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->getDomainID(), $this->trxShortId );
1136                 }
1137
1138                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1139                         $this->queryLogger->debug( "{$this->getDomainID()} {$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,
1243                         $startTime,
1244                         $isWrite,
1245                         $isWrite ? $this->affectedRows() : $this->numRows( $ret )
1246                 );
1247                 $this->queryLogger->debug( $sql, [
1248                         'method' => $fname,
1249                         'master' => $isMaster,
1250                         'runtime' => $queryRuntime,
1251                 ] );
1252
1253                 return $ret;
1254         }
1255
1256         /**
1257          * Update the estimated run-time of a query, not counting large row lock times
1258          *
1259          * LoadBalancer can be set to rollback transactions that will create huge replication
1260          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1261          * queries, like inserting a row can take a long time due to row locking. This method
1262          * uses some simple heuristics to discount those cases.
1263          *
1264          * @param string $sql A SQL write query
1265          * @param float $runtime Total runtime, including RTT
1266          * @param int $affected Affected row count
1267          */
1268         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1269                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1270                 $indicativeOfReplicaRuntime = true;
1271                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1272                         $verb = $this->getQueryVerb( $sql );
1273                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1274                         if ( $verb === 'INSERT' ) {
1275                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1276                         } elseif ( $verb === 'REPLACE' ) {
1277                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1278                         }
1279                 }
1280
1281                 $this->trxWriteDuration += $runtime;
1282                 $this->trxWriteQueryCount += 1;
1283                 $this->trxWriteAffectedRows += $affected;
1284                 if ( $indicativeOfReplicaRuntime ) {
1285                         $this->trxWriteAdjDuration += $runtime;
1286                         $this->trxWriteAdjQueryCount += 1;
1287                 }
1288         }
1289
1290         /**
1291          * @param string $sql
1292          * @param string $fname
1293          * @throws DBTransactionStateError
1294          */
1295         private function assertTransactionStatus( $sql, $fname ) {
1296                 if ( $this->getQueryVerb( $sql ) === 'ROLLBACK' ) { // transaction/savepoint
1297                         return;
1298                 }
1299
1300                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1301                         throw new DBTransactionStateError(
1302                                 $this,
1303                                 "Cannot execute query from $fname while transaction status is ERROR.",
1304                                 [],
1305                                 $this->trxStatusCause
1306                         );
1307                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1308                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1309                         call_user_func( $this->deprecationLogger,
1310                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1311                                 "[$iLastErrno] $iLastError"
1312                         );
1313                         $this->trxStatusIgnoredCause = null;
1314                 }
1315         }
1316
1317         /**
1318          * Determine whether or not it is safe to retry queries after a database
1319          * connection is lost
1320          *
1321          * @param string $sql SQL query
1322          * @param bool $priorWritesPending Whether there is a transaction open with
1323          *     possible write queries or transaction pre-commit/idle callbacks
1324          *     waiting on it to finish.
1325          * @return bool True if it is safe to retry the query, false otherwise
1326          */
1327         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1328                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1329                 # Dropped connections also mean that named locks are automatically released.
1330                 # Only allow error suppression in autocommit mode or when the lost transaction
1331                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1332                 if ( $this->namedLocksHeld ) {
1333                         return false; // possible critical section violation
1334                 } elseif ( $this->sessionTempTables ) {
1335                         return false; // tables might be queried latter
1336                 } elseif ( $sql === 'COMMIT' ) {
1337                         return !$priorWritesPending; // nothing written anyway? (T127428)
1338                 } elseif ( $sql === 'ROLLBACK' ) {
1339                         return true; // transaction lost...which is also what was requested :)
1340                 } elseif ( $this->explicitTrxActive() ) {
1341                         return false; // don't drop atomocity and explicit snapshots
1342                 } elseif ( $priorWritesPending ) {
1343                         return false; // prior writes lost from implicit transaction
1344                 }
1345
1346                 return true;
1347         }
1348
1349         /**
1350          * Clean things up after session (and thus transaction) loss
1351          */
1352         private function handleSessionLoss() {
1353                 // Clean up tracking of session-level things...
1354                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1355                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1356                 $this->sessionTempTables = [];
1357                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1358                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1359                 $this->namedLocksHeld = [];
1360                 // Session loss implies transaction loss
1361                 $this->handleTransactionLoss();
1362         }
1363
1364         /**
1365          * Clean things up after transaction loss
1366          */
1367         private function handleTransactionLoss() {
1368                 $this->trxLevel = 0;
1369                 $this->trxAtomicCounter = 0;
1370                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1371                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1372                 try {
1373                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1374                         // If callback suppression is set then the array will remain unhandled.
1375                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1376                 } catch ( Exception $ex ) {
1377                         // Already logged; move on...
1378                 }
1379                 try {
1380                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1381                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1382                 } catch ( Exception $ex ) {
1383                         // Already logged; move on...
1384                 }
1385         }
1386
1387         /**
1388          * Checks whether the cause of the error is detected to be a timeout.
1389          *
1390          * It returns false by default, and not all engines support detecting this yet.
1391          * If this returns false, it will be treated as a generic query error.
1392          *
1393          * @param string $error Error text
1394          * @param int $errno Error number
1395          * @return bool
1396          */
1397         protected function wasQueryTimeout( $error, $errno ) {
1398                 return false;
1399         }
1400
1401         /**
1402          * Report a query error. Log the error, and if neither the object ignore
1403          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1404          *
1405          * @param string $error
1406          * @param int $errno
1407          * @param string $sql
1408          * @param string $fname
1409          * @param bool $tempIgnore
1410          * @throws DBQueryError
1411          */
1412         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1413                 if ( $tempIgnore ) {
1414                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1415                 } else {
1416                         $exception = $this->makeQueryException( $error, $errno, $sql, $fname );
1417
1418                         throw $exception;
1419                 }
1420         }
1421
1422         /**
1423          * @param string $error
1424          * @param string|int $errno
1425          * @param string $sql
1426          * @param string $fname
1427          * @return DBError
1428          */
1429         private function makeQueryException( $error, $errno, $sql, $fname ) {
1430                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1431                 $this->queryLogger->error(
1432                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1433                         $this->getLogContext( [
1434                                 'method' => __METHOD__,
1435                                 'errno' => $errno,
1436                                 'error' => $error,
1437                                 'sql1line' => $sql1line,
1438                                 'fname' => $fname,
1439                         ] )
1440                 );
1441                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1442                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1443                 if ( $wasQueryTimeout ) {
1444                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1445                 } else {
1446                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1447                 }
1448
1449                 return $e;
1450         }
1451
1452         public function freeResult( $res ) {
1453         }
1454
1455         public function selectField(
1456                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1457         ) {
1458                 if ( $var === '*' ) { // sanity
1459                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1460                 }
1461
1462                 if ( !is_array( $options ) ) {
1463                         $options = [ $options ];
1464                 }
1465
1466                 $options['LIMIT'] = 1;
1467
1468                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1469                 if ( $res === false || !$this->numRows( $res ) ) {
1470                         return false;
1471                 }
1472
1473                 $row = $this->fetchRow( $res );
1474
1475                 if ( $row !== false ) {
1476                         return reset( $row );
1477                 } else {
1478                         return false;
1479                 }
1480         }
1481
1482         public function selectFieldValues(
1483                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1484         ) {
1485                 if ( $var === '*' ) { // sanity
1486                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1487                 } elseif ( !is_string( $var ) ) { // sanity
1488                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1489                 }
1490
1491                 if ( !is_array( $options ) ) {
1492                         $options = [ $options ];
1493                 }
1494
1495                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1496                 if ( $res === false ) {
1497                         return false;
1498                 }
1499
1500                 $values = [];
1501                 foreach ( $res as $row ) {
1502                         $values[] = $row->$var;
1503                 }
1504
1505                 return $values;
1506         }
1507
1508         /**
1509          * Returns an optional USE INDEX clause to go after the table, and a
1510          * string to go at the end of the query.
1511          *
1512          * @param array $options Associative array of options to be turned into
1513          *   an SQL query, valid keys are listed in the function.
1514          * @return array
1515          * @see Database::select()
1516          */
1517         protected function makeSelectOptions( $options ) {
1518                 $preLimitTail = $postLimitTail = '';
1519                 $startOpts = '';
1520
1521                 $noKeyOptions = [];
1522
1523                 foreach ( $options as $key => $option ) {
1524                         if ( is_numeric( $key ) ) {
1525                                 $noKeyOptions[$option] = true;
1526                         }
1527                 }
1528
1529                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1530
1531                 $preLimitTail .= $this->makeOrderBy( $options );
1532
1533                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1534                         $postLimitTail .= ' FOR UPDATE';
1535                 }
1536
1537                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1538                         $postLimitTail .= ' LOCK IN SHARE MODE';
1539                 }
1540
1541                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1542                         $startOpts .= 'DISTINCT';
1543                 }
1544
1545                 # Various MySQL extensions
1546                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1547                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1548                 }
1549
1550                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1551                         $startOpts .= ' HIGH_PRIORITY';
1552                 }
1553
1554                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1555                         $startOpts .= ' SQL_BIG_RESULT';
1556                 }
1557
1558                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1559                         $startOpts .= ' SQL_BUFFER_RESULT';
1560                 }
1561
1562                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1563                         $startOpts .= ' SQL_SMALL_RESULT';
1564                 }
1565
1566                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1567                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1568                 }
1569
1570                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1571                         $startOpts .= ' SQL_CACHE';
1572                 }
1573
1574                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1575                         $startOpts .= ' SQL_NO_CACHE';
1576                 }
1577
1578                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1579                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1580                 } else {
1581                         $useIndex = '';
1582                 }
1583                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1584                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1585                 } else {
1586                         $ignoreIndex = '';
1587                 }
1588
1589                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1590         }
1591
1592         /**
1593          * Returns an optional GROUP BY with an optional HAVING
1594          *
1595          * @param array $options Associative array of options
1596          * @return string
1597          * @see Database::select()
1598          * @since 1.21
1599          */
1600         protected function makeGroupByWithHaving( $options ) {
1601                 $sql = '';
1602                 if ( isset( $options['GROUP BY'] ) ) {
1603                         $gb = is_array( $options['GROUP BY'] )
1604                                 ? implode( ',', $options['GROUP BY'] )
1605                                 : $options['GROUP BY'];
1606                         $sql .= ' GROUP BY ' . $gb;
1607                 }
1608                 if ( isset( $options['HAVING'] ) ) {
1609                         $having = is_array( $options['HAVING'] )
1610                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1611                                 : $options['HAVING'];
1612                         $sql .= ' HAVING ' . $having;
1613                 }
1614
1615                 return $sql;
1616         }
1617
1618         /**
1619          * Returns an optional ORDER BY
1620          *
1621          * @param array $options Associative array of options
1622          * @return string
1623          * @see Database::select()
1624          * @since 1.21
1625          */
1626         protected function makeOrderBy( $options ) {
1627                 if ( isset( $options['ORDER BY'] ) ) {
1628                         $ob = is_array( $options['ORDER BY'] )
1629                                 ? implode( ',', $options['ORDER BY'] )
1630                                 : $options['ORDER BY'];
1631
1632                         return ' ORDER BY ' . $ob;
1633                 }
1634
1635                 return '';
1636         }
1637
1638         public function select(
1639                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1640         ) {
1641                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1642
1643                 return $this->query( $sql, $fname );
1644         }
1645
1646         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1647                 $options = [], $join_conds = []
1648         ) {
1649                 if ( is_array( $vars ) ) {
1650                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1651                 } else {
1652                         $fields = $vars;
1653                 }
1654
1655                 $options = (array)$options;
1656                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1657                         ? $options['USE INDEX']
1658                         : [];
1659                 $ignoreIndexes = (
1660                         isset( $options['IGNORE INDEX'] ) &&
1661                         is_array( $options['IGNORE INDEX'] )
1662                 )
1663                         ? $options['IGNORE INDEX']
1664                         : [];
1665
1666                 if (
1667                         $this->selectOptionsIncludeLocking( $options ) &&
1668                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1669                 ) {
1670                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1671                         // functions. Discourage use of such queries to encourage compatibility.
1672                         call_user_func(
1673                                 $this->deprecationLogger,
1674                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1675                         );
1676                 }
1677
1678                 if ( is_array( $table ) ) {
1679                         $from = ' FROM ' .
