674
1675                 if ( is_array( $table ) ) {
1676                         $from = ' FROM ' .
1677                                 $this->tableNamesWithIndexClauseOrJOIN(
1678                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1679                 } elseif ( $table != '' ) {
1680                         $from = ' FROM ' .
1681                                 $this->tableNamesWithIndexClauseOrJOIN(
1682                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1683                 } else {
1684                         $from = '';
1685                 }
1686
1687                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1688                         $this->makeSelectOptions( $options );
1689
1690                 if ( is_array( $conds ) ) {
1691                         $conds = $this->makeList( $conds, self::LIST_AND );
1692                 }
1693
1694                 if ( $conds === null || $conds === false ) {
1695                         $this->queryLogger->warning(
1696                                 __METHOD__
1697                                 . ' called from '
1698                                 . $fname
1699                                 . ' with incorrect parameters: $conds must be a string or an array'
1700                         );
1701                         $conds = '';
1702                 }
1703
1704                 if ( $conds === '' ) {
1705                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1706                 } elseif ( is_string( $conds ) ) {
1707                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1708                                 "WHERE $conds $preLimitTail";
1709                 } else {
1710                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1711                 }
1712
1713                 if ( isset( $options['LIMIT'] ) ) {
1714                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1715                                 $options['OFFSET'] ?? false );
1716                 }
1717                 $sql = "$sql $postLimitTail";
1718
1719                 if ( isset( $options['EXPLAIN'] ) ) {
1720                         $sql = 'EXPLAIN ' . $sql;
1721                 }
1722
1723                 return $sql;
1724         }
1725
1726         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1727                 $options = [], $join_conds = []
1728         ) {
1729                 $options = (array)$options;
1730                 $options['LIMIT'] = 1;
1731                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1732
1733                 if ( $res === false ) {
1734                         return false;
1735                 }
1736
1737                 if ( !$this->numRows( $res ) ) {
1738                         return false;
1739                 }
1740
1741                 $obj = $this->fetchObject( $res );
1742
1743                 return $obj;
1744         }
1745
1746         public function estimateRowCount(
1747                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1748         ) {
1749                 $conds = $this->normalizeConditions( $conds, $fname );
1750                 $column = $this->extractSingleFieldFromList( $var );
1751                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1752                         $conds[] = "$column IS NOT NULL";
1753                 }
1754
1755                 $res = $this->select(
1756                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1757                 );
1758                 $row = $res ? $this->fetchRow( $res ) : [];
1759
1760                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1761         }
1762
1763         public function selectRowCount(
1764                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1765         ) {
1766                 $conds = $this->normalizeConditions( $conds, $fname );
1767                 $column = $this->extractSingleFieldFromList( $var );
1768                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1769                         $conds[] = "$column IS NOT NULL";
1770                 }
1771
1772                 $res = $this->select(
1773                         [
1774                                 'tmp_count' => $this->buildSelectSubquery(
1775                                         $tables,
1776                                         '1',
1777                                         $conds,
1778                                         $fname,
1779                                         $options,
1780                                         $join_conds
1781                                 )
1782                         ],
1783                         [ 'rowcount' => 'COUNT(*)' ],
1784                         [],
1785                         $fname
1786                 );
1787                 $row = $res ? $this->fetchRow( $res ) : [];
1788
1789                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1790         }
1791
1792         /**
1793          * @param string|array $options
1794          * @return bool
1795          */
1796         private function selectOptionsIncludeLocking( $options ) {
1797                 $options = (array)$options;
1798                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1799                         if ( in_array( $lock, $options, true ) ) {
1800                                 return true;
1801                         }
1802                 }
1803
1804                 return false;
1805         }
1806
1807         /**
1808          * @param array|string $fields
1809          * @param array|string $options
1810          * @return bool
1811          */
1812         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1813                 foreach ( (array)$options as $key => $value ) {
1814                         if ( is_string( $key ) ) {
1815                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1816                                         return true;
1817                                 }
1818                         } elseif ( is_string( $value ) ) {
1819                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1820                                         return true;
1821                                 }
1822                         }
1823                 }
1824
1825                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1826                 foreach ( (array)$fields as $field ) {
1827                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1828                                 return true;
1829                         }
1830                 }
1831
1832                 return false;
1833         }
1834
1835         /**
1836          * @param array|string $conds
1837          * @param string $fname
1838          * @return array
1839          */
1840         final protected function normalizeConditions( $conds, $fname ) {
1841                 if ( $conds === null || $conds === false ) {
1842                         $this->queryLogger->warning(
1843                                 __METHOD__
1844                                 . ' called from '
1845                                 . $fname
1846                                 . ' with incorrect parameters: $conds must be a string or an array'
1847                         );
1848                         $conds = '';
1849                 }
1850
1851                 if ( !is_array( $conds ) ) {
1852                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1853                 }
1854
1855                 return $conds;
1856         }
1857
1858         /**
1859          * @param array|string $var Field parameter in the style of select()
1860          * @return string|null Column name or null; ignores aliases
1861          * @throws DBUnexpectedError Errors out if multiple columns are given
1862          */
1863         final protected function extractSingleFieldFromList( $var ) {
1864                 if ( is_array( $var ) ) {
1865                         if ( !$var ) {
1866                                 $column = null;
1867                         } elseif ( count( $var ) == 1 ) {
1868                                 $column = $var[0] ?? reset( $var );
1869                         } else {
1870                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1871                         }
1872                 } else {
1873                         $column = $var;
1874                 }
1875
1876                 return $column;
1877         }
1878
1879         public function lockForUpdate(
1880                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1881         ) {
1882                 if ( !$this->trxLevel && !$this->getFlag( self::DBO_TRX ) ) {
1883                         throw new DBUnexpectedError(
1884                                 $this,
1885                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
1886                         );
1887                 }
1888
1889                 $options = (array)$options;
1890                 $options[] = 'FOR UPDATE';
1891
1892                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
1893         }
1894
1895         /**
1896          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1897          * It's only slightly flawed. Don't use for anything important.
1898          *
1899          * @param string $sql A SQL Query
1900          *
1901          * @return string
1902          */
1903         protected static function generalizeSQL( $sql ) {
1904                 # This does the same as the regexp below would do, but in such a way
1905                 # as to avoid crashing php on some large strings.
1906                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1907
1908                 $sql = str_replace( "\\\\", '', $sql );
1909                 $sql = str_replace( "\\'", '', $sql );
1910                 $sql = str_replace( "\\\"", '', $sql );
1911                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1912                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1913
1914                 # All newlines, tabs, etc replaced by single space
1915                 $sql = preg_replace( '/\s+/', ' ', $sql );
1916
1917                 # All numbers => N,
1918                 # except the ones surrounded by characters, e.g. l10n
1919                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1920                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1921
1922                 return $sql;
1923         }
1924
1925         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1926                 $info = $this->fieldInfo( $table, $field );
1927
1928                 return (bool)$info;
1929         }
1930
1931         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1932                 if ( !$this->tableExists( $table ) ) {
1933                         return null;
1934                 }
1935
1936                 $info = $this->indexInfo( $table, $index, $fname );
1937                 if ( is_null( $info ) ) {
1938                         return null;
1939                 } else {
1940                         return $info !== false;
1941                 }
1942         }
1943
1944         abstract public function tableExists( $table, $fname = __METHOD__ );
1945
1946         public function indexUnique( $table, $index ) {
1947                 $indexInfo = $this->indexInfo( $table, $index );
1948
1949                 if ( !$indexInfo ) {
1950                         return null;
1951                 }
1952
1953                 return !$indexInfo[0]->Non_unique;
1954         }
1955
1956         /**
1957          * Helper for Database::insert().
1958          *
1959          * @param array $options
1960          * @return string
1961          */
1962         protected function makeInsertOptions( $options ) {
1963                 return implode( ' ', $options );
1964         }
1965
1966         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1967                 # No rows to insert, easy just return now
1968                 if ( !count( $a ) ) {
1969                         return true;
1970                 }
1971
1972                 $table = $this->tableName( $table );
1973
1974                 if ( !is_array( $options ) ) {
1975                         $options = [ $options ];
1976                 }
1977
1978                 $fh = null;
1979                 if ( isset( $options['fileHandle'] ) ) {
1980                         $fh = $options['fileHandle'];
1981                 }
1982                 $options = $this->makeInsertOptions( $options );
1983
1984                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1985                         $multi = true;
1986                         $keys = array_keys( $a[0] );
1987                 } else {
1988                         $multi = false;
1989                         $keys = array_keys( $a );
1990                 }
1991
1992                 $sql = 'INSERT ' . $options .
1993                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1994
1995                 if ( $multi ) {
1996                         $first = true;
1997                         foreach ( $a as $row ) {
1998                                 if ( $first ) {
1999                                         $first = false;
2000                                 } else {
2001                                         $sql .= ',';
2002                                 }
2003                                 $sql .= '(' . $this->makeList( $row ) . ')';
2004                         }
2005                 } else {
2006                         $sql .= '(' . $this->makeList( $a ) . ')';
2007                 }
2008
2009                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
2010                         return false;
2011                 } elseif ( $fh !== null ) {
2012                         return true;
2013                 }
2014
2015                 return (bool)$this->query( $sql, $fname );
2016         }
2017
2018         /**
2019          * Make UPDATE options array for Database::makeUpdateOptions
2020          *
2021          * @param array $options
2022          * @return array
2023          */
2024         protected function makeUpdateOptionsArray( $options ) {
2025                 if ( !is_array( $options ) ) {
2026                         $options = [ $options ];
2027                 }
2028
2029                 $opts = [];
2030
2031                 if ( in_array( 'IGNORE', $options ) ) {
2032                         $opts[] = 'IGNORE';
2033                 }
2034
2035                 return $opts;
2036         }
2037
2038         /**
2039          * Make UPDATE options for the Database::update function
2040          *
2041          * @param array $options The options passed to Database::update
2042          * @return string
2043          */
2044         protected function makeUpdateOptions( $options ) {
2045                 $opts = $this->makeUpdateOptionsArray( $options );
2046
2047                 return implode( ' ', $opts );
2048         }
2049
2050         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2051                 $table = $this->tableName( $table );
2052                 $opts = $this->makeUpdateOptions( $options );
2053                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2054
2055                 if ( $conds !== [] && $conds !== '*' ) {
2056                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2057                 }
2058
2059                 return (bool)$this->query( $sql, $fname );
2060         }
2061
2062         public function makeList( $a, $mode = self::LIST_COMMA ) {
2063                 if ( !is_array( $a ) ) {
2064                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2065                 }
2066
2067                 $first = true;
2068                 $list = '';
2069
2070                 foreach ( $a as $field => $value ) {
2071                         if ( !$first ) {
2072                                 if ( $mode == self::LIST_AND ) {
2073                                         $list .= ' AND ';
2074                                 } elseif ( $mode == self::LIST_OR ) {
2075                                         $list .= ' OR ';
2076                                 } else {
2077                                         $list .= ',';
2078                                 }
2079                         } else {
2080                                 $first = false;
2081                         }
2082
2083                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2084                                 $list .= "($value)";
2085                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2086                                 $list .= "$value";
2087                         } elseif (
2088                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2089                         ) {
2090                                 // Remove null from array to be handled separately if found
2091                                 $includeNull = false;
2092                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2093                                         $includeNull = true;
2094                                         unset( $value[$nullKey] );
2095                                 }
2096                                 if ( count( $value ) == 0 && !$includeNull ) {
2097                                         throw new InvalidArgumentException(
2098                                                 __METHOD__ . ": empty input for field $field" );
2099                                 } elseif ( count( $value ) == 0 ) {
2100                                         // only check if $field is null
2101                                         $list .= "$field IS NULL";
2102                                 } else {
2103                                         // IN clause contains at least one valid element
2104                                         if ( $includeNull ) {
2105                                                 // Group subconditions to ensure correct precedence
2106                                                 $list .= '(';
2107                                         }
2108                                         if ( count( $value ) == 1 ) {
2109                                                 // Special-case single values, as IN isn't terribly efficient
2110                                                 // Don't necessarily assume the single key is 0; we don't
2111                                                 // enforce linear numeric ordering on other arrays here.
