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
 105         /** @var resource|null Database connection */
 106         protected $conn = null;
 107         /** @var bool */
 108         protected $opened = false;
 109
 110         /** @var array[] List of (callable, method name) */
 111         protected $trxIdleCallbacks = [];
 112         /** @var array[] List of (callable, method name) */
 113         protected $trxPreCommitCallbacks = [];
 114         /** @var array[] List of (callable, method name) */
 115         protected $trxEndCallbacks = [];
 116         /** @var callable[] Map of (name => callable) */
 117         protected $trxRecurringCallbacks = [];
 118         /** @var bool Whether to suppress triggering of transaction end callbacks */
 119         protected $trxEndCallbacksSuppressed = false;
 120
 121         /** @var string */
 122         protected $tablePrefix = '';
 123         /** @var string */
 124         protected $schema = '';
 125         /** @var int */
 126         protected $flags;
 127         /** @var array */
 128         protected $lbInfo = [];
 129         /** @var array|bool */
 130         protected $schemaVars = false;
 131         /** @var array */
 132         protected $sessionVars = [];
 133         /** @var array|null */
 134         protected $preparedArgs;
 135         /** @var string|bool|null Stashed value of html_errors INI setting */
 136         protected $htmlErrors;
 137         /** @var string */
 138         protected $delimiter = ';';
 139         /** @var DatabaseDomain */
 140         protected $currentDomain;
 141         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 142         protected $affectedRowCount;
 143
 144         /**
 145          * @var int Transaction status
 146          */
 147         protected $trxStatus = self::STATUS_TRX_NONE;
 148         /**
 149          * @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR
 150          */
 151         protected $trxStatusCause;
 152         /**
 153          * Either 1 if a transaction is active or 0 otherwise.
 154          * The other Trx fields may not be meaningfull if this is 0.
 155          *
 156          * @var int
 157          */
 158         protected $trxLevel = 0;
 159         /**
 160          * Either a short hexidecimal string if a transaction is active or ""
 161          *
 162          * @var string
 163          * @see Database::trxLevel
 164          */
 165         protected $trxShortId = '';
 166         /**
 167          * The UNIX time that the transaction started. Callers can assume that if
 168          * snapshot isolation is used, then the data is *at least* up to date to that
 169          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 170          *
 171          * @var float|null
 172          * @see Database::trxLevel
 173          */
 174         private $trxTimestamp = null;
 175         /** @var float Lag estimate at the time of BEGIN */
 176         private $trxReplicaLag = null;
 177         /**
 178          * Remembers the function name given for starting the most recent transaction via begin().
 179          * Used to provide additional context for error reporting.
 180          *
 181          * @var string
 182          * @see Database::trxLevel
 183          */
 184         private $trxFname = null;
 185         /**
 186          * Record if possible write queries were done in the last transaction started
 187          *
 188          * @var bool
 189          * @see Database::trxLevel
 190          */
 191         private $trxDoneWrites = false;
 192         /**
 193          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 194          *
 195          * @var bool
 196          * @see Database::trxLevel
 197          */
 198         private $trxAutomatic = false;
 199         /**
 200          * Counter for atomic savepoint identifiers. Reset when a new transaction begins.
 201          *
 202          * @var int
 203          */
 204         private $trxAtomicCounter = 0;
 205         /**
 206          * Array of levels of atomicity within transactions
 207          *
 208          * @var array
 209          */
 210         private $trxAtomicLevels = [];
 211         /**
 212          * Record if the current transaction was started implicitly by Database::startAtomic
 213          *
 214          * @var bool
 215          */
 216         private $trxAutomaticAtomic = false;
 217         /**
 218          * Track the write query callers of the current transaction
 219          *
 220          * @var string[]
 221          */
 222         private $trxWriteCallers = [];
 223         /**
 224          * @var float Seconds spent in write queries for the current transaction
 225          */
 226         private $trxWriteDuration = 0.0;
 227         /**
 228          * @var int Number of write queries for the current transaction
 229          */
 230         private $trxWriteQueryCount = 0;
 231         /**
 232          * @var int Number of rows affected by write queries for the current transaction
 233          */
 234         private $trxWriteAffectedRows = 0;
 235         /**
 236          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 237          */
 238         private $trxWriteAdjDuration = 0.0;
 239         /**
 240          * @var int Number of write queries counted in trxWriteAdjDuration
 241          */
 242         private $trxWriteAdjQueryCount = 0;
 243         /**
 244          * @var float RTT time estimate
 245          */
 246         private $rttEstimate = 0.0;
 247
 248         /** @var array Map of (name => 1) for locks obtained via lock() */
 249         private $namedLocksHeld = [];
 250         /** @var array Map of (table name => 1) for TEMPORARY tables */
 251         protected $sessionTempTables = [];
 252
 253         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 254         private $lazyMasterHandle;
 255
 256         /** @var float UNIX timestamp */
 257         protected $lastPing = 0.0;
 258
 259         /** @var int[] Prior flags member variable values */
 260         private $priorFlags = [];
 261
 262         /** @var object|string Class name or object With profileIn/profileOut methods */
 263         protected $profiler;
 264         /** @var TransactionProfiler */
 265         protected $trxProfiler;
 266
 267         /** @var int */
 268         protected $nonNativeInsertSelectBatchSize = 10000;
 269
 270         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 271         const STATUS_TRX_ERROR = 1;
 272         /** @var int Transaction is active and in a normal state */
 273         const STATUS_TRX_OK = 2;
 274         /** @var int No transaction is active */
 275         const STATUS_TRX_NONE = 3;
 276
 277         /**
 278          * @note: exceptions for missing libraries/drivers should be thrown in initConnection()
 279          * @param array $params Parameters passed from Database::factory()
 280          */
 281         protected function __construct( array $params ) {
 282                 foreach ( [ 'host', 'user', 'password', 'dbname' ] as $name ) {
 283                         $this->connectionParams[$name] = $params[$name];
 284                 }
 285
 286                 $this->schema = $params['schema'];
 287                 $this->tablePrefix = $params['tablePrefix'];
 288
 289                 $this->cliMode = $params['cliMode'];
 290                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 291                 $this->agent = str_replace( '/', '-', $params['agent'] );
 292
 293                 $this->flags = $params['flags'];
 294                 if ( $this->flags & self::DBO_DEFAULT ) {
 295                         if ( $this->cliMode ) {
 296                                 $this->flags &= ~self::DBO_TRX;
 297                         } else {
 298                                 $this->flags |= self::DBO_TRX;
 299                         }
 300                 }
 301                 // Disregard deprecated DBO_IGNORE flag (T189999)
 302                 $this->flags &= ~self::DBO_IGNORE;
 303
 304                 $this->sessionVars = $params['variables'];
 305
 306                 $this->srvCache = isset( $params['srvCache'] )
 307                         ? $params['srvCache']
 308                         : new HashBagOStuff();
 309
 310                 $this->profiler = $params['profiler'];
 311                 $this->trxProfiler = $params['trxProfiler'];
 312                 $this->connLogger = $params['connLogger'];
 313                 $this->queryLogger = $params['queryLogger'];
 314                 $this->errorLogger = $params['errorLogger'];
 315
 316                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 317                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 318                 }
 319
 320                 // Set initial dummy domain until open() sets the final DB/prefix
 321                 $this->currentDomain = DatabaseDomain::newUnspecified();
 322         }
 323
 324         /**
 325          * Initialize the connection to the database over the wire (or to local files)
 326          *
 327          * @throws LogicException
 328          * @throws InvalidArgumentException
 329          * @throws DBConnectionError
 330          * @since 1.31
 331          */
 332         final public function initConnection() {
 333                 if ( $this->isOpen() ) {
 334                         throw new LogicException( __METHOD__ . ': already connected.' );
 335                 }
 336                 // Establish the connection
 337                 $this->doInitConnection();
 338                 // Set the domain object after open() sets the relevant fields
 339                 if ( $this->dbName != '' ) {
 340                         // Domains with server scope but a table prefix are not used by IDatabase classes
 341                         $this->currentDomain = new DatabaseDomain( $this->dbName, null, $this->tablePrefix );
 342                 }
 343         }
 344
 345         /**
 346          * Actually connect to the database over the wire (or to local files)
 347          *
 348          * @throws InvalidArgumentException
 349          * @throws DBConnectionError
 350          * @since 1.31
 351          */
 352         protected function doInitConnection() {
 353                 if ( strlen( $this->connectionParams['user'] ) ) {
 354                         $this->open(
 355                                 $this->connectionParams['host'],
 356                                 $this->connectionParams['user'],
 357                                 $this->connectionParams['password'],
 358                                 $this->connectionParams['dbname']
 359                         );
 360                 } else {
 361                         throw new InvalidArgumentException( "No database user provided." );
 362                 }
 363         }
 364
 365         /**
 366          * Construct a Database subclass instance given a database type and parameters
 367          *
 368          * This also connects to the database immediately upon object construction
 369          *
 370          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 371          * @param array $p Parameter map with keys:
 372          *   - host : The hostname of the DB server
 373          *   - user : The name of the database user the client operates under
 374          *   - password : The password for the database user
 375          *   - dbname : The name of the database to use where queries do not specify one.
 376          *      The database must exist or an error might be thrown. Setting this to the empty string
 377          *      will avoid any such errors and make the handle have no implicit database scope. This is
 378          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 379          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 380          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 381          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 382          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 383          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 384          *      recognized in queries. This can be used in place of schemas for handle site farms.