1680                                 $this->tableNamesWithIndexClauseOrJOIN(
1681                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1682                 } elseif ( $table != '' ) {
1683                         $from = ' FROM ' .
1684                                 $this->tableNamesWithIndexClauseOrJOIN(
1685                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1686                 } else {
1687                         $from = '';
1688                 }
1689
1690                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1691                         $this->makeSelectOptions( $options );
1692
1693                 if ( is_array( $conds ) ) {
1694                         $conds = $this->makeList( $conds, self::LIST_AND );
1695                 }
1696
1697                 if ( $conds === null || $conds === false ) {
1698                         $this->queryLogger->warning(
1699                                 __METHOD__
1700                                 . ' called from '
1701                                 . $fname
1702                                 . ' with incorrect parameters: $conds must be a string or an array'
1703                         );
1704                         $conds = '';
1705                 }
1706
1707                 if ( $conds === '' ) {
1708                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1709                 } elseif ( is_string( $conds ) ) {
1710                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1711                                 "WHERE $conds $preLimitTail";
1712                 } else {
1713                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1714                 }
1715
1716                 if ( isset( $options['LIMIT'] ) ) {
1717                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1718                                 $options['OFFSET'] ?? false );
1719                 }
1720                 $sql = "$sql $postLimitTail";
1721
1722                 if ( isset( $options['EXPLAIN'] ) ) {
1723                         $sql = 'EXPLAIN ' . $sql;
1724                 }
1725
1726                 return $sql;
1727         }
1728
1729         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1730                 $options = [], $join_conds = []
1731         ) {
1732                 $options = (array)$options;
1733                 $options['LIMIT'] = 1;
1734                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1735
1736                 if ( $res === false ) {
1737                         return false;
1738                 }
1739
1740                 if ( !$this->numRows( $res ) ) {
1741                         return false;
1742                 }
1743
1744                 $obj = $this->fetchObject( $res );
1745
1746                 return $obj;
1747         }
1748
1749         public function estimateRowCount(
1750                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1751         ) {
1752                 $conds = $this->normalizeConditions( $conds, $fname );
1753                 $column = $this->extractSingleFieldFromList( $var );
1754                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1755                         $conds[] = "$column IS NOT NULL";
1756                 }
1757
1758                 $res = $this->select(
1759                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1760                 );
1761                 $row = $res ? $this->fetchRow( $res ) : [];
1762
1763                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1764         }
1765
1766         public function selectRowCount(
1767                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1768         ) {
1769                 $conds = $this->normalizeConditions( $conds, $fname );
1770                 $column = $this->extractSingleFieldFromList( $var );
1771                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1772                         $conds[] = "$column IS NOT NULL";
1773                 }
1774
1775                 $res = $this->select(
1776                         [
1777                                 'tmp_count' => $this->buildSelectSubquery(
1778                                         $tables,
1779                                         '1',
1780                                         $conds,
1781                                         $fname,
1782                                         $options,
1783                                         $join_conds
1784                                 )
1785                         ],
1786                         [ 'rowcount' => 'COUNT(*)' ],
1787                         [],
1788                         $fname
1789                 );
1790                 $row = $res ? $this->fetchRow( $res ) : [];
1791
1792                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1793         }
1794
1795         /**
1796          * @param string|array $options
1797          * @return bool
1798          */
1799         private function selectOptionsIncludeLocking( $options ) {
1800                 $options = (array)$options;
1801                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1802                         if ( in_array( $lock, $options, true ) ) {
1803                                 return true;
1804                         }
1805                 }
1806
1807                 return false;
1808         }
1809
1810         /**
1811          * @param array|string $fields
1812          * @param array|string $options
1813          * @return bool
1814          */
1815         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1816                 foreach ( (array)$options as $key => $value ) {
1817                         if ( is_string( $key ) ) {
1818                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1819                                         return true;
1820                                 }
1821                         } elseif ( is_string( $value ) ) {
1822                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1823                                         return true;
1824                                 }
1825                         }
1826                 }
1827
1828                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1829                 foreach ( (array)$fields as $field ) {
1830                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1831                                 return true;
1832                         }
1833                 }
1834
1835                 return false;
1836         }
1837
1838         /**
1839          * @param array|string $conds
1840          * @param string $fname
1841          * @return array
1842          */
1843         final protected function normalizeConditions( $conds, $fname ) {
1844                 if ( $conds === null || $conds === false ) {
1845                         $this->queryLogger->warning(
1846                                 __METHOD__
1847                                 . ' called from '
1848                                 . $fname
1849                                 . ' with incorrect parameters: $conds must be a string or an array'
1850                         );
1851                         $conds = '';
1852                 }
1853
1854                 if ( !is_array( $conds ) ) {
1855                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1856                 }
1857
1858                 return $conds;
1859         }
1860
1861         /**
1862          * @param array|string $var Field parameter in the style of select()
1863          * @return string|null Column name or null; ignores aliases
1864          * @throws DBUnexpectedError Errors out if multiple columns are given
1865          */
1866         final protected function extractSingleFieldFromList( $var ) {
1867                 if ( is_array( $var ) ) {
1868                         if ( !$var ) {
1869                                 $column = null;
1870                         } elseif ( count( $var ) == 1 ) {
1871                                 $column = $var[0] ?? reset( $var );
1872                         } else {
1873                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1874                         }
1875                 } else {
1876                         $column = $var;
1877                 }
1878
1879                 return $column;
1880         }
1881
1882         public function lockForUpdate(
1883                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1884         ) {
1885                 if ( !$this->trxLevel && !$this->getFlag( self::DBO_TRX ) ) {
1886                         throw new DBUnexpectedError(
1887                                 $this,
1888                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
1889                         );
1890                 }
1891
1892                 $options = (array)$options;
1893                 $options[] = 'FOR UPDATE';
1894
1895                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
1896         }
1897
1898         /**
1899          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1900          * It's only slightly flawed. Don't use for anything important.
1901          *
1902          * @param string $sql A SQL Query
1903          *
1904          * @return string
1905          */
1906         protected static function generalizeSQL( $sql ) {
1907                 # This does the same as the regexp below would do, but in such a way
1908                 # as to avoid crashing php on some large strings.
1909                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1910
1911                 $sql = str_replace( "\\\\", '', $sql );
1912                 $sql = str_replace( "\\'", '', $sql );
1913                 $sql = str_replace( "\\\"", '', $sql );
1914                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1915                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1916
1917                 # All newlines, tabs, etc replaced by single space
1918                 $sql = preg_replace( '/\s+/', ' ', $sql );
1919
1920                 # All numbers => N,
1921                 # except the ones surrounded by characters, e.g. l10n
1922                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1923                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1924
1925                 return $sql;
1926         }
1927
1928         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1929                 $info = $this->fieldInfo( $table, $field );
1930
1931                 return (bool)$info;
1932         }
1933
1934         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1935                 if ( !$this->tableExists( $table ) ) {
1936                         return null;
1937                 }
1938
1939                 $info = $this->indexInfo( $table, $index, $fname );
1940                 if ( is_null( $info ) ) {
1941                         return null;
1942                 } else {
1943                         return $info !== false;
1944                 }
1945         }
1946
1947         abstract public function tableExists( $table, $fname = __METHOD__ );
1948
1949         public function indexUnique( $table, $index ) {
1950                 $indexInfo = $this->indexInfo( $table, $index );
1951
1952                 if ( !$indexInfo ) {
1953                         return null;
1954                 }
1955
1956                 return !$indexInfo[0]->Non_unique;
1957         }
1958
1959         /**
1960          * Helper for Database::insert().
1961          *
1962          * @param array $options
1963          * @return string
1964          */
1965         protected function makeInsertOptions( $options ) {
1966                 return implode( ' ', $options );
1967         }
1968
1969         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1970                 # No rows to insert, easy just return now
1971                 if ( !count( $a ) ) {
1972                         return true;
1973                 }
1974
1975                 $table = $this->tableName( $table );
1976
1977                 if ( !is_array( $options ) ) {
1978                         $options = [ $options ];
1979                 }
1980
1981                 $fh = null;
1982                 if ( isset( $options['fileHandle'] ) ) {
1983                         $fh = $options['fileHandle'];
1984                 }
1985                 $options = $this->makeInsertOptions( $options );
1986
1987                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1988                         $multi = true;
1989                         $keys = array_keys( $a[0] );
1990                 } else {
1991                         $multi = false;
1992                         $keys = array_keys( $a );
1993                 }
1994
1995                 $sql = 'INSERT ' . $options .
1996                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1997
1998                 if ( $multi ) {
1999                         $first = true;
2000                         foreach ( $a as $row ) {
2001                                 if ( $first ) {
2002                                         $first = false;
2003                                 } else {
2004                                         $sql .= ',';
2005                                 }
2006                                 $sql .= '(' . $this->makeList( $row ) . ')';
2007                         }
2008                 } else {
2009                         $sql .= '(' . $this->makeList( $a ) . ')';
2010                 }
2011
2012                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
2013                         return false;
2014                 } elseif ( $fh !== null ) {
2015                         return true;
2016                 }
2017
2018                 return (bool)$this->query( $sql, $fname );
2019         }
2020
2021         /**
2022          * Make UPDATE options array for Database::makeUpdateOptions
2023          *
2024          * @param array $options
2025          * @return array
2026          */
2027         protected function makeUpdateOptionsArray( $options ) {
2028                 if ( !is_array( $options ) ) {
2029                         $options = [ $options ];
2030                 }
2031
2032                 $opts = [];
2033
2034                 if ( in_array( 'IGNORE', $options ) ) {
2035                         $opts[] = 'IGNORE';
2036                 }
2037
2038                 return $opts;
2039         }
2040
2041         /**
2042          * Make UPDATE options for the Database::update function
2043          *
2044          * @param array $options The options passed to Database::update
2045          * @return string
2046          */
2047         protected function makeUpdateOptions( $options ) {
2048                 $opts = $this->makeUpdateOptionsArray( $options );
2049
2050                 return implode( ' ', $opts );
2051         }
2052
2053         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2054                 $table = $this->tableName( $table );
2055                 $opts = $this->makeUpdateOptions( $options );
2056                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2057
2058                 if ( $conds !== [] && $conds !== '*' ) {
2059                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2060                 }
2061
2062                 return (bool)$this->query( $sql, $fname );
2063         }
2064
2065         public function makeList( $a, $mode = self::LIST_COMMA ) {
2066                 if ( !is_array( $a ) ) {
2067                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2068                 }
2069
2070                 $first = true;
2071                 $list = '';
2072
2073                 foreach ( $a as $field => $value ) {
2074                         if ( !$first ) {
2075                                 if ( $mode == self::LIST_AND ) {
2076                                         $list .= ' AND ';
2077                                 } elseif ( $mode == self::LIST_OR ) {
2078                                         $list .= ' OR ';
2079                                 } else {
2080                                         $list .= ',';
2081                                 }
2082                         } else {
2083                                 $first = false;
2084                         }
2085
2086                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2087                                 $list .= "($value)";
2088                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2089                                 $list .= "$value";
2090                         } elseif (
2091                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2092                         ) {
2093                                 // Remove null from array to be handled separately if found
2094                                 $includeNull = false;
2095                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2096                                         $includeNull = true;
2097                                         unset( $value[$nullKey] );
2098                                 }
2099                                 if ( count( $value ) == 0 && !$includeNull ) {
2100                                         throw new InvalidArgumentException(
2101                                                 __METHOD__ . ": empty input for field $field" );
2102                                 } elseif ( count( $value ) == 0 ) {
2103                                         // only check if $field is null
2104                                         $list .= "$field IS NULL";
2105                                 } else {
2106                                         // IN clause contains at least one valid element
2107                                         if ( $includeNull ) {
2108                                                 // Group subconditions to ensure correct precedence
2109                                                 $list .= '(';
2110                                         }
2111                                         if ( count( $value ) == 1 ) {
2112                                                 // Special-case single values, as IN isn't terribly efficient
2113                                                 // Don't necessarily assume the single key is 0; we don't
2114                                                 // enforce linear numeric ordering on other arrays here.