2112                                                 $value = array_values( $value )[0];
2113                                                 $list .= $field . " = " . $this->addQuotes( $value );
2114                                         } else {
2115                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2116                                         }
2117                                         // if null present in array, append IS NULL
2118                                         if ( $includeNull ) {
2119                                                 $list .= " OR $field IS NULL)";
2120                                         }
2121                                 }
2122                         } elseif ( $value === null ) {
2123                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2124                                         $list .= "$field IS ";
2125                                 } elseif ( $mode == self::LIST_SET ) {
2126                                         $list .= "$field = ";
2127                                 }
2128                                 $list .= 'NULL';
2129                         } else {
2130                                 if (
2131                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2132                                 ) {
2133                                         $list .= "$field = ";
2134                                 }
2135                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2136                         }
2137                 }
2138
2139                 return $list;
2140         }
2141
2142         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2143                 $conds = [];
2144
2145                 foreach ( $data as $base => $sub ) {
2146                         if ( count( $sub ) ) {
2147                                 $conds[] = $this->makeList(
2148                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2149                                         self::LIST_AND );
2150                         }
2151                 }
2152
2153                 if ( $conds ) {
2154                         return $this->makeList( $conds, self::LIST_OR );
2155                 } else {
2156                         // Nothing to search for...
2157                         return false;
2158                 }
2159         }
2160
2161         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2162                 return $valuename;
2163         }
2164
2165         public function bitNot( $field ) {
2166                 return "(~$field)";
2167         }
2168
2169         public function bitAnd( $fieldLeft, $fieldRight ) {
2170                 return "($fieldLeft & $fieldRight)";
2171         }
2172
2173         public function bitOr( $fieldLeft, $fieldRight ) {
2174                 return "($fieldLeft | $fieldRight)";
2175         }
2176
2177         public function buildConcat( $stringList ) {
2178                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2179         }
2180
2181         public function buildGroupConcatField(
2182                 $delim, $table, $field, $conds = '', $join_conds = []
2183         ) {
2184                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2185
2186                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2187         }
2188
2189         public function buildSubstring( $input, $startPosition, $length = null ) {
2190                 $this->assertBuildSubstringParams( $startPosition, $length );
2191                 $functionBody = "$input FROM $startPosition";
2192                 if ( $length !== null ) {
2193                         $functionBody .= " FOR $length";
2194                 }
2195                 return 'SUBSTRING(' . $functionBody . ')';
2196         }
2197
2198         /**
2199          * Check type and bounds for parameters to self::buildSubstring()
2200          *
2201          * All supported databases have substring functions that behave the same for
2202          * positive $startPosition and non-negative $length, but behaviors differ when
2203          * given 0 or negative $startPosition or negative $length. The simplest
2204          * solution to that is to just forbid those values.
2205          *
2206          * @param int $startPosition
2207          * @param int|null $length
2208          * @since 1.31
2209          */
2210         protected function assertBuildSubstringParams( $startPosition, $length ) {
2211                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2212                         throw new InvalidArgumentException(
2213                                 '$startPosition must be a positive integer'
2214                         );
2215                 }
2216                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2217                         throw new InvalidArgumentException(
2218                                 '$length must be null or an integer greater than or equal to 0'
2219                         );
2220                 }
2221         }
2222
2223         public function buildStringCast( $field ) {
2224                 return $field;
2225         }
2226
2227         public function buildIntegerCast( $field ) {
2228                 return 'CAST( ' . $field . ' AS INTEGER )';
2229         }
2230
2231         public function buildSelectSubquery(
2232                 $table, $vars, $conds = '', $fname = __METHOD__,
2233                 $options = [], $join_conds = []
2234         ) {
2235                 return new Subquery(
2236                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2237                 );
2238         }
2239
2240         public function databasesAreIndependent() {
2241                 return false;
2242         }
2243
2244         public function selectDB( $db ) {
2245                 # Stub. Shouldn't cause serious problems if it's not overridden, but
2246                 # if your database engine supports a concept similar to MySQL's
2247                 # databases you may as well.
2248                 $this->dbName = $db;
2249
2250                 return true;
2251         }
2252
2253         public function getDBname() {
2254                 return $this->dbName;
2255         }
2256
2257         public function getServer() {
2258                 return $this->server;
2259         }
2260
2261         public function tableName( $name, $format = 'quoted' ) {
2262                 if ( $name instanceof Subquery ) {
2263                         throw new DBUnexpectedError(
2264                                 $this,
2265                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2266                         );
2267                 }
2268
2269                 # Skip the entire process when we have a string quoted on both ends.
2270                 # Note that we check the end so that we will still quote any use of
2271                 # use of `database`.table. But won't break things if someone wants
2272                 # to query a database table with a dot in the name.
2273                 if ( $this->isQuotedIdentifier( $name ) ) {
2274                         return $name;
2275                 }
2276
2277                 # Lets test for any bits of text that should never show up in a table
2278                 # name. Basically anything like JOIN or ON which are actually part of
2279                 # SQL queries, but may end up inside of the table value to combine
2280                 # sql. Such as how the API is doing.
2281                 # Note that we use a whitespace test rather than a \b test to avoid
2282                 # any remote case where a word like on may be inside of a table name
2283                 # surrounded by symbols which may be considered word breaks.
2284                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2285                         $this->queryLogger->warning(
2286                                 __METHOD__ . ": use of subqueries is not supported this way.",
2287                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2288                         );
2289
2290                         return $name;
2291                 }
2292
2293                 # Split database and table into proper variables.
2294                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2295
2296                 # Quote $table and apply the prefix if not quoted.
2297                 # $tableName might be empty if this is called from Database::replaceVars()
2298                 $tableName = "{$prefix}{$table}";
2299                 if ( $format === 'quoted'
2300                         && !$this->isQuotedIdentifier( $tableName )
2301                         && $tableName !== ''
2302                 ) {
2303                         $tableName = $this->addIdentifierQuotes( $tableName );
2304                 }
2305
2306                 # Quote $schema and $database and merge them with the table name if needed
2307                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2308                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2309
2310                 return $tableName;
2311         }
2312
2313         /**
2314          * Get the table components needed for a query given the currently selected database
2315          *
2316          * @param string $name Table name in the form of db.schema.table, db.table, or table
2317          * @return array (DB name or "" for default, schema name, table prefix, table name)
2318          */
2319         protected function qualifiedTableComponents( $name ) {
2320                 # We reverse the explode so that database.table and table both output the correct table.
2321                 $dbDetails = explode( '.', $name, 3 );
2322                 if ( count( $dbDetails ) == 3 ) {
2323                         list( $database, $schema, $table ) = $dbDetails;
2324                         # We don't want any prefix added in this case
2325                         $prefix = '';
2326                 } elseif ( count( $dbDetails ) == 2 ) {
2327                         list( $database, $table ) = $dbDetails;
2328                         # We don't want any prefix added in this case
2329                         $prefix = '';
2330                         # In dbs that support it, $database may actually be the schema
2331                         # but that doesn't affect any of the functionality here
2332                         $schema = '';
2333                 } else {
2334                         list( $table ) = $dbDetails;
2335                         if ( isset( $this->tableAliases[$table] ) ) {
2336                                 $database = $this->tableAliases[$table]['dbname'];
2337                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2338                                         ? $this->tableAliases[$table]['schema']
2339                                         : $this->schema;
2340                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2341                                         ? $this->tableAliases[$table]['prefix']
2342                                         : $this->tablePrefix;
2343                         } else {
2344                                 $database = '';
2345                                 $schema = $this->schema; # Default schema
2346                                 $prefix = $this->tablePrefix; # Default prefix
2347                         }
2348                 }
2349
2350                 return [ $database, $schema, $prefix, $table ];
2351         }
2352
2353         /**
2354          * @param string|null $namespace Database or schema
2355          * @param string $relation Name of table, view, sequence, etc...