 385          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 386          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 387          *      flag in place UNLESS this this database simply acts as a key/value store.
 388          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 389          *      'mysqli' driver; the old one 'mysql' has been removed.
 390          *   - variables: Optional map of session variables to set after connecting. This can be
 391          *      used to adjust lock timeouts or encoding modes and the like.
 392          *   - connLogger: Optional PSR-3 logger interface instance.
 393          *   - queryLogger: Optional PSR-3 logger interface instance.
 394          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 395          *      These will be called in query(), using a simplified version of the SQL that also
 396          *      includes the agent as a SQL comment.
 397          *   - trxProfiler: Optional TransactionProfiler instance.
 398          *   - errorLogger: Optional callback that takes an Exception and logs it.
 399          *   - cliMode: Whether to consider the execution context that of a CLI script.
 400          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 401          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 402          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 403          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 404          * @return Database|null If the database driver or extension cannot be found
 405          * @throws InvalidArgumentException If the database driver or extension cannot be found
 406          * @since 1.18
 407          */
 408         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 409                 $class = self::getClass( $dbType, isset( $p['driver'] ) ? $p['driver'] : null );
 410
 411                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 412                         // Resolve some defaults for b/c
 413                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 414                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 415                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 416                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 417                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 418                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 419                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 420                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 421                         $p['cliMode'] = isset( $p['cliMode'] )
 422                                 ? $p['cliMode']
 423                                 : ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 424                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 425                         if ( !isset( $p['connLogger'] ) ) {
 426                                 $p['connLogger'] = new NullLogger();
 427                         }
 428                         if ( !isset( $p['queryLogger'] ) ) {
 429                                 $p['queryLogger'] = new NullLogger();
 430                         }
 431                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 432                         if ( !isset( $p['trxProfiler'] ) ) {
 433                                 $p['trxProfiler'] = new TransactionProfiler();
 434                         }
 435                         if ( !isset( $p['errorLogger'] ) ) {
 436                                 $p['errorLogger'] = function ( Exception $e ) {
 437                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 438                                 };
 439                         }
 440
 441                         /** @var Database $conn */
 442                         $conn = new $class( $p );
 443                         if ( $connect == self::NEW_CONNECTED ) {
 444                                 $conn->initConnection();
 445                         }
 446                 } else {
 447                         $conn = null;
 448                 }
 449
 450                 return $conn;
 451         }
 452
 453         /**
 454          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 455          * @param string|null $driver Optional name of a specific DB client driver
 456          * @return array Map of (Database::ATTRIBUTE_* constant => value) for all such constants
 457          * @throws InvalidArgumentException
 458          * @since 1.31
 459          */
 460         final public static function attributesFromType( $dbType, $driver = null ) {
 461                 static $defaults = [ self::ATTR_DB_LEVEL_LOCKING => false ];
 462
 463                 $class = self::getClass( $dbType, $driver );
 464
 465                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 466         }
 467
 468         /**
 469          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 470          * @param string|null $driver Optional name of a specific DB client driver
 471          * @return string Database subclass name to use
 472          * @throws InvalidArgumentException
 473          */
 474         private static function getClass( $dbType, $driver = null ) {
 475                 // For database types with built-in support, the below maps type to IDatabase
 476                 // implementations. For types with multipe driver implementations (PHP extensions),
 477                 // an array can be used, keyed by extension name. In case of an array, the
 478                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 479                 // we auto-detect the first available driver. For types without built-in support,
 480                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 481                 static $builtinTypes = [
 482                         'mssql' => DatabaseMssql::class,
 483                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 484                         'sqlite' => DatabaseSqlite::class,
 485                         'postgres' => DatabasePostgres::class,
 486                 ];
 487
 488                 $dbType = strtolower( $dbType );
 489                 $class = false;
 490
 491                 if ( isset( $builtinTypes[$dbType] ) ) {
 492                         $possibleDrivers = $builtinTypes[$dbType];
 493                         if ( is_string( $possibleDrivers ) ) {
 494                                 $class = $possibleDrivers;
 495                         } else {
 496                                 if ( (string)$driver !== '' ) {
 497                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 498                                                 throw new InvalidArgumentException( __METHOD__ .
 499                                                         " type '$dbType' does not support driver '{$driver}'" );
 500                                         } else {
 501                                                 $class = $possibleDrivers[$driver];
 502                                         }
 503                                 } else {
 504                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 505                                                 if ( extension_loaded( $posDriver ) ) {
 506                                                         $class = $possibleClass;
 507                                                         break;
 508                                                 }
 509                                         }
 510                                 }
 511                         }
 512                 } else {
 513                         $class = 'Database' . ucfirst( $dbType );
 514                 }
 515
 516                 if ( $class === false ) {
 517                         throw new InvalidArgumentException( __METHOD__ .
 518                                 " no viable database extension found for type '$dbType'" );
 519                 }
 520
 521                 return $class;
 522         }
 523
 524         /**
 525          * @return array Map of (Database::ATTRIBUTE_* constant => value
 526          * @since 1.31
 527          */
 528         protected static function getAttributes() {
 529                 return [];
 530         }
 531
 532         /**
 533          * Set the PSR-3 logger interface to use for query logging. (The logger
 534          * interfaces for connection logging and error logging can be set with the
 535          * constructor.)
 536          *
 537          * @param LoggerInterface $logger
 538          */
 539         public function setLogger( LoggerInterface $logger ) {
 540                 $this->queryLogger = $logger;
 541         }
 542
 543         public function getServerInfo() {
 544                 return $this->getServerVersion();
 545         }
 546
 547         public function bufferResults( $buffer = null ) {
 548                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 549                 if ( $buffer !== null ) {
 550                         $buffer
 551                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 552                                 : $this->setFlag( self::DBO_NOBUFFER );
 553                 }
 554
 555                 return $res;
 556         }
 557
 558         public function trxLevel() {
 559                 return $this->trxLevel;
 560         }
 561
 562         public function trxTimestamp() {
 563                 return $this->trxLevel ? $this->trxTimestamp : null;
 564         }
 565
 566         /**
 567          * @return int One of the STATUS_TRX_* class constants
 568          * @since 1.31
 569          */
 570         public function trxStatus() {
 571                 return $this->trxStatus;
 572         }
 573
 574         public function tablePrefix( $prefix = null ) {
 575                 $old = $this->tablePrefix;
 576                 if ( $prefix !== null ) {
 577                         $this->tablePrefix = $prefix;
 578                         $this->currentDomain = ( $this->dbName != '' )
 579                                 ? new DatabaseDomain( $this->dbName, null, $this->tablePrefix )
 580                                 : DatabaseDomain::newUnspecified();
 581                 }
 582
 583                 return $old;
 584         }
 585
 586         public function dbSchema( $schema = null ) {
 587                 $old = $this->schema;
 588                 if ( $schema !== null ) {
 589                         $this->schema = $schema;
 590                 }
 591
 592                 return $old;
 593         }
 594
 595         public function getLBInfo( $name = null ) {
 596                 if ( is_null( $name ) ) {
 597                         return $this->lbInfo;
 598                 } else {
 599                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 600                                 return $this->lbInfo[$name];
 601                         } else {
 602                                 return null;
 603                         }
 604                 }
 605         }
 606
 607         public function setLBInfo( $name, $value = null ) {
 608                 if ( is_null( $value ) ) {
 609                         $this->lbInfo = $name;
 610                 } else {
 611                         $this->lbInfo[$name] = $value;
 612                 }
 613         }
 614
 615         public function setLazyMasterHandle( IDatabase $conn ) {
 616                 $this->lazyMasterHandle = $conn;
 617         }
 618
 619         /**
 620          * @return IDatabase|null
 621          * @see setLazyMasterHandle()
 622          * @since 1.27
 623          */
 624         protected function getLazyMasterHandle() {
 625                 return $this->lazyMasterHandle;
 626         }
 627
 628         public function implicitGroupby() {
 629                 return true;
 630         }
 631
 632         public function implicitOrderby() {
 633                 return true;
 634         }
 635
 636         public function lastQuery() {
 637                 return $this->lastQuery;
 638         }
 639
 640         public function doneWrites() {
 641                 return (bool)$this->lastWriteTime;
 642         }
 643
 644         public function lastDoneWrites() {
 645                 return $this->lastWriteTime ?: false;
 646         }
 647
 648         public function writesPending() {
 649                 return $this->trxLevel && $this->trxDoneWrites;
 650         }
 651
 652         public function writesOrCallbacksPending() {
 653                 return $this->trxLevel && (
 654                         $this->trxDoneWrites ||
 655                         $this->trxIdleCallbacks ||
 656                         $this->trxPreCommitCallbacks ||
 657                         $this->trxEndCallbacks
 658                 );
 659         }
 660
 661         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 662                 if ( !$this->trxLevel ) {
 663                         return false;
 664                 } elseif ( !$this->trxDoneWrites ) {
 665                         return 0.0;
 666                 }
 667
 668                 switch ( $type ) {
 669                         case self::ESTIMATE_DB_APPLY:
 670                                 $this->ping( $rtt );
 671                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 672                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 673                                 // For omitted queries, make them count as something at least