2115                                                 $value = array_values( $value )[0];
2116                                                 $list .= $field . " = " . $this->addQuotes( $value );
2117                                         } else {
2118                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2119                                         }
2120                                         // if null present in array, append IS NULL
2121                                         if ( $includeNull ) {
2122                                                 $list .= " OR $field IS NULL)";
2123                                         }
2124                                 }
2125                         } elseif ( $value === null ) {
2126                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2127                                         $list .= "$field IS ";
2128                                 } elseif ( $mode == self::LIST_SET ) {
2129                                         $list .= "$field = ";
2130                                 }
2131                                 $list .= 'NULL';
2132                         } else {
2133                                 if (
2134                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2135                                 ) {
2136                                         $list .= "$field = ";
2137                                 }
2138                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2139                         }
2140                 }
2141
2142                 return $list;
2143         }
2144
2145         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2146                 $conds = [];
2147
2148                 foreach ( $data as $base => $sub ) {
2149                         if ( count( $sub ) ) {
2150                                 $conds[] = $this->makeList(
2151                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2152                                         self::LIST_AND );
2153                         }
2154                 }
2155
2156                 if ( $conds ) {
2157                         return $this->makeList( $conds, self::LIST_OR );
2158                 } else {
2159                         // Nothing to search for...
2160                         return false;
2161                 }
2162         }
2163
2164         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2165                 return $valuename;
2166         }
2167
2168         public function bitNot( $field ) {
2169                 return "(~$field)";
2170         }
2171
2172         public function bitAnd( $fieldLeft, $fieldRight ) {
2173                 return "($fieldLeft & $fieldRight)";
2174         }
2175
2176         public function bitOr( $fieldLeft, $fieldRight ) {
2177                 return "($fieldLeft | $fieldRight)";
2178         }
2179
2180         public function buildConcat( $stringList ) {
2181                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2182         }
2183
2184         public function buildGroupConcatField(
2185                 $delim, $table, $field, $conds = '', $join_conds = []
2186         ) {
2187                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2188
2189                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2190         }
2191
2192         public function buildSubstring( $input, $startPosition, $length = null ) {
2193                 $this->assertBuildSubstringParams( $startPosition, $length );
2194                 $functionBody = "$input FROM $startPosition";
2195                 if ( $length !== null ) {
2196                         $functionBody .= " FOR $length";
2197                 }
2198                 return 'SUBSTRING(' . $functionBody . ')';
2199         }
2200
2201         /**
2202          * Check type and bounds for parameters to self::buildSubstring()
2203          *
2204          * All supported databases have substring functions that behave the same for
2205          * positive $startPosition and non-negative $length, but behaviors differ when
2206          * given 0 or negative $startPosition or negative $length. The simplest
2207          * solution to that is to just forbid those values.
2208          *
2209          * @param int $startPosition
2210          * @param int|null $length
2211          * @since 1.31
2212          */
2213         protected function assertBuildSubstringParams( $startPosition, $length ) {
2214                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2215                         throw new InvalidArgumentException(
2216                                 '$startPosition must be a positive integer'
2217                         );
2218                 }
2219                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2220                         throw new InvalidArgumentException(
2221                                 '$length must be null or an integer greater than or equal to 0'
2222                         );
2223                 }
2224         }
2225
2226         public function buildStringCast( $field ) {
2227                 return $field;
2228         }
2229
2230         public function buildIntegerCast( $field ) {
2231                 return 'CAST( ' . $field . ' AS INTEGER )';
2232         }
2233
2234         public function buildSelectSubquery(
2235                 $table, $vars, $conds = '', $fname = __METHOD__,
2236                 $options = [], $join_conds = []
2237         ) {
2238                 return new Subquery(
2239                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2240                 );
2241         }
2242
2243         public function databasesAreIndependent() {
2244                 return false;
2245         }
2246
2247         public function selectDB( $db ) {
2248                 # Stub. Shouldn't cause serious problems if it's not overridden, but
2249                 # if your database engine supports a concept similar to MySQL's
2250                 # databases you may as well.
2251                 $this->dbName = $db;
2252
2253                 return true;
2254         }
2255
2256         public function getDBname() {
2257                 return $this->dbName;
2258         }
2259
2260         public function getServer() {
2261                 return $this->server;
2262         }
2263
2264         public function tableName( $name, $format = 'quoted' ) {
2265                 if ( $name instanceof Subquery ) {
2266                         throw new DBUnexpectedError(
2267                                 $this,
2268                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2269                         );
2270                 }
2271
2272                 # Skip the entire process when we have a string quoted on both ends.
2273                 # Note that we check the end so that we will still quote any use of
2274                 # use of `database`.table. But won't break things if someone wants
2275                 # to query a database table with a dot in the name.
2276                 if ( $this->isQuotedIdentifier( $name ) ) {
2277                         return $name;
2278                 }
2279
2280                 # Lets test for any bits of text that should never show up in a table
2281                 # name. Basically anything like JOIN or ON which are actually part of
2282                 # SQL queries, but may end up inside of the table value to combine
2283                 # sql. Such as how the API is doing.
2284                 # Note that we use a whitespace test rather than a \b test to avoid
2285                 # any remote case where a word like on may be inside of a table name
2286                 # surrounded by symbols which may be considered word breaks.
2287                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2288                         $this->queryLogger->warning(
2289                                 __METHOD__ . ": use of subqueries is not supported this way.",
2290                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2291                         );
2292
2293                         return $name;
2294                 }
2295
2296                 # Split database and table into proper variables.
2297                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2298
2299                 # Quote $table and apply the prefix if not quoted.
2300                 # $tableName might be empty if this is called from Database::replaceVars()
2301                 $tableName = "{$prefix}{$table}";
2302                 if ( $format === 'quoted'
2303                         && !$this->isQuotedIdentifier( $tableName )
2304                         && $tableName !== ''
2305                 ) {
2306                         $tableName = $this->addIdentifierQuotes( $tableName );
2307                 }
2308
2309                 # Quote $schema and $database and merge them with the table name if needed
2310                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2311                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2312
2313                 return $tableName;
2314         }
2315
2316         /**
2317          * Get the table components needed for a query given the currently selected database
2318          *
2319          * @param string $name Table name in the form of db.schema.table, db.table, or table
2320          * @return array (DB name or "" for default, schema name, table prefix, table name)
2321          */
2322         protected function qualifiedTableComponents( $name ) {
2323                 # We reverse the explode so that database.table and table both output the correct table.
2324                 $dbDetails = explode( '.', $name, 3 );
2325                 if ( count( $dbDetails ) == 3 ) {
2326                         list( $database, $schema, $table ) = $dbDetails;
2327                         # We don't want any prefix added in this case
2328                         $prefix = '';
2329                 } elseif ( count( $dbDetails ) == 2 ) {
2330                         list( $database, $table ) = $dbDetails;
2331                         # We don't want any prefix added in this case
2332                         $prefix = '';
2333                         # In dbs that support it, $database may actually be the schema
2334                         # but that doesn't affect any of the functionality here
2335                         $schema = '';
2336                 } else {
2337                         list( $table ) = $dbDetails;
2338                         if ( isset( $this->tableAliases[$table] ) ) {
2339                                 $database = $this->tableAliases[$table]['dbname'];
2340                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2341                                         ? $this->tableAliases[$table]['schema']
2342                                         : $this->schema;
2343                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2344                                         ? $this->tableAliases[$table]['prefix']
2345                                         : $this->tablePrefix;
2346                         } else {
2347                                 $database = '';
2348                                 $schema = $this->schema; # Default schema
2349                                 $prefix = $this->tablePrefix; # Default prefix
2350                         }
2351                 }
2352
2353                 return [ $database, $schema, $prefix, $table ];
2354         }
2355
2356         /**
2357          * @param string|null $namespace Database or schema
2358          * @param string $relation Name of table, view, sequence, etc...
2359          * @param string $format One of (raw, quoted)
2360          * @return string Relation name with quoted and merged $namespace as needed
2361          */
2362         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2363                 if ( strlen( $namespace ) ) {
2364                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2365                                 $namespace = $this->addIdentifierQuotes( $namespace );
2366                         }
2367                         $relation = $namespace . '.' . $relation;
2368                 }
2369
2370                 return $relation;
2371         }
2372
2373         public function tableNames() {
2374                 $inArray = func_get_args();
2375                 $retVal = [];
2376
2377                 foreach ( $inArray as $name ) {
2378                         $retVal[$name] = $this->tableName( $name );
2379                 }
2380
2381                 return $retVal;
2382         }
2383
2384         public function tableNamesN() {
2385                 $inArray = func_get_args();
2386                 $retVal = [];
2387
2388                 foreach ( $inArray as $name ) {
2389                         $retVal[] = $this->tableName( $name );
2390                 }
2391
2392                 return $retVal;
2393         }
2394
2395         /**
2396          * Get an aliased table name
2397          *
2398          * This returns strings like "tableName AS newTableName" for aliased tables
2399          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2400          *
2401          * @see Database::tableName()
2402          * @param string|Subquery $table Table name or object with a 'sql' field
2403          * @param string|bool $alias Table alias (optional)
2404          * @return string SQL name for aliased table. Will not alias a table to its own name
2405          */
2406         protected function tableNameWithAlias( $table, $alias = false ) {
2407                 if ( is_string( $table ) ) {
2408                         $quotedTable = $this->tableName( $table );
2409                 } elseif ( $table instanceof Subquery ) {
2410                         $quotedTable = (string)$table;
2411                 } else {
2412                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2413                 }
2414
2415                 if ( !strlen( $alias ) || $alias === $table ) {
2416                         if ( $table instanceof Subquery ) {
2417                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2418                         }
2419
2420                         return $quotedTable;
2421                 } else {
2422                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2423                 }
2424         }
2425
2426         /**
2427          * Gets an array of aliased table names
2428          *
2429          * @param array $tables [ [alias] => table ]
2430          * @return string[] See tableNameWithAlias()
2431          */
2432         protected function tableNamesWithAlias( $tables ) {
2433                 $retval = [];
2434                 foreach ( $tables as $alias => $table ) {
2435                         if ( is_numeric( $alias ) ) {
2436                                 $alias = $table;
2437                         }
2438                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2439                 }
2440
2441                 return $retval;
2442         }
2443
2444         /**
2445          * Get an aliased field name
2446          * e.g. fieldName AS newFieldName
2447          *
2448          * @param string $name Field name
2449          * @param string|bool $alias Alias (optional)
2450          * @return string SQL name for aliased field. Will not alias a field to its own name
2451          */
2452         protected function fieldNameWithAlias( $name, $alias = false ) {
2453                 if ( !$alias || (string)$alias === (string)$name ) {
2454                         return $name;
2455                 } else {
2456                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2457                 }
2458         }
2459
2460         /**
2461          * Gets an array of aliased field names
2462          *
2463          * @param array $fields [ [alias] => field ]
2464          * @return string[] See fieldNameWithAlias()
2465          */
2466         protected function fieldNamesWithAlias( $fields ) {
2467                 $retval = [];
2468                 foreach ( $fields as $alias => $field ) {
2469                         if ( is_numeric( $alias ) ) {
2470                                 $alias = $field;
2471                         }
2472                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2473                 }
2474
2475                 return $retval;
2476         }
2477
2478         /**
2479          * Get the aliased table name clause for a FROM clause
2480          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2481          *
2482          * @param array $tables ( [alias] => table )
2483          * @param array $use_index Same as for select()
2484          * @param array $ignore_index Same as for select()
2485          * @param array $join_conds Same as for select()
2486          * @return string
2487          */
2488         protected function tableNamesWithIndexClauseOrJOIN(
2489                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2490         ) {
2491                 $ret = [];
2492                 $retJOIN = [];
2493                 $use_index = (array)$use_index;
2494                 $ignore_index = (array)$ignore_index;
2495                 $join_conds = (array)$join_conds;
2496
2497                 foreach ( $tables as $alias => $table ) {
2498                         if ( !is_string( $alias ) ) {
2499                                 // No alias? Set it equal to the table name
2500                                 $alias = $table;
2501                         }
2502
2503                         if ( is_array( $table ) ) {
2504                                 // A parenthesized group
2505                                 if ( count( $table ) > 1 ) {
2506                                         $joinedTable = '(' .
2507                                                 $this->tableNamesWithIndexClauseOrJOIN(
2508                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2509                                 } else {
2510                                         // Degenerate case
2511                                         $innerTable = reset( $table );
2512                                         $innerAlias = key( $table );
2513                                         $joinedTable = $this->tableNameWithAlias(
2514                                                 $innerTable,
2515                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2516                                         );
2517                                 }
2518                         } else {
2519                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2520                         }
2521
2522                         // Is there a JOIN clause for this table?