2356          * @param string $format One of (raw, quoted)
2357          * @return string Relation name with quoted and merged $namespace as needed
2358          */
2359         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2360                 if ( strlen( $namespace ) ) {
2361                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2362                                 $namespace = $this->addIdentifierQuotes( $namespace );
2363                         }
2364                         $relation = $namespace . '.' . $relation;
2365                 }
2366
2367                 return $relation;
2368         }
2369
2370         public function tableNames() {
2371                 $inArray = func_get_args();
2372                 $retVal = [];
2373
2374                 foreach ( $inArray as $name ) {
2375                         $retVal[$name] = $this->tableName( $name );
2376                 }
2377
2378                 return $retVal;
2379         }
2380
2381         public function tableNamesN() {
2382                 $inArray = func_get_args();
2383                 $retVal = [];
2384
2385                 foreach ( $inArray as $name ) {
2386                         $retVal[] = $this->tableName( $name );
2387                 }
2388
2389                 return $retVal;
2390         }
2391
2392         /**
2393          * Get an aliased table name
2394          *
2395          * This returns strings like "tableName AS newTableName" for aliased tables
2396          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2397          *
2398          * @see Database::tableName()
2399          * @param string|Subquery $table Table name or object with a 'sql' field
2400          * @param string|bool $alias Table alias (optional)
2401          * @return string SQL name for aliased table. Will not alias a table to its own name
2402          */
2403         protected function tableNameWithAlias( $table, $alias = false ) {
2404                 if ( is_string( $table ) ) {
2405                         $quotedTable = $this->tableName( $table );
2406                 } elseif ( $table instanceof Subquery ) {
2407                         $quotedTable = (string)$table;
2408                 } else {
2409                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2410                 }
2411
2412                 if ( !strlen( $alias ) || $alias === $table ) {
2413                         if ( $table instanceof Subquery ) {
2414                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2415                         }
2416
2417                         return $quotedTable;
2418                 } else {
2419                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2420                 }
2421         }
2422
2423         /**
2424          * Gets an array of aliased table names
2425          *
2426          * @param array $tables [ [alias] => table ]
2427          * @return string[] See tableNameWithAlias()
2428          */
2429         protected function tableNamesWithAlias( $tables ) {
2430                 $retval = [];
2431                 foreach ( $tables as $alias => $table ) {
2432                         if ( is_numeric( $alias ) ) {
2433                                 $alias = $table;
2434                         }
2435                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2436                 }
2437
2438                 return $retval;
2439         }
2440
2441         /**
2442          * Get an aliased field name
2443          * e.g. fieldName AS newFieldName
2444          *
2445          * @param string $name Field name
2446          * @param string|bool $alias Alias (optional)
2447          * @return string SQL name for aliased field. Will not alias a field to its own name
2448          */
2449         protected function fieldNameWithAlias( $name, $alias = false ) {
2450                 if ( !$alias || (string)$alias === (string)$name ) {
2451                         return $name;
2452                 } else {
2453                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2454                 }
2455         }
2456
2457         /**
2458          * Gets an array of aliased field names
2459          *
2460          * @param array $fields [ [alias] => field ]
2461          * @return string[] See fieldNameWithAlias()
2462          */
2463         protected function fieldNamesWithAlias( $fields ) {
2464                 $retval = [];
2465                 foreach ( $fields as $alias => $field ) {
2466                         if ( is_numeric( $alias ) ) {
2467                                 $alias = $field;
2468                         }
2469                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2470                 }
2471
2472                 return $retval;
2473         }
2474
2475         /**
2476          * Get the aliased table name clause for a FROM clause
2477          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2478          *
2479          * @param array $tables ( [alias] => table )
2480          * @param array $use_index Same as for select()
2481          * @param array $ignore_index Same as for select()
2482          * @param array $join_conds Same as for select()
2483          * @return string
2484          */
2485         protected function tableNamesWithIndexClauseOrJOIN(
2486                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2487         ) {
2488                 $ret = [];
2489                 $retJOIN = [];
2490                 $use_index = (array)$use_index;
2491                 $ignore_index = (array)$ignore_index;
2492                 $join_conds = (array)$join_conds;
2493
2494                 foreach ( $tables as $alias => $table ) {
2495                         if ( !is_string( $alias ) ) {
2496                                 // No alias? Set it equal to the table name
2497                                 $alias = $table;
2498                         }
2499
2500                         if ( is_array( $table ) ) {
2501                                 // A parenthesized group
2502                                 if ( count( $table ) > 1 ) {
2503                                         $joinedTable = '(' .
2504                                                 $this->tableNamesWithIndexClauseOrJOIN(
2505                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2506                                 } else {
2507                                         // Degenerate case
2508                                         $innerTable = reset( $table );
2509                                         $innerAlias = key( $table );
2510                                         $joinedTable = $this->tableNameWithAlias(
2511                                                 $innerTable,
2512                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2513                                         );
2514                                 }
2515                         } else {
2516                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2517                         }
2518
2519                         // Is there a JOIN clause for this table?
2520                         if ( isset( $join_conds[$alias] ) ) {
2521                                 list( $joinType, $conds ) = $join_conds[$alias];
2522                                 $tableClause = $joinType;
2523                                 $tableClause .= ' ' . $joinedTable;
2524                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2525                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2526                                         if ( $use != '' ) {
2527                                                 $tableClause .= ' ' . $use;
2528                                         }
2529                                 }
2530                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2531                                         $ignore = $this->ignoreIndexClause(
2532                                                 implode( ',', (array)$ignore_index[$alias] ) );
2533                                         if ( $ignore != '' ) {
2534                                                 $tableClause .= ' ' . $ignore;
2535                                         }
2536                                 }
2537                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2538                                 if ( $on != '' ) {
2539                                         $tableClause .= ' ON (' . $on . ')';
2540                                 }
2541
2542                                 $retJOIN[] = $tableClause;
2543                         } elseif ( isset( $use_index[$alias] ) ) {
2544                                 // Is there an INDEX clause for this table?
2545                                 $tableClause = $joinedTable;
2546                                 $tableClause .= ' ' . $this->useIndexClause(
2547                                                 implode( ',', (array)$use_index[$alias] )
2548                                         );
2549
2550                                 $ret[] = $tableClause;
2551                         } elseif ( isset( $ignore_index[$alias] ) ) {
2552                                 // Is there an INDEX clause for this table?
2553                                 $tableClause = $joinedTable;
2554                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2555                                                 implode( ',', (array)$ignore_index[$alias] )
2556                                         );
2557
2558                                 $ret[] = $tableClause;
2559                         } else {
2560                                 $tableClause = $joinedTable;
2561
2562                                 $ret[] = $tableClause;
2563                         }
2564                 }
2565
2566                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2567                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2568                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2569
2570                 // Compile our final table clause
2571                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2572         }
2573
2574         /**
2575          * Allows for index remapping in queries where this is not consistent across DBMS
2576          *
2577          * @param string $index
2578          * @return string
2579          */
2580         protected function indexName( $index ) {
2581                 return $this->indexAliases[$index] ?? $index;
2582         }
2583
2584         public function addQuotes( $s ) {
2585                 if ( $s instanceof Blob ) {
2586                         $s = $s->fetch();
2587                 }
2588                 if ( $s === null ) {
2589                         return 'NULL';
2590                 } elseif ( is_bool( $s ) ) {
2591                         return (int)$s;
2592                 } else {
2593                         # This will also quote numeric values. This should be harmless,
2594                         # and protects against weird problems that occur when they really
2595                         # _are_ strings such as article titles and string->number->string
2596                         # conversion is not 1:1.
2597                         return "'" . $this->strencode( $s ) . "'";
2598                 }
2599         }
2600
2601         /**
2602          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2603          * MySQL uses `backticks` while basically everything else uses double quotes.
2604          * Since MySQL is the odd one out here the double quotes are our generic
2605          * and we implement backticks in DatabaseMysqlBase.
2606          *
2607          * @param string $s
2608          * @return string
2609          */
2610         public function addIdentifierQuotes( $s ) {
2611                 return '"' . str_replace( '"', '""', $s ) . '"';
2612         }
2613
2614         /**
2615          * Returns if the given identifier looks quoted or not according to
2616          * the database convention for quoting identifiers .
2617          *
2618          * @note Do not use this to determine if untrusted input is safe.
2619          *   A malicious user can trick this function.
2620          * @param string $name
2621          * @return bool
2622          */
2623         public function isQuotedIdentifier( $name ) {
2624                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2625         }
2626
2627         /**
2628          * @param string $s
2629          * @param string $escapeChar
2630          * @return string
2631          */
2632         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2633                 return str_replace( [ $escapeChar, '%', '_' ],
2634                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2635                         $s );
2636         }
2637
2638         public function buildLike() {
2639                 $params = func_get_args();
2640
2641                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2642                         $params = $params[0];
2643                 }
2644
2645                 $s = '';
2646
2647                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2648                 // may escape backslashes, creating problems of double escaping. The `
2649                 // character has good cross-DBMS compatibility, avoiding special operators
2650                 // in MS SQL like ^ and %
2651                 $escapeChar = '`';
2652
2653                 foreach ( $params as $value ) {
2654                         if ( $value instanceof LikeMatch ) {
2655                                 $s .= $value->toString();
2656                         } else {
2657                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2658                         }
2659                 }
2660
2661                 return ' LIKE ' .
2662                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2663         }
2664
2665         public function anyChar() {
2666                 return new LikeMatch( '_' );
2667         }
2668
2669         public function anyString() {
2670                 return new LikeMatch( '%' );
2671         }
2672
2673         public function nextSequenceValue( $seqName ) {
2674                 return null;
2675         }
2676
2677         /**
2678          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2679          * is only needed because a) MySQL must be as efficient as possible due to
2680          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2681          * which index to pick. Anyway, other databases might have different
2682          * indexes on a given table. So don't bother overriding this unless you're
2683          * MySQL.
2684          * @param string $index
2685          * @return string
2686          */
2687         public function useIndexClause( $index ) {
2688                 return '';
2689         }
2690
2691         /**
2692          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2693          * is only needed because a) MySQL must be as efficient as possible due to
2694          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2695          * which index to pick. Anyway, other databases might have different
2696          * indexes on a given table. So don't bother overriding this unless you're
2697          * MySQL.
2698          * @param string $index
2699          * @return string
2700          */
2701         public function ignoreIndexClause( $index ) {
2702                 return '';
2703         }
2704
2705         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2706                 if ( count( $rows ) == 0 ) {
2707                         return;
2708                 }
2709
2710                 // Single row case
2711                 if ( !is_array( reset( $rows ) ) ) {
2712                         $rows = [ $rows ];
2713                 }
2714
2715                 try {
2716                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2717                         $affectedRowCount = 0;
2718                         foreach ( $rows as $row ) {
2719                                 // Delete rows which collide with this one
2720                                 $indexWhereClauses = [];
2721                                 foreach ( $uniqueIndexes as $index ) {
2722                                         $indexColumns = (array)$index;
2723                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2724                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2725                                                 throw new DBUnexpectedError(
2726                                                         $this,
2727                                                         'New record does not provide all values for unique key (' .
2728                                                         implode( ', ', $indexColumns ) . ')'
2729                                                 );
2730                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2731                                                 throw new DBUnexpectedError(
2732                                                         $this,
2733                                                         'New record has a null value for unique key (' .
2734                                                         implode( ', ', $indexColumns ) . ')'
2735                                                 );
2736                                         }
2737                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2738                                 }
2739
2740                                 if ( $indexWhereClauses ) {
2741                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2742                                         $affectedRowCount += $this->affectedRows();
2743                                 }
2744
2745                                 // Now insert the row
2746                                 $this->insert( $table, $row, $fname );
2747                                 $affectedRowCount += $this->affectedRows();
2748                         }
2749                         $this->endAtomic( $fname );
2750                         $this->affectedRowCount = $affectedRowCount;
2751                 } catch ( Exception $e ) {
2752                         $this->cancelAtomic( $fname );
2753                         throw $e;
2754                 }
2755         }
2756
2757         /**
2758          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2759          * statement.