 674                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 675                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 676
 677                                 return $applyTime;
 678                         default: // everything
 679                                 return $this->trxWriteDuration;
 680                 }
 681         }
 682
 683         public function pendingWriteCallers() {
 684                 return $this->trxLevel ? $this->trxWriteCallers : [];
 685         }
 686
 687         public function pendingWriteRowsAffected() {
 688                 return $this->trxWriteAffectedRows;
 689         }
 690
 691         /**
 692          * Get the list of method names that have pending write queries or callbacks
 693          * for this transaction
 694          *
 695          * @return array
 696          */
 697         protected function pendingWriteAndCallbackCallers() {
 698                 if ( !$this->trxLevel ) {
 699                         return [];
 700                 }
 701
 702                 $fnames = $this->trxWriteCallers;
 703                 foreach ( [
 704                         $this->trxIdleCallbacks,
 705                         $this->trxPreCommitCallbacks,
 706                         $this->trxEndCallbacks
 707                 ] as $callbacks ) {
 708                         foreach ( $callbacks as $callback ) {
 709                                 $fnames[] = $callback[1];
 710                         }
 711                 }
 712
 713                 return $fnames;
 714         }
 715
 716         /**
 717          * @return string
 718          */
 719         private function flatAtomicSectionList() {
 720                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 721                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 722                 } );
 723         }
 724
 725         public function isOpen() {
 726                 return $this->opened;
 727         }
 728
 729         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 730                 if ( ( $flag & self::DBO_IGNORE ) ) {
 731                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 732                 }
 733
 734                 if ( $remember === self::REMEMBER_PRIOR ) {
 735                         array_push( $this->priorFlags, $this->flags );
 736                 }
 737                 $this->flags |= $flag;
 738         }
 739
 740         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 741                 if ( ( $flag & self::DBO_IGNORE ) ) {
 742                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 743                 }
 744
 745                 if ( $remember === self::REMEMBER_PRIOR ) {
 746                         array_push( $this->priorFlags, $this->flags );
 747                 }
 748                 $this->flags &= ~$flag;
 749         }
 750
 751         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 752                 if ( !$this->priorFlags ) {
 753                         return;
 754                 }
 755
 756                 if ( $state === self::RESTORE_INITIAL ) {
 757                         $this->flags = reset( $this->priorFlags );
 758                         $this->priorFlags = [];
 759                 } else {
 760                         $this->flags = array_pop( $this->priorFlags );
 761                 }
 762         }
 763
 764         public function getFlag( $flag ) {
 765                 return !!( $this->flags & $flag );
 766         }
 767
 768         /**
 769          * @param string $name Class field name
 770          * @return mixed
 771          * @deprecated Since 1.28
 772          */
 773         public function getProperty( $name ) {
 774                 return $this->$name;
 775         }
 776
 777         public function getDomainID() {
 778                 return $this->currentDomain->getId();
 779         }
 780
 781         final public function getWikiID() {
 782                 return $this->getDomainID();
 783         }
 784
 785         /**
 786          * Get information about an index into an object
 787          * @param string $table Table name
 788          * @param string $index Index name
 789          * @param string $fname Calling function name
 790          * @return mixed Database-specific index description class or false if the index does not exist
 791          */
 792         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 793
 794         /**
 795          * Wrapper for addslashes()
 796          *
 797          * @param string $s String to be slashed.
 798          * @return string Slashed string.
 799          */
 800         abstract function strencode( $s );
 801
 802         /**
 803          * Set a custom error handler for logging errors during database connection
 804          */
 805         protected function installErrorHandler() {
 806                 $this->phpError = false;
 807                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 808                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 809         }
 810
 811         /**
 812          * Restore the previous error handler and return the last PHP error for this DB
 813          *
 814          * @return bool|string
 815          */
 816         protected function restoreErrorHandler() {
 817                 restore_error_handler();
 818                 if ( $this->htmlErrors !== false ) {
 819                         ini_set( 'html_errors', $this->htmlErrors );
 820                 }
 821
 822                 return $this->getLastPHPError();
 823         }
 824
 825         /**
 826          * @return string|bool Last PHP error for this DB (typically connection errors)
 827          */
 828         protected function getLastPHPError() {
 829                 if ( $this->phpError ) {
 830                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 831                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 832
 833                         return $error;
 834                 }
 835
 836                 return false;
 837         }
 838
 839         /**
 840          * Error handler for logging errors during database connection
 841          * This method should not be used outside of Database classes
 842          *
 843          * @param int $errno
 844          * @param string $errstr
 845          */
 846         public function connectionErrorLogger( $errno, $errstr ) {
 847                 $this->phpError = $errstr;
 848         }
 849
 850         /**
 851          * Create a log context to pass to PSR-3 logger functions.
 852          *
 853          * @param array $extras Additional data to add to context
 854          * @return array
 855          */
 856         protected function getLogContext( array $extras = [] ) {
 857                 return array_merge(
 858                         [
 859                                 'db_server' => $this->server,
 860                                 'db_name' => $this->dbName,
 861                                 'db_user' => $this->user,
 862                         ],
 863                         $extras
 864                 );
 865         }
 866
 867         final public function close() {
 868                 $exception = null; // error to throw after disconnecting
 869
 870                 if ( $this->conn ) {
 871                         // Resolve any dangling transaction first
 872                         if ( $this->trxLevel ) {
 873                                 // Meaningful transactions should ideally have been resolved by now
 874                                 if ( $this->writesOrCallbacksPending() ) {
 875                                         $this->queryLogger->warning(
 876                                                 __METHOD__ . ": writes or callbacks still pending.",
 877                                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
 878                                         );
 879                                         // Cannot let incomplete atomic sections be committed
 880                                         if ( $this->trxAtomicLevels ) {
 881                                                 $levels = $this->flatAtomicSectionList();
 882                                                 $exception = new DBUnexpectedError(
 883                                                         $this,
 884                                                         __METHOD__ . ": atomic sections $levels are still open."
 885                                                 );
 886                                         // Check if it is possible to properly commit and trigger callbacks
 887                                         } elseif ( $this->trxEndCallbacksSuppressed ) {
 888                                                 $exception = new DBUnexpectedError(
 889                                                         $this,
 890                                                         __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 891                                                 );
 892                                         }
 893                                 }
 894                                 // Commit or rollback the changes and run any callbacks as needed
 895                                 if ( $this->trxStatus === self::STATUS_TRX_OK && !$exception ) {
 896                                         $this->commit( __METHOD__, self::TRANSACTION_INTERNAL );
 897                                 } else {
 898                                         $this->rollback( __METHOD__, self::TRANSACTION_INTERNAL );
 899                                 }
 900                         }
 901                         // Close the actual connection in the binding handle
 902                         $closed = $this->closeConnection();
 903                         $this->conn = false;
 904                 } else {
 905                         $closed = true; // already closed; nothing to do
 906                 }
 907
 908                 $this->opened = false;
 909
 910                 // Throw any unexpected errors after having disconnected
 911                 if ( $exception instanceof Exception ) {
 912                         throw $exception;
 913                 }
 914
 915                 // Sanity check that no callbacks are dangling
 916                 if (
 917                         $this->trxIdleCallbacks || $this->trxPreCommitCallbacks || $this->trxEndCallbacks
 918                 ) {
 919                         throw new RuntimeException(
 920                                 "Transaction callbacks are still pending:\n" .
 921                                 implode( ', ', $this->pendingWriteAndCallbackCallers() )
 922                         );
 923                 }
 924
 925                 return $closed;
 926         }
 927
 928         /**
 929          * Make sure isOpen() returns true as a sanity check
 930          *
 931          * @throws DBUnexpectedError
 932          */
 933         protected function assertOpen() {
 934                 if ( !$this->isOpen() ) {
 935                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 936                 }
 937         }
 938
 939         /**
 940          * Closes underlying database connection
 941          * @since 1.20
 942          * @return bool Whether connection was closed successfully
 943          */
 944         abstract protected function closeConnection();
 945
 946         /**
 947          * @param string $error Fallback error message, used if none is given by DB
 948          * @throws DBConnectionError
 949          */
 950         public function reportConnectionError( $error = 'Unknown error' ) {
 951                 $myError = $this->lastError();
 952                 if ( $myError ) {
 953                         $error = $myError;
 954                 }
 955
 956                 # New method
 957                 throw new DBConnectionError( $this, $error );
 958         }
 959
 960         /**
 961          * Run a query and return a DBMS-dependent wrapper (that has all IResultWrapper methods)
 962          *
 963          * This might return things, such as mysqli_result, that do not formally implement
 964          * IResultWrapper, but nonetheless implement all of its methods correctly
 965          *
 966          * @param string $sql SQL query.
 967          * @return IResultWrapper|bool Iterator to feed to fetchObject/fetchRow; false on failure
 968          */
 969         abstract protected function doQuery( $sql );
 970
 971         /**
 972          * Determine whether a query writes to the DB.
 973          * Should return true if unsure.
 974          *
 975          * @param string $sql
 976          * @return bool
 977          */
 978         protected function isWriteQuery( $sql ) {
 979                 return !preg_match(
 980                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 981         }
 982
 983         /**
 984          * @param string $sql
 985          * @return string|null
 986          */
 987         protected function getQueryVerb( $sql ) {
 988                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 989         }
 990
 991         /**
 992          * Determine whether a SQL statement is sensitive to isolation level.
 993          * A SQL statement is considered transactable if its result could vary
 994          * depending on the transaction isolation level. Operational commands
 995          * such as 'SET' and 'SHOW' are not considered to be transactable.
