includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Psr\Log\NullLogger;
  31 use Wikimedia\ScopedCallback;
  32 use Wikimedia\Timestamp\ConvertibleTimestamp;
  33 use Wikimedia;
  34 use BagOStuff;
  35 use HashBagOStuff;
  36 use LogicException;
  37 use InvalidArgumentException;
  38 use UnexpectedValueException;
  39 use Exception;
  40 use RuntimeException;
  41
  42 /**
  43  * Relational database abstraction object
  44  *
  45  * @ingroup Database
  46  * @since 1.28
  47  */
  48 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  49         /** Number of times to re-try an operation in case of deadlock */
  50         const DEADLOCK_TRIES = 4;
  51         /** Minimum time to wait before retry, in microseconds */
  52         const DEADLOCK_DELAY_MIN = 500000;
  53         /** Maximum time to wait before retry */
  54         const DEADLOCK_DELAY_MAX = 1500000;
  55
  56         /** How long before it is worth doing a dummy query to test the connection */
  57         const PING_TTL = 1.0;
  58         const PING_QUERY = 'SELECT 1 AS ping';
  59
  60         const TINY_WRITE_SEC = 0.010;
  61         const SLOW_WRITE_SEC = 0.500;
  62         const SMALL_WRITE_ROWS = 100;
  63
  64         /** @var string Whether lock granularity is on the level of the entire database */
  65         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
  66
  67         /** @var int New Database instance will not be connected yet when returned */
  68         const NEW_UNCONNECTED = 0;
  69         /** @var int New Database instance will already be connected when returned */
  70         const NEW_CONNECTED = 1;
  71
  72         /** @var string SQL query */
  73         protected $lastQuery = '';
  74         /** @var float|bool UNIX timestamp of last write query */
  75         protected $lastWriteTime = false;
  76         /** @var string|bool */
  77         protected $phpError = false;
  78         /** @var string Server that this instance is currently connected to */
  79         protected $server;
  80         /** @var string User that this instance is currently connected under the name of */
  81         protected $user;
  82         /** @var string Password used to establish the current connection */
  83         protected $password;
  84         /** @var string Database that this instance is currently connected to */
  85         protected $dbName;
  86         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  87         protected $tableAliases = [];
  88         /** @var string[] Map of (index alias => index) */
  89         protected $indexAliases = [];
  90         /** @var bool Whether this PHP instance is for a CLI script */
  91         protected $cliMode;
  92         /** @var string Agent name for query profiling */
  93         protected $agent;
  94         /** @var array Parameters used by initConnection() to establish a connection */
  95         protected $connectionParams = [];
  96         /** @var BagOStuff APC cache */
  97         protected $srvCache;
  98         /** @var LoggerInterface */
  99         protected $connLogger;
 100         /** @var LoggerInterface */
 101         protected $queryLogger;
 102         /** @var callback Error logging callback */
 103         protected $errorLogger;
 104         /** @var callback Deprecation logging callback */
 105         protected $deprecationLogger;
 106
 107         /** @var resource|null Database connection */
 108         protected $conn = null;
 109         /** @var bool */
 110         protected $opened = false;
 111
 112         /** @var array[] List of (callable, method name, atomic section id) */
 113         protected $trxIdleCallbacks = [];
 114         /** @var array[] List of (callable, method name, atomic section id) */
 115         protected $trxPreCommitCallbacks = [];
 116         /** @var array[] List of (callable, method name, atomic section id) */
 117         protected $trxEndCallbacks = [];
 118         /** @var callable[] Map of (name => callable) */
 119         protected $trxRecurringCallbacks = [];
 120         /** @var bool Whether to suppress triggering of transaction end callbacks */
 121         protected $trxEndCallbacksSuppressed = false;
 122
 123         /** @var string */
 124         protected $tablePrefix = '';
 125         /** @var string */
 126         protected $schema = '';
 127         /** @var int */
 128         protected $flags;
 129         /** @var array */
 130         protected $lbInfo = [];
 131         /** @var array|bool */
 132         protected $schemaVars = false;
 133         /** @var array */
 134         protected $sessionVars = [];
 135         /** @var array|null */
 136         protected $preparedArgs;
 137         /** @var string|bool|null Stashed value of html_errors INI setting */
 138         protected $htmlErrors;
 139         /** @var string */
 140         protected $delimiter = ';';
 141         /** @var DatabaseDomain */
 142         protected $currentDomain;
 143         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 144         protected $affectedRowCount;
 145
 146         /**
 147          * @var int Transaction status
 148          */
 149         protected $trxStatus = self::STATUS_TRX_NONE;
 150         /**
 151          * @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR
 152          */
 153         protected $trxStatusCause;
 154         /**
 155          * @var array|null If wasKnownStatementRollbackError() prevented trxStatus from being set,
 156          *  the relevant details are stored here.
 157          */
 158         protected $trxStatusIgnoredCause;
 159         /**
 160          * Either 1 if a transaction is active or 0 otherwise.
 161          * The other Trx fields may not be meaningfull if this is 0.
 162          *
 163          * @var int
 164          */
 165         protected $trxLevel = 0;
 166         /**
 167          * Either a short hexidecimal string if a transaction is active or ""
 168          *
 169          * @var string
 170          * @see Database::trxLevel
 171          */
 172         protected $trxShortId = '';
 173         /**
 174          * The UNIX time that the transaction started. Callers can assume that if
 175          * snapshot isolation is used, then the data is *at least* up to date to that
 176          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 177          *
 178          * @var float|null
 179          * @see Database::trxLevel
 180          */
 181         private $trxTimestamp = null;
 182         /** @var float Lag estimate at the time of BEGIN */
 183         private $trxReplicaLag = null;
 184         /**
 185          * Remembers the function name given for starting the most recent transaction via begin().
 186          * Used to provide additional context for error reporting.
 187          *
 188          * @var string
 189          * @see Database::trxLevel
 190          */
 191         private $trxFname = null;
 192         /**
 193          * Record if possible write queries were done in the last transaction started
 194          *
 195          * @var bool
 196          * @see Database::trxLevel
 197          */
 198         private $trxDoneWrites = false;
 199         /**
 200          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 201          *
 202          * @var bool
 203          * @see Database::trxLevel
 204          */
 205         private $trxAutomatic = false;
 206         /**
 207          * Counter for atomic savepoint identifiers. Reset when a new transaction begins.
 208          *
 209          * @var int
 210          */
 211         private $trxAtomicCounter = 0;
 212         /**
 213          * Array of levels of atomicity within transactions
 214          *
 215          * @var array List of (name, unique ID, savepoint ID)
 216          */
 217         private $trxAtomicLevels = [];
 218         /**
 219          * Record if the current transaction was started implicitly by Database::startAtomic
 220          *
 221          * @var bool
 222          */
 223         private $trxAutomaticAtomic = false;
 224         /**
 225          * Track the write query callers of the current transaction
 226          *
 227          * @var string[]
 228          */
 229         private $trxWriteCallers = [];
 230         /**
 231          * @var float Seconds spent in write queries for the current transaction
 232          */
 233         private $trxWriteDuration = 0.0;
 234         /**
 235          * @var int Number of write queries for the current transaction
 236          */
 237         private $trxWriteQueryCount = 0;
 238         /**
 239          * @var int Number of rows affected by write queries for the current transaction
 240          */
 241         private $trxWriteAffectedRows = 0;
 242         /**
 243          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 244          */
 245         private $trxWriteAdjDuration = 0.0;
 246         /**
 247          * @var int Number of write queries counted in trxWriteAdjDuration
 248          */
 249         private $trxWriteAdjQueryCount = 0;
 250         /**
 251          * @var float RTT time estimate
 252          */
 253         private $rttEstimate = 0.0;
 254
 255         /** @var array Map of (name => 1) for locks obtained via lock() */
 256         private $namedLocksHeld = [];
 257         /** @var array Map of (table name => 1) for TEMPORARY tables */
 258         protected $sessionTempTables = [];
 259
 260         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 261         private $lazyMasterHandle;
 262
 263         /** @var float UNIX timestamp */
 264         protected $lastPing = 0.0;
 265
 266         /** @var int[] Prior flags member variable values */
 267         private $priorFlags = [];
 268
 269         /** @var object|string Class name or object With profileIn/profileOut methods */
 270         protected $profiler;
 271         /** @var TransactionProfiler */
 272         protected $trxProfiler;
 273
 274         /** @var int */
 275         protected $nonNativeInsertSelectBatchSize = 10000;
 276
 277         /** @var string Idiom used when a cancelable atomic section started the transaction */
 278         private static $NOT_APPLICABLE = 'n/a';
 279         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 280         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 281
 282         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 283         const STATUS_TRX_ERROR = 1;
 284         /** @var int Transaction is active and in a normal state */
 285         const STATUS_TRX_OK = 2;
 286         /** @var int No transaction is active */
 287         const STATUS_TRX_NONE = 3;
 288
 289         /**
 290          * @note: exceptions for missing libraries/drivers should be thrown in initConnection()
 291          * @param array $params Parameters passed from Database::factory()
 292          */
 293         protected function __construct( array $params ) {
 294                 foreach ( [ 'host', 'user', 'password', 'dbname' ] as $name ) {
 295                         $this->connectionParams[$name] = $params[$name];
 296                 }
 297
 298                 $this->schema = $params['schema'];
 299                 $this->tablePrefix = $params['tablePrefix'];
 300
 301                 $this->cliMode = $params['cliMode'];
 302                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 303                 $this->agent = str_replace( '/', '-', $params['agent'] );
 304
 305                 $this->flags = $params['flags'];
 306                 if ( $this->flags & self::DBO_DEFAULT ) {
 307                         if ( $this->cliMode ) {
 308                                 $this->flags &= ~self::DBO_TRX;
 309                         } else {
 310                                 $this->flags |= self::DBO_TRX;
 311                         }
 312                 }
 313                 // Disregard deprecated DBO_IGNORE flag (T189999)
 314                 $this->flags &= ~self::DBO_IGNORE;
 315
 316                 $this->sessionVars = $params['variables'];
 317
 318                 $this->srvCache = isset( $params['srvCache'] )
 319                         ? $params['srvCache']
 320                         : new HashBagOStuff();
 321
 322                 $this->profiler = $params['profiler'];
 323                 $this->trxProfiler = $params['trxProfiler'];
 324                 $this->connLogger = $params['connLogger'];
 325                 $this->queryLogger = $params['queryLogger'];
 326                 $this->errorLogger = $params['errorLogger'];
 327                 $this->deprecationLogger = $params['deprecationLogger'];
 328
 329                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 330                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 331                 }
 332
 333                 // Set initial dummy domain until open() sets the final DB/prefix
 334                 $this->currentDomain = DatabaseDomain::newUnspecified();
 335         }
 336
 337         /**
 338          * Initialize the connection to the database over the wire (or to local files)
 339          *
 340          * @throws LogicException
 341          * @throws InvalidArgumentException
 342          * @throws DBConnectionError
 343          * @since 1.31
 344          */
 345         final public function initConnection() {
 346                 if ( $this->isOpen() ) {
 347                         throw new LogicException( __METHOD__ . ': already connected.' );
 348                 }
 349                 // Establish the connection
 350                 $this->doInitConnection();
 351                 // Set the domain object after open() sets the relevant fields
 352                 if ( $this->dbName != '' ) {
 353                         // Domains with server scope but a table prefix are not used by IDatabase classes
 354                         $this->currentDomain = new DatabaseDomain( $this->dbName, null, $this->tablePrefix );
 355                 }
 356         }
 357
 358         /**
 359          * Actually connect to the database over the wire (or to local files)
 360          *
 361          * @throws InvalidArgumentException
 362          * @throws DBConnectionError
 363          * @since 1.31
 364          */
 365         protected function doInitConnection() {
 366                 if ( strlen( $this->connectionParams['user'] ) ) {
 367                         $this->open(
 368                                 $this->connectionParams['host'],
 369                                 $this->connectionParams['user'],
 370                                 $this->connectionParams['password'],
 371                                 $this->connectionParams['dbname']
 372                         );
 373                 } else {
 374                         throw new InvalidArgumentException( "No database user provided." );
 375                 }
 376         }
 377
 378         /**
 379          * Construct a Database subclass instance given a database type and parameters
 380          *
 381          * This also connects to the database immediately upon object construction
 382          *
 383          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 384          * @param array $p Parameter map with keys:
 385          *   - host : The hostname of the DB server
 386          *   - user : The name of the database user the client operates under
 387          *   - password : The password for the database user
 388          *   - dbname : The name of the database to use where queries do not specify one.
 389          *      The database must exist or an error might be thrown. Setting this to the empty string
 390          *      will avoid any such errors and make the handle have no implicit database scope. This is
 391          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 392          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 393          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 394          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 395          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 396          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 397          *      recognized in queries. This can be used in place of schemas for handle site farms.
 398          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 399          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 400          *      flag in place UNLESS this this database simply acts as a key/value store.
 401          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 402          *      'mysqli' driver; the old one 'mysql' has been removed.
 403          *   - variables: Optional map of session variables to set after connecting. This can be
 404          *      used to adjust lock timeouts or encoding modes and the like.
 405          *   - connLogger: Optional PSR-3 logger interface instance.
 406          *   - queryLogger: Optional PSR-3 logger interface instance.
 407          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 408          *      These will be called in query(), using a simplified version of the SQL that also
 409          *      includes the agent as a SQL comment.
 410          *   - trxProfiler: Optional TransactionProfiler instance.
 411          *   - errorLogger: Optional callback that takes an Exception and logs it.
 412          *   - deprecationLogger: Optional callback that takes a string and logs it.
 413          *   - cliMode: Whether to consider the execution context that of a CLI script.
 414          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 415          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 416          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 417          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 418          * @return Database|null If the database driver or extension cannot be found
 419          * @throws InvalidArgumentException If the database driver or extension cannot be found
 420          * @since 1.18
 421          */
 422         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 423                 $class = self::getClass( $dbType, isset( $p['driver'] ) ? $p['driver'] : null );
 424
 425                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 426                         // Resolve some defaults for b/c
 427                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 428                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 429                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 430                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 431                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 432                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 433                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 434                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 435                         $p['cliMode'] = isset( $p['cliMode'] )
 436                                 ? $p['cliMode']
 437                                 : ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 438                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 439                         if ( !isset( $p['connLogger'] ) ) {
 440                                 $p['connLogger'] = new NullLogger();
 441                         }
 442                         if ( !isset( $p['queryLogger'] ) ) {
 443                                 $p['queryLogger'] = new NullLogger();
 444                         }
 445                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 446                         if ( !isset( $p['trxProfiler'] ) ) {
 447                                 $p['trxProfiler'] = new TransactionProfiler();
 448                         }
 449                         if ( !isset( $p['errorLogger'] ) ) {
 450                                 $p['errorLogger'] = function ( Exception $e ) {
 451                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 452                                 };
 453                         }
 454                         if ( !isset( $p['deprecationLogger'] ) ) {
 455                                 $p['deprecationLogger'] = function ( $msg ) {
 456                                         trigger_error( $msg, E_USER_DEPRECATED );
 457                                 };
 458                         }
 459
 460                         /** @var Database $conn */
 461                         $conn = new $class( $p );
 462                         if ( $connect == self::NEW_CONNECTED ) {
 463                                 $conn->initConnection();
 464                         }
 465                 } else {
 466                         $conn = null;
 467                 }
 468
 469                 return $conn;
 470         }
 471
 472         /**
 473          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 474          * @param string|null $driver Optional name of a specific DB client driver
 475          * @return array Map of (Database::ATTRIBUTE_* constant => value) for all such constants
 476          * @throws InvalidArgumentException
 477          * @since 1.31
 478          */
 479         final public static function attributesFromType( $dbType, $driver = null ) {
 480                 static $defaults = [ self::ATTR_DB_LEVEL_LOCKING => false ];
 481
 482                 $class = self::getClass( $dbType, $driver );
 483
 484                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 485         }
 486
 487         /**
 488          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 489          * @param string|null $driver Optional name of a specific DB client driver
 490          * @return string Database subclass name to use
 491          * @throws InvalidArgumentException
 492          */
 493         private static function getClass( $dbType, $driver = null ) {
 494                 // For database types with built-in support, the below maps type to IDatabase
 495                 // implementations. For types with multipe driver implementations (PHP extensions),
 496                 // an array can be used, keyed by extension name. In case of an array, the
 497                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 498                 // we auto-detect the first available driver. For types without built-in support,
 499                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 500                 static $builtinTypes = [
 501                         'mssql' => DatabaseMssql::class,
 502                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 503                         'sqlite' => DatabaseSqlite::class,
 504                         'postgres' => DatabasePostgres::class,
 505                 ];
 506
 507                 $dbType = strtolower( $dbType );
 508                 $class = false;
 509
 510                 if ( isset( $builtinTypes[$dbType] ) ) {
 511                         $possibleDrivers = $builtinTypes[$dbType];
 512                         if ( is_string( $possibleDrivers ) ) {
 513                                 $class = $possibleDrivers;
 514                         } else {
 515                                 if ( (string)$driver !== '' ) {
 516                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 517                                                 throw new InvalidArgumentException( __METHOD__ .