2760          *
2761          * @param string $table Table name
2762          * @param array|string $rows Row(s) to insert
2763          * @param string $fname Caller function name
2764          *
2765          * @return ResultWrapper
2766          */
2767         protected function nativeReplace( $table, $rows, $fname ) {
2768                 $table = $this->tableName( $table );
2769
2770                 # Single row case
2771                 if ( !is_array( reset( $rows ) ) ) {
2772                         $rows = [ $rows ];
2773                 }
2774
2775                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2776                 $first = true;
2777
2778                 foreach ( $rows as $row ) {
2779                         if ( $first ) {
2780                                 $first = false;
2781                         } else {
2782                                 $sql .= ',';
2783                         }
2784
2785                         $sql .= '(' . $this->makeList( $row ) . ')';
2786                 }
2787
2788                 return $this->query( $sql, $fname );
2789         }
2790
2791         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2792                 $fname = __METHOD__
2793         ) {
2794                 if ( !count( $rows ) ) {
2795                         return true; // nothing to do
2796                 }
2797
2798                 if ( !is_array( reset( $rows ) ) ) {
2799                         $rows = [ $rows ];
2800                 }
2801
2802                 if ( count( $uniqueIndexes ) ) {
2803                         $clauses = []; // list WHERE clauses that each identify a single row
2804                         foreach ( $rows as $row ) {
2805                                 foreach ( $uniqueIndexes as $index ) {
2806                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2807                                         $rowKey = []; // unique key to this row
2808                                         foreach ( $index as $column ) {
2809                                                 $rowKey[$column] = $row[$column];
2810                                         }
2811                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2812                                 }
2813                         }
2814                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2815                 } else {
2816                         $where = false;
2817                 }
2818
2819                 $affectedRowCount = 0;
2820                 try {
2821                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2822                         # Update any existing conflicting row(s)
2823                         if ( $where !== false ) {
2824                                 $ok = $this->update( $table, $set, $where, $fname );
2825                                 $affectedRowCount += $this->affectedRows();
2826                         } else {
2827                                 $ok = true;
2828                         }
2829                         # Now insert any non-conflicting row(s)
2830                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2831                         $affectedRowCount += $this->affectedRows();
2832                         $this->endAtomic( $fname );
2833                         $this->affectedRowCount = $affectedRowCount;
2834                 } catch ( Exception $e ) {
2835                         $this->cancelAtomic( $fname );
2836                         throw $e;
2837                 }
2838
2839                 return $ok;
2840         }
2841
2842         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2843                 $fname = __METHOD__
2844         ) {
2845                 if ( !$conds ) {
2846                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2847                 }
2848
2849                 $delTable = $this->tableName( $delTable );
2850                 $joinTable = $this->tableName( $joinTable );
2851                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2852                 if ( $conds != '*' ) {
2853                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2854                 }
2855                 $sql .= ')';
2856
2857                 $this->query( $sql, $fname );
2858         }
2859
2860         public function textFieldSize( $table, $field ) {
2861                 $table = $this->tableName( $table );
2862                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2863                 $res = $this->query( $sql, __METHOD__ );
2864                 $row = $this->fetchObject( $res );
2865
2866                 $m = [];
2867
2868                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2869                         $size = $m[1];
2870                 } else {
2871                         $size = -1;
2872                 }
2873
2874                 return $size;
2875         }
2876
2877         public function delete( $table, $conds, $fname = __METHOD__ ) {
2878                 if ( !$conds ) {
2879                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2880                 }
2881
2882                 $table = $this->tableName( $table );
2883                 $sql = "DELETE FROM $table";
2884
2885                 if ( $conds != '*' ) {
2886                         if ( is_array( $conds ) ) {
2887                                 $conds = $this->makeList( $conds, self::LIST_AND );
2888                         }
2889                         $sql .= ' WHERE ' . $conds;
2890                 }
2891
2892                 return $this->query( $sql, $fname );
2893         }
2894
2895         final public function insertSelect(
2896                 $destTable, $srcTable, $varMap, $conds,
2897                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2898         ) {
2899                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2900
2901                 $insertOptions = (array)$insertOptions;
2902                 $selectOptions = (array)$selectOptions;
2903
2904                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2905                         // For massive migrations with downtime, we don't want to select everything
2906                         // into memory and OOM, so do all this native on the server side if possible.
2907                         return $this->nativeInsertSelect(
2908                                 $destTable,
2909                                 $srcTable,
2910                                 $varMap,
2911                                 $conds,
2912                                 $fname,
2913                                 array_diff( $insertOptions, $hints ),
2914                                 $selectOptions,
2915                                 $selectJoinConds
2916                         );
2917                 }
2918
2919                 return $this->nonNativeInsertSelect(
2920                         $destTable,
2921                         $srcTable,
2922                         $varMap,
2923                         $conds,
2924                         $fname,
2925                         array_diff( $insertOptions, $hints ),
2926                         $selectOptions,
2927                         $selectJoinConds
2928                 );
2929         }
2930
2931         /**
2932          * @param array $insertOptions INSERT options
2933          * @param array $selectOptions SELECT options
2934          * @return bool Whether an INSERT SELECT with these options will be replication safe
2935          * @since 1.31
2936          */
2937         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
2938                 return true;
2939         }
2940
2941         /**
2942          * Implementation of insertSelect() based on select() and insert()
2943          *
2944          * @see IDatabase::insertSelect()
2945          * @since 1.30
2946          * @param string $destTable
2947          * @param string|array $srcTable
2948          * @param array $varMap
2949          * @param array $conds
2950          * @param string $fname
2951          * @param array $insertOptions
2952          * @param array $selectOptions
2953          * @param array $selectJoinConds
2954          * @return bool
2955          */
2956         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2957                 $fname = __METHOD__,
2958                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2959         ) {
2960                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2961                 // on only the master (without needing row-based-replication). It also makes it easy to
2962                 // know how big the INSERT is going to be.
2963                 $fields = [];
2964                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2965                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2966                 }
2967                 $selectOptions[] = 'FOR UPDATE';
2968                 $res = $this->select(
2969                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2970                 );
2971                 if ( !$res ) {
2972                         return false;
2973                 }
2974
2975                 try {
2976                         $affectedRowCount = 0;
2977                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2978                         $rows = [];
2979                         $ok = true;
2980                         foreach ( $res as $row ) {
2981                                 $rows[] = (array)$row;
2982
2983                                 // Avoid inserts that are too huge
2984                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
2985                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2986                                         if ( !$ok ) {
2987                                                 break;
2988                                         }
2989                                         $affectedRowCount += $this->affectedRows();
2990                                         $rows = [];
2991                                 }
2992                         }
2993                         if ( $rows && $ok ) {
2994                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2995                                 if ( $ok ) {
2996                                         $affectedRowCount += $this->affectedRows();
2997                                 }
2998                         }
2999                         if ( $ok ) {
3000                                 $this->endAtomic( $fname );
3001                                 $this->affectedRowCount = $affectedRowCount;
3002                         } else {
3003                                 $this->cancelAtomic( $fname );
3004                         }
3005                         return $ok;
3006                 } catch ( Exception $e ) {
3007                         $this->cancelAtomic( $fname );
3008                         throw $e;
3009                 }
3010         }
3011
3012         /**
3013          * Native server-side implementation of insertSelect() for situations where
3014          * we don't want to select everything into memory
3015          *
3016          * @see IDatabase::insertSelect()
3017          * @param string $destTable
3018          * @param string|array $srcTable
3019          * @param array $varMap
3020          * @param array $conds
3021          * @param string $fname
3022          * @param array $insertOptions
3023          * @param array $selectOptions
3024          * @param array $selectJoinConds
3025          * @return bool
3026          */
3027         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3028                 $fname = __METHOD__,
3029                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3030         ) {
3031                 $destTable = $this->tableName( $destTable );
3032
3033                 if ( !is_array( $insertOptions ) ) {
3034                         $insertOptions = [ $insertOptions ];
3035                 }
3036
3037                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3038
3039                 $selectSql = $this->selectSQLText(
3040                         $srcTable,
3041                         array_values( $varMap ),
3042                         $conds,
3043                         $fname,
3044                         $selectOptions,
3045                         $selectJoinConds
3046                 );
3047
3048                 $sql = "INSERT $insertOptions" .
3049                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3050                         $selectSql;
3051
3052                 return $this->query( $sql, $fname );
3053         }
3054
3055         /**
3056          * Construct a LIMIT query with optional offset. This is used for query
3057          * pages. The SQL should be adjusted so that only the first $limit rows
3058          * are returned. If $offset is provided as well, then the first $offset
3059          * rows should be discarded, and the next $limit rows should be returned.
3060          * If the result of the query is not ordered, then the rows to be returned
3061          * are theoretically arbitrary.
3062          *
3063          * $sql is expected to be a SELECT, if that makes a difference.
3064          *
3065          * The version provided by default works in MySQL and SQLite. It will very
3066          * likely need to be overridden for most other DBMSes.
3067          *
3068          * @param string $sql SQL query we will append the limit too
3069          * @param int $limit The SQL limit
3070          * @param int|bool $offset The SQL offset (default false)
3071          * @throws DBUnexpectedError
3072          * @return string
3073          */
3074         public function limitResult( $sql, $limit, $offset = false ) {
3075                 if ( !is_numeric( $limit ) ) {
3076                         throw new DBUnexpectedError( $this,
3077                                 "Invalid non-numeric limit passed to limitResult()\n" );
3078                 }
3079
3080                 return "$sql LIMIT "
3081                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3082                 . "{$limit} ";
3083         }
3084
3085         public function unionSupportsOrderAndLimit() {
3086                 return true; // True for almost every DB supported
3087         }
3088
3089         public function unionQueries( $sqls, $all ) {
3090                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3091
3092                 return '(' . implode( $glue, $sqls ) . ')';
3093         }
3094
3095         public function unionConditionPermutations(
3096                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3097                 $options = [], $join_conds = []
3098         ) {
3099                 // First, build the Cartesian product of $permute_conds
3100                 $conds = [ [] ];
3101                 foreach ( $permute_conds as $field => $values ) {
3102                         if ( !$values ) {
3103                                 // Skip empty $values
3104                                 continue;
3105                         }
3106                         $values = array_unique( $values ); // For sanity
3107                         $newConds = [];
3108                         foreach ( $conds as $cond ) {
3109                                 foreach ( $values as $value ) {
3110                                         $cond[$field] = $value;
3111                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3112                                 }
3113                         }
3114                         $conds = $newConds;
3115                 }
3116
3117                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3118
3119                 // If there's just one condition and no subordering, hand off to
3120                 // selectSQLText directly.
3121                 if ( count( $conds ) === 1 &&
3122                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3123                 ) {
3124                         return $this->selectSQLText(
3125                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3126                         );
3127                 }
3128
3129                 // Otherwise, we need to pull out the order and limit to apply after
3130                 // the union. Then build the SQL queries for each set of conditions in
3131                 // $conds. Then union them together (using UNION ALL, because the
3132                 // product *should* already be distinct).
3133                 $orderBy = $this->makeOrderBy( $options );
3134                 $limit = $options['LIMIT'] ?? null;
3135                 $offset = $options['OFFSET'] ?? false;
3136                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3137                 if ( !$this->unionSupportsOrderAndLimit() ) {
3138                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3139                 } else {
3140                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3141                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3142                         }
3143                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3144                                 // We need to increase the limit by the offset rather than
3145                                 // using the offset directly, otherwise it'll skip incorrectly
3146                                 // in the subqueries.