 996          *
 997          * @param string $sql
 998          * @return bool
 999          */
1000         protected function isTransactableQuery( $sql ) {
1001                 return !in_array(
1002                         $this->getQueryVerb( $sql ),
1003                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
1004                         true
1005                 );
1006         }
1007
1008         /**
1009          * @param string $sql A SQL query
1010          * @return bool Whether $sql is SQL for TEMPORARY table operation
1011          */
1012         protected function registerTempTableOperation( $sql ) {
1013                 if ( preg_match(
1014                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1015                         $sql,
1016                         $matches
1017                 ) ) {
1018                         $this->sessionTempTables[$matches[1]] = 1;
1019
1020                         return true;
1021                 } elseif ( preg_match(
1022                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1023                         $sql,
1024                         $matches
1025                 ) ) {
1026                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
1027                         unset( $this->sessionTempTables[$matches[1]] );
1028
1029                         return $isTemp;
1030                 } elseif ( preg_match(
1031                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1032                         $sql,
1033                         $matches
1034                 ) ) {
1035                         return isset( $this->sessionTempTables[$matches[1]] );
1036                 } elseif ( preg_match(
1037                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
1038                         $sql,
1039                         $matches
1040                 ) ) {
1041                         return isset( $this->sessionTempTables[$matches[1]] );
1042                 }
1043
1044                 return false;
1045         }
1046
1047         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1048                 $this->assertTransactionStatus( $sql, $fname );
1049
1050                 $priorWritesPending = $this->writesOrCallbacksPending();
1051                 $this->lastQuery = $sql;
1052
1053                 $isWrite = $this->isWriteQuery( $sql );
1054                 if ( $isWrite ) {
1055                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
1056                 } else {
1057                         $isNonTempWrite = false;
1058                 }
1059
1060                 if ( $isWrite ) {
1061                         if ( $this->getLBInfo( 'replica' ) === true ) {
1062                                 throw new DBError(
1063                                         $this,
1064                                         'Write operations are not allowed on replica database connections.'
1065                                 );
1066                         }
1067                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1068                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1069                         $reason = $this->getReadOnlyReason();
1070                         if ( $reason !== false ) {
1071                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1072                         }
1073                         # Set a flag indicating that writes have been done
1074                         $this->lastWriteTime = microtime( true );
1075                 }
1076
1077                 # Add trace comment to the begin of the sql string, right after the operator.
1078                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1079                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1080
1081                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
1082                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
1083                         && $this->isTransactableQuery( $sql )
1084                 ) {
1085                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1086                         $this->trxAutomatic = true;
1087                 }
1088
1089                 # Keep track of whether the transaction has write queries pending
1090                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
1091                         $this->trxDoneWrites = true;
1092                         $this->trxProfiler->transactionWritingIn(
1093                                 $this->server, $this->dbName, $this->trxShortId );
1094                 }
1095
1096                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1097                         $this->queryLogger->debug( "{$this->dbName} {$commentedSql}" );
1098                 }
1099
1100                 # Avoid fatals if close() was called
1101                 $this->assertOpen();
1102
1103                 # Send the query to the server and fetch any corresponding errors
1104                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1105                 $lastError = $this->lastError();
1106                 $lastErrno = $this->lastErrno();
1107
1108                 # Try reconnecting if the connection was lost
1109                 if ( $ret === false && $this->wasConnectionLoss() ) {
1110                         # Check if any meaningful session state was lost
1111                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1112                         # Update session state tracking and try to restore the connection
1113                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1114                         # Silently resend the query to the server if it is safe and possible
1115                         if ( $reconnected && $recoverable ) {
1116                                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1117                                 $lastError = $this->lastError();
1118                                 $lastErrno = $this->lastErrno();
1119
1120                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1121                                         # Query probably causes disconnects; reconnect and do not re-run it
1122                                         $this->replaceLostConnection( __METHOD__ );
1123                                 }
1124                         }
1125                 }
1126
1127                 if ( $ret === false ) {
1128                         if ( $this->trxLevel && !$this->wasKnownStatementRollbackError() ) {
1129                                 # Either the query was aborted or all queries after BEGIN where aborted.
1130                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
1131                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1132                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1133                                         # option is ROLLBACK, since the snapshots would have been released.
1134                                         if ( is_object( $tempIgnore ) ) {
1135                                                 // Ugly hack to know that savepoints are in use for postgres
1136                                                 // FIXME: remove this and make DatabasePostgres use ATOMIC_CANCELABLE
1137                                         } else {
1138                                                 $this->trxStatus = self::STATUS_TRX_ERROR;
1139                                                 $this->trxStatusCause =
1140                                                         $this->makeQueryException( $lastError, $lastErrno, $sql, $fname );
1141                                                 $tempIgnore = false; // cannot recover
1142                                         }
1143                                 } else {
1144                                         # Nothing prior was there to lose from the transaction
1145                                         $this->trxStatus = self::STATUS_TRX_OK;
1146                                 }
1147                         }
1148
1149                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1150                 }
1151
1152                 return $this->resultObject( $ret );
1153         }
1154
1155         /**
1156          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1157          *
1158          * @param string $sql Original SQL query
1159          * @param string $commentedSql SQL query with debugging/trace comment
1160          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1161          * @param string $fname Name of the calling function
1162          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1163          *     object for a successful read query, or false on failure
1164          */
1165         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1166                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1167                 # generalizeSQL() will probably cut down the query to reasonable
1168                 # logging size most of the time. The substr is really just a sanity check.
1169                 if ( $isMaster ) {
1170                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1171                 } else {
1172                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1173                 }
1174
1175                 # Include query transaction state
1176                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1177
1178                 $startTime = microtime( true );
1179                 if ( $this->profiler ) {
1180                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1181                 }
1182                 $this->affectedRowCount = null;
1183                 $ret = $this->doQuery( $commentedSql );
1184                 $this->affectedRowCount = $this->affectedRows();
1185                 if ( $this->profiler ) {
1186                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1187                 }
1188                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1189
1190                 unset( $queryProfSection ); // profile out (if set)
1191
1192                 if ( $ret !== false ) {
1193                         $this->lastPing = $startTime;
1194                         if ( $isWrite && $this->trxLevel ) {
1195                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1196                                 $this->trxWriteCallers[] = $fname;
1197                         }
1198                 }
1199
1200                 if ( $sql === self::PING_QUERY ) {
1201                         $this->rttEstimate = $queryRuntime;
1202                 }
1203
1204                 $this->trxProfiler->recordQueryCompletion(
1205                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1206                 );
1207                 $this->queryLogger->debug( $sql, [
1208                         'method' => $fname,
1209                         'master' => $isMaster,
1210                         'runtime' => $queryRuntime,
1211                 ] );
1212
1213                 return $ret;
1214         }
1215
1216         /**
1217          * Update the estimated run-time of a query, not counting large row lock times
1218          *
1219          * LoadBalancer can be set to rollback transactions that will create huge replication
1220          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1221          * queries, like inserting a row can take a long time due to row locking. This method
1222          * uses some simple heuristics to discount those cases.
1223          *
1224          * @param string $sql A SQL write query
1225          * @param float $runtime Total runtime, including RTT
1226          * @param int $affected Affected row count
1227          */
1228         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1229                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1230                 $indicativeOfReplicaRuntime = true;
1231                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1232                         $verb = $this->getQueryVerb( $sql );
1233                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1234                         if ( $verb === 'INSERT' ) {
1235                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1236                         } elseif ( $verb === 'REPLACE' ) {
1237                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1238                         }
1239                 }
1240
1241                 $this->trxWriteDuration += $runtime;
1242                 $this->trxWriteQueryCount += 1;
1243                 $this->trxWriteAffectedRows += $affected;
1244                 if ( $indicativeOfReplicaRuntime ) {
1245                         $this->trxWriteAdjDuration += $runtime;
1246                         $this->trxWriteAdjQueryCount += 1;
1247                 }
1248         }
1249
1250         /**
1251          * @param string $sql
1252          * @param string $fname
1253          * @throws DBTransactionStateError
1254          */
1255         private function assertTransactionStatus( $sql, $fname ) {
1256                 if (
1257                         $this->trxStatus < self::STATUS_TRX_OK &&
1258                         $this->getQueryVerb( $sql ) !== 'ROLLBACK' // transaction/savepoint
1259                 ) {
1260                         throw new DBTransactionStateError(
1261                                 $this,
1262                                 "Cannot execute query from $fname while transaction status is ERROR. ",
1263                                 [],
1264                                 $this->trxStatusCause
1265                         );
1266                 }
1267         }
1268
1269         /**
1270          * Determine whether or not it is safe to retry queries after a database
1271          * connection is lost
1272          *
1273          * @param string $sql SQL query
1274          * @param bool $priorWritesPending Whether there is a transaction open with
1275          *     possible write queries or transaction pre-commit/idle callbacks
1276          *     waiting on it to finish.
1277          * @return bool True if it is safe to retry the query, false otherwise
1278          */
1279         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1280                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1281                 # Dropped connections also mean that named locks are automatically released.