 518                                                         " type '$dbType' does not support driver '{$driver}'" );
 519                                         } else {
 520                                                 $class = $possibleDrivers[$driver];
 521                                         }
 522                                 } else {
 523                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 524                                                 if ( extension_loaded( $posDriver ) ) {
 525                                                         $class = $possibleClass;
 526                                                         break;
 527                                                 }
 528                                         }
 529                                 }
 530                         }
 531                 } else {
 532                         $class = 'Database' . ucfirst( $dbType );
 533                 }
 534
 535                 if ( $class === false ) {
 536                         throw new InvalidArgumentException( __METHOD__ .
 537                                 " no viable database extension found for type '$dbType'" );
 538                 }
 539
 540                 return $class;
 541         }
 542
 543         /**
 544          * @return array Map of (Database::ATTRIBUTE_* constant => value
 545          * @since 1.31
 546          */
 547         protected static function getAttributes() {
 548                 return [];
 549         }
 550
 551         /**
 552          * Set the PSR-3 logger interface to use for query logging. (The logger
 553          * interfaces for connection logging and error logging can be set with the
 554          * constructor.)
 555          *
 556          * @param LoggerInterface $logger
 557          */
 558         public function setLogger( LoggerInterface $logger ) {
 559                 $this->queryLogger = $logger;
 560         }
 561
 562         public function getServerInfo() {
 563                 return $this->getServerVersion();
 564         }
 565
 566         public function bufferResults( $buffer = null ) {
 567                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 568                 if ( $buffer !== null ) {
 569                         $buffer
 570                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 571                                 : $this->setFlag( self::DBO_NOBUFFER );
 572                 }
 573
 574                 return $res;
 575         }
 576
 577         public function trxLevel() {
 578                 return $this->trxLevel;
 579         }
 580
 581         public function trxTimestamp() {
 582                 return $this->trxLevel ? $this->trxTimestamp : null;
 583         }
 584
 585         /**
 586          * @return int One of the STATUS_TRX_* class constants
 587          * @since 1.31
 588          */
 589         public function trxStatus() {
 590                 return $this->trxStatus;
 591         }
 592
 593         public function tablePrefix( $prefix = null ) {
 594                 $old = $this->tablePrefix;
 595                 if ( $prefix !== null ) {
 596                         $this->tablePrefix = $prefix;
 597                         $this->currentDomain = ( $this->dbName != '' )
 598                                 ? new DatabaseDomain( $this->dbName, null, $this->tablePrefix )
 599                                 : DatabaseDomain::newUnspecified();
 600                 }
 601
 602                 return $old;
 603         }
 604
 605         public function dbSchema( $schema = null ) {
 606                 $old = $this->schema;
 607                 if ( $schema !== null ) {
 608                         $this->schema = $schema;
 609                 }
 610
 611                 return $old;
 612         }
 613
 614         public function getLBInfo( $name = null ) {
 615                 if ( is_null( $name ) ) {
 616                         return $this->lbInfo;
 617                 } else {
 618                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 619                                 return $this->lbInfo[$name];
 620                         } else {
 621                                 return null;
 622                         }
 623                 }
 624         }
 625
 626         public function setLBInfo( $name, $value = null ) {
 627                 if ( is_null( $value ) ) {
 628                         $this->lbInfo = $name;
 629                 } else {
 630                         $this->lbInfo[$name] = $value;
 631                 }
 632         }
 633
 634         public function setLazyMasterHandle( IDatabase $conn ) {
 635                 $this->lazyMasterHandle = $conn;
 636         }
 637
 638         /**
 639          * @return IDatabase|null
 640          * @see setLazyMasterHandle()
 641          * @since 1.27
 642          */
 643         protected function getLazyMasterHandle() {
 644                 return $this->lazyMasterHandle;
 645         }
 646
 647         public function implicitGroupby() {
 648                 return true;
 649         }
 650
 651         public function implicitOrderby() {
 652                 return true;
 653         }
 654
 655         public function lastQuery() {
 656                 return $this->lastQuery;
 657         }
 658
 659         public function doneWrites() {
 660                 return (bool)$this->lastWriteTime;
 661         }
 662
 663         public function lastDoneWrites() {
 664                 return $this->lastWriteTime ?: false;
 665         }
 666
 667         public function writesPending() {
 668                 return $this->trxLevel && $this->trxDoneWrites;
 669         }
 670
 671         public function writesOrCallbacksPending() {
 672                 return $this->trxLevel && (
 673                         $this->trxDoneWrites ||
 674                         $this->trxIdleCallbacks ||
 675                         $this->trxPreCommitCallbacks ||
 676                         $this->trxEndCallbacks
 677                 );
 678         }
 679
 680         /**
 681          * @return string|null
 682          */
 683         final protected function getTransactionRoundId() {
 684                 // If transaction round participation is enabled, see if one is active
 685                 if ( $this->getFlag( self::DBO_TRX ) ) {
 686                         $id = $this->getLBInfo( 'trxRoundId' );
 687
 688                         return is_string( $id ) ? $id : null;
 689                 }
 690
 691                 return null;
 692         }
 693
 694         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 695                 if ( !$this->trxLevel ) {
 696                         return false;
 697                 } elseif ( !$this->trxDoneWrites ) {
 698                         return 0.0;
 699                 }
 700
 701                 switch ( $type ) {
 702                         case self::ESTIMATE_DB_APPLY:
 703                                 $this->ping( $rtt );
 704                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 705                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 706                                 // For omitted queries, make them count as something at least
 707                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 708                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 709
 710                                 return $applyTime;
 711                         default: // everything
 712                                 return $this->trxWriteDuration;
 713                 }
 714         }
 715
 716         public function pendingWriteCallers() {
 717                 return $this->trxLevel ? $this->trxWriteCallers : [];
 718         }
 719
 720         public function pendingWriteRowsAffected() {
 721                 return $this->trxWriteAffectedRows;
 722         }
 723
 724         /**
 725          * List the methods that have write queries or callbacks for the current transaction
 726          *
 727          * This method should not be used outside of Database/LoadBalancer
 728          *
 729          * @return string[]
 730          * @since 1.32
 731          */
 732         public function pendingWriteAndCallbackCallers() {
 733                 $fnames = $this->pendingWriteCallers();
 734                 foreach ( [
 735                         $this->trxIdleCallbacks,
 736                         $this->trxPreCommitCallbacks,
 737                         $this->trxEndCallbacks
 738                 ] as $callbacks ) {
 739                         foreach ( $callbacks as $callback ) {
 740                                 $fnames[] = $callback[1];
 741                         }
 742                 }
 743
 744                 return $fnames;
 745         }
 746
 747         /**
 748          * @return string
 749          */
 750         private function flatAtomicSectionList() {
 751                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 752                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 753                 } );
 754         }
 755
 756         public function isOpen() {
 757                 return $this->opened;
 758         }
 759
 760         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 761                 if ( ( $flag & self::DBO_IGNORE ) ) {
 762                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 763                 }
 764
 765                 if ( $remember === self::REMEMBER_PRIOR ) {
 766                         array_push( $this->priorFlags, $this->flags );
 767                 }
 768                 $this->flags |= $flag;
 769         }
 770
 771         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 772                 if ( ( $flag & self::DBO_IGNORE ) ) {
 773                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 774                 }
 775
 776                 if ( $remember === self::REMEMBER_PRIOR ) {
 777                         array_push( $this->priorFlags, $this->flags );
 778                 }
 779                 $this->flags &= ~$flag;
 780         }
 781
 782         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 783                 if ( !$this->priorFlags ) {
 784                         return;
 785                 }
 786
 787                 if ( $state === self::RESTORE_INITIAL ) {
 788                         $this->flags = reset( $this->priorFlags );
 789                         $this->priorFlags = [];
 790                 } else {
 791                         $this->flags = array_pop( $this->priorFlags );
 792                 }
 793         }
 794
 795         public function getFlag( $flag ) {
 796                 return !!( $this->flags & $flag );
 797         }
 798
 799         /**
 800          * @param string $name Class field name
 801          * @return mixed
 802          * @deprecated Since 1.28
 803          */
 804         public function getProperty( $name ) {
 805                 return $this->$name;
 806         }
 807
 808         public function getDomainID() {
 809                 return $this->currentDomain->getId();
 810         }
 811
 812         final public function getWikiID() {
 813                 return $this->getDomainID();
 814         }
 815
 816         /**
 817          * Get information about an index into an object
 818          * @param string $table Table name
 819          * @param string $index Index name
 820          * @param string $fname Calling function name
 821          * @return mixed Database-specific index description class or false if the index does not exist
 822          */
 823         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 824
 825         /**
 826          * Wrapper for addslashes()
 827          *
 828          * @param string $s String to be slashed.
 829          * @return string Slashed string.
 830          */
 831         abstract function strencode( $s );
 832
 833         /**
 834          * Set a custom error handler for logging errors during database connection
 835          */
 836         protected function installErrorHandler() {
 837                 $this->phpError = false;
 838                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 839                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 840         }
 841
 842         /**
 843          * Restore the previous error handler and return the last PHP error for this DB
 844          *
 845          * @return bool|string
 846          */
 847         protected function restoreErrorHandler() {
 848                 restore_error_handler();
 849                 if ( $this->htmlErrors !== false ) {
 850                         ini_set( 'html_errors', $this->htmlErrors );
 851                 }
 852
 853                 return $this->getLastPHPError();
 854         }
 855
 856         /**
 857          * @return string|bool Last PHP error for this DB (typically connection errors)
 858          */
 859         protected function getLastPHPError() {
 860                 if ( $this->phpError ) {
 861                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 862                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 863
 864                         return $error;
 865                 }
 866
 867                 return false;
 868         }
 869
 870         /**
 871          * Error handler for logging errors during database connection
 872          * This method should not be used outside of Database classes
 873          *
 874          * @param int $errno
 875          * @param string $errstr
 876          */
 877         public function connectionErrorLogger( $errno, $errstr ) {
 878                 $this->phpError = $errstr;
 879         }
 880
 881         /**
 882          * Create a log context to pass to PSR-3 logger functions.
 883          *
 884          * @param array $extras Additional data to add to context
 885          * @return array
 886          */
 887         protected function getLogContext( array $extras = [] ) {
 888                 return array_merge(
 889                         [
 890                                 'db_server' => $this->server,
 891                                 'db_name' => $this->dbName,
 892                                 'db_user' => $this->user,
 893                         ],
 894                         $extras
 895                 );
 896         }
 897
 898         final public function close() {
 899                 $exception = null; // error to throw after disconnecting
 900
 901                 if ( $this->conn ) {
 902                         // Resolve any dangling transaction first
 903                         if ( $this->trxLevel ) {
 904                                 if ( $this->trxAtomicLevels ) {
 905                                         // Cannot let incomplete atomic sections be committed
 906                                         $levels = $this->flatAtomicSectionList();
 907                                         $exception = new DBUnexpectedError(
 908                                                 $this,
 909                                                 __METHOD__ . ": atomic sections $levels are still open."
 910                                         );
 911                                 } elseif ( $this->trxAutomatic ) {
 912                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 913                                         if ( $this->writesOrCallbacksPending() ) {
 914                                                 $exception = new DBUnexpectedError(
 915                                                         $this,
 916                                                         __METHOD__ .
 917                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 918                                                 );
 919                                         }
 920                                 } elseif ( $this->trxLevel ) {
 921                                         // Commit explicit transactions as if this was commit()
 922                                         $this->queryLogger->warning(
 923                                                 __METHOD__ . ": writes or callbacks still pending.",
 924                                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 925                                         );
 926                                 }
 927
 928                                 if ( $this->trxEndCallbacksSuppressed ) {
 929                                         $exception = $exception ?: new DBUnexpectedError(
 930                                                 $this,
 931                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 932                                         );
 933                                 }
 934
 935                                 // Commit or rollback the changes and run any callbacks as needed
 936                                 if ( $this->trxStatus === self::STATUS_TRX_OK && !$exception ) {
 937                                         $this->commit(
 938                                                 __METHOD__,
 939                                                 $this->trxAutomatic ? self::FLUSHING_INTERNAL : self::FLUSHING_ONE
 940                                         );
 941                                 } else {
 942                                         $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 943                                 }
 944                         }
 945
 946                         // Close the actual connection in the binding handle
 947                         $closed = $this->closeConnection();
 948                         $this->conn = false;
 949                 } else {
 950                         $closed = true; // already closed; nothing to do
 951                 }
 952
 953                 $this->opened = false;
 954
 955                 // Throw any unexpected errors after having disconnected
 956                 if ( $exception instanceof Exception ) {
 957                         throw $exception;
 958                 }
 959
 960                 // Sanity check that no callbacks are dangling
 961                 $fnames = $this->pendingWriteAndCallbackCallers();
 962                 if ( $fnames ) {
 963                         throw new RuntimeException(
 964                                 "Transaction callbacks are still pending:\n" . implode( ', ', $fnames )
 965                         );
 966                 }
 967
 968                 return $closed;
 969         }
 970
 971         /**
 972          * Make sure isOpen() returns true as a sanity check
 973          *
 974          * @throws DBUnexpectedError
 975          */
 976         protected function assertOpen() {
 977                 if ( !$this->isOpen() ) {
 978                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 979                 }
 980         }
 981
 982         /**
 983          * Closes underlying database connection
 984          * @since 1.20
 985          * @return bool Whether connection was closed successfully
 986          */
 987         abstract protected function closeConnection();
 988
 989         /**
 990          * @deprecated since 1.32
 991          * @param string $error Fallback message, if none is given by DB
 992          * @throws DBConnectionError
 993          */
 994         public function reportConnectionError( $error = 'Unknown error' ) {
 995                 call_user_func( $this->deprecationLogger, 'Use of ' . __METHOD__ . ' is deprecated.' );
 996                 throw new DBConnectionError( $this, $this->lastError() ?: $error );
 997         }
 998
 999         /**
1000          * Run a query and return a DBMS-dependent wrapper (that has all IResultWrapper methods)
1001          *
1002          * This might return things, such as mysqli_result, that do not formally implement
1003          * IResultWrapper, but nonetheless implement all of its methods correctly
1004          *
1005          * @param string $sql SQL query.
1006          * @return IResultWrapper|bool Iterator to feed to fetchObject/fetchRow; false on failure
1007          */
1008         abstract protected function doQuery( $sql );
1009
1010         /**
1011          * Determine whether a query writes to the DB.
1012          * Should return true if unsure.
1013          *
1014          * @param string $sql
1015          * @return bool
1016          */
1017         protected function isWriteQuery( $sql ) {
1018                 return !preg_match(
1019                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
1020         }
1021
1022         /**
1023          * @param string $sql
1024          * @return string|null
1025          */
1026         protected function getQueryVerb( $sql ) {
1027                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1028         }
1029
1030         /**
1031          * Determine whether a SQL statement is sensitive to isolation level.
1032          * A SQL statement is considered transactable if its result could vary
1033          * depending on the transaction isolation level. Operational commands
1034          * such as 'SET' and 'SHOW' are not considered to be transactable.
1035          *
1036          * @param string $sql
1037          * @return bool
1038          */
1039         protected function isTransactableQuery( $sql ) {
1040                 return !in_array(
1041                         $this->getQueryVerb( $sql ),
1042                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
1043                         true
1044                 );
1045         }
1046
1047         /**
1048          * @param string $sql A SQL query
1049          * @return bool Whether $sql is SQL for TEMPORARY table operation
1050          */
1051         protected function registerTempTableOperation( $sql ) {
1052                 if ( preg_match(
1053                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1054                         $sql,
1055                         $matches
1056                 ) ) {
1057                         $this->sessionTempTables[$matches[1]] = 1;
1058
1059                         return true;
1060                 } elseif ( preg_match(
1061                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1062                         $sql,
1063                         $matches
1064                 ) ) {
1065                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
1066                         unset( $this->sessionTempTables[$matches[1]] );
1067
1068                         return $isTemp;
1069                 } elseif ( preg_match(
1070                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1071                         $sql,
1072                         $matches
1073                 ) ) {
1074                         return isset( $this->sessionTempTables[$matches[1]] );
1075                 } elseif ( preg_match(
1076                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
1077                         $sql,
1078                         $matches
1079                 ) ) {
1080                         return isset( $this->sessionTempTables[$matches[1]] );
1081                 }
1082
1083                 return false;
1084         }
1085
1086         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1087                 $this->assertTransactionStatus( $sql, $fname );
1088
1089                 # Avoid fatals if close() was called
1090                 $this->assertOpen();
1091
1092                 $priorWritesPending = $this->writesOrCallbacksPending();
1093                 $this->lastQuery = $sql;
1094
1095                 $isWrite = $this->isWriteQuery( $sql );
1096                 if ( $isWrite ) {
1097                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
1098                 } else {
1099                         $isNonTempWrite = false;
1100                 }
1101
1102                 if ( $isWrite ) {
1103                         if ( $this->getLBInfo( 'replica' ) === true ) {
1104                                 throw new DBError(
1105                                         $this,
1106                                         'Write operations are not allowed on replica database connections.'