3147                                 $options['LIMIT'] = $limit + $offset;
3148                                 unset( $options['OFFSET'] );
3149                         }
3150                 }
3151
3152                 $sqls = [];
3153                 foreach ( $conds as $cond ) {
3154                         $sqls[] = $this->selectSQLText(
3155                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3156                         );
3157                 }
3158                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3159                 if ( $limit !== null ) {
3160                         $sql = $this->limitResult( $sql, $limit, $offset );
3161                 }
3162
3163                 return $sql;
3164         }
3165
3166         public function conditional( $cond, $trueVal, $falseVal ) {
3167                 if ( is_array( $cond ) ) {
3168                         $cond = $this->makeList( $cond, self::LIST_AND );
3169                 }
3170
3171                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3172         }
3173
3174         public function strreplace( $orig, $old, $new ) {
3175                 return "REPLACE({$orig}, {$old}, {$new})";
3176         }
3177
3178         public function getServerUptime() {
3179                 return 0;
3180         }
3181
3182         public function wasDeadlock() {
3183                 return false;
3184         }
3185
3186         public function wasLockTimeout() {
3187                 return false;
3188         }
3189
3190         public function wasConnectionLoss() {
3191                 return $this->wasConnectionError( $this->lastErrno() );
3192         }
3193
3194         public function wasReadOnlyError() {
3195                 return false;
3196         }
3197
3198         public function wasErrorReissuable() {
3199                 return (
3200                         $this->wasDeadlock() ||
3201                         $this->wasLockTimeout() ||
3202                         $this->wasConnectionLoss()
3203                 );
3204         }
3205
3206         /**
3207          * Do not use this method outside of Database/DBError classes
3208          *
3209          * @param int|string $errno
3210          * @return bool Whether the given query error was a connection drop
3211          */
3212         public function wasConnectionError( $errno ) {
3213                 return false;
3214         }
3215
3216         /**
3217          * @return bool Whether it is safe to assume the given error only caused statement rollback
3218          * @note This is for backwards compatibility for callers catching DBError exceptions in
3219          *   order to ignore problems like duplicate key errors or foriegn key violations
3220          * @since 1.31
3221          */
3222         protected function wasKnownStatementRollbackError() {
3223                 return false; // don't know; it could have caused a transaction rollback
3224         }
3225
3226         public function deadlockLoop() {
3227                 $args = func_get_args();
3228                 $function = array_shift( $args );
3229                 $tries = self::DEADLOCK_TRIES;
3230
3231                 $this->begin( __METHOD__ );
3232
3233                 $retVal = null;
3234                 /** @var Exception $e */
3235                 $e = null;
3236                 do {
3237                         try {
3238                                 $retVal = $function( ...$args );
3239                                 break;
3240                         } catch ( DBQueryError $e ) {
3241                                 if ( $this->wasDeadlock() ) {
3242                                         // Retry after a randomized delay
3243                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3244                                 } else {
3245                                         // Throw the error back up
3246                                         throw $e;
3247                                 }
3248                         }
3249                 } while ( --$tries > 0 );
3250
3251                 if ( $tries <= 0 ) {
3252                         // Too many deadlocks; give up
3253                         $this->rollback( __METHOD__ );
3254                         throw $e;
3255                 } else {
3256                         $this->commit( __METHOD__ );
3257
3258                         return $retVal;
3259                 }
3260         }
3261
3262         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3263                 # Real waits are implemented in the subclass.
3264                 return 0;
3265         }
3266
3267         public function getReplicaPos() {
3268                 # Stub
3269                 return false;
3270         }
3271
3272         public function getMasterPos() {
3273                 # Stub
3274                 return false;
3275         }
3276
3277         public function serverIsReadOnly() {
3278                 return false;
3279         }
3280
3281         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3282                 if ( !$this->trxLevel ) {
3283                         throw new DBUnexpectedError( $this, "No transaction is active." );
3284                 }
3285                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3286         }
3287
3288         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3289                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3290                         // Start an implicit transaction similar to how query() does
3291                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3292                         $this->trxAutomatic = true;
3293                 }
3294
3295                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3296                 if ( !$this->trxLevel ) {
3297                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3298                 }
3299         }
3300
3301         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3302                 $this->onTransactionCommitOrIdle( $callback, $fname );
3303         }
3304
3305         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3306                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3307                         // Start an implicit transaction similar to how query() does
3308                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3309                         $this->trxAutomatic = true;
3310                 }
3311
3312                 if ( $this->trxLevel ) {
3313                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3314                 } else {
3315                         // No transaction is active nor will start implicitly, so make one for this callback
3316                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3317                         try {
3318                                 $callback( $this );
3319                                 $this->endAtomic( __METHOD__ );
3320                         } catch ( Exception $e ) {
3321                                 $this->cancelAtomic( __METHOD__ );
3322                                 throw $e;
3323                         }
3324                 }
3325         }
3326
3327         /**
3328          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3329          */
3330         private function currentAtomicSectionId() {
3331                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3332                         $levelInfo = end( $this->trxAtomicLevels );
3333
3334                         return $levelInfo[1];
3335                 }
3336
3337                 return null;
3338         }
3339
3340         /**
3341          * @param AtomicSectionIdentifier $old
3342          * @param AtomicSectionIdentifier $new
3343          */
3344         private function reassignCallbacksForSection(
3345                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3346         ) {
3347                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3348                         if ( $info[2] === $old ) {
3349                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3350                         }
3351                 }
3352                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3353                         if ( $info[2] === $old ) {
3354                                 $this->trxIdleCallbacks[$key][2] = $new;
3355                         }
3356                 }
3357                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3358                         if ( $info[2] === $old ) {
3359                                 $this->trxEndCallbacks[$key][2] = $new;
3360                         }
3361                 }
3362         }
3363
3364         /**
3365          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3366          * @throws UnexpectedValueException
3367          */
3368         private function modifyCallbacksForCancel( array $sectionIds ) {
3369                 // Cancel the "on commit" callbacks owned by this savepoint
3370                 $this->trxIdleCallbacks = array_filter(
3371                         $this->trxIdleCallbacks,
3372                         function ( $entry ) use ( $sectionIds ) {
3373                                 return !in_array( $entry[2], $sectionIds, true );
3374                         }
3375                 );
3376                 $this->trxPreCommitCallbacks = array_filter(
3377                         $this->trxPreCommitCallbacks,
3378                         function ( $entry ) use ( $sectionIds ) {
3379                                 return !in_array( $entry[2], $sectionIds, true );
3380                         }
3381                 );
3382                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3383                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3384                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3385                                 $callback = $entry[0];
3386                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3387                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3388                                 };
3389                         }
3390                 }
3391         }
3392
3393         final public function setTransactionListener( $name, callable $callback = null ) {
3394                 if ( $callback ) {
3395                         $this->trxRecurringCallbacks[$name] = $callback;
3396                 } else {
3397                         unset( $this->trxRecurringCallbacks[$name] );
3398                 }
3399         }
3400
3401         /**
3402          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3403          *
3404          * This method should not be used outside of Database/LoadBalancer
3405          *
3406          * @param bool $suppress
3407          * @since 1.28
3408          */
3409         final public function setTrxEndCallbackSuppression( $suppress ) {
3410                 $this->trxEndCallbacksSuppressed = $suppress;
3411         }
3412
3413         /**
3414          * Actually consume and run any "on transaction idle/resolution" callbacks.
3415          *
3416          * This method should not be used outside of Database/LoadBalancer
3417          *
3418          * @param int $trigger IDatabase::TRIGGER_* constant
3419          * @return int Number of callbacks attempted
3420          * @since 1.20
3421          * @throws Exception
3422          */
3423         public function runOnTransactionIdleCallbacks( $trigger ) {
3424                 if ( $this->trxLevel ) { // sanity
3425                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3426                 }
3427
3428                 if ( $this->trxEndCallbacksSuppressed ) {
3429                         return 0;
3430                 }
3431
3432                 $count = 0;
3433                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3434                 /** @var Exception $e */
3435                 $e = null; // first exception
3436                 do { // callbacks may add callbacks :)
3437                         $callbacks = array_merge(
3438                                 $this->trxIdleCallbacks,
3439                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3440                         );
3441                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3442                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3443                         foreach ( $callbacks as $callback ) {
3444                                 ++$count;
3445                                 list( $phpCallback ) = $callback;
3446                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3447                                 try {
3448                                         call_user_func( $phpCallback, $trigger, $this );
3449                                 } catch ( Exception $ex ) {
3450                                         call_user_func( $this->errorLogger, $ex );
3451                                         $e = $e ?: $ex;
3452                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3453                                         // their transactions are ended so other callbacks don't fail
3454                                         if ( $this->trxLevel() ) {
3455                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3456                                         }
3457                                 } finally {
3458                                         if ( $autoTrx ) {
3459                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3460                                         } else {
3461                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3462                                         }
3463                                 }
3464                         }
3465                 } while ( count( $this->trxIdleCallbacks ) );
3466
3467                 if ( $e instanceof Exception ) {
3468                         throw $e; // re-throw any first exception
3469                 }
3470
3471                 return $count;
3472         }
3473
3474         /**
3475          * Actually consume and run any "on transaction pre-commit" callbacks.
3476          *
3477          * This method should not be used outside of Database/LoadBalancer
3478          *
3479          * @since 1.22
3480          * @return int Number of callbacks attempted
3481          * @throws Exception
3482          */
3483         public function runOnTransactionPreCommitCallbacks() {
3484                 $count = 0;
3485
3486                 $e = null; // first exception
3487                 do { // callbacks may add callbacks :)
3488                         $callbacks = $this->trxPreCommitCallbacks;
3489                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3490                         foreach ( $callbacks as $callback ) {
3491                                 try {
3492                                         ++$count;
3493                                         list( $phpCallback ) = $callback;
3494                                         $phpCallback( $this );
3495                                 } catch ( Exception $ex ) {
3496                                         $this->errorLogger( $ex );
3497                                         $e = $e ?: $ex;
3498                                 }
3499                         }
3500                 } while ( count( $this->trxPreCommitCallbacks ) );
3501
3502                 if ( $e instanceof Exception ) {
3503                         throw $e; // re-throw any first exception
3504                 }
3505
3506                 return $count;
3507         }
3508
3509         /**
3510          * Actually run any "transaction listener" callbacks.