1282                 # Only allow error suppression in autocommit mode or when the lost transaction
1283                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1284                 if ( $this->namedLocksHeld ) {
1285                         return false; // possible critical section violation
1286                 } elseif ( $this->sessionTempTables ) {
1287                         return false; // tables might be queried latter
1288                 } elseif ( $sql === 'COMMIT' ) {
1289                         return !$priorWritesPending; // nothing written anyway? (T127428)
1290                 } elseif ( $sql === 'ROLLBACK' ) {
1291                         return true; // transaction lost...which is also what was requested :)
1292                 } elseif ( $this->explicitTrxActive() ) {
1293                         return false; // don't drop atomocity and explicit snapshots
1294                 } elseif ( $priorWritesPending ) {
1295                         return false; // prior writes lost from implicit transaction
1296                 }
1297
1298                 return true;
1299         }
1300
1301         /**
1302          * Clean things up after session (and thus transaction) loss
1303          */
1304         private function handleSessionLoss() {
1305                 // Clean up tracking of session-level things...
1306                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1307                 // https://www.postgresql.org/docs/9.1/static/sql-createtable.html (ignoring ON COMMIT)
1308                 $this->sessionTempTables = [];
1309                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1310                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1311                 $this->namedLocksHeld = [];
1312                 // Session loss implies transaction loss
1313                 $this->handleTransactionLoss();
1314         }
1315
1316         /**
1317          * Clean things up after transaction loss
1318          */
1319         private function handleTransactionLoss() {
1320                 $this->trxLevel = 0;
1321                 $this->trxAtomicCounter = 0;
1322                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1323                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1324                 try {
1325                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1326                         // If callback suppression is set then the array will remain unhandled.
1327                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1328                 } catch ( Exception $ex ) {
1329                         // Already logged; move on...
1330                 }
1331                 try {
1332                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1333                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1334                 } catch ( Exception $ex ) {
1335                         // Already logged; move on...
1336                 }
1337         }
1338
1339         /**
1340          * Checks whether the cause of the error is detected to be a timeout.
1341          *
1342          * It returns false by default, and not all engines support detecting this yet.
1343          * If this returns false, it will be treated as a generic query error.
1344          *
1345          * @param string $error Error text
1346          * @param int $errno Error number
1347          * @return bool
1348          */
1349         protected function wasQueryTimeout( $error, $errno ) {
1350                 return false;
1351         }
1352
1353         /**
1354          * Report a query error. Log the error, and if neither the object ignore
1355          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1356          *
1357          * @param string $error
1358          * @param int $errno
1359          * @param string $sql
1360          * @param string $fname
1361          * @param bool $tempIgnore
1362          * @throws DBQueryError
1363          */
1364         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1365                 if ( $tempIgnore ) {
1366                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1367                 } else {
1368                         $exception = $this->makeQueryException( $error, $errno, $sql, $fname );
1369
1370                         throw $exception;
1371                 }
1372         }
1373
1374         /**
1375          * @param string $error
1376          * @param string|int $errno
1377          * @param string $sql
1378          * @param string $fname
1379          * @return DBError
1380          */
1381         private function makeQueryException( $error, $errno, $sql, $fname ) {
1382                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1383                 $this->queryLogger->error(
1384                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1385                         $this->getLogContext( [
1386                                 'method' => __METHOD__,
1387                                 'errno' => $errno,
1388                                 'error' => $error,
1389                                 'sql1line' => $sql1line,
1390                                 'fname' => $fname,
1391                         ] )
1392                 );
1393                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1394                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1395                 if ( $wasQueryTimeout ) {
1396                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1397                 } else {
1398                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1399                 }
1400
1401                 return $e;
1402         }
1403
1404         public function freeResult( $res ) {
1405         }
1406
1407         public function selectField(
1408                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1409         ) {
1410                 if ( $var === '*' ) { // sanity
1411                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1412                 }
1413
1414                 if ( !is_array( $options ) ) {
1415                         $options = [ $options ];
1416                 }
1417
1418                 $options['LIMIT'] = 1;
1419
1420                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1421                 if ( $res === false || !$this->numRows( $res ) ) {
1422                         return false;
1423                 }
1424
1425                 $row = $this->fetchRow( $res );
1426
1427                 if ( $row !== false ) {
1428                         return reset( $row );
1429                 } else {
1430                         return false;
1431                 }
1432         }
1433
1434         public function selectFieldValues(
1435                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1436         ) {
1437                 if ( $var === '*' ) { // sanity
1438                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1439                 } elseif ( !is_string( $var ) ) { // sanity
1440                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1441                 }
1442
1443                 if ( !is_array( $options ) ) {
1444                         $options = [ $options ];
1445                 }
1446
1447                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1448                 if ( $res === false ) {
1449                         return false;
1450                 }
1451
1452                 $values = [];
1453                 foreach ( $res as $row ) {
1454                         $values[] = $row->$var;
1455                 }
1456
1457                 return $values;
1458         }
1459
1460         /**
1461          * Returns an optional USE INDEX clause to go after the table, and a
1462          * string to go at the end of the query.
1463          *
1464          * @param array $options Associative array of options to be turned into
1465          *   an SQL query, valid keys are listed in the function.
1466          * @return array
1467          * @see Database::select()
1468          */
1469         protected function makeSelectOptions( $options ) {
1470                 $preLimitTail = $postLimitTail = '';
1471                 $startOpts = '';
1472
1473                 $noKeyOptions = [];
1474
1475                 foreach ( $options as $key => $option ) {
1476                         if ( is_numeric( $key ) ) {
1477                                 $noKeyOptions[$option] = true;
1478                         }
1479                 }
1480
1481                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1482
1483                 $preLimitTail .= $this->makeOrderBy( $options );
1484
1485                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1486                         $postLimitTail .= ' FOR UPDATE';
1487                 }
1488
1489                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1490                         $postLimitTail .= ' LOCK IN SHARE MODE';
1491                 }
1492
1493                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1494                         $startOpts .= 'DISTINCT';
1495                 }
1496
1497                 # Various MySQL extensions
1498                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1499                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1500                 }
1501
1502                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1503                         $startOpts .= ' HIGH_PRIORITY';
1504                 }
1505
1506                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1507                         $startOpts .= ' SQL_BIG_RESULT';
1508                 }
1509
1510                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1511                         $startOpts .= ' SQL_BUFFER_RESULT';
1512                 }
1513
1514                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1515                         $startOpts .= ' SQL_SMALL_RESULT';
1516                 }
1517
1518                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1519                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1520                 }
1521
1522                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1523                         $startOpts .= ' SQL_CACHE';
1524                 }
1525
1526                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1527                         $startOpts .= ' SQL_NO_CACHE';
1528                 }
1529
1530                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1531                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1532                 } else {
1533                         $useIndex = '';
1534                 }
1535                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1536                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1537                 } else {
1538                         $ignoreIndex = '';
1539                 }
1540
1541                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1542         }
1543
1544         /**
1545          * Returns an optional GROUP BY with an optional HAVING
1546          *
1547          * @param array $options Associative array of options
1548          * @return string
1549          * @see Database::select()
1550          * @since 1.21
1551          */
1552         protected function makeGroupByWithHaving( $options ) {
1553                 $sql = '';
1554                 if ( isset( $options['GROUP BY'] ) ) {
1555                         $gb = is_array( $options['GROUP BY'] )
1556                                 ? implode( ',', $options['GROUP BY'] )
1557                                 : $options['GROUP BY'];
1558                         $sql .= ' GROUP BY ' . $gb;
1559                 }
1560                 if ( isset( $options['HAVING'] ) ) {
1561                         $having = is_array( $options['HAVING'] )
1562                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1563                                 : $options['HAVING'];
1564                         $sql .= ' HAVING ' . $having;
1565                 }
1566
1567                 return $sql;
1568         }
1569
1570         /**
1571          * Returns an optional ORDER BY
1572          *
1573          * @param array $options Associative array of options
1574          * @return string
1575          * @see Database::select()
1576          * @since 1.21
1577          */
1578         protected function makeOrderBy( $options ) {
1579                 if ( isset( $options['ORDER BY'] ) ) {
1580                         $ob = is_array( $options['ORDER BY'] )
1581                                 ? implode( ',', $options['ORDER BY'] )
1582                                 : $options['ORDER BY'];
1583
1584                         return ' ORDER BY ' . $ob;
1585                 }
1586
1587                 return '';
1588         }
1589
1590         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1591                 $options = [], $join_conds = [] ) {
1592                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1593
1594                 return $this->query( $sql, $fname );
1595         }
1596
1597         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1598                 $options = [], $join_conds = []
1599         ) {
1600                 if ( is_array( $vars ) ) {
1601                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1602                 }
1603
1604                 $options = (array)$options;
1605                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1606                         ? $options['USE INDEX']
1607                         : [];
1608                 $ignoreIndexes = (
1609                         isset( $options['IGNORE INDEX'] ) &&
1610                         is_array( $options['IGNORE INDEX'] )
1611                 )
1612                         ? $options['IGNORE INDEX']
1613                         : [];
1614
1615                 if ( is_array( $table ) ) {
1616                         $from = ' FROM ' .
1617                                 $this->tableNamesWithIndexClauseOrJOIN(
1618                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1619                 } elseif ( $table != '' ) {
1620                         $from = ' FROM ' .