2523                         if ( isset( $join_conds[$alias] ) ) {
2524                                 list( $joinType, $conds ) = $join_conds[$alias];
2525                                 $tableClause = $joinType;
2526                                 $tableClause .= ' ' . $joinedTable;
2527                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2528                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2529                                         if ( $use != '' ) {
2530                                                 $tableClause .= ' ' . $use;
2531                                         }
2532                                 }
2533                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2534                                         $ignore = $this->ignoreIndexClause(
2535                                                 implode( ',', (array)$ignore_index[$alias] ) );
2536                                         if ( $ignore != '' ) {
2537                                                 $tableClause .= ' ' . $ignore;
2538                                         }
2539                                 }
2540                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2541                                 if ( $on != '' ) {
2542                                         $tableClause .= ' ON (' . $on . ')';
2543                                 }
2544
2545                                 $retJOIN[] = $tableClause;
2546                         } elseif ( isset( $use_index[$alias] ) ) {
2547                                 // Is there an INDEX clause for this table?
2548                                 $tableClause = $joinedTable;
2549                                 $tableClause .= ' ' . $this->useIndexClause(
2550                                                 implode( ',', (array)$use_index[$alias] )
2551                                         );
2552
2553                                 $ret[] = $tableClause;
2554                         } elseif ( isset( $ignore_index[$alias] ) ) {
2555                                 // Is there an INDEX clause for this table?
2556                                 $tableClause = $joinedTable;
2557                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2558                                                 implode( ',', (array)$ignore_index[$alias] )
2559                                         );
2560
2561                                 $ret[] = $tableClause;
2562                         } else {
2563                                 $tableClause = $joinedTable;
2564
2565                                 $ret[] = $tableClause;
2566                         }
2567                 }
2568
2569                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2570                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2571                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2572
2573                 // Compile our final table clause
2574                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2575         }
2576
2577         /**
2578          * Allows for index remapping in queries where this is not consistent across DBMS
2579          *
2580          * @param string $index
2581          * @return string
2582          */
2583         protected function indexName( $index ) {
2584                 return $this->indexAliases[$index] ?? $index;
2585         }
2586
2587         public function addQuotes( $s ) {
2588                 if ( $s instanceof Blob ) {
2589                         $s = $s->fetch();
2590                 }
2591                 if ( $s === null ) {
2592                         return 'NULL';
2593                 } elseif ( is_bool( $s ) ) {
2594                         return (int)$s;
2595                 } else {
2596                         # This will also quote numeric values. This should be harmless,
2597                         # and protects against weird problems that occur when they really
2598                         # _are_ strings such as article titles and string->number->string
2599                         # conversion is not 1:1.
2600                         return "'" . $this->strencode( $s ) . "'";
2601                 }
2602         }
2603
2604         /**
2605          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2606          * MySQL uses `backticks` while basically everything else uses double quotes.
2607          * Since MySQL is the odd one out here the double quotes are our generic
2608          * and we implement backticks in DatabaseMysqlBase.
2609          *
2610          * @param string $s
2611          * @return string
2612          */
2613         public function addIdentifierQuotes( $s ) {
2614                 return '"' . str_replace( '"', '""', $s ) . '"';
2615         }
2616
2617         /**
2618          * Returns if the given identifier looks quoted or not according to
2619          * the database convention for quoting identifiers .
2620          *
2621          * @note Do not use this to determine if untrusted input is safe.
2622          *   A malicious user can trick this function.
2623          * @param string $name
2624          * @return bool
2625          */
2626         public function isQuotedIdentifier( $name ) {
2627                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2628         }
2629
2630         /**
2631          * @param string $s
2632          * @param string $escapeChar
2633          * @return string
2634          */
2635         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2636                 return str_replace( [ $escapeChar, '%', '_' ],
2637                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2638                         $s );
2639         }
2640
2641         public function buildLike() {
2642                 $params = func_get_args();
2643
2644                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2645                         $params = $params[0];
2646                 }
2647
2648                 $s = '';
2649
2650                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2651                 // may escape backslashes, creating problems of double escaping. The `
2652                 // character has good cross-DBMS compatibility, avoiding special operators
2653                 // in MS SQL like ^ and %
2654                 $escapeChar = '`';
2655
2656                 foreach ( $params as $value ) {
2657                         if ( $value instanceof LikeMatch ) {
2658                                 $s .= $value->toString();
2659                         } else {
2660                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2661                         }
2662                 }
2663
2664                 return ' LIKE ' .
2665                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2666         }
2667
2668         public function anyChar() {
2669                 return new LikeMatch( '_' );
2670         }
2671
2672         public function anyString() {
2673                 return new LikeMatch( '%' );
2674         }
2675
2676         public function nextSequenceValue( $seqName ) {
2677                 return null;
2678         }
2679
2680         /**
2681          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2682          * is only needed because a) MySQL must be as efficient as possible due to
2683          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2684          * which index to pick. Anyway, other databases might have different
2685          * indexes on a given table. So don't bother overriding this unless you're
2686          * MySQL.
2687          * @param string $index
2688          * @return string
2689          */
2690         public function useIndexClause( $index ) {
2691                 return '';
2692         }
2693
2694         /**
2695          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2696          * is only needed because a) MySQL must be as efficient as possible due to
2697          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2698          * which index to pick. Anyway, other databases might have different
2699          * indexes on a given table. So don't bother overriding this unless you're
2700          * MySQL.
2701          * @param string $index
2702          * @return string
2703          */
2704         public function ignoreIndexClause( $index ) {
2705                 return '';
2706         }
2707
2708         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2709                 if ( count( $rows ) == 0 ) {
2710                         return;
2711                 }
2712
2713                 // Single row case
2714                 if ( !is_array( reset( $rows ) ) ) {
2715                         $rows = [ $rows ];
2716                 }
2717
2718                 try {
2719                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2720                         $affectedRowCount = 0;
2721                         foreach ( $rows as $row ) {
2722                                 // Delete rows which collide with this one
2723                                 $indexWhereClauses = [];
2724                                 foreach ( $uniqueIndexes as $index ) {
2725                                         $indexColumns = (array)$index;
2726                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2727                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2728                                                 throw new DBUnexpectedError(
2729                                                         $this,
2730                                                         'New record does not provide all values for unique key (' .
2731                                                         implode( ', ', $indexColumns ) . ')'
2732                                                 );
2733                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2734                                                 throw new DBUnexpectedError(
2735                                                         $this,
2736                                                         'New record has a null value for unique key (' .
2737                                                         implode( ', ', $indexColumns ) . ')'
2738                                                 );
2739                                         }
2740                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2741                                 }
2742
2743                                 if ( $indexWhereClauses ) {
2744                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2745                                         $affectedRowCount += $this->affectedRows();
2746                                 }
2747
2748                                 // Now insert the row
2749                                 $this->insert( $table, $row, $fname );
2750                                 $affectedRowCount += $this->affectedRows();
2751                         }
2752                         $this->endAtomic( $fname );
2753                         $this->affectedRowCount = $affectedRowCount;
2754                 } catch ( Exception $e ) {
2755                         $this->cancelAtomic( $fname );
2756                         throw $e;
2757                 }
2758         }
2759
2760         /**
2761          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2762          * statement.
2763          *
2764          * @param string $table Table name
2765          * @param array|string $rows Row(s) to insert
2766          * @param string $fname Caller function name
2767          *
2768          * @return ResultWrapper
2769          */
2770         protected function nativeReplace( $table, $rows, $fname ) {
2771                 $table = $this->tableName( $table );
2772
2773                 # Single row case
2774                 if ( !is_array( reset( $rows ) ) ) {
2775                         $rows = [ $rows ];
2776                 }
2777
2778                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2779                 $first = true;
2780
2781                 foreach ( $rows as $row ) {
2782                         if ( $first ) {
2783                                 $first = false;
2784                         } else {
2785                                 $sql .= ',';
2786                         }
2787
2788                         $sql .= '(' . $this->makeList( $row ) . ')';
2789                 }
2790
2791                 return $this->query( $sql, $fname );
2792         }
2793
2794         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2795                 $fname = __METHOD__
2796         ) {
2797                 if ( !count( $rows ) ) {
2798                         return true; // nothing to do
2799                 }
2800
2801                 if ( !is_array( reset( $rows ) ) ) {
2802                         $rows = [ $rows ];
2803                 }
2804
2805                 if ( count( $uniqueIndexes ) ) {
2806                         $clauses = []; // list WHERE clauses that each identify a single row
2807                         foreach ( $rows as $row ) {
2808                                 foreach ( $uniqueIndexes as $index ) {
2809                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2810                                         $rowKey = []; // unique key to this row
2811                                         foreach ( $index as $column ) {
2812                                                 $rowKey[$column] = $row[$column];
2813                                         }
2814                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2815                                 }
2816                         }
2817                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2818                 } else {
2819                         $where = false;
2820                 }
2821
2822                 $affectedRowCount = 0;
2823                 try {
2824                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2825                         # Update any existing conflicting row(s)
2826                         if ( $where !== false ) {
2827                                 $ok = $this->update( $table, $set, $where, $fname );
2828                                 $affectedRowCount += $this->affectedRows();
2829                         } else {
2830                                 $ok = true;
2831                         }
2832                         # Now insert any non-conflicting row(s)
2833                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2834                         $affectedRowCount += $this->affectedRows();
2835                         $this->endAtomic( $fname );
2836                         $this->affectedRowCount = $affectedRowCount;
2837                 } catch ( Exception $e ) {
2838                         $this->cancelAtomic( $fname );
2839                         throw $e;
2840                 }
2841
2842                 return $ok;
2843         }
2844
2845         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2846                 $fname = __METHOD__
2847         ) {
2848                 if ( !$conds ) {
2849                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2850                 }
2851
2852                 $delTable = $this->tableName( $delTable );
2853                 $joinTable = $this->tableName( $joinTable );
2854                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2855                 if ( $conds != '*' ) {
2856                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2857                 }
2858                 $sql .= ')';
2859
2860                 $this->query( $sql, $fname );
2861         }
2862
2863         public function textFieldSize( $table, $field ) {
2864                 $table = $this->tableName( $table );
2865                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2866                 $res = $this->query( $sql, __METHOD__ );
2867                 $row = $this->fetchObject( $res );
2868
2869                 $m = [];
2870
2871                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2872                         $size = $m[1];
2873                 } else {
2874                         $size = -1;
2875                 }
2876
2877                 return $size;
2878         }
2879
2880         public function delete( $table, $conds, $fname = __METHOD__ ) {
2881                 if ( !$conds ) {
2882                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2883                 }
2884
2885                 $table = $this->tableName( $table );
2886                 $sql = "DELETE FROM $table";
2887
2888                 if ( $conds != '*' ) {
2889                         if ( is_array( $conds ) ) {
2890                                 $conds = $this->makeList( $conds, self::LIST_AND );
2891                         }
2892                         $sql .= ' WHERE ' . $conds;
2893                 }
2894
2895                 return $this->query( $sql, $fname );
2896         }
2897
2898         final public function insertSelect(
2899                 $destTable, $srcTable, $varMap, $conds,
2900                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2901         ) {
2902                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2903
2904                 $insertOptions = (array)$insertOptions;
2905                 $selectOptions = (array)$selectOptions;
2906
2907                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2908                         // For massive migrations with downtime, we don't want to select everything
2909                         // into memory and OOM, so do all this native on the server side if possible.
2910                         return $this->nativeInsertSelect(
2911                                 $destTable,
2912                                 $srcTable,
2913                                 $varMap,
2914                                 $conds,
2915                                 $fname,
2916                                 array_diff( $insertOptions, $hints ),
2917                                 $selectOptions,
2918                                 $selectJoinConds
2919                         );
2920                 }
2921
2922                 return $this->nonNativeInsertSelect(
2923                         $destTable,
2924                         $srcTable,
2925                         $varMap,
2926                         $conds,
2927                         $fname,
2928                         array_diff( $insertOptions, $hints ),
2929                         $selectOptions,
2930                         $selectJoinConds
2931                 );
2932         }
2933
2934         /**
2935          * @param array $insertOptions INSERT options
2936          * @param array $selectOptions SELECT options
2937          * @return bool Whether an INSERT SELECT with these options will be replication safe
2938          * @since 1.31
2939          */
2940         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
2941                 return true;
2942         }
2943
2944         /**
2945          * Implementation of insertSelect() based on select() and insert()
2946          *
2947          * @see IDatabase::insertSelect()
2948          * @since 1.30
2949          * @param string $destTable
2950          * @param string|array $srcTable
2951          * @param array $varMap
2952          * @param array $conds
2953          * @param string $fname
2954          * @param array $insertOptions
2955          * @param array $selectOptions
2956          * @param array $selectJoinConds
2957          * @return bool
2958          */
2959         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2960                 $fname = __METHOD__,
2961                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2962         ) {
2963                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2964                 // on only the master (without needing row-based-replication). It also makes it easy to
2965                 // know how big the INSERT is going to be.