1107                                 );
1108                         }
1109                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1110                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1111                         $reason = $this->getReadOnlyReason();
1112                         if ( $reason !== false ) {
1113                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1114                         }
1115                         # Set a flag indicating that writes have been done
1116                         $this->lastWriteTime = microtime( true );
1117                 }
1118
1119                 # Add trace comment to the begin of the sql string, right after the operator.
1120                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1121                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1122
1123                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
1124                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
1125                         && $this->isTransactableQuery( $sql )
1126                 ) {
1127                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1128                         $this->trxAutomatic = true;
1129                 }
1130
1131                 # Keep track of whether the transaction has write queries pending
1132                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
1133                         $this->trxDoneWrites = true;
1134                         $this->trxProfiler->transactionWritingIn(
1135                                 $this->server, $this->dbName, $this->trxShortId );
1136                 }
1137
1138                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1139                         $this->queryLogger->debug( "{$this->dbName} {$commentedSql}" );
1140                 }
1141
1142                 # Send the query to the server and fetch any corresponding errors
1143                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1144                 $lastError = $this->lastError();
1145                 $lastErrno = $this->lastErrno();
1146
1147                 # Try reconnecting if the connection was lost
1148                 if ( $ret === false && $this->wasConnectionLoss() ) {
1149                         # Check if any meaningful session state was lost
1150                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1151                         # Update session state tracking and try to restore the connection
1152                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1153                         # Silently resend the query to the server if it is safe and possible
1154                         if ( $reconnected && $recoverable ) {
1155                                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1156                                 $lastError = $this->lastError();
1157                                 $lastErrno = $this->lastErrno();
1158
1159                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1160                                         # Query probably causes disconnects; reconnect and do not re-run it
1161                                         $this->replaceLostConnection( __METHOD__ );
1162                                 }
1163                         }
1164                 }
1165
1166                 if ( $ret === false ) {
1167                         if ( $this->trxLevel ) {
1168                                 if ( !$this->wasKnownStatementRollbackError() ) {
1169                                         # Either the query was aborted or all queries after BEGIN where aborted.
1170                                         if ( $this->explicitTrxActive() || $priorWritesPending ) {
1171                                                 # In the first case, the only options going forward are (a) ROLLBACK, or
1172                                                 # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1173                                                 # option is ROLLBACK, since the snapshots would have been released.
1174                                                 $this->trxStatus = self::STATUS_TRX_ERROR;
1175                                                 $this->trxStatusCause =
1176                                                         $this->makeQueryException( $lastError, $lastErrno, $sql, $fname );
1177                                                 $tempIgnore = false; // cannot recover
1178                                         } else {
1179                                                 # Nothing prior was there to lose from the transaction,
1180                                                 # so just roll it back.
1181                                                 $this->rollback( __METHOD__ . " ($fname)", self::FLUSHING_INTERNAL );
1182                                         }
1183                                         $this->trxStatusIgnoredCause = null;
1184                                 } else {
1185                                         # We're ignoring an error that caused just the current query to be aborted.
1186                                         # But log the cause so we can log a deprecation notice if a
1187                                         # caller actually does ignore it.
1188                                         $this->trxStatusIgnoredCause = [ $lastError, $lastErrno, $fname ];
1189                                 }
1190                         }
1191
1192                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1193                 }
1194
1195                 return $this->resultObject( $ret );
1196         }
1197
1198         /**
1199          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1200          *
1201          * @param string $sql Original SQL query
1202          * @param string $commentedSql SQL query with debugging/trace comment
1203          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1204          * @param string $fname Name of the calling function
1205          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1206          *     object for a successful read query, or false on failure
1207          */
1208         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1209                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1210                 # generalizeSQL() will probably cut down the query to reasonable
1211                 # logging size most of the time. The substr is really just a sanity check.
1212                 if ( $isMaster ) {
1213                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1214                 } else {
1215                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1216                 }
1217
1218                 # Include query transaction state
1219                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1220
1221                 $startTime = microtime( true );
1222                 if ( $this->profiler ) {
1223                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1224                 }
1225                 $this->affectedRowCount = null;
1226                 $ret = $this->doQuery( $commentedSql );
1227                 $this->affectedRowCount = $this->affectedRows();
1228                 if ( $this->profiler ) {
1229                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1230                 }
1231                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1232
1233                 unset( $queryProfSection ); // profile out (if set)
1234
1235                 if ( $ret !== false ) {
1236                         $this->lastPing = $startTime;
1237                         if ( $isWrite && $this->trxLevel ) {
1238                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1239                                 $this->trxWriteCallers[] = $fname;
1240                         }
1241                 }
1242
1243                 if ( $sql === self::PING_QUERY ) {
1244                         $this->rttEstimate = $queryRuntime;
1245                 }
1246
1247                 $this->trxProfiler->recordQueryCompletion(
1248                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1249                 );
1250                 $this->queryLogger->debug( $sql, [
1251                         'method' => $fname,
1252                         'master' => $isMaster,
1253                         'runtime' => $queryRuntime,
1254                 ] );
1255
1256                 return $ret;
1257         }
1258
1259         /**
1260          * Update the estimated run-time of a query, not counting large row lock times
1261          *
1262          * LoadBalancer can be set to rollback transactions that will create huge replication
1263          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1264          * queries, like inserting a row can take a long time due to row locking. This method
1265          * uses some simple heuristics to discount those cases.
1266          *
1267          * @param string $sql A SQL write query
1268          * @param float $runtime Total runtime, including RTT
1269          * @param int $affected Affected row count
1270          */
1271         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1272                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1273                 $indicativeOfReplicaRuntime = true;
1274                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1275                         $verb = $this->getQueryVerb( $sql );
1276                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1277                         if ( $verb === 'INSERT' ) {
1278                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1279                         } elseif ( $verb === 'REPLACE' ) {
1280                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1281                         }
1282                 }
1283
1284                 $this->trxWriteDuration += $runtime;
1285                 $this->trxWriteQueryCount += 1;
1286                 $this->trxWriteAffectedRows += $affected;
1287                 if ( $indicativeOfReplicaRuntime ) {
1288                         $this->trxWriteAdjDuration += $runtime;
1289                         $this->trxWriteAdjQueryCount += 1;
1290                 }
1291         }
1292
1293         /**
1294          * @param string $sql
1295          * @param string $fname
1296          * @throws DBTransactionStateError
1297          */
1298         private function assertTransactionStatus( $sql, $fname ) {
1299                 if ( $this->getQueryVerb( $sql ) === 'ROLLBACK' ) { // transaction/savepoint
1300                         return;
1301                 }
1302
1303                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1304                         throw new DBTransactionStateError(
1305                                 $this,
1306                                 "Cannot execute query from $fname while transaction status is ERROR.",
1307                                 [],
1308                                 $this->trxStatusCause
1309                         );
1310                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1311                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1312                         call_user_func( $this->deprecationLogger,
1313                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1314                                 "[$iLastErrno] $iLastError"
1315                         );
1316                         $this->trxStatusIgnoredCause = null;
1317                 }
1318         }
1319
1320         /**
1321          * Determine whether or not it is safe to retry queries after a database
1322          * connection is lost
1323          *
1324          * @param string $sql SQL query
1325          * @param bool $priorWritesPending Whether there is a transaction open with
1326          *     possible write queries or transaction pre-commit/idle callbacks
1327          *     waiting on it to finish.
1328          * @return bool True if it is safe to retry the query, false otherwise
1329          */
1330         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1331                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1332                 # Dropped connections also mean that named locks are automatically released.
1333                 # Only allow error suppression in autocommit mode or when the lost transaction
1334                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1335                 if ( $this->namedLocksHeld ) {
1336                         return false; // possible critical section violation
1337                 } elseif ( $this->sessionTempTables ) {
1338                         return false; // tables might be queried latter
1339                 } elseif ( $sql === 'COMMIT' ) {
1340                         return !$priorWritesPending; // nothing written anyway? (T127428)
1341                 } elseif ( $sql === 'ROLLBACK' ) {
1342                         return true; // transaction lost...which is also what was requested :)
1343                 } elseif ( $this->explicitTrxActive() ) {
1344                         return false; // don't drop atomocity and explicit snapshots
1345                 } elseif ( $priorWritesPending ) {
1346                         return false; // prior writes lost from implicit transaction
1347                 }
1348
1349                 return true;
1350         }
1351
1352         /**
1353          * Clean things up after session (and thus transaction) loss
1354          */
1355         private function handleSessionLoss() {
1356                 // Clean up tracking of session-level things...
1357                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1358                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1359                 $this->sessionTempTables = [];
1360                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1361                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1362                 $this->namedLocksHeld = [];
1363                 // Session loss implies transaction loss
1364                 $this->handleTransactionLoss();
1365         }
1366
1367         /**
1368          * Clean things up after transaction loss
1369          */
1370         private function handleTransactionLoss() {
1371                 $this->trxLevel = 0;
1372                 $this->trxAtomicCounter = 0;
1373                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1374                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1375                 try {
1376                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1377                         // If callback suppression is set then the array will remain unhandled.
1378                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1379                 } catch ( Exception $ex ) {
1380                         // Already logged; move on...
1381                 }
1382                 try {
1383                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1384                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1385                 } catch ( Exception $ex ) {
1386                         // Already logged; move on...
1387                 }
1388         }
1389
1390         /**
1391          * Checks whether the cause of the error is detected to be a timeout.
1392          *
1393          * It returns false by default, and not all engines support detecting this yet.
1394          * If this returns false, it will be treated as a generic query error.
1395          *
1396          * @param string $error Error text
1397          * @param int $errno Error number
1398          * @return bool
1399          */
1400         protected function wasQueryTimeout( $error, $errno ) {
1401                 return false;
1402         }
1403
1404         /**
1405          * Report a query error. Log the error, and if neither the object ignore
1406          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1407          *
1408          * @param string $error
1409          * @param int $errno
1410          * @param string $sql
1411          * @param string $fname
1412          * @param bool $tempIgnore
1413          * @throws DBQueryError
1414          */
1415         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1416                 if ( $tempIgnore ) {
1417                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1418                 } else {
1419                         $exception = $this->makeQueryException( $error, $errno, $sql, $fname );
1420
1421                         throw $exception;
1422                 }
1423         }
1424
1425         /**
1426          * @param string $error
1427          * @param string|int $errno
1428          * @param string $sql
1429          * @param string $fname
1430          * @return DBError
1431          */
1432         private function makeQueryException( $error, $errno, $sql, $fname ) {
1433                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1434                 $this->queryLogger->error(
1435                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1436                         $this->getLogContext( [
1437                                 'method' => __METHOD__,
1438                                 'errno' => $errno,
1439                                 'error' => $error,
1440                                 'sql1line' => $sql1line,
1441                                 'fname' => $fname,
1442                         ] )
1443                 );
1444                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1445                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1446                 if ( $wasQueryTimeout ) {
1447                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1448                 } else {
1449                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1450                 }
1451
1452                 return $e;
1453         }
1454
1455         public function freeResult( $res ) {
1456         }
1457
1458         public function selectField(
1459                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1460         ) {
1461                 if ( $var === '*' ) { // sanity
1462                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1463                 }
1464
1465                 if ( !is_array( $options ) ) {
1466                         $options = [ $options ];
1467                 }
1468
1469                 $options['LIMIT'] = 1;
1470
1471                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1472                 if ( $res === false || !$this->numRows( $res ) ) {
1473                         return false;
1474                 }
1475
1476                 $row = $this->fetchRow( $res );
1477
1478                 if ( $row !== false ) {
1479                         return reset( $row );
1480                 } else {
1481                         return false;
1482                 }
1483         }
1484
1485         public function selectFieldValues(
1486                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1487         ) {
1488                 if ( $var === '*' ) { // sanity
1489                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1490                 } elseif ( !is_string( $var ) ) { // sanity
1491                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1492                 }
1493
1494                 if ( !is_array( $options ) ) {
1495                         $options = [ $options ];
1496                 }
1497
1498                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1499                 if ( $res === false ) {
1500                         return false;
1501                 }
1502
1503                 $values = [];
1504                 foreach ( $res as $row ) {
1505                         $values[] = $row->$var;
1506                 }
1507
1508                 return $values;
1509         }
1510
1511         /**
1512          * Returns an optional USE INDEX clause to go after the table, and a
1513          * string to go at the end of the query.
1514          *
1515          * @param array $options Associative array of options to be turned into
1516          *   an SQL query, valid keys are listed in the function.
1517          * @return array
1518          * @see Database::select()
1519          */
1520         protected function makeSelectOptions( $options ) {
1521                 $preLimitTail = $postLimitTail = '';
1522                 $startOpts = '';
1523
1524                 $noKeyOptions = [];
1525
1526                 foreach ( $options as $key => $option ) {
1527                         if ( is_numeric( $key ) ) {
1528                                 $noKeyOptions[$option] = true;
1529                         }
1530                 }
1531
1532                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1533
1534                 $preLimitTail .= $this->makeOrderBy( $options );
1535
1536                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1537                         $postLimitTail .= ' FOR UPDATE';
1538                 }
1539
1540                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1541                         $postLimitTail .= ' LOCK IN SHARE MODE';
1542                 }
1543
1544                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1545                         $startOpts .= 'DISTINCT';
1546                 }
1547
1548                 # Various MySQL extensions
1549                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1550                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1551                 }
1552
1553                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1554                         $startOpts .= ' HIGH_PRIORITY';
1555                 }
1556
1557                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1558                         $startOpts .= ' SQL_BIG_RESULT';
1559                 }
1560
1561                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1562                         $startOpts .= ' SQL_BUFFER_RESULT';
1563                 }
1564
1565                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1566                         $startOpts .= ' SQL_SMALL_RESULT';
1567                 }
1568
1569                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1570                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1571                 }
1572
1573                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1574                         $startOpts .= ' SQL_CACHE';
1575                 }
1576
1577                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1578                         $startOpts .= ' SQL_NO_CACHE';
1579                 }
1580
1581                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1582                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1583                 } else {
1584                         $useIndex = '';
1585                 }
1586                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1587                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1588                 } else {
1589                         $ignoreIndex = '';
1590                 }
1591
1592                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1593         }
1594
1595         /**
1596          * Returns an optional GROUP BY with an optional HAVING
1597          *
1598          * @param array $options Associative array of options
1599          * @return string
1600          * @see Database::select()
1601          * @since 1.21
1602          */
1603         protected function makeGroupByWithHaving( $options ) {
1604                 $sql = '';
1605                 if ( isset( $options['GROUP BY'] ) ) {
1606                         $gb = is_array( $options['GROUP BY'] )
1607                                 ? implode( ',', $options['GROUP BY'] )
1608                                 : $options['GROUP BY'];
1609                         $sql .= ' GROUP BY ' . $gb;
1610                 }
1611                 if ( isset( $options['HAVING'] ) ) {
1612                         $having = is_array( $options['HAVING'] )
1613                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1614                                 : $options['HAVING'];
1615                         $sql .= ' HAVING ' . $having;
1616                 }
1617
1618                 return $sql;
1619         }
1620
1621         /**
1622          * Returns an optional ORDER BY
1623          *
1624          * @param array $options Associative array of options
1625          * @return string
1626          * @see Database::select()
1627          * @since 1.21
1628          */
1629         protected function makeOrderBy( $options ) {
1630                 if ( isset( $options['ORDER BY'] ) ) {
1631                         $ob = is_array( $options['ORDER BY'] )
1632                                 ? implode( ',', $options['ORDER BY'] )
1633                                 : $options['ORDER BY'];
1634
1635                         return ' ORDER BY ' . $ob;
1636                 }
1637
1638                 return '';
1639         }
1640
1641         public function select(
1642                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1643         ) {
1644                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1645
1646                 return $this->query( $sql, $fname );
1647         }
1648
1649         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1650                 $options = [], $join_conds = []
1651         ) {
1652                 if ( is_array( $vars ) ) {
1653                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1654                 } else {
1655                         $fields = $vars;
1656                 }
1657
1658                 $options = (array)$options;
1659                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1660                         ? $options['USE INDEX']
1661                         : [];
1662                 $ignoreIndexes = (
1663                         isset( $options['IGNORE INDEX'] ) &&
1664                         is_array( $options['IGNORE INDEX'] )
1665                 )
1666                         ? $options['IGNORE INDEX']
1667                         : [];
1668
1669                 if (
1670                         $this->selectOptionsIncludeLocking( $options ) &&
1671                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1672                 ) {
1673                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1674                         // functions. Discourage use of such queries to encourage compatibility.
1675                         call_user_func(
1676                                 $this->deprecationLogger,
1677                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1678                         );
1679                 }
1680
1681                 if ( is_array( $table ) ) {
1682                         $from = ' FROM ' .
1683                                 $this->tableNamesWithIndexClauseOrJOIN(
1684                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1685                 } elseif ( $table != '' ) {
1686                         $from = ' FROM ' .