1621                                 $this->tableNamesWithIndexClauseOrJOIN(
1622                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1623                 } else {
1624                         $from = '';
1625                 }
1626
1627                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1628                         $this->makeSelectOptions( $options );
1629
1630                 if ( is_array( $conds ) ) {
1631                         $conds = $this->makeList( $conds, self::LIST_AND );
1632                 }
1633
1634                 if ( $conds === null || $conds === false ) {
1635                         $this->queryLogger->warning(
1636                                 __METHOD__
1637                                 . ' called from '
1638                                 . $fname
1639                                 . ' with incorrect parameters: $conds must be a string or an array'
1640                         );
1641                         $conds = '';
1642                 }
1643
1644                 if ( $conds === '' ) {
1645                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1646                 } elseif ( is_string( $conds ) ) {
1647                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1648                                 "WHERE $conds $preLimitTail";
1649                 } else {
1650                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1651                 }
1652
1653                 if ( isset( $options['LIMIT'] ) ) {
1654                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1655                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1656                 }
1657                 $sql = "$sql $postLimitTail";
1658
1659                 if ( isset( $options['EXPLAIN'] ) ) {
1660                         $sql = 'EXPLAIN ' . $sql;
1661                 }
1662
1663                 return $sql;
1664         }
1665
1666         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1667                 $options = [], $join_conds = []
1668         ) {
1669                 $options = (array)$options;
1670                 $options['LIMIT'] = 1;
1671                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1672
1673                 if ( $res === false ) {
1674                         return false;
1675                 }
1676
1677                 if ( !$this->numRows( $res ) ) {
1678                         return false;
1679                 }
1680
1681                 $obj = $this->fetchObject( $res );
1682
1683                 return $obj;
1684         }
1685
1686         public function estimateRowCount(
1687                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1688         ) {
1689                 $conds = $this->normalizeConditions( $conds, $fname );
1690                 $column = $this->extractSingleFieldFromList( $var );
1691                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1692                         $conds[] = "$column IS NOT NULL";
1693                 }
1694
1695                 $res = $this->select(
1696                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1697                 );
1698                 $row = $res ? $this->fetchRow( $res ) : [];
1699
1700                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1701         }
1702
1703         public function selectRowCount(
1704                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1705         ) {
1706                 $conds = $this->normalizeConditions( $conds, $fname );
1707                 $column = $this->extractSingleFieldFromList( $var );
1708                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1709                         $conds[] = "$column IS NOT NULL";
1710                 }
1711
1712                 $res = $this->select(
1713                         [
1714                                 'tmp_count' => $this->buildSelectSubquery(
1715                                         $tables,
1716                                         '1',
1717                                         $conds,
1718                                         $fname,
1719                                         $options,
1720                                         $join_conds
1721                                 )
1722                         ],
1723                         [ 'rowcount' => 'COUNT(*)' ],
1724                         [],
1725                         $fname
1726                 );
1727                 $row = $res ? $this->fetchRow( $res ) : [];
1728
1729                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1730         }
1731
1732         /**
1733          * @param array|string $conds
1734          * @param string $fname
1735          * @return array
1736          */
1737         final protected function normalizeConditions( $conds, $fname ) {
1738                 if ( $conds === null || $conds === false ) {
1739                         $this->queryLogger->warning(
1740                                 __METHOD__
1741                                 . ' called from '
1742                                 . $fname
1743                                 . ' with incorrect parameters: $conds must be a string or an array'
1744                         );
1745                         $conds = '';
1746                 }
1747
1748                 if ( !is_array( $conds ) ) {
1749                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1750                 }
1751
1752                 return $conds;
1753         }
1754
1755         /**
1756          * @param array|string $var Field parameter in the style of select()
1757          * @return string|null Column name or null; ignores aliases
1758          * @throws DBUnexpectedError Errors out if multiple columns are given
1759          */
1760         final protected function extractSingleFieldFromList( $var ) {
1761                 if ( is_array( $var ) ) {
1762                         if ( !$var ) {
1763                                 $column = null;
1764                         } elseif ( count( $var ) == 1 ) {
1765                                 $column = isset( $var[0] ) ? $var[0] : reset( $var );
1766                         } else {
1767                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1768                         }
1769                 } else {
1770                         $column = $var;
1771                 }
1772
1773                 return $column;
1774         }
1775
1776         /**
1777          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1778          * It's only slightly flawed. Don't use for anything important.
1779          *
1780          * @param string $sql A SQL Query
1781          *
1782          * @return string
1783          */
1784         protected static function generalizeSQL( $sql ) {
1785                 # This does the same as the regexp below would do, but in such a way
1786                 # as to avoid crashing php on some large strings.
1787                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1788
1789                 $sql = str_replace( "\\\\", '', $sql );
1790                 $sql = str_replace( "\\'", '', $sql );
1791                 $sql = str_replace( "\\\"", '', $sql );
1792                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1793                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1794
1795                 # All newlines, tabs, etc replaced by single space
1796                 $sql = preg_replace( '/\s+/', ' ', $sql );
1797
1798                 # All numbers => N,
1799                 # except the ones surrounded by characters, e.g. l10n
1800                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1801                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1802
1803                 return $sql;
1804         }
1805
1806         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1807                 $info = $this->fieldInfo( $table, $field );
1808
1809                 return (bool)$info;
1810         }
1811
1812         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1813                 if ( !$this->tableExists( $table ) ) {
1814                         return null;
1815                 }
1816
1817                 $info = $this->indexInfo( $table, $index, $fname );
1818                 if ( is_null( $info ) ) {
1819                         return null;
1820                 } else {
1821                         return $info !== false;
1822                 }
1823         }
1824
1825         public function tableExists( $table, $fname = __METHOD__ ) {
1826                 $tableRaw = $this->tableName( $table, 'raw' );
1827                 if ( isset( $this->sessionTempTables[$tableRaw] ) ) {
1828                         return true; // already known to exist
1829                 }
1830
1831                 $table = $this->tableName( $table );
1832                 $ignoreErrors = true;
1833                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1834
1835                 return (bool)$res;
1836         }
1837
1838         public function indexUnique( $table, $index ) {
1839                 $indexInfo = $this->indexInfo( $table, $index );
1840
1841                 if ( !$indexInfo ) {
1842                         return null;
1843                 }
1844
1845                 return !$indexInfo[0]->Non_unique;
1846         }
1847
1848         /**
1849          * Helper for Database::insert().
1850          *
1851          * @param array $options
1852          * @return string
1853          */
1854         protected function makeInsertOptions( $options ) {
1855                 return implode( ' ', $options );
1856         }
1857
1858         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1859                 # No rows to insert, easy just return now
1860                 if ( !count( $a ) ) {
1861                         return true;
1862                 }
1863
1864                 $table = $this->tableName( $table );
1865
1866                 if ( !is_array( $options ) ) {
1867                         $options = [ $options ];
1868                 }
1869
1870                 $fh = null;
1871                 if ( isset( $options['fileHandle'] ) ) {
1872                         $fh = $options['fileHandle'];
1873                 }
1874                 $options = $this->makeInsertOptions( $options );
1875
1876                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1877                         $multi = true;
1878                         $keys = array_keys( $a[0] );
1879                 } else {
1880                         $multi = false;
1881                         $keys = array_keys( $a );
1882                 }
1883
1884                 $sql = 'INSERT ' . $options .
1885                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1886
1887                 if ( $multi ) {
1888                         $first = true;
1889                         foreach ( $a as $row ) {
1890                                 if ( $first ) {
1891                                         $first = false;
1892                                 } else {
1893                                         $sql .= ',';
1894                                 }
1895                                 $sql .= '(' . $this->makeList( $row ) . ')';
1896                         }
1897                 } else {
1898                         $sql .= '(' . $this->makeList( $a ) . ')';
1899                 }
1900
1901                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1902                         return false;
1903                 } elseif ( $fh !== null ) {
1904                         return true;
1905                 }
1906
1907                 return (bool)$this->query( $sql, $fname );
1908         }
1909
1910         /**
1911          * Make UPDATE options array for Database::makeUpdateOptions
1912          *
1913          * @param array $options
1914          * @return array
1915          */
1916         protected function makeUpdateOptionsArray( $options ) {
1917                 if ( !is_array( $options ) ) {
1918                         $options = [ $options ];
1919                 }
1920
1921                 $opts = [];
1922
1923                 if ( in_array( 'IGNORE', $options ) ) {
1924                         $opts[] = 'IGNORE';
1925                 }
1926
1927                 return $opts;
1928         }
1929
1930         /**
1931          * Make UPDATE options for the Database::update function
1932          *
1933          * @param array $options The options passed to Database::update
1934          * @return string
1935          */
1936         protected function makeUpdateOptions( $options ) {
1937                 $opts = $this->makeUpdateOptionsArray( $options );
1938
1939                 return implode( ' ', $opts );
1940         }
1941
1942         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1943                 $table = $this->tableName( $table );
1944                 $opts = $this->makeUpdateOptions( $options );
1945                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1946
1947                 if ( $conds !== [] && $conds !== '*' ) {
1948                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1949                 }
1950
1951                 return (bool)$this->query( $sql, $fname );
1952         }
1953
1954         public function makeList( $a, $mode = self::LIST_COMMA ) {
1955                 if ( !is_array( $a ) ) {
1956                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1957                 }
1958
1959                 $first = true;
1960                 $list = '';
1961
1962                 foreach ( $a as $field => $value ) {
1963                         if ( !$first ) {
1964                                 if ( $mode == self::LIST_AND ) {
1965                                         $list .= ' AND ';
1966                                 } elseif ( $mode == self::LIST_OR ) {
1967                                         $list .= ' OR ';
1968                                 } else {
1969                                         $list .= ',';
1970                                 }
1971                         } else {
1972                                 $first = false;
1973                         }
1974
1975                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1976                                 $list .= "($value)";
1977                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1978                                 $list .= "$value";
1979                         } elseif (
1980                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1981                         ) {
1982                                 // Remove null from array to be handled separately if found
1983                                 $includeNull = false;
1984                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1985                                         $includeNull = true;
1986                                         unset( $value[$nullKey] );
1987                                 }
1988                                 if ( count( $value ) == 0 && !$includeNull ) {
1989                                         throw new InvalidArgumentException(
1990                                                 __METHOD__ . ": empty input for field $field" );
1991                                 } elseif ( count( $value ) == 0 ) {
1992                                         // only check if $field is null
1993                                         $list .= "$field IS NULL";
1994                                 } else {
1995                                         // IN clause contains at least one valid element
1996                                         if ( $includeNull ) {
1997                                                 // Group subconditions to ensure correct precedence
1998                                                 $list .= '(';
1999                                         }
2000                                         if ( count( $value ) == 1 ) {
2001                                                 // Special-case single values, as IN isn't terribly efficient
2002                                                 // Don't necessarily assume the single key is 0; we don't
2003                                                 // enforce linear numeric ordering on other arrays here.