2966                 $fields = [];
2967                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2968                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2969                 }
2970                 $selectOptions[] = 'FOR UPDATE';
2971                 $res = $this->select(
2972                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2973                 );
2974                 if ( !$res ) {
2975                         return false;
2976                 }
2977
2978                 try {
2979                         $affectedRowCount = 0;
2980                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2981                         $rows = [];
2982                         $ok = true;
2983                         foreach ( $res as $row ) {
2984                                 $rows[] = (array)$row;
2985
2986                                 // Avoid inserts that are too huge
2987                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
2988                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2989                                         if ( !$ok ) {
2990                                                 break;
2991                                         }
2992                                         $affectedRowCount += $this->affectedRows();
2993                                         $rows = [];
2994                                 }
2995                         }
2996                         if ( $rows && $ok ) {
2997                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2998                                 if ( $ok ) {
2999                                         $affectedRowCount += $this->affectedRows();
3000                                 }
3001                         }
3002                         if ( $ok ) {
3003                                 $this->endAtomic( $fname );
3004                                 $this->affectedRowCount = $affectedRowCount;
3005                         } else {
3006                                 $this->cancelAtomic( $fname );
3007                         }
3008                         return $ok;
3009                 } catch ( Exception $e ) {
3010                         $this->cancelAtomic( $fname );
3011                         throw $e;
3012                 }
3013         }
3014
3015         /**
3016          * Native server-side implementation of insertSelect() for situations where
3017          * we don't want to select everything into memory
3018          *
3019          * @see IDatabase::insertSelect()
3020          * @param string $destTable
3021          * @param string|array $srcTable
3022          * @param array $varMap
3023          * @param array $conds
3024          * @param string $fname
3025          * @param array $insertOptions
3026          * @param array $selectOptions
3027          * @param array $selectJoinConds
3028          * @return bool
3029          */
3030         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3031                 $fname = __METHOD__,
3032                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3033         ) {
3034                 $destTable = $this->tableName( $destTable );
3035
3036                 if ( !is_array( $insertOptions ) ) {
3037                         $insertOptions = [ $insertOptions ];
3038                 }
3039
3040                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3041
3042                 $selectSql = $this->selectSQLText(
3043                         $srcTable,
3044                         array_values( $varMap ),
3045                         $conds,
3046                         $fname,
3047                         $selectOptions,
3048                         $selectJoinConds
3049                 );
3050
3051                 $sql = "INSERT $insertOptions" .
3052                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3053                         $selectSql;
3054
3055                 return $this->query( $sql, $fname );
3056         }
3057
3058         /**
3059          * Construct a LIMIT query with optional offset. This is used for query
3060          * pages. The SQL should be adjusted so that only the first $limit rows
3061          * are returned. If $offset is provided as well, then the first $offset
3062          * rows should be discarded, and the next $limit rows should be returned.
3063          * If the result of the query is not ordered, then the rows to be returned
3064          * are theoretically arbitrary.
3065          *
3066          * $sql is expected to be a SELECT, if that makes a difference.
3067          *
3068          * The version provided by default works in MySQL and SQLite. It will very
3069          * likely need to be overridden for most other DBMSes.
3070          *
3071          * @param string $sql SQL query we will append the limit too
3072          * @param int $limit The SQL limit
3073          * @param int|bool $offset The SQL offset (default false)
3074          * @throws DBUnexpectedError
3075          * @return string
3076          */
3077         public function limitResult( $sql, $limit, $offset = false ) {
3078                 if ( !is_numeric( $limit ) ) {
3079                         throw new DBUnexpectedError( $this,
3080                                 "Invalid non-numeric limit passed to limitResult()\n" );
3081                 }
3082
3083                 return "$sql LIMIT "
3084                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3085                 . "{$limit} ";
3086         }
3087
3088         public function unionSupportsOrderAndLimit() {
3089                 return true; // True for almost every DB supported
3090         }
3091
3092         public function unionQueries( $sqls, $all ) {
3093                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3094
3095                 return '(' . implode( $glue, $sqls ) . ')';
3096         }
3097
3098         public function unionConditionPermutations(
3099                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3100                 $options = [], $join_conds = []
3101         ) {
3102                 // First, build the Cartesian product of $permute_conds
3103                 $conds = [ [] ];
3104                 foreach ( $permute_conds as $field => $values ) {
3105                         if ( !$values ) {
3106                                 // Skip empty $values
3107                                 continue;
3108                         }
3109                         $values = array_unique( $values ); // For sanity
3110                         $newConds = [];
3111                         foreach ( $conds as $cond ) {
3112                                 foreach ( $values as $value ) {
3113                                         $cond[$field] = $value;
3114                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3115                                 }
3116                         }
3117                         $conds = $newConds;
3118                 }
3119
3120                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3121
3122                 // If there's just one condition and no subordering, hand off to
3123                 // selectSQLText directly.
3124                 if ( count( $conds ) === 1 &&
3125                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3126                 ) {
3127                         return $this->selectSQLText(
3128                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3129                         );
3130                 }
3131
3132                 // Otherwise, we need to pull out the order and limit to apply after
3133                 // the union. Then build the SQL queries for each set of conditions in
3134                 // $conds. Then union them together (using UNION ALL, because the
3135                 // product *should* already be distinct).
3136                 $orderBy = $this->makeOrderBy( $options );
3137                 $limit = $options['LIMIT'] ?? null;
3138                 $offset = $options['OFFSET'] ?? false;
3139                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3140                 if ( !$this->unionSupportsOrderAndLimit() ) {
3141                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3142                 } else {
3143                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3144                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3145                         }
3146                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3147                                 // We need to increase the limit by the offset rather than
3148                                 // using the offset directly, otherwise it'll skip incorrectly
3149                                 // in the subqueries.
3150                                 $options['LIMIT'] = $limit + $offset;
3151                                 unset( $options['OFFSET'] );
3152                         }
3153                 }
3154
3155                 $sqls = [];
3156                 foreach ( $conds as $cond ) {
3157                         $sqls[] = $this->selectSQLText(
3158                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3159                         );
3160                 }
3161                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3162                 if ( $limit !== null ) {
3163                         $sql = $this->limitResult( $sql, $limit, $offset );
3164                 }
3165
3166                 return $sql;
3167         }
3168
3169         public function conditional( $cond, $trueVal, $falseVal ) {
3170                 if ( is_array( $cond ) ) {
3171                         $cond = $this->makeList( $cond, self::LIST_AND );
3172                 }
3173
3174                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3175         }
3176
3177         public function strreplace( $orig, $old, $new ) {
3178                 return "REPLACE({$orig}, {$old}, {$new})";
3179         }
3180
3181         public function getServerUptime() {
3182                 return 0;
3183         }
3184
3185         public function wasDeadlock() {
3186                 return false;
3187         }
3188
3189         public function wasLockTimeout() {
3190                 return false;
3191         }
3192
3193         public function wasConnectionLoss() {
3194                 return $this->wasConnectionError( $this->lastErrno() );
3195         }
3196
3197         public function wasReadOnlyError() {
3198                 return false;
3199         }
3200
3201         public function wasErrorReissuable() {
3202                 return (
3203                         $this->wasDeadlock() ||
3204                         $this->wasLockTimeout() ||
3205                         $this->wasConnectionLoss()
3206                 );
3207         }
3208
3209         /**
3210          * Do not use this method outside of Database/DBError classes
3211          *
3212          * @param int|string $errno
3213          * @return bool Whether the given query error was a connection drop
3214          */
3215         public function wasConnectionError( $errno ) {
3216                 return false;
3217         }
3218
3219         /**
3220          * @return bool Whether it is safe to assume the given error only caused statement rollback
3221          * @note This is for backwards compatibility for callers catching DBError exceptions in
3222          *   order to ignore problems like duplicate key errors or foriegn key violations
3223          * @since 1.31
3224          */
3225         protected function wasKnownStatementRollbackError() {
3226                 return false; // don't know; it could have caused a transaction rollback
3227         }
3228
3229         public function deadlockLoop() {
3230                 $args = func_get_args();
3231                 $function = array_shift( $args );
3232                 $tries = self::DEADLOCK_TRIES;
3233
3234                 $this->begin( __METHOD__ );
3235
3236                 $retVal = null;
3237                 /** @var Exception $e */
3238                 $e = null;
3239                 do {
3240                         try {
3241                                 $retVal = $function( ...$args );
3242                                 break;
3243                         } catch ( DBQueryError $e ) {
3244                                 if ( $this->wasDeadlock() ) {
3245                                         // Retry after a randomized delay
3246                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3247                                 } else {
3248                                         // Throw the error back up
3249                                         throw $e;
3250                                 }
3251                         }
3252                 } while ( --$tries > 0 );
3253
3254                 if ( $tries <= 0 ) {
3255                         // Too many deadlocks; give up
3256                         $this->rollback( __METHOD__ );
3257                         throw $e;
3258                 } else {
3259                         $this->commit( __METHOD__ );
3260
3261                         return $retVal;
3262                 }
3263         }
3264
3265         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3266                 # Real waits are implemented in the subclass.
3267                 return 0;
3268         }
3269
3270         public function getReplicaPos() {
3271                 # Stub
3272                 return false;
3273         }
3274
3275         public function getMasterPos() {
3276                 # Stub
3277                 return false;
3278         }
3279
3280         public function serverIsReadOnly() {
3281                 return false;
3282         }
3283
3284         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3285                 if ( !$this->trxLevel ) {
3286                         throw new DBUnexpectedError( $this, "No transaction is active." );
3287                 }
3288                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3289         }
3290
3291         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3292                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3293                         // Start an implicit transaction similar to how query() does
3294                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3295                         $this->trxAutomatic = true;
3296                 }
3297
3298                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3299                 if ( !$this->trxLevel ) {
3300                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3301                 }
3302         }
3303
3304         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3305                 $this->onTransactionCommitOrIdle( $callback, $fname );
3306         }
3307
3308         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3309                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3310                         // Start an implicit transaction similar to how query() does
3311                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3312                         $this->trxAutomatic = true;
3313                 }
3314
3315                 if ( $this->trxLevel ) {
3316                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3317                 } else {
3318                         // No transaction is active nor will start implicitly, so make one for this callback
3319                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3320                         try {
3321                                 $callback( $this );
3322                                 $this->endAtomic( __METHOD__ );
3323                         } catch ( Exception $e ) {
3324                                 $this->cancelAtomic( __METHOD__ );
3325                                 throw $e;
3326                         }
3327                 }
3328         }
3329
3330         /**
3331          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3332          */
3333         private function currentAtomicSectionId() {
3334                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3335                         $levelInfo = end( $this->trxAtomicLevels );
3336
3337                         return $levelInfo[1];
3338                 }
3339
3340                 return null;
3341         }
3342
3343         /**
3344          * @param AtomicSectionIdentifier $old
3345          * @param AtomicSectionIdentifier $new
3346          */
3347         private function reassignCallbacksForSection(
3348                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3349         ) {
3350                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3351                         if ( $info[2] === $old ) {
3352                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3353                         }
3354                 }
3355                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3356                         if ( $info[2] === $old ) {
3357                                 $this->trxIdleCallbacks[$key][2] = $new;
3358                         }
3359                 }
3360                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3361                         if ( $info[2] === $old ) {
3362                                 $this->trxEndCallbacks[$key][2] = $new;
3363                         }
3364                 }
3365         }
3366
3367         /**
3368          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3369          * @throws UnexpectedValueException
3370          */
3371         private function modifyCallbacksForCancel( array $sectionIds ) {
3372                 // Cancel the "on commit" callbacks owned by this savepoint
3373                 $this->trxIdleCallbacks = array_filter(
3374                         $this->trxIdleCallbacks,
3375                         function ( $entry ) use ( $sectionIds ) {
3376                                 return !in_array( $entry[2], $sectionIds, true );
3377                         }
3378                 );
3379                 $this->trxPreCommitCallbacks = array_filter(
3380                         $this->trxPreCommitCallbacks,
3381                         function ( $entry ) use ( $sectionIds ) {
3382                                 return !in_array( $entry[2], $sectionIds, true );
3383                         }
3384                 );
3385                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3386                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3387                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3388                                 $callback = $entry[0];
3389                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3390                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3391                                 };
3392                         }
3393                 }
3394         }
3395
3396         final public function setTransactionListener( $name, callable $callback = null ) {
3397                 if ( $callback ) {
3398                         $this->trxRecurringCallbacks[$name] = $callback;
3399                 } else {
3400                         unset( $this->trxRecurringCallbacks[$name] );
3401                 }
3402         }
3403
3404         /**
3405          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3406          *
3407          * This method should not be used outside of Database/LoadBalancer
3408          *
3409          * @param bool $suppress
3410          * @since 1.28
3411          */
3412         final public function setTrxEndCallbackSuppression( $suppress ) {
3413                 $this->trxEndCallbacksSuppressed = $suppress;
3414         }
3415
3416         /**
3417          * Actually consume and run any "on transaction idle/resolution" callbacks.