1687                                 $this->tableNamesWithIndexClauseOrJOIN(
1688                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1689                 } else {
1690                         $from = '';
1691                 }
1692
1693                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1694                         $this->makeSelectOptions( $options );
1695
1696                 if ( is_array( $conds ) ) {
1697                         $conds = $this->makeList( $conds, self::LIST_AND );
1698                 }
1699
1700                 if ( $conds === null || $conds === false ) {
1701                         $this->queryLogger->warning(
1702                                 __METHOD__
1703                                 . ' called from '
1704                                 . $fname
1705                                 . ' with incorrect parameters: $conds must be a string or an array'
1706                         );
1707                         $conds = '';
1708                 }
1709
1710                 if ( $conds === '' ) {
1711                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1712                 } elseif ( is_string( $conds ) ) {
1713                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1714                                 "WHERE $conds $preLimitTail";
1715                 } else {
1716                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1717                 }
1718
1719                 if ( isset( $options['LIMIT'] ) ) {
1720                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1721                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1722                 }
1723                 $sql = "$sql $postLimitTail";
1724
1725                 if ( isset( $options['EXPLAIN'] ) ) {
1726                         $sql = 'EXPLAIN ' . $sql;
1727                 }
1728
1729                 return $sql;
1730         }
1731
1732         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1733                 $options = [], $join_conds = []
1734         ) {
1735                 $options = (array)$options;
1736                 $options['LIMIT'] = 1;
1737                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1738
1739                 if ( $res === false ) {
1740                         return false;
1741                 }
1742
1743                 if ( !$this->numRows( $res ) ) {
1744                         return false;
1745                 }
1746
1747                 $obj = $this->fetchObject( $res );
1748
1749                 return $obj;
1750         }
1751
1752         public function estimateRowCount(
1753                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1754         ) {
1755                 $conds = $this->normalizeConditions( $conds, $fname );
1756                 $column = $this->extractSingleFieldFromList( $var );
1757                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1758                         $conds[] = "$column IS NOT NULL";
1759                 }
1760
1761                 $res = $this->select(
1762                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1763                 );
1764                 $row = $res ? $this->fetchRow( $res ) : [];
1765
1766                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1767         }
1768
1769         public function selectRowCount(
1770                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1771         ) {
1772                 $conds = $this->normalizeConditions( $conds, $fname );
1773                 $column = $this->extractSingleFieldFromList( $var );
1774                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1775                         $conds[] = "$column IS NOT NULL";
1776                 }
1777
1778                 $res = $this->select(
1779                         [
1780                                 'tmp_count' => $this->buildSelectSubquery(
1781                                         $tables,
1782                                         '1',
1783                                         $conds,
1784                                         $fname,
1785                                         $options,
1786                                         $join_conds
1787                                 )
1788                         ],
1789                         [ 'rowcount' => 'COUNT(*)' ],
1790                         [],
1791                         $fname
1792                 );
1793                 $row = $res ? $this->fetchRow( $res ) : [];
1794
1795                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1796         }
1797
1798         /**
1799          * @param string|array $options
1800          * @return bool
1801          */
1802         private function selectOptionsIncludeLocking( $options ) {
1803                 $options = (array)$options;
1804                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1805                         if ( in_array( $lock, $options, true ) ) {
1806                                 return true;
1807                         }
1808                 }
1809
1810                 return false;
1811         }
1812
1813         /**
1814          * @param array|string $fields
1815          * @param array|string $options
1816          * @return bool
1817          */
1818         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1819                 foreach ( (array)$options as $key => $value ) {
1820                         if ( is_string( $key ) ) {
1821                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1822                                         return true;
1823                                 }
1824                         } elseif ( is_string( $value ) ) {
1825                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1826                                         return true;
1827                                 }
1828                         }
1829                 }
1830
1831                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1832                 foreach ( (array)$fields as $field ) {
1833                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1834                                 return true;
1835                         }
1836                 }
1837
1838                 return false;
1839         }
1840
1841         /**
1842          * @param array|string $conds
1843          * @param string $fname
1844          * @return array
1845          */
1846         final protected function normalizeConditions( $conds, $fname ) {
1847                 if ( $conds === null || $conds === false ) {
1848                         $this->queryLogger->warning(
1849                                 __METHOD__
1850                                 . ' called from '
1851                                 . $fname
1852                                 . ' with incorrect parameters: $conds must be a string or an array'
1853                         );
1854                         $conds = '';
1855                 }
1856
1857                 if ( !is_array( $conds ) ) {
1858                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1859                 }
1860
1861                 return $conds;
1862         }
1863
1864         /**
1865          * @param array|string $var Field parameter in the style of select()
1866          * @return string|null Column name or null; ignores aliases
1867          * @throws DBUnexpectedError Errors out if multiple columns are given
1868          */
1869         final protected function extractSingleFieldFromList( $var ) {
1870                 if ( is_array( $var ) ) {
1871                         if ( !$var ) {
1872                                 $column = null;
1873                         } elseif ( count( $var ) == 1 ) {
1874                                 $column = isset( $var[0] ) ? $var[0] : reset( $var );
1875                         } else {
1876                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1877                         }
1878                 } else {
1879                         $column = $var;
1880                 }
1881
1882                 return $column;
1883         }
1884
1885         /**
1886          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1887          * It's only slightly flawed. Don't use for anything important.
1888          *
1889          * @param string $sql A SQL Query
1890          *
1891          * @return string
1892          */
1893         protected static function generalizeSQL( $sql ) {
1894                 # This does the same as the regexp below would do, but in such a way
1895                 # as to avoid crashing php on some large strings.
1896                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1897
1898                 $sql = str_replace( "\\\\", '', $sql );
1899                 $sql = str_replace( "\\'", '', $sql );
1900                 $sql = str_replace( "\\\"", '', $sql );
1901                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1902                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1903
1904                 # All newlines, tabs, etc replaced by single space
1905                 $sql = preg_replace( '/\s+/', ' ', $sql );
1906
1907                 # All numbers => N,
1908                 # except the ones surrounded by characters, e.g. l10n
1909                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1910                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1911
1912                 return $sql;
1913         }
1914
1915         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1916                 $info = $this->fieldInfo( $table, $field );
1917
1918                 return (bool)$info;
1919         }
1920
1921         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1922                 if ( !$this->tableExists( $table ) ) {
1923                         return null;
1924                 }
1925
1926                 $info = $this->indexInfo( $table, $index, $fname );
1927                 if ( is_null( $info ) ) {
1928                         return null;
1929                 } else {
1930                         return $info !== false;
1931                 }
1932         }
1933
1934         public function tableExists( $table, $fname = __METHOD__ ) {
1935                 $tableRaw = $this->tableName( $table, 'raw' );
1936                 if ( isset( $this->sessionTempTables[$tableRaw] ) ) {
1937                         return true; // already known to exist
1938                 }
1939
1940                 $table = $this->tableName( $table );
1941                 $ignoreErrors = true;
1942                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1943
1944                 return (bool)$res;
1945         }
1946
1947         public function indexUnique( $table, $index ) {
1948                 $indexInfo = $this->indexInfo( $table, $index );
1949
1950                 if ( !$indexInfo ) {
1951                         return null;
1952                 }
1953
1954                 return !$indexInfo[0]->Non_unique;
1955         }
1956
1957         /**
1958          * Helper for Database::insert().
1959          *
1960          * @param array $options
1961          * @return string
1962          */
1963         protected function makeInsertOptions( $options ) {
1964                 return implode( ' ', $options );
1965         }
1966
1967         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1968                 # No rows to insert, easy just return now
1969                 if ( !count( $a ) ) {
1970                         return true;
1971                 }
1972
1973                 $table = $this->tableName( $table );
1974
1975                 if ( !is_array( $options ) ) {
1976                         $options = [ $options ];
1977                 }
1978
1979                 $fh = null;
1980                 if ( isset( $options['fileHandle'] ) ) {
1981                         $fh = $options['fileHandle'];
1982                 }
1983                 $options = $this->makeInsertOptions( $options );
1984
1985                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1986                         $multi = true;
1987                         $keys = array_keys( $a[0] );
1988                 } else {
1989                         $multi = false;
1990                         $keys = array_keys( $a );
1991                 }
1992
1993                 $sql = 'INSERT ' . $options .
1994                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1995
1996                 if ( $multi ) {
1997                         $first = true;
1998                         foreach ( $a as $row ) {
1999                                 if ( $first ) {
2000                                         $first = false;
2001                                 } else {
2002                                         $sql .= ',';
2003                                 }
2004                                 $sql .= '(' . $this->makeList( $row ) . ')';
2005                         }
2006                 } else {
2007                         $sql .= '(' . $this->makeList( $a ) . ')';
2008                 }
2009
2010                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
2011                         return false;
2012                 } elseif ( $fh !== null ) {
2013                         return true;
2014                 }
2015
2016                 return (bool)$this->query( $sql, $fname );
2017         }
2018
2019         /**
2020          * Make UPDATE options array for Database::makeUpdateOptions
2021          *
2022          * @param array $options
2023          * @return array
2024          */
2025         protected function makeUpdateOptionsArray( $options ) {
2026                 if ( !is_array( $options ) ) {
2027                         $options = [ $options ];
2028                 }
2029
2030                 $opts = [];
2031
2032                 if ( in_array( 'IGNORE', $options ) ) {
2033                         $opts[] = 'IGNORE';
2034                 }
2035
2036                 return $opts;
2037         }
2038
2039         /**
2040          * Make UPDATE options for the Database::update function
2041          *
2042          * @param array $options The options passed to Database::update
2043          * @return string
2044          */
2045         protected function makeUpdateOptions( $options ) {
2046                 $opts = $this->makeUpdateOptionsArray( $options );
2047
2048                 return implode( ' ', $opts );
2049         }
2050
2051         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2052                 $table = $this->tableName( $table );
2053                 $opts = $this->makeUpdateOptions( $options );
2054                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2055
2056                 if ( $conds !== [] && $conds !== '*' ) {
2057                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2058                 }
2059
2060                 return (bool)$this->query( $sql, $fname );
2061         }
2062
2063         public function makeList( $a, $mode = self::LIST_COMMA ) {
2064                 if ( !is_array( $a ) ) {
2065                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2066                 }
2067
2068                 $first = true;
2069                 $list = '';
2070
2071                 foreach ( $a as $field => $value ) {
2072                         if ( !$first ) {
2073                                 if ( $mode == self::LIST_AND ) {
2074                                         $list .= ' AND ';
2075                                 } elseif ( $mode == self::LIST_OR ) {
2076                                         $list .= ' OR ';
2077                                 } else {
2078                                         $list .= ',';
2079                                 }
2080                         } else {
2081                                 $first = false;
2082                         }
2083
2084                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2085                                 $list .= "($value)";
2086                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2087                                 $list .= "$value";
2088                         } elseif (
2089                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2090                         ) {
2091                                 // Remove null from array to be handled separately if found
2092                                 $includeNull = false;
2093                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2094                                         $includeNull = true;
2095                                         unset( $value[$nullKey] );
2096                                 }
2097                                 if ( count( $value ) == 0 && !$includeNull ) {
2098                                         throw new InvalidArgumentException(
2099                                                 __METHOD__ . ": empty input for field $field" );
2100                                 } elseif ( count( $value ) == 0 ) {
2101                                         // only check if $field is null
2102                                         $list .= "$field IS NULL";
2103                                 } else {
2104                                         // IN clause contains at least one valid element
2105                                         if ( $includeNull ) {
2106                                                 // Group subconditions to ensure correct precedence
2107                                                 $list .= '(';
2108                                         }
2109                                         if ( count( $value ) == 1 ) {
2110                                                 // Special-case single values, as IN isn't terribly efficient
2111                                                 // Don't necessarily assume the single key is 0; we don't
2112                                                 // enforce linear numeric ordering on other arrays here.
2113                                                 $value = array_values( $value )[0];
2114                                                 $list .= $field . " = " . $this->addQuotes( $value );
2115                                         } else {
2116                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2117                                         }
2118                                         // if null present in array, append IS NULL
2119                                         if ( $includeNull ) {
2120                                                 $list .= " OR $field IS NULL)";
2121                                         }
2122                                 }
2123                         } elseif ( $value === null ) {
2124                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2125                                         $list .= "$field IS ";
2126                                 } elseif ( $mode == self::LIST_SET ) {
2127                                         $list .= "$field = ";
2128                                 }
2129                                 $list .= 'NULL';
2130                         } else {
2131                                 if (
2132                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2133                                 ) {
2134                                         $list .= "$field = ";
2135                                 }
2136                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2137                         }
2138                 }
2139
2140                 return $list;
2141         }
2142
2143         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2144                 $conds = [];
2145
2146                 foreach ( $data as $base => $sub ) {
2147                         if ( count( $sub ) ) {
2148                                 $conds[] = $this->makeList(
2149                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2150                                         self::LIST_AND );
2151                         }
2152                 }
2153
2154                 if ( $conds ) {
2155                         return $this->makeList( $conds, self::LIST_OR );
2156                 } else {
2157                         // Nothing to search for...
2158                         return false;
2159                 }
2160         }
2161
2162         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2163                 return $valuename;
2164         }
2165
2166         public function bitNot( $field ) {
2167                 return "(~$field)";
2168         }
2169
2170         public function bitAnd( $fieldLeft, $fieldRight ) {
2171                 return "($fieldLeft & $fieldRight)";
2172         }
2173
2174         public function bitOr( $fieldLeft, $fieldRight ) {
2175                 return "($fieldLeft | $fieldRight)";
2176         }
2177
2178         public function buildConcat( $stringList ) {
2179                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2180         }
2181
2182         public function buildGroupConcatField(
2183                 $delim, $table, $field, $conds = '', $join_conds = []
2184         ) {
2185                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2186
2187                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2188         }
2189
2190         public function buildSubstring( $input, $startPosition, $length = null ) {
2191                 $this->assertBuildSubstringParams( $startPosition, $length );
2192                 $functionBody = "$input FROM $startPosition";
2193                 if ( $length !== null ) {
2194                         $functionBody .= " FOR $length";
2195                 }
2196                 return 'SUBSTRING(' . $functionBody . ')';
2197         }
2198
2199         /**
2200          * Check type and bounds for parameters to self::buildSubstring()
2201          *
2202          * All supported databases have substring functions that behave the same for
2203          * positive $startPosition and non-negative $length, but behaviors differ when
2204          * given 0 or negative $startPosition or negative $length. The simplest
2205          * solution to that is to just forbid those values.
2206          *
2207          * @param int $startPosition
2208          * @param int|null $length
2209          * @since 1.31
2210          */
2211         protected function assertBuildSubstringParams( $startPosition, $length ) {
2212                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2213                         throw new InvalidArgumentException(
2214                                 '$startPosition must be a positive integer'
2215                         );
2216                 }
2217                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2218                         throw new InvalidArgumentException(
2219                                 '$length must be null or an integer greater than or equal to 0'
2220                         );
2221                 }
2222         }
2223
2224         public function buildStringCast( $field ) {
2225                 return $field;
2226         }
2227
2228         public function buildIntegerCast( $field ) {
2229                 return 'CAST( ' . $field . ' AS INTEGER )';
2230         }
2231
2232         public function buildSelectSubquery(
2233                 $table, $vars, $conds = '', $fname = __METHOD__,
2234                 $options = [], $join_conds = []
2235         ) {
2236                 return new Subquery(
2237                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2238                 );
2239         }
2240
2241         public function databasesAreIndependent() {
2242                 return false;
2243         }
2244
2245         public function selectDB( $db ) {
2246                 # Stub. Shouldn't cause serious problems if it's not overridden, but
2247                 # if your database engine supports a concept similar to MySQL's
2248                 # databases you may as well.
2249                 $this->dbName = $db;
2250
2251                 return true;
2252         }
2253
2254         public function getDBname() {
2255                 return $this->dbName;
2256         }
2257
2258         public function getServer() {
2259                 return $this->server;
2260         }
2261
2262         public function tableName( $name, $format = 'quoted' ) {
2263                 if ( $name instanceof Subquery ) {
2264                         throw new DBUnexpectedError(
2265                                 $this,
2266                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2267                         );
2268                 }
2269
2270                 # Skip the entire process when we have a string quoted on both ends.
2271                 # Note that we check the end so that we will still quote any use of
2272                 # use of `database`.table. But won't break things if someone wants
2273                 # to query a database table with a dot in the name.
2274                 if ( $this->isQuotedIdentifier( $name ) ) {
2275                         return $name;
2276                 }
2277
2278                 # Lets test for any bits of text that should never show up in a table
2279                 # name. Basically anything like JOIN or ON which are actually part of
2280                 # SQL queries, but may end up inside of the table value to combine
2281                 # sql. Such as how the API is doing.
2282                 # Note that we use a whitespace test rather than a \b test to avoid
2283                 # any remote case where a word like on may be inside of a table name
2284                 # surrounded by symbols which may be considered word breaks.
2285                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2286                         $this->queryLogger->warning(
2287                                 __METHOD__ . ": use of subqueries is not supported this way.",
2288                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2289                         );
2290
2291                         return $name;
2292                 }
2293
2294                 # Split database and table into proper variables.