2004                                                 $value = array_values( $value )[0];
2005                                                 $list .= $field . " = " . $this->addQuotes( $value );
2006                                         } else {
2007                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2008                                         }
2009                                         // if null present in array, append IS NULL
2010                                         if ( $includeNull ) {
2011                                                 $list .= " OR $field IS NULL)";
2012                                         }
2013                                 }
2014                         } elseif ( $value === null ) {
2015                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2016                                         $list .= "$field IS ";
2017                                 } elseif ( $mode == self::LIST_SET ) {
2018                                         $list .= "$field = ";
2019                                 }
2020                                 $list .= 'NULL';
2021                         } else {
2022                                 if (
2023                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2024                                 ) {
2025                                         $list .= "$field = ";
2026                                 }
2027                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2028                         }
2029                 }
2030
2031                 return $list;
2032         }
2033
2034         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2035                 $conds = [];
2036
2037                 foreach ( $data as $base => $sub ) {
2038                         if ( count( $sub ) ) {
2039                                 $conds[] = $this->makeList(
2040                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2041                                         self::LIST_AND );
2042                         }
2043                 }
2044
2045                 if ( $conds ) {
2046                         return $this->makeList( $conds, self::LIST_OR );
2047                 } else {
2048                         // Nothing to search for...
2049                         return false;
2050                 }
2051         }
2052
2053         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2054                 return $valuename;
2055         }
2056
2057         public function bitNot( $field ) {
2058                 return "(~$field)";
2059         }
2060
2061         public function bitAnd( $fieldLeft, $fieldRight ) {
2062                 return "($fieldLeft & $fieldRight)";
2063         }
2064
2065         public function bitOr( $fieldLeft, $fieldRight ) {
2066                 return "($fieldLeft | $fieldRight)";
2067         }
2068
2069         public function buildConcat( $stringList ) {
2070                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2071         }
2072
2073         public function buildGroupConcatField(
2074                 $delim, $table, $field, $conds = '', $join_conds = []
2075         ) {
2076                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2077
2078                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2079         }
2080
2081         public function buildSubstring( $input, $startPosition, $length = null ) {
2082                 $this->assertBuildSubstringParams( $startPosition, $length );
2083                 $functionBody = "$input FROM $startPosition";
2084                 if ( $length !== null ) {
2085                         $functionBody .= " FOR $length";
2086                 }
2087                 return 'SUBSTRING(' . $functionBody . ')';
2088         }
2089
2090         /**
2091          * Check type and bounds for parameters to self::buildSubstring()
2092          *
2093          * All supported databases have substring functions that behave the same for
2094          * positive $startPosition and non-negative $length, but behaviors differ when
2095          * given 0 or negative $startPosition or negative $length. The simplest
2096          * solution to that is to just forbid those values.
2097          *
2098          * @param int $startPosition
2099          * @param int|null $length
2100          * @since 1.31
2101          */
2102         protected function assertBuildSubstringParams( $startPosition, $length ) {
2103                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2104                         throw new InvalidArgumentException(
2105                                 '$startPosition must be a positive integer'
2106                         );
2107                 }
2108                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2109                         throw new InvalidArgumentException(
2110                                 '$length must be null or an integer greater than or equal to 0'
2111                         );
2112                 }
2113         }
2114
2115         public function buildStringCast( $field ) {
2116                 return $field;
2117         }
2118
2119         public function buildIntegerCast( $field ) {
2120                 return 'CAST( ' . $field . ' AS INTEGER )';
2121         }
2122
2123         public function buildSelectSubquery(
2124                 $table, $vars, $conds = '', $fname = __METHOD__,
2125                 $options = [], $join_conds = []
2126         ) {
2127                 return new Subquery(
2128                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2129                 );
2130         }
2131
2132         public function databasesAreIndependent() {
2133                 return false;
2134         }
2135
2136         public function selectDB( $db ) {
2137                 # Stub. Shouldn't cause serious problems if it's not overridden, but
2138                 # if your database engine supports a concept similar to MySQL's
2139                 # databases you may as well.
2140                 $this->dbName = $db;
2141
2142                 return true;
2143         }
2144
2145         public function getDBname() {
2146                 return $this->dbName;
2147         }
2148
2149         public function getServer() {
2150                 return $this->server;
2151         }
2152
2153         public function tableName( $name, $format = 'quoted' ) {
2154                 if ( $name instanceof Subquery ) {
2155                         throw new DBUnexpectedError(
2156                                 $this,
2157                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2158                         );
2159                 }
2160
2161                 # Skip the entire process when we have a string quoted on both ends.
2162                 # Note that we check the end so that we will still quote any use of
2163                 # use of `database`.table. But won't break things if someone wants
2164                 # to query a database table with a dot in the name.
2165                 if ( $this->isQuotedIdentifier( $name ) ) {
2166                         return $name;
2167                 }
2168
2169                 # Lets test for any bits of text that should never show up in a table
2170                 # name. Basically anything like JOIN or ON which are actually part of
2171                 # SQL queries, but may end up inside of the table value to combine
2172                 # sql. Such as how the API is doing.
2173                 # Note that we use a whitespace test rather than a \b test to avoid
2174                 # any remote case where a word like on may be inside of a table name
2175                 # surrounded by symbols which may be considered word breaks.
2176                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2177                         $this->queryLogger->warning(
2178                                 __METHOD__ . ": use of subqueries is not supported this way.",
2179                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2180                         );
2181
2182                         return $name;
2183                 }
2184
2185                 # Split database and table into proper variables.
2186                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2187
2188                 # Quote $table and apply the prefix if not quoted.
2189                 # $tableName might be empty if this is called from Database::replaceVars()
2190                 $tableName = "{$prefix}{$table}";
2191                 if ( $format === 'quoted'
2192                         && !$this->isQuotedIdentifier( $tableName )
2193                         && $tableName !== ''
2194                 ) {
2195                         $tableName = $this->addIdentifierQuotes( $tableName );
2196                 }
2197
2198                 # Quote $schema and $database and merge them with the table name if needed
2199                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2200                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2201
2202                 return $tableName;
2203         }
2204
2205         /**
2206          * Get the table components needed for a query given the currently selected database
2207          *
2208          * @param string $name Table name in the form of db.schema.table, db.table, or table
2209          * @return array (DB name or "" for default, schema name, table prefix, table name)
2210          */
2211         protected function qualifiedTableComponents( $name ) {
2212                 # We reverse the explode so that database.table and table both output the correct table.
2213                 $dbDetails = explode( '.', $name, 3 );
2214                 if ( count( $dbDetails ) == 3 ) {
2215                         list( $database, $schema, $table ) = $dbDetails;
2216                         # We don't want any prefix added in this case
2217                         $prefix = '';
2218                 } elseif ( count( $dbDetails ) == 2 ) {
2219                         list( $database, $table ) = $dbDetails;
2220                         # We don't want any prefix added in this case
2221                         $prefix = '';
2222                         # In dbs that support it, $database may actually be the schema
2223                         # but that doesn't affect any of the functionality here
2224                         $schema = '';
2225                 } else {
2226                         list( $table ) = $dbDetails;
2227                         if ( isset( $this->tableAliases[$table] ) ) {
2228                                 $database = $this->tableAliases[$table]['dbname'];
2229                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2230                                         ? $this->tableAliases[$table]['schema']
2231                                         : $this->schema;
2232                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2233                                         ? $this->tableAliases[$table]['prefix']
2234                                         : $this->tablePrefix;
2235                         } else {
2236                                 $database = '';
2237                                 $schema = $this->schema; # Default schema
2238                                 $prefix = $this->tablePrefix; # Default prefix
2239                         }
2240                 }
2241
2242                 return [ $database, $schema, $prefix, $table ];
2243         }
2244
2245         /**
2246          * @param string|null $namespace Database or schema
2247          * @param string $relation Name of table, view, sequence, etc...