3418          *
3419          * This method should not be used outside of Database/LoadBalancer
3420          *
3421          * @param int $trigger IDatabase::TRIGGER_* constant
3422          * @return int Number of callbacks attempted
3423          * @since 1.20
3424          * @throws Exception
3425          */
3426         public function runOnTransactionIdleCallbacks( $trigger ) {
3427                 if ( $this->trxLevel ) { // sanity
3428                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3429                 }
3430
3431                 if ( $this->trxEndCallbacksSuppressed ) {
3432                         return 0;
3433                 }
3434
3435                 $count = 0;
3436                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3437                 /** @var Exception $e */
3438                 $e = null; // first exception
3439                 do { // callbacks may add callbacks :)
3440                         $callbacks = array_merge(
3441                                 $this->trxIdleCallbacks,
3442                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3443                         );
3444                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3445                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3446                         foreach ( $callbacks as $callback ) {
3447                                 ++$count;
3448                                 list( $phpCallback ) = $callback;
3449                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3450                                 try {
3451                                         call_user_func( $phpCallback, $trigger, $this );
3452                                 } catch ( Exception $ex ) {
3453                                         call_user_func( $this->errorLogger, $ex );
3454                                         $e = $e ?: $ex;
3455                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3456                                         // their transactions are ended so other callbacks don't fail
3457                                         if ( $this->trxLevel() ) {
3458                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3459                                         }
3460                                 } finally {
3461                                         if ( $autoTrx ) {
3462                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3463                                         } else {
3464                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3465                                         }
3466                                 }
3467                         }
3468                 } while ( count( $this->trxIdleCallbacks ) );
3469
3470                 if ( $e instanceof Exception ) {
3471                         throw $e; // re-throw any first exception
3472                 }
3473
3474                 return $count;
3475         }
3476
3477         /**
3478          * Actually consume and run any "on transaction pre-commit" callbacks.
3479          *
3480          * This method should not be used outside of Database/LoadBalancer
3481          *
3482          * @since 1.22
3483          * @return int Number of callbacks attempted
3484          * @throws Exception
3485          */
3486         public function runOnTransactionPreCommitCallbacks() {
3487                 $count = 0;
3488
3489                 $e = null; // first exception
3490                 do { // callbacks may add callbacks :)
3491                         $callbacks = $this->trxPreCommitCallbacks;
3492                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3493                         foreach ( $callbacks as $callback ) {
3494                                 try {
3495                                         ++$count;
3496                                         list( $phpCallback ) = $callback;
3497                                         $phpCallback( $this );
3498                                 } catch ( Exception $ex ) {
3499                                         $this->errorLogger( $ex );
3500                                         $e = $e ?: $ex;
3501                                 }
3502                         }
3503                 } while ( count( $this->trxPreCommitCallbacks ) );
3504
3505                 if ( $e instanceof Exception ) {
3506                         throw $e; // re-throw any first exception
3507                 }
3508
3509                 return $count;
3510         }
3511
3512         /**
3513          * Actually run any "transaction listener" callbacks.
3514          *
3515          * This method should not be used outside of Database/LoadBalancer
3516          *
3517          * @param int $trigger IDatabase::TRIGGER_* constant
3518          * @throws Exception
3519          * @since 1.20
3520          */
3521         public function runTransactionListenerCallbacks( $trigger ) {
3522                 if ( $this->trxEndCallbacksSuppressed ) {
3523                         return;
3524                 }
3525
3526                 /** @var Exception $e */
3527                 $e = null; // first exception
3528
3529                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3530                         try {
3531                                 $phpCallback( $trigger, $this );
3532                         } catch ( Exception $ex ) {
3533                                 ( $this->errorLogger )( $ex );
3534                                 $e = $e ?: $ex;
3535                         }
3536                 }
3537
3538                 if ( $e instanceof Exception ) {
3539                         throw $e; // re-throw any first exception
3540                 }
3541         }
3542
3543         /**
3544          * Create a savepoint
3545          *
3546          * This is used internally to implement atomic sections. It should not be
3547          * used otherwise.
3548          *
3549          * @since 1.31
3550          * @param string $identifier Identifier for the savepoint
3551          * @param string $fname Calling function name
3552          */
3553         protected function doSavepoint( $identifier, $fname ) {
3554                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3555         }
3556
3557         /**
3558          * Release a savepoint
3559          *
3560          * This is used internally to implement atomic sections. It should not be
3561          * used otherwise.
3562          *
3563          * @since 1.31
3564          * @param string $identifier Identifier for the savepoint
3565          * @param string $fname Calling function name
3566          */
3567         protected function doReleaseSavepoint( $identifier, $fname ) {
3568                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3569         }
3570
3571         /**
3572          * Rollback to a savepoint
3573          *
3574          * This is used internally to implement atomic sections. It should not be
3575          * used otherwise.
3576          *
3577          * @since 1.31
3578          * @param string $identifier Identifier for the savepoint
3579          * @param string $fname Calling function name
3580          */
3581         protected function doRollbackToSavepoint( $identifier, $fname ) {
3582                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3583         }
3584
3585         /**
3586          * @param string $fname
3587          * @return string
3588          */
3589         private function nextSavepointId( $fname ) {
3590                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3591                 if ( strlen( $savepointId ) > 30 ) {
3592                         // 30 == Oracle's identifier length limit (pre 12c)
3593                         // With a 22 character prefix, that puts the highest number at 99999999.
3594                         throw new DBUnexpectedError(
3595                                 $this,
3596                                 'There have been an excessively large number of atomic sections in a transaction'
3597                                 . " started by $this->trxFname (at $fname)"
3598                         );
3599                 }
3600
3601                 return $savepointId;
3602         }
3603
3604         final public function startAtomic(
3605                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3606         ) {
3607                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3608
3609                 if ( !$this->trxLevel ) {
3610                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3611                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3612                         // in all changes being in one transaction to keep requests transactional.
3613                         if ( $this->getFlag( self::DBO_TRX ) ) {
3614                                 // Since writes could happen in between the topmost atomic sections as part
3615                                 // of the transaction, those sections will need savepoints.
3616                                 $savepointId = $this->nextSavepointId( $fname );
3617                                 $this->doSavepoint( $savepointId, $fname );
3618                         } else {
3619                                 $this->trxAutomaticAtomic = true;
3620                         }
3621                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3622                         $savepointId = $this->nextSavepointId( $fname );
3623                         $this->doSavepoint( $savepointId, $fname );
3624                 }
3625
3626                 $sectionId = new AtomicSectionIdentifier;
3627                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3628
3629                 return $sectionId;
3630         }
3631
3632         final public function endAtomic( $fname = __METHOD__ ) {
3633                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3634                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3635                 }
3636
3637                 // Check if the current section matches $fname
3638                 $pos = count( $this->trxAtomicLevels ) - 1;
3639                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3640
3641                 if ( $savedFname !== $fname ) {
3642                         throw new DBUnexpectedError(
3643                                 $this,
3644                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3645                         );
3646                 }
3647
3648                 // Remove the last section (no need to re-index the array)
3649                 array_pop( $this->trxAtomicLevels );
3650
3651                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3652                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3653                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3654                         $this->doReleaseSavepoint( $savepointId, $fname );
3655                 }
3656
3657                 // Hoist callback ownership for callbacks in the section that just ended;
3658                 // all callbacks should have an owner that is present in trxAtomicLevels.
3659                 $currentSectionId = $this->currentAtomicSectionId();
3660                 if ( $currentSectionId ) {
3661                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3662                 }
3663         }
3664
3665         final public function cancelAtomic(
3666                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3667         ) {
3668                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3669                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3670                 }
3671
3672                 if ( $sectionId !== null ) {
3673                         // Find the (last) section with the given $sectionId
3674                         $pos = -1;
3675                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3676                                 if ( $asId === $sectionId ) {
3677                                         $pos = $i;
3678                                 }
3679                         }
3680                         if ( $pos < 0 ) {
3681                                 throw new DBUnexpectedError( "Atomic section not found (for $fname)" );
3682                         }
3683                         // Remove all descendant sections and re-index the array
3684                         $excisedIds = [];
3685                         $len = count( $this->trxAtomicLevels );
3686                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3687                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3688                         }
3689                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3690                         $this->modifyCallbacksForCancel( $excisedIds );
3691                 }
3692
3693                 // Check if the current section matches $fname
3694                 $pos = count( $this->trxAtomicLevels ) - 1;
3695                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3696
3697                 if ( $savedFname !== $fname ) {
3698                         throw new DBUnexpectedError(
3699                                 $this,
3700                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3701                         );
3702                 }
3703
3704                 // Remove the last section (no need to re-index the array)
3705                 array_pop( $this->trxAtomicLevels );
3706                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3707
3708                 if ( $savepointId !== null ) {
3709                         // Rollback the transaction to the state just before this atomic section
3710                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3711                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3712                         } else {
3713                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3714                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3715                                 $this->trxStatusIgnoredCause = null;
3716                         }
3717                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3718                         // Put the transaction into an error state if it's not already in one
3719                         $this->trxStatus = self::STATUS_TRX_ERROR;
3720                         $this->trxStatusCause = new DBUnexpectedError(
3721                                 $this,
3722                                 "Uncancelable atomic section canceled (got $fname)."
3723                         );
3724                 }
3725
3726                 $this->affectedRowCount = 0; // for the sake of consistency
3727         }
3728
3729         final public function doAtomicSection(
3730                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3731         ) {
3732                 $sectionId = $this->startAtomic( $fname, $cancelable );
3733                 try {
3734                         $res = $callback( $this, $fname );
3735                 } catch ( Exception $e ) {
3736                         $this->cancelAtomic( $fname, $sectionId );
3737
3738                         throw $e;
3739                 }
3740                 $this->endAtomic( $fname );
3741
3742                 return $res;
3743         }
3744
3745         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3746                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3747                 if ( !in_array( $mode, $modes, true ) ) {
3748                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3749                 }
3750
3751                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3752                 if ( $this->trxLevel ) {
3753                         if ( $this->trxAtomicLevels ) {
3754                                 $levels = $this->flatAtomicSectionList();
3755                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3756                                 throw new DBUnexpectedError( $this, $msg );
3757                         } elseif ( !$this->trxAutomatic ) {
3758                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3759                                 throw new DBUnexpectedError( $this, $msg );
3760                         } else {
3761                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3762                                 throw new DBUnexpectedError( $this, $msg );
3763                         }
3764                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3765                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3766                         throw new DBUnexpectedError( $this, $msg );
3767                 }
3768
3769                 // Avoid fatals if close() was called
3770                 $this->assertOpen();
3771
3772                 $this->doBegin( $fname );
3773                 $this->trxStatus = self::STATUS_TRX_OK;
3774                 $this->trxStatusIgnoredCause = null;
3775                 $this->trxAtomicCounter = 0;
3776                 $this->trxTimestamp = microtime( true );
3777                 $this->trxFname = $fname;
3778                 $this->trxDoneWrites = false;
3779                 $this->trxAutomaticAtomic = false;
3780                 $this->trxAtomicLevels = [];
3781                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3782                 $this->trxWriteDuration = 0.0;
3783                 $this->trxWriteQueryCount = 0;
3784                 $this->trxWriteAffectedRows = 0;
3785                 $this->trxWriteAdjDuration = 0.0;
3786                 $this->trxWriteAdjQueryCount = 0;
3787                 $this->trxWriteCallers = [];
3788                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3789                 // Get an estimate of the replication lag before any such queries.