3511          *
3512          * This method should not be used outside of Database/LoadBalancer
3513          *
3514          * @param int $trigger IDatabase::TRIGGER_* constant
3515          * @throws Exception
3516          * @since 1.20
3517          */
3518         public function runTransactionListenerCallbacks( $trigger ) {
3519                 if ( $this->trxEndCallbacksSuppressed ) {
3520                         return;
3521                 }
3522
3523                 /** @var Exception $e */
3524                 $e = null; // first exception
3525
3526                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3527                         try {
3528                                 $phpCallback( $trigger, $this );
3529                         } catch ( Exception $ex ) {
3530                                 ( $this->errorLogger )( $ex );
3531                                 $e = $e ?: $ex;
3532                         }
3533                 }
3534
3535                 if ( $e instanceof Exception ) {
3536                         throw $e; // re-throw any first exception
3537                 }
3538         }
3539
3540         /**
3541          * Create a savepoint
3542          *
3543          * This is used internally to implement atomic sections. It should not be
3544          * used otherwise.
3545          *
3546          * @since 1.31
3547          * @param string $identifier Identifier for the savepoint
3548          * @param string $fname Calling function name
3549          */
3550         protected function doSavepoint( $identifier, $fname ) {
3551                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3552         }
3553
3554         /**
3555          * Release a savepoint
3556          *
3557          * This is used internally to implement atomic sections. It should not be
3558          * used otherwise.
3559          *
3560          * @since 1.31
3561          * @param string $identifier Identifier for the savepoint
3562          * @param string $fname Calling function name
3563          */
3564         protected function doReleaseSavepoint( $identifier, $fname ) {
3565                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3566         }
3567
3568         /**
3569          * Rollback to a savepoint
3570          *
3571          * This is used internally to implement atomic sections. It should not be
3572          * used otherwise.
3573          *
3574          * @since 1.31
3575          * @param string $identifier Identifier for the savepoint
3576          * @param string $fname Calling function name
3577          */
3578         protected function doRollbackToSavepoint( $identifier, $fname ) {
3579                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3580         }
3581
3582         /**
3583          * @param string $fname
3584          * @return string
3585          */
3586         private function nextSavepointId( $fname ) {
3587                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3588                 if ( strlen( $savepointId ) > 30 ) {
3589                         // 30 == Oracle's identifier length limit (pre 12c)
3590                         // With a 22 character prefix, that puts the highest number at 99999999.
3591                         throw new DBUnexpectedError(
3592                                 $this,
3593                                 'There have been an excessively large number of atomic sections in a transaction'
3594                                 . " started by $this->trxFname (at $fname)"
3595                         );
3596                 }
3597
3598                 return $savepointId;
3599         }
3600
3601         final public function startAtomic(
3602                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3603         ) {
3604                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3605
3606                 if ( !$this->trxLevel ) {
3607                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3608                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3609                         // in all changes being in one transaction to keep requests transactional.
3610                         if ( $this->getFlag( self::DBO_TRX ) ) {
3611                                 // Since writes could happen in between the topmost atomic sections as part
3612                                 // of the transaction, those sections will need savepoints.
3613                                 $savepointId = $this->nextSavepointId( $fname );
3614                                 $this->doSavepoint( $savepointId, $fname );
3615                         } else {
3616                                 $this->trxAutomaticAtomic = true;
3617                         }
3618                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3619                         $savepointId = $this->nextSavepointId( $fname );
3620                         $this->doSavepoint( $savepointId, $fname );
3621                 }
3622
3623                 $sectionId = new AtomicSectionIdentifier;
3624                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3625
3626                 return $sectionId;
3627         }
3628
3629         final public function endAtomic( $fname = __METHOD__ ) {
3630                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3631                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3632                 }
3633
3634                 // Check if the current section matches $fname
3635                 $pos = count( $this->trxAtomicLevels ) - 1;
3636                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3637
3638                 if ( $savedFname !== $fname ) {
3639                         throw new DBUnexpectedError(
3640                                 $this,
3641                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3642                         );
3643                 }
3644
3645                 // Remove the last section (no need to re-index the array)
3646                 array_pop( $this->trxAtomicLevels );
3647
3648                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3649                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3650                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3651                         $this->doReleaseSavepoint( $savepointId, $fname );
3652                 }
3653
3654                 // Hoist callback ownership for callbacks in the section that just ended;
3655                 // all callbacks should have an owner that is present in trxAtomicLevels.
3656                 $currentSectionId = $this->currentAtomicSectionId();
3657                 if ( $currentSectionId ) {
3658                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3659                 }
3660         }
3661
3662         final public function cancelAtomic(
3663                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3664         ) {
3665                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3666                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3667                 }
3668
3669                 if ( $sectionId !== null ) {
3670                         // Find the (last) section with the given $sectionId
3671                         $pos = -1;
3672                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3673                                 if ( $asId === $sectionId ) {
3674                                         $pos = $i;
3675                                 }
3676                         }
3677                         if ( $pos < 0 ) {
3678                                 throw new DBUnexpectedError( "Atomic section not found (for $fname)" );
3679                         }
3680                         // Remove all descendant sections and re-index the array
3681                         $excisedIds = [];
3682                         $len = count( $this->trxAtomicLevels );
3683                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3684                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3685                         }
3686                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3687                         $this->modifyCallbacksForCancel( $excisedIds );
3688                 }
3689
3690                 // Check if the current section matches $fname
3691                 $pos = count( $this->trxAtomicLevels ) - 1;
3692                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3693
3694                 if ( $savedFname !== $fname ) {
3695                         throw new DBUnexpectedError(
3696                                 $this,
3697                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3698                         );
3699                 }
3700
3701                 // Remove the last section (no need to re-index the array)
3702                 array_pop( $this->trxAtomicLevels );
3703                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3704
3705                 if ( $savepointId !== null ) {
3706                         // Rollback the transaction to the state just before this atomic section
3707                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3708                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3709                         } else {
3710                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3711                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3712                                 $this->trxStatusIgnoredCause = null;
3713                         }
3714                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3715                         // Put the transaction into an error state if it's not already in one
3716                         $this->trxStatus = self::STATUS_TRX_ERROR;
3717                         $this->trxStatusCause = new DBUnexpectedError(
3718                                 $this,
3719                                 "Uncancelable atomic section canceled (got $fname)."
3720                         );
3721                 }
3722
3723                 $this->affectedRowCount = 0; // for the sake of consistency
3724         }
3725
3726         final public function doAtomicSection(
3727                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3728         ) {
3729                 $sectionId = $this->startAtomic( $fname, $cancelable );
3730                 try {
3731                         $res = $callback( $this, $fname );
3732                 } catch ( Exception $e ) {
3733                         $this->cancelAtomic( $fname, $sectionId );
3734
3735                         throw $e;
3736                 }
3737                 $this->endAtomic( $fname );
3738
3739                 return $res;
3740         }
3741
3742         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3743                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3744                 if ( !in_array( $mode, $modes, true ) ) {
3745                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3746                 }
3747
3748                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3749                 if ( $this->trxLevel ) {
3750                         if ( $this->trxAtomicLevels ) {
3751                                 $levels = $this->flatAtomicSectionList();
3752                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3753                                 throw new DBUnexpectedError( $this, $msg );
3754                         } elseif ( !$this->trxAutomatic ) {
3755                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3756                                 throw new DBUnexpectedError( $this, $msg );
3757                         } else {
3758                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3759                                 throw new DBUnexpectedError( $this, $msg );
3760                         }
3761                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3762                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3763                         throw new DBUnexpectedError( $this, $msg );
3764                 }
3765
3766                 // Avoid fatals if close() was called
3767                 $this->assertOpen();
3768
3769                 $this->doBegin( $fname );
3770                 $this->trxStatus = self::STATUS_TRX_OK;
3771                 $this->trxStatusIgnoredCause = null;
3772                 $this->trxAtomicCounter = 0;
3773                 $this->trxTimestamp = microtime( true );
3774                 $this->trxFname = $fname;
3775                 $this->trxDoneWrites = false;
3776                 $this->trxAutomaticAtomic = false;
3777                 $this->trxAtomicLevels = [];
3778                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3779                 $this->trxWriteDuration = 0.0;
3780                 $this->trxWriteQueryCount = 0;
3781                 $this->trxWriteAffectedRows = 0;
3782                 $this->trxWriteAdjDuration = 0.0;
3783                 $this->trxWriteAdjQueryCount = 0;
3784                 $this->trxWriteCallers = [];
3785                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3786                 // Get an estimate of the replication lag before any such queries.
3787                 $this->trxReplicaLag = null; // clear cached value first
3788                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3789                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3790                 // caller will think its OK to muck around with the transaction just because startAtomic()
3791                 // has not yet completed (e.g. setting trxAtomicLevels).
3792                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3793         }
3794
3795         /**
3796          * Issues the BEGIN command to the database server.
3797          *
3798          * @see Database::begin()
3799          * @param string $fname
3800          */
3801         protected function doBegin( $fname ) {
3802                 $this->query( 'BEGIN', $fname );
3803                 $this->trxLevel = 1;
3804         }
3805
3806         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3807                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3808                 if ( !in_array( $flush, $modes, true ) ) {
3809                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3810                 }
3811
3812                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3813                         // There are still atomic sections open; this cannot be ignored
3814                         $levels = $this->flatAtomicSectionList();
3815                         throw new DBUnexpectedError(
3816                                 $this,
3817                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3818                         );
3819                 }
3820
3821                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3822                         if ( !$this->trxLevel ) {
3823                                 return; // nothing to do
3824                         } elseif ( !$this->trxAutomatic ) {
3825                                 throw new DBUnexpectedError(
3826                                         $this,
3827                                         "$fname: Flushing an explicit transaction, getting out of sync."
3828                                 );
3829                         }
3830                 } else {
3831                         if ( !$this->trxLevel ) {
3832                                 $this->queryLogger->error(
3833                                         "$fname: No transaction to commit, something got out of sync." );
3834                                 return; // nothing to do
3835                         } elseif ( $this->trxAutomatic ) {
3836                                 throw new DBUnexpectedError(
3837                                         $this,
3838                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3839                                 );
3840                         }
3841                 }
3842
3843                 // Avoid fatals if close() was called
3844                 $this->assertOpen();
3845
3846                 $this->runOnTransactionPreCommitCallbacks();
3847
3848                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3849                 $this->doCommit( $fname );
3850                 $this->trxStatus = self::STATUS_TRX_NONE;
3851
3852                 if ( $this->trxDoneWrites ) {
3853                         $this->lastWriteTime = microtime( true );
3854                         $this->trxProfiler->transactionWritingOut(
3855                                 $this->server,
3856                                 $this->dbName,
3857                                 $this->trxShortId,
3858                                 $writeTime,
3859                                 $this->trxWriteAffectedRows
3860                         );
3861                 }
3862
3863                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3864                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
3865                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3866                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3867                 }
3868         }
3869
3870         /**
3871          * Issues the COMMIT command to the database server.