2295                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2296
2297                 # Quote $table and apply the prefix if not quoted.
2298                 # $tableName might be empty if this is called from Database::replaceVars()
2299                 $tableName = "{$prefix}{$table}";
2300                 if ( $format === 'quoted'
2301                         && !$this->isQuotedIdentifier( $tableName )
2302                         && $tableName !== ''
2303                 ) {
2304                         $tableName = $this->addIdentifierQuotes( $tableName );
2305                 }
2306
2307                 # Quote $schema and $database and merge them with the table name if needed
2308                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2309                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2310
2311                 return $tableName;
2312         }
2313
2314         /**
2315          * Get the table components needed for a query given the currently selected database
2316          *
2317          * @param string $name Table name in the form of db.schema.table, db.table, or table
2318          * @return array (DB name or "" for default, schema name, table prefix, table name)
2319          */
2320         protected function qualifiedTableComponents( $name ) {
2321                 # We reverse the explode so that database.table and table both output the correct table.
2322                 $dbDetails = explode( '.', $name, 3 );
2323                 if ( count( $dbDetails ) == 3 ) {
2324                         list( $database, $schema, $table ) = $dbDetails;
2325                         # We don't want any prefix added in this case
2326                         $prefix = '';
2327                 } elseif ( count( $dbDetails ) == 2 ) {
2328                         list( $database, $table ) = $dbDetails;
2329                         # We don't want any prefix added in this case
2330                         $prefix = '';
2331                         # In dbs that support it, $database may actually be the schema
2332                         # but that doesn't affect any of the functionality here
2333                         $schema = '';
2334                 } else {
2335                         list( $table ) = $dbDetails;
2336                         if ( isset( $this->tableAliases[$table] ) ) {
2337                                 $database = $this->tableAliases[$table]['dbname'];
2338                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2339                                         ? $this->tableAliases[$table]['schema']
2340                                         : $this->schema;
2341                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2342                                         ? $this->tableAliases[$table]['prefix']
2343                                         : $this->tablePrefix;
2344                         } else {
2345                                 $database = '';
2346                                 $schema = $this->schema; # Default schema
2347                                 $prefix = $this->tablePrefix; # Default prefix
2348                         }
2349                 }
2350
2351                 return [ $database, $schema, $prefix, $table ];
2352         }
2353
2354         /**
2355          * @param string|null $namespace Database or schema
2356          * @param string $relation Name of table, view, sequence, etc...
2357          * @param string $format One of (raw, quoted)
2358          * @return string Relation name with quoted and merged $namespace as needed
2359          */
2360         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2361                 if ( strlen( $namespace ) ) {
2362                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2363                                 $namespace = $this->addIdentifierQuotes( $namespace );
2364                         }
2365                         $relation = $namespace . '.' . $relation;
2366                 }
2367
2368                 return $relation;
2369         }
2370
2371         public function tableNames() {
2372                 $inArray = func_get_args();
2373                 $retVal = [];
2374
2375                 foreach ( $inArray as $name ) {
2376                         $retVal[$name] = $this->tableName( $name );
2377                 }
2378
2379                 return $retVal;
2380         }
2381
2382         public function tableNamesN() {
2383                 $inArray = func_get_args();
2384                 $retVal = [];
2385
2386                 foreach ( $inArray as $name ) {
2387                         $retVal[] = $this->tableName( $name );
2388                 }
2389
2390                 return $retVal;
2391         }
2392
2393         /**
2394          * Get an aliased table name
2395          *
2396          * This returns strings like "tableName AS newTableName" for aliased tables
2397          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2398          *
2399          * @see Database::tableName()
2400          * @param string|Subquery $table Table name or object with a 'sql' field
2401          * @param string|bool $alias Table alias (optional)
2402          * @return string SQL name for aliased table. Will not alias a table to its own name
2403          */
2404         protected function tableNameWithAlias( $table, $alias = false ) {
2405                 if ( is_string( $table ) ) {
2406                         $quotedTable = $this->tableName( $table );
2407                 } elseif ( $table instanceof Subquery ) {
2408                         $quotedTable = (string)$table;
2409                 } else {
2410                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2411                 }
2412
2413                 if ( !strlen( $alias ) || $alias === $table ) {
2414                         if ( $table instanceof Subquery ) {
2415                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2416                         }
2417
2418                         return $quotedTable;
2419                 } else {
2420                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2421                 }
2422         }
2423
2424         /**
2425          * Gets an array of aliased table names
2426          *
2427          * @param array $tables [ [alias] => table ]
2428          * @return string[] See tableNameWithAlias()
2429          */
2430         protected function tableNamesWithAlias( $tables ) {
2431                 $retval = [];
2432                 foreach ( $tables as $alias => $table ) {
2433                         if ( is_numeric( $alias ) ) {
2434                                 $alias = $table;
2435                         }
2436                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2437                 }
2438
2439                 return $retval;
2440         }
2441
2442         /**
2443          * Get an aliased field name
2444          * e.g. fieldName AS newFieldName
2445          *
2446          * @param string $name Field name
2447          * @param string|bool $alias Alias (optional)
2448          * @return string SQL name for aliased field. Will not alias a field to its own name
2449          */
2450         protected function fieldNameWithAlias( $name, $alias = false ) {
2451                 if ( !$alias || (string)$alias === (string)$name ) {
2452                         return $name;
2453                 } else {
2454                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2455                 }
2456         }
2457
2458         /**
2459          * Gets an array of aliased field names
2460          *
2461          * @param array $fields [ [alias] => field ]
2462          * @return string[] See fieldNameWithAlias()
2463          */
2464         protected function fieldNamesWithAlias( $fields ) {
2465                 $retval = [];
2466                 foreach ( $fields as $alias => $field ) {
2467                         if ( is_numeric( $alias ) ) {
2468                                 $alias = $field;
2469                         }
2470                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2471                 }
2472
2473                 return $retval;
2474         }
2475
2476         /**
2477          * Get the aliased table name clause for a FROM clause
2478          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2479          *
2480          * @param array $tables ( [alias] => table )
2481          * @param array $use_index Same as for select()
2482          * @param array $ignore_index Same as for select()
2483          * @param array $join_conds Same as for select()
2484          * @return string
2485          */
2486         protected function tableNamesWithIndexClauseOrJOIN(
2487                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2488         ) {
2489                 $ret = [];
2490                 $retJOIN = [];
2491                 $use_index = (array)$use_index;
2492                 $ignore_index = (array)$ignore_index;
2493                 $join_conds = (array)$join_conds;
2494
2495                 foreach ( $tables as $alias => $table ) {
2496                         if ( !is_string( $alias ) ) {
2497                                 // No alias? Set it equal to the table name
2498                                 $alias = $table;
2499                         }
2500
2501                         if ( is_array( $table ) ) {
2502                                 // A parenthesized group
2503                                 if ( count( $table ) > 1 ) {
2504                                         $joinedTable = '(' .
2505                                                 $this->tableNamesWithIndexClauseOrJOIN(
2506                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2507                                 } else {
2508                                         // Degenerate case
2509                                         $innerTable = reset( $table );
2510                                         $innerAlias = key( $table );
2511                                         $joinedTable = $this->tableNameWithAlias(
2512                                                 $innerTable,
2513                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2514                                         );
2515                                 }
2516                         } else {
2517                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2518                         }
2519
2520                         // Is there a JOIN clause for this table?
2521                         if ( isset( $join_conds[$alias] ) ) {
2522                                 list( $joinType, $conds ) = $join_conds[$alias];
2523                                 $tableClause = $joinType;
2524                                 $tableClause .= ' ' . $joinedTable;
2525                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2526                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2527                                         if ( $use != '' ) {
2528                                                 $tableClause .= ' ' . $use;
2529                                         }
2530                                 }
2531                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2532                                         $ignore = $this->ignoreIndexClause(
2533                                                 implode( ',', (array)$ignore_index[$alias] ) );
2534                                         if ( $ignore != '' ) {
2535                                                 $tableClause .= ' ' . $ignore;
2536                                         }
2537                                 }
2538                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2539                                 if ( $on != '' ) {
2540                                         $tableClause .= ' ON (' . $on . ')';
2541                                 }
2542
2543                                 $retJOIN[] = $tableClause;
2544                         } elseif ( isset( $use_index[$alias] ) ) {
2545                                 // Is there an INDEX clause for this table?
2546                                 $tableClause = $joinedTable;
2547                                 $tableClause .= ' ' . $this->useIndexClause(
2548                                                 implode( ',', (array)$use_index[$alias] )
2549                                         );
2550
2551                                 $ret[] = $tableClause;
2552                         } elseif ( isset( $ignore_index[$alias] ) ) {
2553                                 // Is there an INDEX clause for this table?
2554                                 $tableClause = $joinedTable;
2555                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2556                                                 implode( ',', (array)$ignore_index[$alias] )
2557                                         );
2558
2559                                 $ret[] = $tableClause;
2560                         } else {
2561                                 $tableClause = $joinedTable;
2562
2563                                 $ret[] = $tableClause;
2564                         }
2565                 }
2566
2567                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2568                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2569                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2570
2571                 // Compile our final table clause
2572                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2573         }
2574
2575         /**
2576          * Allows for index remapping in queries where this is not consistent across DBMS
2577          *
2578          * @param string $index
2579          * @return string
2580          */
2581         protected function indexName( $index ) {
2582                 return isset( $this->indexAliases[$index] )
2583                         ? $this->indexAliases[$index]
2584                         : $index;
2585         }
2586
2587         public function addQuotes( $s ) {
2588                 if ( $s instanceof Blob ) {
2589                         $s = $s->fetch();
2590                 }
2591                 if ( $s === null ) {
2592                         return 'NULL';
2593                 } elseif ( is_bool( $s ) ) {
2594                         return (int)$s;
2595                 } else {
2596                         # This will also quote numeric values. This should be harmless,
2597                         # and protects against weird problems that occur when they really
2598                         # _are_ strings such as article titles and string->number->string
2599                         # conversion is not 1:1.
2600                         return "'" . $this->strencode( $s ) . "'";
2601                 }
2602         }
2603
2604         /**
2605          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2606          * MySQL uses `backticks` while basically everything else uses double quotes.
2607          * Since MySQL is the odd one out here the double quotes are our generic
2608          * and we implement backticks in DatabaseMysqlBase.
2609          *
2610          * @param string $s
2611          * @return string
2612          */
2613         public function addIdentifierQuotes( $s ) {
2614                 return '"' . str_replace( '"', '""', $s ) . '"';
2615         }
2616
2617         /**
2618          * Returns if the given identifier looks quoted or not according to
2619          * the database convention for quoting identifiers .
2620          *
2621          * @note Do not use this to determine if untrusted input is safe.
2622          *   A malicious user can trick this function.
2623          * @param string $name
2624          * @return bool
2625          */
2626         public function isQuotedIdentifier( $name ) {
2627                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2628         }
2629
2630         /**
2631          * @param string $s
2632          * @param string $escapeChar
2633          * @return string
2634          */
2635         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2636                 return str_replace( [ $escapeChar, '%', '_' ],
2637                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2638                         $s );
2639         }
2640
2641         public function buildLike() {
2642                 $params = func_get_args();
2643
2644                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2645                         $params = $params[0];
2646                 }
2647
2648                 $s = '';
2649
2650                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2651                 // may escape backslashes, creating problems of double escaping. The `
2652                 // character has good cross-DBMS compatibility, avoiding special operators
2653                 // in MS SQL like ^ and %
2654                 $escapeChar = '`';
2655
2656                 foreach ( $params as $value ) {
2657                         if ( $value instanceof LikeMatch ) {
2658                                 $s .= $value->toString();
2659                         } else {
2660                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2661                         }
2662                 }
2663
2664                 return ' LIKE ' .
2665                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2666         }
2667
2668         public function anyChar() {
2669                 return new LikeMatch( '_' );
2670         }
2671
2672         public function anyString() {
2673                 return new LikeMatch( '%' );
2674         }
2675
2676         public function nextSequenceValue( $seqName ) {
2677                 return null;
2678         }
2679
2680         /**
2681          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2682          * is only needed because a) MySQL must be as efficient as possible due to
2683          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2684          * which index to pick. Anyway, other databases might have different
2685          * indexes on a given table. So don't bother overriding this unless you're
2686          * MySQL.
2687          * @param string $index
2688          * @return string
2689          */
2690         public function useIndexClause( $index ) {
2691                 return '';
2692         }
2693
2694         /**
2695          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2696          * is only needed because a) MySQL must be as efficient as possible due to
2697          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2698          * which index to pick. Anyway, other databases might have different
2699          * indexes on a given table. So don't bother overriding this unless you're
2700          * MySQL.
2701          * @param string $index
2702          * @return string
2703          */
2704         public function ignoreIndexClause( $index ) {
2705                 return '';
2706         }
2707
2708         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2709                 if ( count( $rows ) == 0 ) {
2710                         return;
2711                 }
2712
2713                 // Single row case
2714                 if ( !is_array( reset( $rows ) ) ) {
2715                         $rows = [ $rows ];
2716                 }
2717
2718                 try {
2719                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2720                         $affectedRowCount = 0;
2721                         foreach ( $rows as $row ) {
2722                                 // Delete rows which collide with this one
2723                                 $indexWhereClauses = [];
2724                                 foreach ( $uniqueIndexes as $index ) {
2725                                         $indexColumns = (array)$index;
2726                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2727                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2728                                                 throw new DBUnexpectedError(
2729                                                         $this,
2730                                                         'New record does not provide all values for unique key (' .
2731                                                         implode( ', ', $indexColumns ) . ')'
2732                                                 );
2733                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2734                                                 throw new DBUnexpectedError(
2735                                                         $this,
2736                                                         'New record has a null value for unique key (' .
2737                                                         implode( ', ', $indexColumns ) . ')'
2738                                                 );
2739                                         }
2740                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2741                                 }
2742
2743                                 if ( $indexWhereClauses ) {
2744                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2745                                         $affectedRowCount += $this->affectedRows();
2746                                 }
2747
2748                                 // Now insert the row
2749                                 $this->insert( $table, $row, $fname );
2750                                 $affectedRowCount += $this->affectedRows();
2751                         }
2752                         $this->endAtomic( $fname );
2753                         $this->affectedRowCount = $affectedRowCount;
2754                 } catch ( Exception $e ) {
2755                         $this->cancelAtomic( $fname );
2756                         throw $e;
2757                 }
2758         }
2759
2760         /**
2761          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2762          * statement.
2763          *
2764          * @param string $table Table name
2765          * @param array|string $rows Row(s) to insert
2766          * @param string $fname Caller function name
2767          *
2768          * @return ResultWrapper
2769          */
2770         protected function nativeReplace( $table, $rows, $fname ) {
2771                 $table = $this->tableName( $table );
2772
2773                 # Single row case
2774                 if ( !is_array( reset( $rows ) ) ) {
2775                         $rows = [ $rows ];
2776                 }
2777
2778                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2779                 $first = true;
2780
2781                 foreach ( $rows as $row ) {
2782                         if ( $first ) {
2783                                 $first = false;
2784                         } else {
2785                                 $sql .= ',';
2786                         }
2787
2788                         $sql .= '(' . $this->makeList( $row ) . ')';
2789                 }
2790
2791                 return $this->query( $sql, $fname );
2792         }
2793
2794         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2795                 $fname = __METHOD__
2796         ) {
2797                 if ( !count( $rows ) ) {
2798                         return true; // nothing to do
2799                 }
2800
2801                 if ( !is_array( reset( $rows ) ) ) {
2802                         $rows = [ $rows ];
2803                 }
2804
2805                 if ( count( $uniqueIndexes ) ) {
2806                         $clauses = []; // list WHERE clauses that each identify a single row
2807                         foreach ( $rows as $row ) {
2808                                 foreach ( $uniqueIndexes as $index ) {
2809                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2810                                         $rowKey = []; // unique key to this row
2811                                         foreach ( $index as $column ) {
2812                                                 $rowKey[$column] = $row[$column];
2813                                         }
2814                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2815                                 }
2816                         }
2817                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2818                 } else {
2819                         $where = false;
2820                 }
2821
2822                 $affectedRowCount = 0;
2823                 try {
2824                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2825                         # Update any existing conflicting row(s)
2826                         if ( $where !== false ) {
2827                                 $ok = $this->update( $table, $set, $where, $fname );
2828                                 $affectedRowCount += $this->affectedRows();
2829                         } else {
2830                                 $ok = true;
2831                         }
2832                         # Now insert any non-conflicting row(s)
2833                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2834                         $affectedRowCount += $this->affectedRows();
2835                         $this->endAtomic( $fname );
2836                         $this->affectedRowCount = $affectedRowCount;
2837                 } catch ( Exception $e ) {
2838                         $this->cancelAtomic( $fname );
2839                         throw $e;
2840                 }
2841
2842                 return $ok;
2843         }
2844
2845         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2846                 $fname = __METHOD__
2847         ) {
2848                 if ( !$conds ) {
2849                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2850                 }
2851
2852                 $delTable = $this->tableName( $delTable );
2853                 $joinTable = $this->tableName( $joinTable );
2854                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2855                 if ( $conds != '*' ) {
2856                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2857                 }
2858                 $sql .= ')';
2859
2860                 $this->query( $sql, $fname );
2861         }
2862
2863         public function textFieldSize( $table, $field ) {
2864                 $table = $this->tableName( $table );
2865                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2866                 $res = $this->query( $sql, __METHOD__ );
2867                 $row = $this->fetchObject( $res );
2868
2869                 $m = [];
2870
2871                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2872                         $size = $m[1];
2873                 } else {
2874                         $size = -1;
2875                 }
2876
2877                 return $size;
2878         }
2879
2880         public function delete( $table, $conds, $fname = __METHOD__ ) {
2881                 if ( !$conds ) {
2882                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2883                 }
2884
2885                 $table = $this->tableName( $table );
2886                 $sql = "DELETE FROM $table";
2887
2888                 if ( $conds != '*' ) {
2889                         if ( is_array( $conds ) ) {
2890                                 $conds = $this->makeList( $conds, self::LIST_AND );
2891                         }
2892                         $sql .= ' WHERE ' . $conds;
2893                 }
2894
2895                 return $this->query( $sql, $fname );
2896         }
2897
2898         final public function insertSelect(
2899                 $destTable, $srcTable, $varMap, $conds,
2900                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2901         ) {
2902                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2903
2904                 $insertOptions = (array)$insertOptions;
2905                 $selectOptions = (array)$selectOptions;
2906
2907                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2908                         // For massive migrations with downtime, we don't want to select everything
2909                         // into memory and OOM, so do all this native on the server side if possible.