3790                 $this->trxReplicaLag = null; // clear cached value first
3791                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3792                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3793                 // caller will think its OK to muck around with the transaction just because startAtomic()
3794                 // has not yet completed (e.g. setting trxAtomicLevels).
3795                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3796         }
3797
3798         /**
3799          * Issues the BEGIN command to the database server.
3800          *
3801          * @see Database::begin()
3802          * @param string $fname
3803          */
3804         protected function doBegin( $fname ) {
3805                 $this->query( 'BEGIN', $fname );
3806                 $this->trxLevel = 1;
3807         }
3808
3809         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3810                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3811                 if ( !in_array( $flush, $modes, true ) ) {
3812                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3813                 }
3814
3815                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3816                         // There are still atomic sections open; this cannot be ignored
3817                         $levels = $this->flatAtomicSectionList();
3818                         throw new DBUnexpectedError(
3819                                 $this,
3820                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3821                         );
3822                 }
3823
3824                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3825                         if ( !$this->trxLevel ) {
3826                                 return; // nothing to do
3827                         } elseif ( !$this->trxAutomatic ) {
3828                                 throw new DBUnexpectedError(
3829                                         $this,
3830                                         "$fname: Flushing an explicit transaction, getting out of sync."
3831                                 );
3832                         }
3833                 } else {
3834                         if ( !$this->trxLevel ) {
3835                                 $this->queryLogger->error(
3836                                         "$fname: No transaction to commit, something got out of sync." );
3837                                 return; // nothing to do
3838                         } elseif ( $this->trxAutomatic ) {
3839                                 throw new DBUnexpectedError(
3840                                         $this,
3841                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3842                                 );
3843                         }
3844                 }
3845
3846                 // Avoid fatals if close() was called
3847                 $this->assertOpen();
3848
3849                 $this->runOnTransactionPreCommitCallbacks();
3850
3851                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3852                 $this->doCommit( $fname );
3853                 $this->trxStatus = self::STATUS_TRX_NONE;
3854
3855                 if ( $this->trxDoneWrites ) {
3856                         $this->lastWriteTime = microtime( true );
3857                         $this->trxProfiler->transactionWritingOut(
3858                                 $this->server,
3859                                 $this->getDomainID(),
3860                                 $this->trxShortId,
3861                                 $writeTime,
3862                                 $this->trxWriteAffectedRows
3863                         );
3864                 }
3865
3866                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3867                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
3868                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3869                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3870                 }
3871         }
3872
3873         /**
3874          * Issues the COMMIT command to the database server.
3875          *
3876          * @see Database::commit()
3877          * @param string $fname
3878          */
3879         protected function doCommit( $fname ) {
3880                 if ( $this->trxLevel ) {
3881                         $this->query( 'COMMIT', $fname );
3882                         $this->trxLevel = 0;
3883                 }
3884         }
3885
3886         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3887                 $trxActive = $this->trxLevel;
3888
3889                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3890                         if ( $this->getFlag( self::DBO_TRX ) ) {
3891                                 throw new DBUnexpectedError(
3892                                         $this,
3893                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3894                                 );
3895                         }
3896                 }
3897
3898                 if ( $trxActive ) {
3899                         // Avoid fatals if close() was called
3900                         $this->assertOpen();
3901
3902                         $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3903                         $this->doRollback( $fname );
3904                         $this->trxStatus = self::STATUS_TRX_NONE;
3905                         $this->trxAtomicLevels = [];
3906
3907                         if ( $this->trxDoneWrites ) {
3908                                 $this->trxProfiler->transactionWritingOut(
3909                                         $this->server,
3910                                         $this->getDomainID(),
3911                                         $this->trxShortId,
3912                                         $writeTime,
3913                                         $this->trxWriteAffectedRows
3914                                 );
3915                         }
3916                 }
3917
3918                 // Clear any commit-dependant callbacks. They might even be present
3919                 // only due to transaction rounds, with no SQL transaction being active
3920                 $this->trxIdleCallbacks = [];
3921                 $this->trxPreCommitCallbacks = [];
3922
3923                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3924                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
3925                         try {
3926                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3927                         } catch ( Exception $e ) {
3928                                 // already logged; finish and let LoadBalancer move on during mass-rollback
3929                         }
3930                         try {
3931                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3932                         } catch ( Exception $e ) {
3933                                 // already logged; let LoadBalancer move on during mass-rollback
3934                         }
3935
3936                         $this->affectedRowCount = 0; // for the sake of consistency
3937                 }
3938         }
3939
3940         /**
3941          * Issues the ROLLBACK command to the database server.
3942          *
3943          * @see Database::rollback()
3944          * @param string $fname
3945          */
3946         protected function doRollback( $fname ) {
3947                 if ( $this->trxLevel ) {
3948                         # Disconnects cause rollback anyway, so ignore those errors
3949                         $ignoreErrors = true;
3950                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3951                         $this->trxLevel = 0;
3952                 }
3953         }
3954
3955         public function flushSnapshot( $fname = __METHOD__ ) {
3956                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3957                         // This only flushes transactions to clear snapshots, not to write data
3958                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3959                         throw new DBUnexpectedError(
3960                                 $this,
3961                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3962                         );
3963                 }
3964
3965                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3966         }
3967
3968         public function explicitTrxActive() {
3969                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
3970         }
3971
3972         public function duplicateTableStructure(
3973                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3974         ) {
3975                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3976         }
3977
3978         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3979                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3980         }
3981
3982         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3983                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3984         }
3985
3986         public function timestamp( $ts = 0 ) {
3987                 $t = new ConvertibleTimestamp( $ts );
3988                 // Let errors bubble up to avoid putting garbage in the DB
3989                 return $t->getTimestamp( TS_MW );
3990         }
3991
3992         public function timestampOrNull( $ts = null ) {
3993                 if ( is_null( $ts ) ) {
3994                         return null;
3995                 } else {
3996                         return $this->timestamp( $ts );
3997                 }
3998         }
3999
4000         public function affectedRows() {
4001                 return ( $this->affectedRowCount === null )
4002                         ? $this->fetchAffectedRowCount() // default to driver value
4003                         : $this->affectedRowCount;
4004         }
4005
4006         /**
4007          * @return int Number of retrieved rows according to the driver
4008          */
4009         abstract protected function fetchAffectedRowCount();
4010
4011         /**
4012          * Take the result from a query, and wrap it in a ResultWrapper if
4013          * necessary. Boolean values are passed through as is, to indicate success
4014          * of write queries or failure.
4015          *
4016          * Once upon a time, Database::query() returned a bare MySQL result
4017          * resource, and it was necessary to call this function to convert it to
4018          * a wrapper. Nowadays, raw database objects are never exposed to external
4019          * callers, so this is unnecessary in external code.
4020          *
4021          * @param bool|ResultWrapper|resource|object $result
4022          * @return bool|ResultWrapper
4023          */
4024         protected function resultObject( $result ) {
4025                 if ( !$result ) {
4026                         return false;
4027                 } elseif ( $result instanceof ResultWrapper ) {
4028                         return $result;
4029                 } elseif ( $result === true ) {
4030                         // Successful write query
4031                         return $result;
4032                 } else {
4033                         return new ResultWrapper( $this, $result );
4034                 }
4035         }
4036
4037         public function ping( &$rtt = null ) {
4038                 // Avoid hitting the server if it was hit recently
4039                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
4040                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
4041                                 $rtt = $this->rttEstimate;
4042                                 return true; // don't care about $rtt
4043                         }
4044                 }
4045
4046                 // This will reconnect if possible or return false if not
4047                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4048                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
4049                 $this->restoreFlags( self::RESTORE_PRIOR );
4050
4051                 if ( $ok ) {
4052                         $rtt = $this->rttEstimate;
4053                 }
4054
4055                 return $ok;
4056         }
4057
4058         /**
4059          * Close any existing (dead) database connection and open a new connection
4060          *
4061          * @param string $fname
4062          * @return bool True if new connection is opened successfully, false if error
4063          */
4064         protected function replaceLostConnection( $fname ) {
4065                 $this->closeConnection();
4066                 $this->opened = false;
4067                 $this->conn = false;
4068                 try {
4069                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4070                         $this->lastPing = microtime( true );
4071                         $ok = true;
4072
4073                         $this->connLogger->warning(
4074                                 $fname . ': lost connection to {dbserver}; reconnected',
4075                                 [
4076                                         'dbserver' => $this->getServer(),
4077                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4078                                 ]
4079                         );
4080                 } catch ( DBConnectionError $e ) {
4081                         $ok = false;
4082
4083                         $this->connLogger->error(
4084                                 $fname . ': lost connection to {dbserver} permanently',
4085                                 [ 'dbserver' => $this->getServer() ]
4086                         );
4087                 }
4088
4089                 $this->handleSessionLoss();
4090
4091                 return $ok;
4092         }
4093
4094         public function getSessionLagStatus() {
4095                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4096         }
4097
4098         /**
4099          * Get the replica DB lag when the current transaction started
4100          *
4101          * This is useful when transactions might use snapshot isolation
4102          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4103          * is this lag plus transaction duration. If they don't, it is still
4104          * safe to be pessimistic. This returns null if there is no transaction.
4105          *
4106          * This returns null if the lag status for this transaction was not yet recorded.