3872          *
3873          * @see Database::commit()
3874          * @param string $fname
3875          */
3876         protected function doCommit( $fname ) {
3877                 if ( $this->trxLevel ) {
3878                         $this->query( 'COMMIT', $fname );
3879                         $this->trxLevel = 0;
3880                 }
3881         }
3882
3883         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3884                 $trxActive = $this->trxLevel;
3885
3886                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3887                         if ( $this->getFlag( self::DBO_TRX ) ) {
3888                                 throw new DBUnexpectedError(
3889                                         $this,
3890                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3891                                 );
3892                         }
3893                 }
3894
3895                 if ( $trxActive ) {
3896                         // Avoid fatals if close() was called
3897                         $this->assertOpen();
3898
3899                         $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3900                         $this->doRollback( $fname );
3901                         $this->trxStatus = self::STATUS_TRX_NONE;
3902                         $this->trxAtomicLevels = [];
3903
3904                         if ( $this->trxDoneWrites ) {
3905                                 $this->trxProfiler->transactionWritingOut(
3906                                         $this->server,
3907                                         $this->dbName,
3908                                         $this->trxShortId,
3909                                         $writeTime,
3910                                         $this->trxWriteAffectedRows
3911                                 );
3912                         }
3913                 }
3914
3915                 // Clear any commit-dependant callbacks. They might even be present
3916                 // only due to transaction rounds, with no SQL transaction being active
3917                 $this->trxIdleCallbacks = [];
3918                 $this->trxPreCommitCallbacks = [];
3919
3920                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3921                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
3922                         try {
3923                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3924                         } catch ( Exception $e ) {
3925                                 // already logged; finish and let LoadBalancer move on during mass-rollback
3926                         }
3927                         try {
3928                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3929                         } catch ( Exception $e ) {
3930                                 // already logged; let LoadBalancer move on during mass-rollback
3931                         }
3932
3933                         $this->affectedRowCount = 0; // for the sake of consistency
3934                 }
3935         }
3936
3937         /**
3938          * Issues the ROLLBACK command to the database server.
3939          *
3940          * @see Database::rollback()
3941          * @param string $fname
3942          */
3943         protected function doRollback( $fname ) {
3944                 if ( $this->trxLevel ) {
3945                         # Disconnects cause rollback anyway, so ignore those errors
3946                         $ignoreErrors = true;
3947                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3948                         $this->trxLevel = 0;
3949                 }
3950         }
3951
3952         public function flushSnapshot( $fname = __METHOD__ ) {
3953                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3954                         // This only flushes transactions to clear snapshots, not to write data
3955                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3956                         throw new DBUnexpectedError(
3957                                 $this,
3958                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3959                         );
3960                 }
3961
3962                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3963         }
3964
3965         public function explicitTrxActive() {
3966                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
3967         }
3968
3969         public function duplicateTableStructure(
3970                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3971         ) {
3972                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3973         }
3974
3975         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3976                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3977         }
3978
3979         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3980                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3981         }
3982
3983         public function timestamp( $ts = 0 ) {
3984                 $t = new ConvertibleTimestamp( $ts );
3985                 // Let errors bubble up to avoid putting garbage in the DB
3986                 return $t->getTimestamp( TS_MW );
3987         }
3988
3989         public function timestampOrNull( $ts = null ) {
3990                 if ( is_null( $ts ) ) {
3991                         return null;
3992                 } else {
3993                         return $this->timestamp( $ts );
3994                 }
3995         }
3996
3997         public function affectedRows() {
3998                 return ( $this->affectedRowCount === null )
3999                         ? $this->fetchAffectedRowCount() // default to driver value
4000                         : $this->affectedRowCount;
4001         }
4002
4003         /**
4004          * @return int Number of retrieved rows according to the driver
4005          */
4006         abstract protected function fetchAffectedRowCount();
4007
4008         /**
4009          * Take the result from a query, and wrap it in a ResultWrapper if
4010          * necessary. Boolean values are passed through as is, to indicate success
4011          * of write queries or failure.
4012          *
4013          * Once upon a time, Database::query() returned a bare MySQL result
4014          * resource, and it was necessary to call this function to convert it to
4015          * a wrapper. Nowadays, raw database objects are never exposed to external
4016          * callers, so this is unnecessary in external code.
4017          *
4018          * @param bool|ResultWrapper|resource|object $result
4019          * @return bool|ResultWrapper
4020          */
4021         protected function resultObject( $result ) {
4022                 if ( !$result ) {
4023                         return false;
4024                 } elseif ( $result instanceof ResultWrapper ) {
4025                         return $result;
4026                 } elseif ( $result === true ) {
4027                         // Successful write query
4028                         return $result;
4029                 } else {
4030                         return new ResultWrapper( $this, $result );
4031                 }
4032         }
4033
4034         public function ping( &$rtt = null ) {
4035                 // Avoid hitting the server if it was hit recently
4036                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
4037                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
4038                                 $rtt = $this->rttEstimate;
4039                                 return true; // don't care about $rtt
4040                         }
4041                 }
4042
4043                 // This will reconnect if possible or return false if not
4044                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4045                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
4046                 $this->restoreFlags( self::RESTORE_PRIOR );
4047
4048                 if ( $ok ) {
4049                         $rtt = $this->rttEstimate;
4050                 }
4051
4052                 return $ok;
4053         }
4054
4055         /**
4056          * Close any existing (dead) database connection and open a new connection
4057          *
4058          * @param string $fname
4059          * @return bool True if new connection is opened successfully, false if error
4060          */
4061         protected function replaceLostConnection( $fname ) {
4062                 $this->closeConnection();
4063                 $this->opened = false;
4064                 $this->conn = false;
4065                 try {
4066                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4067                         $this->lastPing = microtime( true );
4068                         $ok = true;
4069
4070                         $this->connLogger->warning(
4071                                 $fname . ': lost connection to {dbserver}; reconnected',
4072                                 [
4073                                         'dbserver' => $this->getServer(),
4074                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4075                                 ]
4076                         );
4077                 } catch ( DBConnectionError $e ) {
4078                         $ok = false;
4079
4080                         $this->connLogger->error(
4081                                 $fname . ': lost connection to {dbserver} permanently',
4082                                 [ 'dbserver' => $this->getServer() ]
4083                         );
4084                 }
4085
4086                 $this->handleSessionLoss();
4087
4088                 return $ok;
4089         }
4090
4091         public function getSessionLagStatus() {
4092                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4093         }
4094
4095         /**
4096          * Get the replica DB lag when the current transaction started
4097          *
4098          * This is useful when transactions might use snapshot isolation
4099          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4100          * is this lag plus transaction duration. If they don't, it is still
4101          * safe to be pessimistic. This returns null if there is no transaction.
4102          *
4103          * This returns null if the lag status for this transaction was not yet recorded.
4104          *
4105          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4106          * @since 1.27
4107          */
4108         final protected function getRecordedTransactionLagStatus() {
4109                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4110                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4111                         : null;
4112         }
4113
4114         /**
4115          * Get a replica DB lag estimate for this server
4116          *
4117          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4118          * @since 1.27
4119          */
4120         protected function getApproximateLagStatus() {
4121                 return [
4122                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4123                         'since' => microtime( true )
4124                 ];
4125         }
4126
4127         /**
4128          * Merge the result of getSessionLagStatus() for several DBs
4129          * using the most pessimistic values to estimate the lag of
4130          * any data derived from them in combination
4131          *
4132          * This is information is useful for caching modules
4133          *
4134          * @see WANObjectCache::set()
4135          * @see WANObjectCache::getWithSetCallback()
4136          *
4137          * @param IDatabase $db1
4138          * @param IDatabase|null $db2 [optional]
4139          * @return array Map of values:
4140          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4141          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4142          *   - pending: whether any of the DBs have uncommitted changes
4143          * @throws DBError
4144          * @since 1.27
4145          */
4146         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4147                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4148                 foreach ( func_get_args() as $db ) {
4149                         /** @var IDatabase $db */
4150                         $status = $db->getSessionLagStatus();
4151                         if ( $status['lag'] === false ) {
4152                                 $res['lag'] = false;
4153                         } elseif ( $res['lag'] !== false ) {
4154                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4155                         }
4156                         $res['since'] = min( $res['since'], $status['since'] );
4157                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4158                 }
4159
4160                 return $res;
4161         }
4162
4163         public function getLag() {
4164                 return 0;
4165         }
4166
4167         public function maxListLen() {
4168                 return 0;
4169         }
4170
4171         public function encodeBlob( $b ) {
4172                 return $b;
4173         }
4174
4175         public function decodeBlob( $b ) {
4176                 if ( $b instanceof Blob ) {
4177                         $b = $b->fetch();
4178                 }
4179                 return $b;
4180         }
4181
4182         public function setSessionOptions( array $options ) {
4183         }
4184
4185         public function sourceFile(
4186                 $filename,
4187                 callable $lineCallback = null,
4188                 callable $resultCallback = null,
4189                 $fname = false,
4190                 callable $inputCallback = null
4191         ) {
4192                 Wikimedia\suppressWarnings();
4193                 $fp = fopen( $filename, 'r' );
4194                 Wikimedia\restoreWarnings();
4195
4196                 if ( false === $fp ) {
4197                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4198                 }
4199
4200                 if ( !$fname ) {
4201                         $fname = __METHOD__ . "( $filename )";
4202                 }
4203
4204                 try {
4205                         $error = $this->sourceStream(
4206                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4207                 } catch ( Exception $e ) {
4208                         fclose( $fp );
4209                         throw $e;
4210                 }
4211
4212                 fclose( $fp );
4213
4214                 return $error;
4215         }
4216
4217         public function setSchemaVars( $vars ) {
4218                 $this->schemaVars = $vars;
4219         }
4220
4221         public function sourceStream(
4222                 $fp,
4223                 callable $lineCallback = null,
4224                 callable $resultCallback = null,
4225                 $fname = __METHOD__,
4226                 callable $inputCallback = null
4227         ) {
4228                 $delimiterReset = new ScopedCallback(
4229                         function ( $delimiter ) {
4230                                 $this->delimiter = $delimiter;
4231                         },
4232                         [ $this->delimiter ]
4233                 );
4234                 $cmd = '';
4235
4236                 while ( !feof( $fp ) ) {
4237                         if ( $lineCallback ) {
4238                                 call_user_func( $lineCallback );
4239                         }
4240
4241                         $line = trim( fgets( $fp ) );
4242
4243                         if ( $line == '' ) {
4244                                 continue;
4245                         }
4246
4247                         if ( '-' == $line[0] && '-' == $line[1] ) {
4248                                 continue;
4249                         }
4250
4251                         if ( $cmd != '' ) {
4252                                 $cmd .= ' ';
4253                         }
4254
4255                         $done = $this->streamStatementEnd( $cmd, $line );
4256
4257                         $cmd .= "$line\n";
4258
4259                         if ( $done || feof( $fp ) ) {
4260                                 $cmd = $this->replaceVars( $cmd );
4261
4262                                 if ( $inputCallback ) {
4263                                         $callbackResult = $inputCallback( $cmd );
4264
4265                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4266                                                 $cmd = $callbackResult;
4267                                         }
4268                                 }
4269
4270                                 if ( $cmd ) {
4271                                         $res = $this->query( $cmd, $fname );
4272
4273                                         if ( $resultCallback ) {
4274                                                 $resultCallback( $res, $this );
4275                                         }
4276
4277                                         if ( false === $res ) {
4278                                                 $err = $this->lastError();
4279
4280                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4281                                         }
4282                                 }
4283                                 $cmd = '';
4284                         }
4285                 }
4286
4287                 ScopedCallback::consume( $delimiterReset );
4288                 return true;
4289         }
4290
4291         /**
4292          * Called by sourceStream() to check if we've reached a statement end
4293          *
4294          * @param string &$sql SQL assembled so far
4295          * @param string &$newLine New line about to be added to $sql
4296          * @return bool Whether $newLine contains end of the statement
4297          */
4298         public function streamStatementEnd( &$sql, &$newLine ) {
4299                 if ( $this->delimiter ) {
4300                         $prev = $newLine;
4301                         $newLine = preg_replace(
4302                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4303                         if ( $newLine != $prev ) {
4304                                 return true;
4305                         }
4306                 }
4307
4308                 return false;
4309         }
4310
4311         /**
4312          * Database independent variable replacement. Replaces a set of variables
4313          * in an SQL statement with their contents as given by $this->getSchemaVars().