2910                         return $this->nativeInsertSelect(
2911                                 $destTable,
2912                                 $srcTable,
2913                                 $varMap,
2914                                 $conds,
2915                                 $fname,
2916                                 array_diff( $insertOptions, $hints ),
2917                                 $selectOptions,
2918                                 $selectJoinConds
2919                         );
2920                 }
2921
2922                 return $this->nonNativeInsertSelect(
2923                         $destTable,
2924                         $srcTable,
2925                         $varMap,
2926                         $conds,
2927                         $fname,
2928                         array_diff( $insertOptions, $hints ),
2929                         $selectOptions,
2930                         $selectJoinConds
2931                 );
2932         }
2933
2934         /**
2935          * @param array $insertOptions INSERT options
2936          * @param array $selectOptions SELECT options
2937          * @return bool Whether an INSERT SELECT with these options will be replication safe
2938          * @since 1.31
2939          */
2940         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
2941                 return true;
2942         }
2943
2944         /**
2945          * Implementation of insertSelect() based on select() and insert()
2946          *
2947          * @see IDatabase::insertSelect()
2948          * @since 1.30
2949          * @param string $destTable
2950          * @param string|array $srcTable
2951          * @param array $varMap
2952          * @param array $conds
2953          * @param string $fname
2954          * @param array $insertOptions
2955          * @param array $selectOptions
2956          * @param array $selectJoinConds
2957          * @return bool
2958          */
2959         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2960                 $fname = __METHOD__,
2961                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2962         ) {
2963                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2964                 // on only the master (without needing row-based-replication). It also makes it easy to
2965                 // know how big the INSERT is going to be.
2966                 $fields = [];
2967                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2968                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2969                 }
2970                 $selectOptions[] = 'FOR UPDATE';
2971                 $res = $this->select(
2972                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2973                 );
2974                 if ( !$res ) {
2975                         return false;
2976                 }
2977
2978                 try {
2979                         $affectedRowCount = 0;
2980                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2981                         $rows = [];
2982                         $ok = true;
2983                         foreach ( $res as $row ) {
2984                                 $rows[] = (array)$row;
2985
2986                                 // Avoid inserts that are too huge
2987                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
2988                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2989                                         if ( !$ok ) {
2990                                                 break;
2991                                         }
2992                                         $affectedRowCount += $this->affectedRows();
2993                                         $rows = [];
2994                                 }
2995                         }
2996                         if ( $rows && $ok ) {
2997                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2998                                 if ( $ok ) {
2999                                         $affectedRowCount += $this->affectedRows();
3000                                 }
3001                         }
3002                         if ( $ok ) {
3003                                 $this->endAtomic( $fname );
3004                                 $this->affectedRowCount = $affectedRowCount;
3005                         } else {
3006                                 $this->cancelAtomic( $fname );
3007                         }
3008                         return $ok;
3009                 } catch ( Exception $e ) {
3010                         $this->cancelAtomic( $fname );
3011                         throw $e;
3012                 }
3013         }
3014
3015         /**
3016          * Native server-side implementation of insertSelect() for situations where
3017          * we don't want to select everything into memory
3018          *
3019          * @see IDatabase::insertSelect()
3020          * @param string $destTable
3021          * @param string|array $srcTable
3022          * @param array $varMap
3023          * @param array $conds
3024          * @param string $fname
3025          * @param array $insertOptions
3026          * @param array $selectOptions
3027          * @param array $selectJoinConds
3028          * @return bool
3029          */
3030         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3031                 $fname = __METHOD__,
3032                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3033         ) {
3034                 $destTable = $this->tableName( $destTable );
3035
3036                 if ( !is_array( $insertOptions ) ) {
3037                         $insertOptions = [ $insertOptions ];
3038                 }
3039
3040                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3041
3042                 $selectSql = $this->selectSQLText(
3043                         $srcTable,
3044                         array_values( $varMap ),
3045                         $conds,
3046                         $fname,
3047                         $selectOptions,
3048                         $selectJoinConds
3049                 );
3050
3051                 $sql = "INSERT $insertOptions" .
3052                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3053                         $selectSql;
3054
3055                 return $this->query( $sql, $fname );
3056         }
3057
3058         /**
3059          * Construct a LIMIT query with optional offset. This is used for query
3060          * pages. The SQL should be adjusted so that only the first $limit rows
3061          * are returned. If $offset is provided as well, then the first $offset
3062          * rows should be discarded, and the next $limit rows should be returned.
3063          * If the result of the query is not ordered, then the rows to be returned
3064          * are theoretically arbitrary.
3065          *
3066          * $sql is expected to be a SELECT, if that makes a difference.
3067          *
3068          * The version provided by default works in MySQL and SQLite. It will very
3069          * likely need to be overridden for most other DBMSes.
3070          *
3071          * @param string $sql SQL query we will append the limit too
3072          * @param int $limit The SQL limit
3073          * @param int|bool $offset The SQL offset (default false)
3074          * @throws DBUnexpectedError
3075          * @return string
3076          */
3077         public function limitResult( $sql, $limit, $offset = false ) {
3078                 if ( !is_numeric( $limit ) ) {
3079                         throw new DBUnexpectedError( $this,
3080                                 "Invalid non-numeric limit passed to limitResult()\n" );
3081                 }
3082
3083                 return "$sql LIMIT "
3084                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3085                 . "{$limit} ";
3086         }
3087
3088         public function unionSupportsOrderAndLimit() {
3089                 return true; // True for almost every DB supported
3090         }
3091
3092         public function unionQueries( $sqls, $all ) {
3093                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3094
3095                 return '(' . implode( $glue, $sqls ) . ')';
3096         }
3097
3098         public function unionConditionPermutations(
3099                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3100                 $options = [], $join_conds = []
3101         ) {
3102                 // First, build the Cartesian product of $permute_conds
3103                 $conds = [ [] ];
3104                 foreach ( $permute_conds as $field => $values ) {
3105                         if ( !$values ) {
3106                                 // Skip empty $values
3107                                 continue;
3108                         }
3109                         $values = array_unique( $values ); // For sanity
3110                         $newConds = [];
3111                         foreach ( $conds as $cond ) {
3112                                 foreach ( $values as $value ) {
3113                                         $cond[$field] = $value;
3114                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3115                                 }
3116                         }
3117                         $conds = $newConds;
3118                 }
3119
3120                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3121
3122                 // If there's just one condition and no subordering, hand off to
3123                 // selectSQLText directly.
3124                 if ( count( $conds ) === 1 &&
3125                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3126                 ) {
3127                         return $this->selectSQLText(
3128                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3129                         );
3130                 }
3131
3132                 // Otherwise, we need to pull out the order and limit to apply after
3133                 // the union. Then build the SQL queries for each set of conditions in
3134                 // $conds. Then union them together (using UNION ALL, because the
3135                 // product *should* already be distinct).
3136                 $orderBy = $this->makeOrderBy( $options );
3137                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
3138                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
3139                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3140                 if ( !$this->unionSupportsOrderAndLimit() ) {
3141                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3142                 } else {
3143                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3144                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3145                         }
3146                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3147                                 // We need to increase the limit by the offset rather than
3148                                 // using the offset directly, otherwise it'll skip incorrectly
3149                                 // in the subqueries.
3150                                 $options['LIMIT'] = $limit + $offset;
3151                                 unset( $options['OFFSET'] );
3152                         }
3153                 }
3154
3155                 $sqls = [];
3156                 foreach ( $conds as $cond ) {
3157                         $sqls[] = $this->selectSQLText(
3158                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3159                         );
3160                 }
3161                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3162                 if ( $limit !== null ) {
3163                         $sql = $this->limitResult( $sql, $limit, $offset );
3164                 }
3165
3166                 return $sql;
3167         }
3168
3169         public function conditional( $cond, $trueVal, $falseVal ) {
3170                 if ( is_array( $cond ) ) {
3171                         $cond = $this->makeList( $cond, self::LIST_AND );
3172                 }
3173
3174                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3175         }
3176
3177         public function strreplace( $orig, $old, $new ) {
3178                 return "REPLACE({$orig}, {$old}, {$new})";
3179         }
3180
3181         public function getServerUptime() {
3182                 return 0;
3183         }
3184
3185         public function wasDeadlock() {
3186                 return false;
3187         }
3188
3189         public function wasLockTimeout() {
3190                 return false;
3191         }
3192
3193         public function wasConnectionLoss() {
3194                 return $this->wasConnectionError( $this->lastErrno() );
3195         }
3196
3197         public function wasReadOnlyError() {
3198                 return false;
3199         }
3200
3201         public function wasErrorReissuable() {
3202                 return (
3203                         $this->wasDeadlock() ||
3204                         $this->wasLockTimeout() ||
3205                         $this->wasConnectionLoss()
3206                 );
3207         }
3208
3209         /**
3210          * Do not use this method outside of Database/DBError classes
3211          *
3212          * @param int|string $errno
3213          * @return bool Whether the given query error was a connection drop
3214          */
3215         public function wasConnectionError( $errno ) {
3216                 return false;
3217         }
3218
3219         /**
3220          * @return bool Whether it is safe to assume the given error only caused statement rollback
3221          * @note This is for backwards compatibility for callers catching DBError exceptions in
3222          *   order to ignore problems like duplicate key errors or foriegn key violations
3223          * @since 1.31
3224          */
3225         protected function wasKnownStatementRollbackError() {
3226                 return false; // don't know; it could have caused a transaction rollback
3227         }
3228
3229         public function deadlockLoop() {
3230                 $args = func_get_args();
3231                 $function = array_shift( $args );
3232                 $tries = self::DEADLOCK_TRIES;
3233
3234                 $this->begin( __METHOD__ );
3235
3236                 $retVal = null;
3237                 /** @var Exception $e */
3238                 $e = null;
3239                 do {
3240                         try {
3241                                 $retVal = call_user_func_array( $function, $args );
3242                                 break;
3243                         } catch ( DBQueryError $e ) {
3244                                 if ( $this->wasDeadlock() ) {
3245                                         // Retry after a randomized delay
3246                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3247                                 } else {
3248                                         // Throw the error back up
3249                                         throw $e;
3250                                 }
3251                         }
3252                 } while ( --$tries > 0 );
3253
3254                 if ( $tries <= 0 ) {
3255                         // Too many deadlocks; give up
3256                         $this->rollback( __METHOD__ );
3257                         throw $e;
3258                 } else {
3259                         $this->commit( __METHOD__ );
3260
3261                         return $retVal;
3262                 }
3263         }
3264
3265         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3266                 # Real waits are implemented in the subclass.
3267                 return 0;
3268         }
3269
3270         public function getReplicaPos() {
3271                 # Stub
3272                 return false;
3273         }
3274
3275         public function getMasterPos() {
3276                 # Stub
3277                 return false;
3278         }
3279
3280         public function serverIsReadOnly() {
3281                 return false;
3282         }
3283
3284         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3285                 if ( !$this->trxLevel ) {
3286                         throw new DBUnexpectedError( $this, "No transaction is active." );
3287                 }
3288                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3289         }
3290
3291         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3292                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3293                         // Start an implicit transaction similar to how query() does
3294                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3295                         $this->trxAutomatic = true;
3296                 }
3297
3298                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3299                 if ( !$this->trxLevel ) {
3300                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3301                 }
3302         }
3303
3304         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3305                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3306                         // Start an implicit transaction similar to how query() does
3307                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3308                         $this->trxAutomatic = true;
3309                 }
3310
3311                 if ( $this->trxLevel ) {
3312                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3313                 } else {
3314                         // No transaction is active nor will start implicitly, so make one for this callback
3315                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3316                         try {
3317                                 call_user_func( $callback, $this );
3318                                 $this->endAtomic( __METHOD__ );
3319                         } catch ( Exception $e ) {
3320                                 $this->cancelAtomic( __METHOD__ );
3321                                 throw $e;
3322                         }
3323                 }
3324         }
3325
3326         /**
3327          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3328          */
3329         private function currentAtomicSectionId() {
3330                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3331                         $levelInfo = end( $this->trxAtomicLevels );
3332
3333                         return $levelInfo[1];
3334                 }
3335
3336                 return null;
3337         }
3338
3339         /**
3340          * @param AtomicSectionIdentifier $old
3341          * @param AtomicSectionIdentifier $new
3342          */
3343         private function reassignCallbacksForSection(
3344                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3345         ) {
3346                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3347                         if ( $info[2] === $old ) {
3348                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3349                         }
3350                 }
3351                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3352                         if ( $info[2] === $old ) {
3353                                 $this->trxIdleCallbacks[$key][2] = $new;
3354                         }
3355                 }
3356                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3357                         if ( $info[2] === $old ) {
3358                                 $this->trxEndCallbacks[$key][2] = $new;
3359                         }
3360                 }
3361         }
3362
3363         /**
3364          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3365          * @throws UnexpectedValueException
3366          */
3367         private function modifyCallbacksForCancel( array $sectionIds ) {
3368                 // Cancel the "on commit" callbacks owned by this savepoint
3369                 $this->trxIdleCallbacks = array_filter(
3370                         $this->trxIdleCallbacks,
3371                         function ( $entry ) use ( $sectionIds ) {
3372                                 return !in_array( $entry[2], $sectionIds, true );
3373                         }
3374                 );
3375                 $this->trxPreCommitCallbacks = array_filter(
3376                         $this->trxPreCommitCallbacks,
3377                         function ( $entry ) use ( $sectionIds ) {
3378                                 return !in_array( $entry[2], $sectionIds, true );
3379                         }
3380                 );
3381                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3382                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3383                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3384                                 $callback = $entry[0];
3385                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3386                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3387                                 };
3388                         }
3389                 }
3390         }
3391
3392         final public function setTransactionListener( $name, callable $callback = null ) {
3393                 if ( $callback ) {
3394                         $this->trxRecurringCallbacks[$name] = $callback;
3395                 } else {
3396                         unset( $this->trxRecurringCallbacks[$name] );
3397                 }
3398         }
3399
3400         /**
3401          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3402          *
3403          * This method should not be used outside of Database/LoadBalancer
3404          *
3405          * @param bool $suppress
3406          * @since 1.28
3407          */
3408         final public function setTrxEndCallbackSuppression( $suppress ) {
3409                 $this->trxEndCallbacksSuppressed = $suppress;
3410         }
3411
3412         /**
3413          * Actually consume and run any "on transaction idle/resolution" callbacks.
3414          *
3415          * This method should not be used outside of Database/LoadBalancer
3416          *
3417          * @param int $trigger IDatabase::TRIGGER_* constant
3418          * @return int Number of callbacks attempted
3419          * @since 1.20
3420          * @throws Exception
3421          */
3422         public function runOnTransactionIdleCallbacks( $trigger ) {
3423                 if ( $this->trxLevel ) { // sanity
3424                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3425                 }
3426
3427                 if ( $this->trxEndCallbacksSuppressed ) {
3428                         return 0;
3429                 }
3430
3431                 $count = 0;
3432                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3433                 /** @var Exception $e */
3434                 $e = null; // first exception
3435                 do { // callbacks may add callbacks :)
3436                         $callbacks = array_merge(
3437                                 $this->trxIdleCallbacks,
3438                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3439                         );
3440                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3441                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3442                         foreach ( $callbacks as $callback ) {
3443                                 try {
3444                                         ++$count;
3445                                         list( $phpCallback ) = $callback;
3446                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3447                                         call_user_func( $phpCallback, $trigger, $this );
3448                                         if ( $autoTrx ) {
3449                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3450                                         } else {
3451                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3452                                         }
3453                                 } catch ( Exception $ex ) {
3454                                         call_user_func( $this->errorLogger, $ex );
3455                                         $e = $e ?: $ex;
3456                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3457                                         // their transactions are ended so other callbacks don't fail
3458                                         if ( $this->trxLevel() ) {
3459                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3460                                         }
3461                                 }
3462                         }
3463                 } while ( count( $this->trxIdleCallbacks ) );
3464
3465                 if ( $e instanceof Exception ) {
3466                         throw $e; // re-throw any first exception
3467                 }
3468
3469                 return $count;
3470         }
3471
3472         /**
3473          * Actually consume and run any "on transaction pre-commit" callbacks.