4107          *
4108          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4109          * @since 1.27
4110          */
4111         final protected function getRecordedTransactionLagStatus() {
4112                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4113                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4114                         : null;
4115         }
4116
4117         /**
4118          * Get a replica DB lag estimate for this server
4119          *
4120          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4121          * @since 1.27
4122          */
4123         protected function getApproximateLagStatus() {
4124                 return [
4125                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4126                         'since' => microtime( true )
4127                 ];
4128         }
4129
4130         /**
4131          * Merge the result of getSessionLagStatus() for several DBs
4132          * using the most pessimistic values to estimate the lag of
4133          * any data derived from them in combination
4134          *
4135          * This is information is useful for caching modules
4136          *
4137          * @see WANObjectCache::set()
4138          * @see WANObjectCache::getWithSetCallback()
4139          *
4140          * @param IDatabase $db1
4141          * @param IDatabase|null $db2 [optional]
4142          * @return array Map of values:
4143          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4144          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4145          *   - pending: whether any of the DBs have uncommitted changes
4146          * @throws DBError
4147          * @since 1.27
4148          */
4149         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4150                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4151                 foreach ( func_get_args() as $db ) {
4152                         /** @var IDatabase $db */
4153                         $status = $db->getSessionLagStatus();
4154                         if ( $status['lag'] === false ) {
4155                                 $res['lag'] = false;
4156                         } elseif ( $res['lag'] !== false ) {
4157                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4158                         }
4159                         $res['since'] = min( $res['since'], $status['since'] );
4160                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4161                 }
4162
4163                 return $res;
4164         }
4165
4166         public function getLag() {
4167                 return 0;
4168         }
4169
4170         public function maxListLen() {
4171                 return 0;
4172         }
4173
4174         public function encodeBlob( $b ) {
4175                 return $b;
4176         }
4177
4178         public function decodeBlob( $b ) {
4179                 if ( $b instanceof Blob ) {
4180                         $b = $b->fetch();
4181                 }
4182                 return $b;
4183         }
4184
4185         public function setSessionOptions( array $options ) {
4186         }
4187
4188         public function sourceFile(
4189                 $filename,
4190                 callable $lineCallback = null,
4191                 callable $resultCallback = null,
4192                 $fname = false,
4193                 callable $inputCallback = null
4194         ) {
4195                 Wikimedia\suppressWarnings();
4196                 $fp = fopen( $filename, 'r' );
4197                 Wikimedia\restoreWarnings();
4198
4199                 if ( false === $fp ) {
4200                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4201                 }
4202
4203                 if ( !$fname ) {
4204                         $fname = __METHOD__ . "( $filename )";
4205                 }
4206
4207                 try {
4208                         $error = $this->sourceStream(
4209                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4210                 } catch ( Exception $e ) {
4211                         fclose( $fp );
4212                         throw $e;
4213                 }
4214
4215                 fclose( $fp );
4216
4217                 return $error;
4218         }
4219
4220         public function setSchemaVars( $vars ) {
4221                 $this->schemaVars = $vars;
4222         }
4223
4224         public function sourceStream(
4225                 $fp,
4226                 callable $lineCallback = null,
4227                 callable $resultCallback = null,
4228                 $fname = __METHOD__,
4229                 callable $inputCallback = null
4230         ) {
4231                 $delimiterReset = new ScopedCallback(
4232                         function ( $delimiter ) {
4233                                 $this->delimiter = $delimiter;
4234                         },
4235                         [ $this->delimiter ]
4236                 );
4237                 $cmd = '';
4238
4239                 while ( !feof( $fp ) ) {
4240                         if ( $lineCallback ) {
4241                                 call_user_func( $lineCallback );
4242                         }
4243
4244                         $line = trim( fgets( $fp ) );
4245
4246                         if ( $line == '' ) {
4247                                 continue;
4248                         }
4249
4250                         if ( '-' == $line[0] && '-' == $line[1] ) {
4251                                 continue;
4252                         }
4253
4254                         if ( $cmd != '' ) {
4255                                 $cmd .= ' ';
4256                         }
4257
4258                         $done = $this->streamStatementEnd( $cmd, $line );
4259
4260                         $cmd .= "$line\n";
4261
4262                         if ( $done || feof( $fp ) ) {
4263                                 $cmd = $this->replaceVars( $cmd );
4264
4265                                 if ( $inputCallback ) {
4266                                         $callbackResult = $inputCallback( $cmd );
4267
4268                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4269                                                 $cmd = $callbackResult;
4270                                         }
4271                                 }
4272
4273                                 if ( $cmd ) {
4274                                         $res = $this->query( $cmd, $fname );
4275
4276                                         if ( $resultCallback ) {
4277                                                 $resultCallback( $res, $this );
4278                                         }
4279
4280                                         if ( false === $res ) {
4281                                                 $err = $this->lastError();
4282
4283                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4284                                         }
4285                                 }
4286                                 $cmd = '';
4287                         }
4288                 }
4289
4290                 ScopedCallback::consume( $delimiterReset );
4291                 return true;
4292         }
4293
4294         /**
4295          * Called by sourceStream() to check if we've reached a statement end
4296          *
4297          * @param string &$sql SQL assembled so far
4298          * @param string &$newLine New line about to be added to $sql
4299          * @return bool Whether $newLine contains end of the statement
4300          */
4301         public function streamStatementEnd( &$sql, &$newLine ) {
4302                 if ( $this->delimiter ) {
4303                         $prev = $newLine;
4304                         $newLine = preg_replace(
4305                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4306                         if ( $newLine != $prev ) {
4307                                 return true;
4308                         }
4309                 }
4310
4311                 return false;
4312         }
4313
4314         /**
4315          * Database independent variable replacement. Replaces a set of variables
4316          * in an SQL statement with their contents as given by $this->getSchemaVars().
4317          *
4318          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4319          *
4320          * - '{$var}' should be used for text and is passed through the database's
4321          *   addQuotes method.
4322          * - `{$var}` should be used for identifiers (e.g. table and database names).
4323          *   It is passed through the database's addIdentifierQuotes method which
4324          *   can be overridden if the database uses something other than backticks.
4325          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4326          *   database's tableName method.
4327          * - / *i* / passes the name that follows through the database's indexName method.
4328          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4329          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4330          *
4331          * @param string $ins SQL statement to replace variables in
4332          * @return string The new SQL statement with variables replaced
4333          */
4334         protected function replaceVars( $ins ) {
4335                 $vars = $this->getSchemaVars();
4336                 return preg_replace_callback(
4337                         '!
4338                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4339                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4340                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4341                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4342                         !x',
4343                         function ( $m ) use ( $vars ) {
4344                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4345                                 // check for both nonexistent keys *and* the empty string.
4346                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4347                                         if ( $m[1] === 'i' ) {
4348                                                 return $this->indexName( $m[2] );
4349                                         } else {
4350                                                 return $this->tableName( $m[2] );
4351                                         }
4352                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4353                                         return $this->addQuotes( $vars[$m[3]] );
4354                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4355                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4356                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4357                                         return $vars[$m[5]];
4358                                 } else {
4359                                         return $m[0];
4360                                 }
4361                         },
4362                         $ins
4363                 );
4364         }
4365
4366         /**
4367          * Get schema variables. If none have been set via setSchemaVars(), then
4368          * use some defaults from the current object.
4369          *
4370          * @return array
4371          */
4372         protected function getSchemaVars() {
4373                 if ( $this->schemaVars ) {
4374                         return $this->schemaVars;
4375                 } else {
4376                         return $this->getDefaultSchemaVars();
4377                 }
4378         }
4379
4380         /**
4381          * Get schema variables to use if none have been set via setSchemaVars().
4382          *
4383          * Override this in derived classes to provide variables for tables.sql
4384          * and SQL patch files.
4385          *
4386          * @return array
4387          */
4388         protected function getDefaultSchemaVars() {
4389                 return [];
4390         }
4391
4392         public function lockIsFree( $lockName, $method ) {
4393                 // RDBMs methods for checking named locks may or may not count this thread itself.
4394                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4395                 // the behavior choosen by the interface for this method.
4396                 return !isset( $this->namedLocksHeld[$lockName] );
4397         }
4398
4399         public function lock( $lockName, $method, $timeout = 5 ) {
4400                 $this->namedLocksHeld[$lockName] = 1;
4401
4402                 return true;
4403         }
4404
4405         public function unlock( $lockName, $method ) {
4406                 unset( $this->namedLocksHeld[$lockName] );
4407
4408                 return true;
4409         }
4410
4411         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4412                 if ( $this->writesOrCallbacksPending() ) {
4413                         // This only flushes transactions to clear snapshots, not to write data
4414                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4415                         throw new DBUnexpectedError(
4416                                 $this,
4417                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4418                         );
4419                 }
4420
4421                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4422                         return null;
4423                 }
4424
4425                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4426                         if ( $this->trxLevel() ) {
4427                                 // There is a good chance an exception was thrown, causing any early return
4428                                 // from the caller. Let any error handler get a chance to issue rollback().
4429                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4430                                 $this->onTransactionResolution(
4431                                         function () use ( $lockKey, $fname ) {
4432                                                 $this->unlock( $lockKey, $fname );
4433                                         },
4434                                         $fname
4435                                 );
4436                         } else {
4437                                 $this->unlock( $lockKey, $fname );
4438                         }
4439                 } );
4440
4441                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4442
4443                 return $unlocker;
4444         }
4445
4446         public function namedLocksEnqueue() {
4447                 return false;
4448         }
4449
4450         public function tableLocksHaveTransactionScope() {
4451                 return true;
4452         }
4453
4454         final public function lockTables( array $read, array $write, $method ) {
4455                 if ( $this->writesOrCallbacksPending() ) {
4456                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4457                 }
4458
4459                 if ( $this->tableLocksHaveTransactionScope() ) {
4460                         $this->startAtomic( $method );
4461                 }
4462
4463                 return $this->doLockTables( $read, $write, $method );
4464         }
4465
4466         /**
4467          * Helper function for lockTables() that handles the actual table locking
4468          *
4469          * @param array $read Array of tables to lock for read access
4470          * @param array $write Array of tables to lock for write access
4471          * @param string $method Name of caller
4472          * @return true
4473          */
4474         protected function doLockTables( array $read, array $write, $method ) {
4475                 return true;
4476         }
4477
4478         final public function unlockTables( $method ) {
4479                 if ( $this->tableLocksHaveTransactionScope() ) {
4480                         $this->endAtomic( $method );
4481
4482                         return true; // locks released on COMMIT/ROLLBACK
4483                 }
4484
4485                 return $this->doUnlockTables( $method );
4486         }
4487
4488         /**
4489          * Helper function for unlockTables() that handles the actual table unlocking
4490          *
4491          * @param string $method Name of caller
4492          * @return true
4493          */
4494         protected function doUnlockTables( $method ) {
4495                 return true;
4496         }
4497
4498         /**
4499          * Delete a table
4500          * @param string $tableName
4501          * @param string $fName
4502          * @return bool|ResultWrapper
4503          * @since 1.18
4504          */
4505         public function dropTable( $tableName, $fName = __METHOD__ ) {
4506                 if ( !$this->tableExists( $tableName, $fName ) ) {
4507                         return false;
4508                 }
4509                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4510
4511                 return $this->query( $sql, $fName );
4512         }
4513
4514         public function getInfinity() {
4515                 return 'infinity';
4516         }
4517
4518         public function encodeExpiry( $expiry ) {
4519                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4520                         ? $this->getInfinity()
4521                         : $this->timestamp( $expiry );
4522         }
4523
4524         public function decodeExpiry( $expiry, $format = TS_MW ) {
4525                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4526                         return 'infinity';
4527                 }
4528
4529                 return ConvertibleTimestamp::convert( $format, $expiry );
4530         }
4531
4532         public function setBigSelects( $value = true ) {
4533                 // no-op
4534         }
4535
4536         public function isReadOnly() {
4537                 return ( $this->getReadOnlyReason() !== false );
4538         }
4539
4540         /**
4541          * @return string|bool Reason this DB is read-only or false if it is not
4542          */
4543         protected function getReadOnlyReason() {
4544                 $reason = $this->getLBInfo( 'readOnlyReason' );
4545
4546                 return is_string( $reason ) ? $reason : false;
4547         }
4548
4549         public function setTableAliases( array $aliases ) {
4550                 $this->tableAliases = $aliases;
4551         }
4552
4553         public function setIndexAliases( array $aliases ) {
4554                 $this->indexAliases = $aliases;
4555         }
4556
4557         /**
4558          * Get the underlying binding connection handle
4559          *
4560          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4561          * This catches broken callers than catch and ignore disconnection exceptions.
4562          * Unlike checking isOpen(), this is safe to call inside of open().
4563          *
4564          * @return mixed
4565          * @throws DBUnexpectedError
4566          * @since 1.26
4567          */
4568         protected function getBindingHandle() {
4569                 if ( !$this->conn ) {
4570                         throw new DBUnexpectedError(
4571                                 $this,
4572                                 'DB connection was already closed or the connection dropped.'
4573                         );
4574                 }
4575
4576                 return $this->conn;
4577         }
4578
4579         /**
4580          * @since 1.19
4581          * @return string
4582          */
4583         public function __toString() {
4584                 return (string)$this->conn;
4585         }
4586
4587         /**
4588          * Make sure that copies do not share the same client binding handle
4589          * @throws DBConnectionError
4590          */
4591         public function __clone() {
4592                 $this->connLogger->warning(
4593                         "Cloning " . static::class . " is not recommended; forking connection:\n" .
4594                         ( new RuntimeException() )->getTraceAsString()
4595                 );
4596
4597                 if ( $this->isOpen() ) {
4598                         // Open a new connection resource without messing with the old one
4599                         $this->opened = false;
4600                         $this->conn = false;
4601                         $this->trxEndCallbacks = []; // don't copy
4602                         $this->handleSessionLoss(); // no trx or locks anymore
4603                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4604                         $this->lastPing = microtime( true );
4605                 }
4606         }
4607
4608         /**
4609          * Called by serialize. Throw an exception when DB connection is serialized.
4610          * This causes problems on some database engines because the connection is
4611          * not restored on unserialize.
4612          */
4613         public function __sleep() {
4614                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4615                         'the connection is not restored on wakeup.' );
4616         }
4617
4618         /**
4619          * Run a few simple sanity checks and close dangling connections
4620          */
4621         public function __destruct() {
4622                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4623                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4624                 }
4625
4626                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4627                 if ( $danglingWriters ) {
4628                         $fnames = implode( ', ', $danglingWriters );
4629                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4630                 }
4631
4632                 if ( $this->conn ) {
4633                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4634                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4635                         Wikimedia\suppressWarnings();
4636                         $this->closeConnection();
4637                         Wikimedia\restoreWarnings();
4638                         $this->conn = false;
4639                         $this->opened = false;
4640                 }
4641         }
4642 }
4643
4644 /**
4645  * @deprecated since 1.28
4646  */
4647 class_alias( Database::class, 'DatabaseBase' );
4648
4649 /**
4650  * @deprecated since 1.29
4651  */
4652 class_alias( Database::class, 'Database' );