4314          *
4315          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4316          *
4317          * - '{$var}' should be used for text and is passed through the database's
4318          *   addQuotes method.
4319          * - `{$var}` should be used for identifiers (e.g. table and database names).
4320          *   It is passed through the database's addIdentifierQuotes method which
4321          *   can be overridden if the database uses something other than backticks.
4322          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4323          *   database's tableName method.
4324          * - / *i* / passes the name that follows through the database's indexName method.
4325          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4326          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4327          *
4328          * @param string $ins SQL statement to replace variables in
4329          * @return string The new SQL statement with variables replaced
4330          */
4331         protected function replaceVars( $ins ) {
4332                 $vars = $this->getSchemaVars();
4333                 return preg_replace_callback(
4334                         '!
4335                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4336                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4337                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4338                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4339                         !x',
4340                         function ( $m ) use ( $vars ) {
4341                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4342                                 // check for both nonexistent keys *and* the empty string.
4343                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4344                                         if ( $m[1] === 'i' ) {
4345                                                 return $this->indexName( $m[2] );
4346                                         } else {
4347                                                 return $this->tableName( $m[2] );
4348                                         }
4349                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4350                                         return $this->addQuotes( $vars[$m[3]] );
4351                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4352                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4353                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4354                                         return $vars[$m[5]];
4355                                 } else {
4356                                         return $m[0];
4357                                 }
4358                         },
4359                         $ins
4360                 );
4361         }
4362
4363         /**
4364          * Get schema variables. If none have been set via setSchemaVars(), then
4365          * use some defaults from the current object.
4366          *
4367          * @return array
4368          */
4369         protected function getSchemaVars() {
4370                 if ( $this->schemaVars ) {
4371                         return $this->schemaVars;
4372                 } else {
4373                         return $this->getDefaultSchemaVars();
4374                 }
4375         }
4376
4377         /**
4378          * Get schema variables to use if none have been set via setSchemaVars().
4379          *
4380          * Override this in derived classes to provide variables for tables.sql
4381          * and SQL patch files.
4382          *
4383          * @return array
4384          */
4385         protected function getDefaultSchemaVars() {
4386                 return [];
4387         }
4388
4389         public function lockIsFree( $lockName, $method ) {
4390                 // RDBMs methods for checking named locks may or may not count this thread itself.
4391                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4392                 // the behavior choosen by the interface for this method.
4393                 return !isset( $this->namedLocksHeld[$lockName] );
4394         }
4395
4396         public function lock( $lockName, $method, $timeout = 5 ) {
4397                 $this->namedLocksHeld[$lockName] = 1;
4398
4399                 return true;
4400         }
4401
4402         public function unlock( $lockName, $method ) {
4403                 unset( $this->namedLocksHeld[$lockName] );
4404
4405                 return true;
4406         }
4407
4408         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4409                 if ( $this->writesOrCallbacksPending() ) {
4410                         // This only flushes transactions to clear snapshots, not to write data
4411                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4412                         throw new DBUnexpectedError(
4413                                 $this,
4414                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4415                         );
4416                 }
4417
4418                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4419                         return null;
4420                 }
4421
4422                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4423                         if ( $this->trxLevel() ) {
4424                                 // There is a good chance an exception was thrown, causing any early return
4425                                 // from the caller. Let any error handler get a chance to issue rollback().
4426                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4427                                 $this->onTransactionResolution(
4428                                         function () use ( $lockKey, $fname ) {
4429                                                 $this->unlock( $lockKey, $fname );
4430                                         },
4431                                         $fname
4432                                 );
4433                         } else {
4434                                 $this->unlock( $lockKey, $fname );
4435                         }
4436                 } );
4437
4438                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4439
4440                 return $unlocker;
4441         }
4442
4443         public function namedLocksEnqueue() {
4444                 return false;
4445         }
4446
4447         public function tableLocksHaveTransactionScope() {
4448                 return true;
4449         }
4450
4451         final public function lockTables( array $read, array $write, $method ) {
4452                 if ( $this->writesOrCallbacksPending() ) {
4453                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4454                 }
4455
4456                 if ( $this->tableLocksHaveTransactionScope() ) {
4457                         $this->startAtomic( $method );
4458                 }
4459
4460                 return $this->doLockTables( $read, $write, $method );
4461         }
4462
4463         /**
4464          * Helper function for lockTables() that handles the actual table locking
4465          *
4466          * @param array $read Array of tables to lock for read access
4467          * @param array $write Array of tables to lock for write access
4468          * @param string $method Name of caller
4469          * @return true
4470          */
4471         protected function doLockTables( array $read, array $write, $method ) {
4472                 return true;
4473         }
4474
4475         final public function unlockTables( $method ) {
4476                 if ( $this->tableLocksHaveTransactionScope() ) {
4477                         $this->endAtomic( $method );
4478
4479                         return true; // locks released on COMMIT/ROLLBACK
4480                 }
4481
4482                 return $this->doUnlockTables( $method );
4483         }
4484
4485         /**
4486          * Helper function for unlockTables() that handles the actual table unlocking
4487          *
4488          * @param string $method Name of caller
4489          * @return true
4490          */
4491         protected function doUnlockTables( $method ) {
4492                 return true;
4493         }
4494
4495         /**
4496          * Delete a table
4497          * @param string $tableName
4498          * @param string $fName
4499          * @return bool|ResultWrapper
4500          * @since 1.18
4501          */
4502         public function dropTable( $tableName, $fName = __METHOD__ ) {
4503                 if ( !$this->tableExists( $tableName, $fName ) ) {
4504                         return false;
4505                 }
4506                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4507
4508                 return $this->query( $sql, $fName );
4509         }
4510
4511         public function getInfinity() {
4512                 return 'infinity';
4513         }
4514
4515         public function encodeExpiry( $expiry ) {
4516                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4517                         ? $this->getInfinity()
4518                         : $this->timestamp( $expiry );
4519         }
4520
4521         public function decodeExpiry( $expiry, $format = TS_MW ) {
4522                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4523                         return 'infinity';
4524                 }
4525
4526                 return ConvertibleTimestamp::convert( $format, $expiry );
4527         }
4528
4529         public function setBigSelects( $value = true ) {
4530                 // no-op
4531         }
4532
4533         public function isReadOnly() {
4534                 return ( $this->getReadOnlyReason() !== false );
4535         }
4536
4537         /**
4538          * @return string|bool Reason this DB is read-only or false if it is not
4539          */
4540         protected function getReadOnlyReason() {
4541                 $reason = $this->getLBInfo( 'readOnlyReason' );
4542
4543                 return is_string( $reason ) ? $reason : false;
4544         }
4545
4546         public function setTableAliases( array $aliases ) {
4547                 $this->tableAliases = $aliases;
4548         }
4549
4550         public function setIndexAliases( array $aliases ) {
4551                 $this->indexAliases = $aliases;
4552         }
4553
4554         /**
4555          * Get the underlying binding connection handle
4556          *
4557          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4558          * This catches broken callers than catch and ignore disconnection exceptions.
4559          * Unlike checking isOpen(), this is safe to call inside of open().
4560          *
4561          * @return mixed
4562          * @throws DBUnexpectedError
4563          * @since 1.26
4564          */
4565         protected function getBindingHandle() {
4566                 if ( !$this->conn ) {
4567                         throw new DBUnexpectedError(
4568                                 $this,
4569                                 'DB connection was already closed or the connection dropped.'
4570                         );
4571                 }
4572
4573                 return $this->conn;
4574         }
4575
4576         /**
4577          * @since 1.19
4578          * @return string
4579          */
4580         public function __toString() {
4581                 return (string)$this->conn;
4582         }
4583
4584         /**
4585          * Make sure that copies do not share the same client binding handle
4586          * @throws DBConnectionError
4587          */
4588         public function __clone() {
4589                 $this->connLogger->warning(
4590                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
4591                         ( new RuntimeException() )->getTraceAsString()
4592                 );
4593
4594                 if ( $this->isOpen() ) {
4595                         // Open a new connection resource without messing with the old one
4596                         $this->opened = false;
4597                         $this->conn = false;
4598                         $this->trxEndCallbacks = []; // don't copy
4599                         $this->handleSessionLoss(); // no trx or locks anymore
4600                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4601                         $this->lastPing = microtime( true );
4602                 }
4603         }
4604
4605         /**
4606          * Called by serialize. Throw an exception when DB connection is serialized.
4607          * This causes problems on some database engines because the connection is
4608          * not restored on unserialize.
4609          */
4610         public function __sleep() {
4611                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4612                         'the connection is not restored on wakeup.' );
4613         }
4614
4615         /**
4616          * Run a few simple sanity checks and close dangling connections
4617          */
4618         public function __destruct() {
4619                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4620                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4621                 }
4622
4623                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4624                 if ( $danglingWriters ) {
4625                         $fnames = implode( ', ', $danglingWriters );
4626                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4627                 }
4628
4629                 if ( $this->conn ) {
4630                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4631                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4632                         Wikimedia\suppressWarnings();
4633                         $this->closeConnection();
4634                         Wikimedia\restoreWarnings();
4635                         $this->conn = false;
4636                         $this->opened = false;
4637                 }
4638         }
4639 }
4640
4641 /**
4642  * @deprecated since 1.28
4643  */
4644 class_alias( Database::class, 'DatabaseBase' );
4645
4646 /**
4647  * @deprecated since 1.29
4648  */
4649 class_alias( Database::class, 'Database' );