3474          *
3475          * This method should not be used outside of Database/LoadBalancer
3476          *
3477          * @since 1.22
3478          * @return int Number of callbacks attempted
3479          * @throws Exception
3480          */
3481         public function runOnTransactionPreCommitCallbacks() {
3482                 $count = 0;
3483
3484                 $e = null; // first exception
3485                 do { // callbacks may add callbacks :)
3486                         $callbacks = $this->trxPreCommitCallbacks;
3487                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3488                         foreach ( $callbacks as $callback ) {
3489                                 try {
3490                                         ++$count;
3491                                         list( $phpCallback ) = $callback;
3492                                         call_user_func( $phpCallback, $this );
3493                                 } catch ( Exception $ex ) {
3494                                         call_user_func( $this->errorLogger, $ex );
3495                                         $e = $e ?: $ex;
3496                                 }
3497                         }
3498                 } while ( count( $this->trxPreCommitCallbacks ) );
3499
3500                 if ( $e instanceof Exception ) {
3501                         throw $e; // re-throw any first exception
3502                 }
3503
3504                 return $count;
3505         }
3506
3507         /**
3508          * Actually run any "transaction listener" callbacks.
3509          *
3510          * This method should not be used outside of Database/LoadBalancer
3511          *
3512          * @param int $trigger IDatabase::TRIGGER_* constant
3513          * @throws Exception
3514          * @since 1.20
3515          */
3516         public function runTransactionListenerCallbacks( $trigger ) {
3517                 if ( $this->trxEndCallbacksSuppressed ) {
3518                         return;
3519                 }
3520
3521                 /** @var Exception $e */
3522                 $e = null; // first exception
3523
3524                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3525                         try {
3526                                 $phpCallback( $trigger, $this );
3527                         } catch ( Exception $ex ) {
3528                                 call_user_func( $this->errorLogger, $ex );
3529                                 $e = $e ?: $ex;
3530                         }
3531                 }
3532
3533                 if ( $e instanceof Exception ) {
3534                         throw $e; // re-throw any first exception
3535                 }
3536         }
3537
3538         /**
3539          * Create a savepoint
3540          *
3541          * This is used internally to implement atomic sections. It should not be
3542          * used otherwise.
3543          *
3544          * @since 1.31
3545          * @param string $identifier Identifier for the savepoint
3546          * @param string $fname Calling function name
3547          */
3548         protected function doSavepoint( $identifier, $fname ) {
3549                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3550         }
3551
3552         /**
3553          * Release a savepoint
3554          *
3555          * This is used internally to implement atomic sections. It should not be
3556          * used otherwise.
3557          *
3558          * @since 1.31
3559          * @param string $identifier Identifier for the savepoint
3560          * @param string $fname Calling function name
3561          */
3562         protected function doReleaseSavepoint( $identifier, $fname ) {
3563                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3564         }
3565
3566         /**
3567          * Rollback to a savepoint
3568          *
3569          * This is used internally to implement atomic sections. It should not be
3570          * used otherwise.
3571          *
3572          * @since 1.31
3573          * @param string $identifier Identifier for the savepoint
3574          * @param string $fname Calling function name
3575          */
3576         protected function doRollbackToSavepoint( $identifier, $fname ) {
3577                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3578         }
3579
3580         /**
3581          * @param string $fname
3582          * @return string
3583          */
3584         private function nextSavepointId( $fname ) {
3585                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3586                 if ( strlen( $savepointId ) > 30 ) {
3587                         // 30 == Oracle's identifier length limit (pre 12c)
3588                         // With a 22 character prefix, that puts the highest number at 99999999.
3589                         throw new DBUnexpectedError(
3590                                 $this,
3591                                 'There have been an excessively large number of atomic sections in a transaction'
3592                                 . " started by $this->trxFname (at $fname)"
3593                         );
3594                 }
3595
3596                 return $savepointId;
3597         }
3598
3599         final public function startAtomic(
3600                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3601         ) {
3602                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3603
3604                 if ( !$this->trxLevel ) {
3605                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3606                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3607                         // in all changes being in one transaction to keep requests transactional.
3608                         if ( $this->getFlag( self::DBO_TRX ) ) {
3609                                 // Since writes could happen in between the topmost atomic sections as part
3610                                 // of the transaction, those sections will need savepoints.
3611                                 $savepointId = $this->nextSavepointId( $fname );
3612                                 $this->doSavepoint( $savepointId, $fname );
3613                         } else {
3614                                 $this->trxAutomaticAtomic = true;
3615                         }
3616                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3617                         $savepointId = $this->nextSavepointId( $fname );
3618                         $this->doSavepoint( $savepointId, $fname );
3619                 }
3620
3621                 $sectionId = new AtomicSectionIdentifier;
3622                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3623
3624                 return $sectionId;
3625         }
3626
3627         final public function endAtomic( $fname = __METHOD__ ) {
3628                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3629                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3630                 }
3631
3632                 // Check if the current section matches $fname
3633                 $pos = count( $this->trxAtomicLevels ) - 1;
3634                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3635
3636                 if ( $savedFname !== $fname ) {
3637                         throw new DBUnexpectedError(
3638                                 $this,
3639                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3640                         );
3641                 }
3642
3643                 // Remove the last section (no need to re-index the array)
3644                 array_pop( $this->trxAtomicLevels );
3645
3646                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3647                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3648                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3649                         $this->doReleaseSavepoint( $savepointId, $fname );
3650                 }
3651
3652                 // Hoist callback ownership for callbacks in the section that just ended;
3653                 // all callbacks should have an owner that is present in trxAtomicLevels.
3654                 $currentSectionId = $this->currentAtomicSectionId();
3655                 if ( $currentSectionId ) {
3656                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3657                 }
3658         }
3659
3660         final public function cancelAtomic(
3661                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3662         ) {
3663                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3664                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3665                 }
3666
3667                 if ( $sectionId !== null ) {
3668                         // Find the (last) section with the given $sectionId
3669                         $pos = -1;
3670                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3671                                 if ( $asId === $sectionId ) {
3672                                         $pos = $i;
3673                                 }
3674                         }
3675                         if ( $pos < 0 ) {
3676                                 throw new DBUnexpectedError( "Atomic section not found (for $fname)" );
3677                         }
3678                         // Remove all descendant sections and re-index the array
3679                         $excisedIds = [];
3680                         $len = count( $this->trxAtomicLevels );
3681                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3682                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3683                         }
3684                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3685                         $this->modifyCallbacksForCancel( $excisedIds );
3686                 }
3687
3688                 // Check if the current section matches $fname
3689                 $pos = count( $this->trxAtomicLevels ) - 1;
3690                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3691
3692                 if ( $savedFname !== $fname ) {
3693                         throw new DBUnexpectedError(
3694                                 $this,
3695                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3696                         );
3697                 }
3698
3699                 // Remove the last section (no need to re-index the array)
3700                 array_pop( $this->trxAtomicLevels );
3701                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3702
3703                 if ( $savepointId !== null ) {
3704                         // Rollback the transaction to the state just before this atomic section
3705                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3706                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3707                         } else {
3708                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3709                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3710                                 $this->trxStatusIgnoredCause = null;
3711                         }
3712                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3713                         // Put the transaction into an error state if it's not already in one
3714                         $this->trxStatus = self::STATUS_TRX_ERROR;
3715                         $this->trxStatusCause = new DBUnexpectedError(
3716                                 $this,
3717                                 "Uncancelable atomic section canceled (got $fname)."
3718                         );
3719                 }
3720
3721                 $this->affectedRowCount = 0; // for the sake of consistency
3722         }
3723
3724         final public function doAtomicSection(
3725                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3726         ) {
3727                 $sectionId = $this->startAtomic( $fname, $cancelable );
3728                 try {
3729                         $res = call_user_func_array( $callback, [ $this, $fname ] );
3730                 } catch ( Exception $e ) {
3731                         $this->cancelAtomic( $fname, $sectionId );
3732
3733                         throw $e;
3734                 }
3735                 $this->endAtomic( $fname );
3736
3737                 return $res;
3738         }
3739
3740         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3741                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3742                 if ( !in_array( $mode, $modes, true ) ) {
3743                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3744                 }
3745
3746                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3747                 if ( $this->trxLevel ) {
3748                         if ( $this->trxAtomicLevels ) {
3749                                 $levels = $this->flatAtomicSectionList();
3750                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3751                                 throw new DBUnexpectedError( $this, $msg );
3752                         } elseif ( !$this->trxAutomatic ) {
3753                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3754                                 throw new DBUnexpectedError( $this, $msg );
3755                         } else {
3756                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3757                                 throw new DBUnexpectedError( $this, $msg );
3758                         }
3759                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3760                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3761                         throw new DBUnexpectedError( $this, $msg );
3762                 }
3763
3764                 // Avoid fatals if close() was called
3765                 $this->assertOpen();
3766
3767                 $this->doBegin( $fname );
3768                 $this->trxStatus = self::STATUS_TRX_OK;
3769                 $this->trxStatusIgnoredCause = null;
3770                 $this->trxAtomicCounter = 0;
3771                 $this->trxTimestamp = microtime( true );
3772                 $this->trxFname = $fname;
3773                 $this->trxDoneWrites = false;
3774                 $this->trxAutomaticAtomic = false;
3775                 $this->trxAtomicLevels = [];
3776                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3777                 $this->trxWriteDuration = 0.0;
3778                 $this->trxWriteQueryCount = 0;
3779                 $this->trxWriteAffectedRows = 0;
3780                 $this->trxWriteAdjDuration = 0.0;
3781                 $this->trxWriteAdjQueryCount = 0;
3782                 $this->trxWriteCallers = [];
3783                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3784                 // Get an estimate of the replication lag before any such queries.
3785                 $this->trxReplicaLag = null; // clear cached value first
3786                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3787                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3788                 // caller will think its OK to muck around with the transaction just because startAtomic()
3789                 // has not yet completed (e.g. setting trxAtomicLevels).
3790                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3791         }
3792
3793         /**
3794          * Issues the BEGIN command to the database server.
3795          *
3796          * @see Database::begin()
3797          * @param string $fname
3798          */
3799         protected function doBegin( $fname ) {
3800                 $this->query( 'BEGIN', $fname );
3801                 $this->trxLevel = 1;
3802         }
3803
3804         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3805                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3806                 if ( !in_array( $flush, $modes, true ) ) {
3807                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3808                 }
3809
3810                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3811                         // There are still atomic sections open; this cannot be ignored
3812                         $levels = $this->flatAtomicSectionList();
3813                         throw new DBUnexpectedError(
3814                                 $this,
3815                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3816                         );
3817                 }
3818
3819                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3820                         if ( !$this->trxLevel ) {
3821                                 return; // nothing to do
3822                         } elseif ( !$this->trxAutomatic ) {
3823                                 throw new DBUnexpectedError(
3824                                         $this,
3825                                         "$fname: Flushing an explicit transaction, getting out of sync."
3826                                 );
3827                         }
3828                 } else {
3829                         if ( !$this->trxLevel ) {
3830                                 $this->queryLogger->error(
3831                                         "$fname: No transaction to commit, something got out of sync." );
3832                                 return; // nothing to do
3833                         } elseif ( $this->trxAutomatic ) {
3834                                 throw new DBUnexpectedError(
3835                                         $this,
3836                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3837                                 );
3838                         }
3839                 }
3840
3841                 // Avoid fatals if close() was called
3842                 $this->assertOpen();
3843
3844                 $this->runOnTransactionPreCommitCallbacks();
3845                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3846                 $this->doCommit( $fname );
3847                 $this->trxStatus = self::STATUS_TRX_NONE;
3848                 if ( $this->trxDoneWrites ) {
3849                         $this->lastWriteTime = microtime( true );
3850                         $this->trxProfiler->transactionWritingOut(
3851                                 $this->server,
3852                                 $this->dbName,
3853                                 $this->trxShortId,
3854                                 $writeTime,
3855                                 $this->trxWriteAffectedRows
3856                         );
3857                 }
3858
3859                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3860                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
3861                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3862                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3863                 }
3864         }
3865
3866         /**
3867          * Issues the COMMIT command to the database server.
3868          *
3869          * @see Database::commit()
3870          * @param string $fname
3871          */
3872         protected function doCommit( $fname ) {
3873                 if ( $this->trxLevel ) {
3874                         $this->query( 'COMMIT', $fname );
3875                         $this->trxLevel = 0;
3876                 }
3877         }
3878
3879         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3880                 $trxActive = $this->trxLevel;
3881
3882                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3883                         if ( $this->getFlag( self::DBO_TRX ) ) {
3884                                 throw new DBUnexpectedError(
3885                                         $this,
3886                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3887                                 );
3888                         }
3889                 }
3890
3891                 if ( $trxActive ) {
3892                         // Avoid fatals if close() was called
3893                         $this->assertOpen();
3894
3895                         $this->doRollback( $fname );
3896                         $this->trxStatus = self::STATUS_TRX_NONE;
3897                         $this->trxAtomicLevels = [];
3898                         if ( $this->trxDoneWrites ) {
3899                                 $this->trxProfiler->transactionWritingOut(
3900                                         $this->server,
3901                                         $this->dbName,
3902                                         $this->trxShortId
3903                                 );
3904                         }
3905                 }
3906
3907                 // Clear any commit-dependant callbacks. They might even be present
3908                 // only due to transaction rounds, with no SQL transaction being active
3909                 $this->trxIdleCallbacks = [];
3910                 $this->trxPreCommitCallbacks = [];
3911
3912                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3913                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
3914                         try {
3915                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3916                         } catch ( Exception $e ) {
3917                                 // already logged; finish and let LoadBalancer move on during mass-rollback
3918                         }
3919                         try {
3920                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3921                         } catch ( Exception $e ) {
3922                                 // already logged; let LoadBalancer move on during mass-rollback
3923                         }
3924
3925                         $this->affectedRowCount = 0; // for the sake of consistency
3926                 }
3927         }
3928
3929         /**
3930          * Issues the ROLLBACK command to the database server.
3931          *
3932          * @see Database::rollback()
3933          * @param string $fname
3934          */
3935         protected function doRollback( $fname ) {
3936                 if ( $this->trxLevel ) {
3937                         # Disconnects cause rollback anyway, so ignore those errors
3938                         $ignoreErrors = true;
3939                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3940                         $this->trxLevel = 0;
3941                 }
3942         }
3943
3944         public function flushSnapshot( $fname = __METHOD__ ) {
3945                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3946                         // This only flushes transactions to clear snapshots, not to write data
3947                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3948                         throw new DBUnexpectedError(
3949                                 $this,
3950                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3951                         );
3952                 }
3953
3954                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3955         }
3956
3957         public function explicitTrxActive() {
3958                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
3959         }
3960
3961         public function duplicateTableStructure(
3962                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3963         ) {
3964                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3965         }
3966
3967         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3968                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3969         }
3970
3971         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3972                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3973         }
3974
3975         public function timestamp( $ts = 0 ) {
3976                 $t = new ConvertibleTimestamp( $ts );
3977                 // Let errors bubble up to avoid putting garbage in the DB
3978                 return $t->getTimestamp( TS_MW );
3979         }
3980
3981         public function timestampOrNull( $ts = null ) {
3982                 if ( is_null( $ts ) ) {
3983                         return null;
3984                 } else {
3985                         return $this->timestamp( $ts );
3986                 }
3987         }
3988
3989         public function affectedRows() {
3990                 return ( $this->affectedRowCount === null )
3991                         ? $this->fetchAffectedRowCount() // default to driver value
3992                         : $this->affectedRowCount;
3993         }
3994
3995         /**
3996          * @return int Number of retrieved rows according to the driver
3997          */
3998         abstract protected function fetchAffectedRowCount();
3999
4000         /**
4001          * Take the result from a query, and wrap it in a ResultWrapper if
4002          * necessary. Boolean values are passed through as is, to indicate success
4003          * of write queries or failure.
4004          *
4005          * Once upon a time, Database::query() returned a bare MySQL result
4006          * resource, and it was necessary to call this function to convert it to
4007          * a wrapper. Nowadays, raw database objects are never exposed to external
4008          * callers, so this is unnecessary in external code.
