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