4009          *
4010          * @param bool|ResultWrapper|resource|object $result
4011          * @return bool|ResultWrapper
4012          */
4013         protected function resultObject( $result ) {
4014                 if ( !$result ) {
4015                         return false;
4016                 } elseif ( $result instanceof ResultWrapper ) {
4017                         return $result;
4018                 } elseif ( $result === true ) {
4019                         // Successful write query
4020                         return $result;
4021                 } else {
4022                         return new ResultWrapper( $this, $result );
4023                 }
4024         }
4025
4026         public function ping( &$rtt = null ) {
4027                 // Avoid hitting the server if it was hit recently
4028                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
4029                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
4030                                 $rtt = $this->rttEstimate;
4031                                 return true; // don't care about $rtt
4032                         }
4033                 }
4034
4035                 // This will reconnect if possible or return false if not
4036                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4037                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
4038                 $this->restoreFlags( self::RESTORE_PRIOR );
4039
4040                 if ( $ok ) {
4041                         $rtt = $this->rttEstimate;
4042                 }
4043
4044                 return $ok;
4045         }
4046
4047         /**
4048          * Close any existing (dead) database connection and open a new connection
4049          *
4050          * @param string $fname
4051          * @return bool True if new connection is opened successfully, false if error
4052          */
4053         protected function replaceLostConnection( $fname ) {
4054                 $this->closeConnection();
4055                 $this->opened = false;
4056                 $this->conn = false;
4057                 try {
4058                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4059                         $this->lastPing = microtime( true );
4060                         $ok = true;
4061
4062                         $this->connLogger->warning(
4063                                 $fname . ': lost connection to {dbserver}; reconnected',
4064                                 [
4065                                         'dbserver' => $this->getServer(),
4066                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4067                                 ]
4068                         );
4069                 } catch ( DBConnectionError $e ) {
4070                         $ok = false;
4071
4072                         $this->connLogger->error(
4073                                 $fname . ': lost connection to {dbserver} permanently',
4074                                 [ 'dbserver' => $this->getServer() ]
4075                         );
4076                 }
4077
4078                 $this->handleSessionLoss();
4079
4080                 return $ok;
4081         }
4082
4083         public function getSessionLagStatus() {
4084                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4085         }
4086
4087         /**
4088          * Get the replica DB lag when the current transaction started
4089          *
4090          * This is useful when transactions might use snapshot isolation
4091          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4092          * is this lag plus transaction duration. If they don't, it is still
4093          * safe to be pessimistic. This returns null if there is no transaction.
4094          *
4095          * This returns null if the lag status for this transaction was not yet recorded.
4096          *
4097          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4098          * @since 1.27
4099          */
4100         final protected function getRecordedTransactionLagStatus() {
4101                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4102                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4103                         : null;
4104         }
4105
4106         /**
4107          * Get a replica DB lag estimate for this server
4108          *
4109          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4110          * @since 1.27
4111          */
4112         protected function getApproximateLagStatus() {
4113                 return [
4114                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4115                         'since' => microtime( true )
4116                 ];
4117         }
4118
4119         /**
4120          * Merge the result of getSessionLagStatus() for several DBs
4121          * using the most pessimistic values to estimate the lag of
4122          * any data derived from them in combination
4123          *
4124          * This is information is useful for caching modules
4125          *
4126          * @see WANObjectCache::set()
4127          * @see WANObjectCache::getWithSetCallback()
4128          *
4129          * @param IDatabase $db1
4130          * @param IDatabase $db2 [optional]
4131          * @return array Map of values:
4132          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4133          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4134          *   - pending: whether any of the DBs have uncommitted changes
4135          * @throws DBError
4136          * @since 1.27
4137          */
4138         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4139                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4140                 foreach ( func_get_args() as $db ) {
4141                         /** @var IDatabase $db */
4142                         $status = $db->getSessionLagStatus();
4143                         if ( $status['lag'] === false ) {
4144                                 $res['lag'] = false;
4145                         } elseif ( $res['lag'] !== false ) {
4146                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4147                         }
4148                         $res['since'] = min( $res['since'], $status['since'] );
4149                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4150                 }
4151
4152                 return $res;
4153         }
4154
4155         public function getLag() {
4156                 return 0;
4157         }
4158
4159         public function maxListLen() {
4160                 return 0;
4161         }
4162
4163         public function encodeBlob( $b ) {
4164                 return $b;
4165         }
4166
4167         public function decodeBlob( $b ) {
4168                 if ( $b instanceof Blob ) {
4169                         $b = $b->fetch();
4170                 }
4171                 return $b;
4172         }
4173
4174         public function setSessionOptions( array $options ) {
4175         }
4176
4177         public function sourceFile(
4178                 $filename,
4179                 callable $lineCallback = null,
4180                 callable $resultCallback = null,
4181                 $fname = false,
4182                 callable $inputCallback = null
4183         ) {
4184                 Wikimedia\suppressWarnings();
4185                 $fp = fopen( $filename, 'r' );
4186                 Wikimedia\restoreWarnings();
4187
4188                 if ( false === $fp ) {
4189                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4190                 }
4191
4192                 if ( !$fname ) {
4193                         $fname = __METHOD__ . "( $filename )";
4194                 }
4195
4196                 try {
4197                         $error = $this->sourceStream(
4198                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4199                 } catch ( Exception $e ) {
4200                         fclose( $fp );
4201                         throw $e;
4202                 }
4203
4204                 fclose( $fp );
4205
4206                 return $error;
4207         }
4208
4209         public function setSchemaVars( $vars ) {
4210                 $this->schemaVars = $vars;
4211         }
4212
4213         public function sourceStream(
4214                 $fp,
4215                 callable $lineCallback = null,
4216                 callable $resultCallback = null,
4217                 $fname = __METHOD__,
4218                 callable $inputCallback = null
4219         ) {
4220                 $delimiterReset = new ScopedCallback(
4221                         function ( $delimiter ) {
4222                                 $this->delimiter = $delimiter;
4223                         },
4224                         [ $this->delimiter ]
4225                 );
4226                 $cmd = '';
4227
4228                 while ( !feof( $fp ) ) {
4229                         if ( $lineCallback ) {
4230                                 call_user_func( $lineCallback );
4231                         }
4232
4233                         $line = trim( fgets( $fp ) );
4234
4235                         if ( $line == '' ) {
4236                                 continue;
4237                         }
4238
4239                         if ( '-' == $line[0] && '-' == $line[1] ) {
4240                                 continue;
4241                         }
4242
4243                         if ( $cmd != '' ) {
4244                                 $cmd .= ' ';
4245                         }
4246
4247                         $done = $this->streamStatementEnd( $cmd, $line );
4248
4249                         $cmd .= "$line\n";
4250
4251                         if ( $done || feof( $fp ) ) {
4252                                 $cmd = $this->replaceVars( $cmd );
4253
4254                                 if ( $inputCallback ) {
4255                                         $callbackResult = call_user_func( $inputCallback, $cmd );
4256
4257                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4258                                                 $cmd = $callbackResult;
4259                                         }
4260                                 }
4261
4262                                 if ( $cmd ) {
4263                                         $res = $this->query( $cmd, $fname );
4264
4265                                         if ( $resultCallback ) {
4266                                                 call_user_func( $resultCallback, $res, $this );
4267                                         }
4268
4269                                         if ( false === $res ) {
4270                                                 $err = $this->lastError();
4271
4272                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4273                                         }
4274                                 }
4275                                 $cmd = '';
4276                         }
4277                 }
4278
4279                 ScopedCallback::consume( $delimiterReset );
4280                 return true;
4281         }
4282
4283         /**
4284          * Called by sourceStream() to check if we've reached a statement end
4285          *
4286          * @param string &$sql SQL assembled so far
4287          * @param string &$newLine New line about to be added to $sql
4288          * @return bool Whether $newLine contains end of the statement
4289          */
4290         public function streamStatementEnd( &$sql, &$newLine ) {
4291                 if ( $this->delimiter ) {
4292                         $prev = $newLine;
4293                         $newLine = preg_replace(
4294                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4295                         if ( $newLine != $prev ) {
4296                                 return true;
4297                         }
4298                 }
4299
4300                 return false;
4301         }
4302
4303         /**
4304          * Database independent variable replacement. Replaces a set of variables
4305          * in an SQL statement with their contents as given by $this->getSchemaVars().
4306          *
4307          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4308          *
4309          * - '{$var}' should be used for text and is passed through the database's
4310          *   addQuotes method.
4311          * - `{$var}` should be used for identifiers (e.g. table and database names).
4312          *   It is passed through the database's addIdentifierQuotes method which
4313          *   can be overridden if the database uses something other than backticks.
4314          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4315          *   database's tableName method.
4316          * - / *i* / passes the name that follows through the database's indexName method.
4317          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4318          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4319          *
4320          * @param string $ins SQL statement to replace variables in
4321          * @return string The new SQL statement with variables replaced
4322          */
4323         protected function replaceVars( $ins ) {
4324                 $vars = $this->getSchemaVars();
4325                 return preg_replace_callback(
4326                         '!
4327                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4328                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4329                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4330                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4331                         !x',
4332                         function ( $m ) use ( $vars ) {
4333                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4334                                 // check for both nonexistent keys *and* the empty string.
4335                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4336                                         if ( $m[1] === 'i' ) {
4337                                                 return $this->indexName( $m[2] );
4338                                         } else {
4339                                                 return $this->tableName( $m[2] );
4340                                         }
4341                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4342                                         return $this->addQuotes( $vars[$m[3]] );
4343                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4344                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4345                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4346                                         return $vars[$m[5]];
4347                                 } else {
4348                                         return $m[0];
4349                                 }
4350                         },
4351                         $ins
4352                 );
4353         }
4354
4355         /**
4356          * Get schema variables. If none have been set via setSchemaVars(), then
4357          * use some defaults from the current object.
4358          *
4359          * @return array
4360          */
4361         protected function getSchemaVars() {
4362                 if ( $this->schemaVars ) {
4363                         return $this->schemaVars;
4364                 } else {
4365                         return $this->getDefaultSchemaVars();
4366                 }
4367         }
4368
4369         /**
4370          * Get schema variables to use if none have been set via setSchemaVars().
4371          *
4372          * Override this in derived classes to provide variables for tables.sql
4373          * and SQL patch files.
4374          *
4375          * @return array
4376          */
4377         protected function getDefaultSchemaVars() {
4378                 return [];
4379         }
4380
4381         public function lockIsFree( $lockName, $method ) {
4382                 // RDBMs methods for checking named locks may or may not count this thread itself.
4383                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4384                 // the behavior choosen by the interface for this method.
4385                 return !isset( $this->namedLocksHeld[$lockName] );
4386         }
4387
4388         public function lock( $lockName, $method, $timeout = 5 ) {
4389                 $this->namedLocksHeld[$lockName] = 1;
4390
4391                 return true;
4392         }
4393
4394         public function unlock( $lockName, $method ) {
4395                 unset( $this->namedLocksHeld[$lockName] );
4396
4397                 return true;
4398         }
4399
4400         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4401                 if ( $this->writesOrCallbacksPending() ) {
4402                         // This only flushes transactions to clear snapshots, not to write data
4403                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4404                         throw new DBUnexpectedError(
4405                                 $this,
4406                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4407                         );
4408                 }
4409
4410                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4411                         return null;
4412                 }
4413
4414                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4415                         if ( $this->trxLevel() ) {
4416                                 // There is a good chance an exception was thrown, causing any early return
4417                                 // from the caller. Let any error handler get a chance to issue rollback().
4418                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4419                                 $this->onTransactionResolution(
4420                                         function () use ( $lockKey, $fname ) {
4421                                                 $this->unlock( $lockKey, $fname );
4422                                         },
4423                                         $fname
4424                                 );
4425                         } else {
4426                                 $this->unlock( $lockKey, $fname );
4427                         }
4428                 } );
4429
4430                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4431
4432                 return $unlocker;
4433         }
4434
4435         public function namedLocksEnqueue() {
4436                 return false;
4437         }
4438
4439         public function tableLocksHaveTransactionScope() {
4440                 return true;
4441         }
4442
4443         final public function lockTables( array $read, array $write, $method ) {
4444                 if ( $this->writesOrCallbacksPending() ) {
4445                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4446                 }
4447
4448                 if ( $this->tableLocksHaveTransactionScope() ) {
4449                         $this->startAtomic( $method );
4450                 }
4451
4452                 return $this->doLockTables( $read, $write, $method );
4453         }
4454
4455         /**
4456          * Helper function for lockTables() that handles the actual table locking
4457          *
4458          * @param array $read Array of tables to lock for read access
4459          * @param array $write Array of tables to lock for write access
4460          * @param string $method Name of caller
4461          * @return true
4462          */
4463         protected function doLockTables( array $read, array $write, $method ) {
4464                 return true;
4465         }
4466
4467         final public function unlockTables( $method ) {
4468                 if ( $this->tableLocksHaveTransactionScope() ) {
4469                         $this->endAtomic( $method );
4470
4471                         return true; // locks released on COMMIT/ROLLBACK
4472                 }
4473
4474                 return $this->doUnlockTables( $method );
4475         }
4476
4477         /**
4478          * Helper function for unlockTables() that handles the actual table unlocking
4479          *
4480          * @param string $method Name of caller
4481          * @return true
4482          */
4483         protected function doUnlockTables( $method ) {
4484                 return true;
4485         }
4486
4487         /**
4488          * Delete a table
4489          * @param string $tableName
4490          * @param string $fName
4491          * @return bool|ResultWrapper
4492          * @since 1.18
4493          */
4494         public function dropTable( $tableName, $fName = __METHOD__ ) {
4495                 if ( !$this->tableExists( $tableName, $fName ) ) {
4496                         return false;
4497                 }
4498                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4499
4500                 return $this->query( $sql, $fName );
4501         }
4502
4503         public function getInfinity() {
4504                 return 'infinity';
4505         }
4506
4507         public function encodeExpiry( $expiry ) {
4508                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4509                         ? $this->getInfinity()
4510                         : $this->timestamp( $expiry );
4511         }
4512
4513         public function decodeExpiry( $expiry, $format = TS_MW ) {
4514                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4515                         return 'infinity';
4516                 }
4517
4518                 return ConvertibleTimestamp::convert( $format, $expiry );
4519         }
4520
4521         public function setBigSelects( $value = true ) {
4522                 // no-op
4523         }
4524
4525         public function isReadOnly() {
4526                 return ( $this->getReadOnlyReason() !== false );
4527         }
4528
4529         /**
4530          * @return string|bool Reason this DB is read-only or false if it is not
4531          */
4532         protected function getReadOnlyReason() {
4533                 $reason = $this->getLBInfo( 'readOnlyReason' );
4534
4535                 return is_string( $reason ) ? $reason : false;
4536         }
4537
4538         public function setTableAliases( array $aliases ) {
4539                 $this->tableAliases = $aliases;
4540         }
4541
4542         public function setIndexAliases( array $aliases ) {
4543                 $this->indexAliases = $aliases;
4544         }
4545
4546         /**
4547          * Get the underlying binding connection handle
4548          *
4549          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4550          * This catches broken callers than catch and ignore disconnection exceptions.
4551          * Unlike checking isOpen(), this is safe to call inside of open().
4552          *
4553          * @return mixed
4554          * @throws DBUnexpectedError
4555          * @since 1.26
4556          */
4557         protected function getBindingHandle() {
4558                 if ( !$this->conn ) {
4559                         throw new DBUnexpectedError(
4560                                 $this,
4561                                 'DB connection was already closed or the connection dropped.'
4562                         );
4563                 }
4564
4565                 return $this->conn;
4566         }
4567
4568         /**
4569          * @since 1.19
4570          * @return string
4571          */
4572         public function __toString() {
4573                 return (string)$this->conn;
4574         }
4575
4576         /**
4577          * Make sure that copies do not share the same client binding handle
4578          * @throws DBConnectionError
4579          */
4580         public function __clone() {
4581                 $this->connLogger->warning(
4582                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
4583                         ( new RuntimeException() )->getTraceAsString()
4584                 );
4585
4586                 if ( $this->isOpen() ) {
4587                         // Open a new connection resource without messing with the old one
4588                         $this->opened = false;
4589                         $this->conn = false;
4590                         $this->trxEndCallbacks = []; // don't copy
4591                         $this->handleSessionLoss(); // no trx or locks anymore
4592                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4593                         $this->lastPing = microtime( true );
4594                 }
4595         }
4596
4597         /**
4598          * Called by serialize. Throw an exception when DB connection is serialized.
4599          * This causes problems on some database engines because the connection is
4600          * not restored on unserialize.
4601          */
4602         public function __sleep() {
4603                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4604                         'the connection is not restored on wakeup.' );
4605         }
4606
4607         /**
4608          * Run a few simple sanity checks and close dangling connections
4609          */
4610         public function __destruct() {
4611                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4612                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4613                 }
4614
4615                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4616                 if ( $danglingWriters ) {
4617                         $fnames = implode( ', ', $danglingWriters );
4618                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4619                 }
4620
4621                 if ( $this->conn ) {
4622                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4623                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4624                         Wikimedia\suppressWarnings();
4625                         $this->closeConnection();
4626                         Wikimedia\restoreWarnings();
4627                         $this->conn = false;
4628                         $this->opened = false;
4629                 }
4630         }
4631 }
4632
4633 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
4634 class_alias( Database::class, 'Database' ); // b/c global alias