2248          * @param string $format One of (raw, quoted)
2249          * @return string Relation name with quoted and merged $namespace as needed
2250          */
2251         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2252                 if ( strlen( $namespace ) ) {
2253                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2254                                 $namespace = $this->addIdentifierQuotes( $namespace );
2255                         }
2256                         $relation = $namespace . '.' . $relation;
2257                 }
2258
2259                 return $relation;
2260         }
2261
2262         public function tableNames() {
2263                 $inArray = func_get_args();
2264                 $retVal = [];
2265
2266                 foreach ( $inArray as $name ) {
2267                         $retVal[$name] = $this->tableName( $name );
2268                 }
2269
2270                 return $retVal;
2271         }
2272
2273         public function tableNamesN() {
2274                 $inArray = func_get_args();
2275                 $retVal = [];
2276
2277                 foreach ( $inArray as $name ) {
2278                         $retVal[] = $this->tableName( $name );
2279                 }
2280
2281                 return $retVal;
2282         }
2283
2284         /**
2285          * Get an aliased table name
2286          *
2287          * This returns strings like "tableName AS newTableName" for aliased tables
2288          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2289          *
2290          * @see Database::tableName()
2291          * @param string|Subquery $table Table name or object with a 'sql' field
2292          * @param string|bool $alias Table alias (optional)
2293          * @return string SQL name for aliased table. Will not alias a table to its own name
2294          */
2295         protected function tableNameWithAlias( $table, $alias = false ) {
2296                 if ( is_string( $table ) ) {
2297                         $quotedTable = $this->tableName( $table );
2298                 } elseif ( $table instanceof Subquery ) {
2299                         $quotedTable = (string)$table;
2300                 } else {
2301                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2302                 }
2303
2304                 if ( !strlen( $alias ) || $alias === $table ) {
2305                         if ( $table instanceof Subquery ) {
2306                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2307                         }
2308
2309                         return $quotedTable;
2310                 } else {
2311                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2312                 }
2313         }
2314
2315         /**
2316          * Gets an array of aliased table names
2317          *
2318          * @param array $tables [ [alias] => table ]
2319          * @return string[] See tableNameWithAlias()
2320          */
2321         protected function tableNamesWithAlias( $tables ) {
2322                 $retval = [];
2323                 foreach ( $tables as $alias => $table ) {
2324                         if ( is_numeric( $alias ) ) {
2325                                 $alias = $table;
2326                         }
2327                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2328                 }
2329
2330                 return $retval;
2331         }
2332
2333         /**
2334          * Get an aliased field name
2335          * e.g. fieldName AS newFieldName
2336          *
2337          * @param string $name Field name
2338          * @param string|bool $alias Alias (optional)
2339          * @return string SQL name for aliased field. Will not alias a field to its own name
2340          */
2341         protected function fieldNameWithAlias( $name, $alias = false ) {
2342                 if ( !$alias || (string)$alias === (string)$name ) {
2343                         return $name;
2344                 } else {
2345                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2346                 }
2347         }
2348
2349         /**
2350          * Gets an array of aliased field names
2351          *
2352          * @param array $fields [ [alias] => field ]
2353          * @return string[] See fieldNameWithAlias()
2354          */
2355         protected function fieldNamesWithAlias( $fields ) {
2356                 $retval = [];
2357                 foreach ( $fields as $alias => $field ) {
2358                         if ( is_numeric( $alias ) ) {
2359                                 $alias = $field;
2360                         }
2361                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2362                 }
2363
2364                 return $retval;
2365         }
2366
2367         /**
2368          * Get the aliased table name clause for a FROM clause
2369          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2370          *
2371          * @param array $tables ( [alias] => table )
2372          * @param array $use_index Same as for select()
2373          * @param array $ignore_index Same as for select()
2374          * @param array $join_conds Same as for select()
2375          * @return string
2376          */
2377         protected function tableNamesWithIndexClauseOrJOIN(
2378                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2379         ) {
2380                 $ret = [];
2381                 $retJOIN = [];
2382                 $use_index = (array)$use_index;
2383                 $ignore_index = (array)$ignore_index;
2384                 $join_conds = (array)$join_conds;
2385
2386                 foreach ( $tables as $alias => $table ) {
2387                         if ( !is_string( $alias ) ) {
2388                                 // No alias? Set it equal to the table name
2389                                 $alias = $table;
2390                         }
2391
2392                         if ( is_array( $table ) ) {
2393                                 // A parenthesized group
2394                                 if ( count( $table ) > 1 ) {
2395                                         $joinedTable = '(' .
2396                                                 $this->tableNamesWithIndexClauseOrJOIN(
2397                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2398                                 } else {
2399                                         // Degenerate case
2400                                         $innerTable = reset( $table );
2401                                         $innerAlias = key( $table );
2402                                         $joinedTable = $this->tableNameWithAlias(
2403                                                 $innerTable,
2404                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2405                                         );
2406                                 }
2407                         } else {
2408                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2409                         }
2410
2411                         // Is there a JOIN clause for this table?
2412                         if ( isset( $join_conds[$alias] ) ) {
2413                                 list( $joinType, $conds ) = $join_conds[$alias];
2414                                 $tableClause = $joinType;
2415                                 $tableClause .= ' ' . $joinedTable;
2416                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2417                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2418                                         if ( $use != '' ) {
2419                                                 $tableClause .= ' ' . $use;
2420                                         }
2421                                 }
2422                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2423                                         $ignore = $this->ignoreIndexClause(
2424                                                 implode( ',', (array)$ignore_index[$alias] ) );
2425                                         if ( $ignore != '' ) {
2426                                                 $tableClause .= ' ' . $ignore;
2427                                         }
2428                                 }
2429                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2430                                 if ( $on != '' ) {
2431                                         $tableClause .= ' ON (' . $on . ')';
2432                                 }
2433
2434                                 $retJOIN[] = $tableClause;
2435                         } elseif ( isset( $use_index[$alias] ) ) {
2436                                 // Is there an INDEX clause for this table?
2437                                 $tableClause = $joinedTable;
2438                                 $tableClause .= ' ' . $this->useIndexClause(
2439                                                 implode( ',', (array)$use_index[$alias] )
2440                                         );
2441
2442                                 $ret[] = $tableClause;
2443                         } elseif ( isset( $ignore_index[$alias] ) ) {
2444                                 // Is there an INDEX clause for this table?
2445                                 $tableClause = $joinedTable;
2446                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2447                                                 implode( ',', (array)$ignore_index[$alias] )
2448                                         );
2449
2450                                 $ret[] = $tableClause;
2451                         } else {
2452                                 $tableClause = $joinedTable;
2453
2454                                 $ret[] = $tableClause;
2455                         }
2456                 }
2457
2458                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2459                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2460                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2461
2462                 // Compile our final table clause
2463                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2464         }
2465
2466         /**
2467          * Allows for index remapping in queries where this is not consistent across DBMS
2468          *
2469          * @param string $index
2470          * @return string
2471          */
2472         protected function indexName( $index ) {
2473                 return isset( $this->indexAliases[$index] )
2474                         ? $this->indexAliases[$index]
2475                         : $index;
2476         }
2477
2478         public function addQuotes( $s ) {
2479                 if ( $s instanceof Blob ) {
2480                         $s = $s->fetch();
2481                 }
2482                 if ( $s === null ) {
2483                         return 'NULL';
2484                 } elseif ( is_bool( $s ) ) {
2485                         return (int)$s;
2486                 } else {
2487                         # This will also quote numeric values. This should be harmless,
2488                         # and protects against weird problems that occur when they really
2489                         # _are_ strings such as article titles and string->number->string
2490                         # conversion is not 1:1.
2491                         return "'" . $this->strencode( $s ) . "'";
2492                 }
2493         }
2494
2495         /**
2496          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2497          * MySQL uses `backticks` while basically everything else uses double quotes.
2498          * Since MySQL is the odd one out here the double quotes are our generic
2499          * and we implement backticks in DatabaseMysqlBase.
2500          *
2501          * @param string $s
2502          * @return string
2503          */
2504         public function addIdentifierQuotes( $s ) {
2505                 return '"' . str_replace( '"', '""', $s ) . '"';
2506         }
2507
2508         /**
2509          * Returns if the given identifier looks quoted or not according to
2510          * the database convention for quoting identifiers .
2511          *
2512          * @note Do not use this to determine if untrusted input is safe.
2513          *   A malicious user can trick this function.
2514          * @param string $name
2515          * @return bool
2516          */
2517         public function isQuotedIdentifier( $name ) {
2518                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2519         }
2520
2521         /**
2522          * @param string $s
2523          * @param string $escapeChar
2524          * @return string
2525          */
2526         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2527                 return str_replace( [ $escapeChar, '%', '_' ],
2528                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2529                         $s );
2530         }
2531
2532         public function buildLike() {
2533                 $params = func_get_args();
2534
2535                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2536                         $params = $params[0];
2537                 }
2538
2539                 $s = '';
2540
2541                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2542                 // may escape backslashes, creating problems of double escaping. The `
2543                 // character has good cross-DBMS compatibility, avoiding special operators
2544                 // in MS SQL like ^ and %
2545                 $escapeChar = '`';
2546
2547                 foreach ( $params as $value ) {
2548                         if ( $value instanceof LikeMatch ) {
2549                                 $s .= $value->toString();
2550                         } else {
2551                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2552                         }
2553                 }
2554
2555                 return ' LIKE ' .
2556                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2557         }
2558
2559         public function anyChar() {
2560                 return new LikeMatch( '_' );
2561         }
2562
2563         public function anyString() {
2564                 return new LikeMatch( '%' );
2565         }
2566
2567         public function nextSequenceValue( $seqName ) {
2568                 return null;
2569         }
2570
2571         /**
2572          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2573          * is only needed because a) MySQL must be as efficient as possible due to
2574          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2575          * which index to pick. Anyway, other databases might have different
2576          * indexes on a given table. So don't bother overriding this unless you're
2577          * MySQL.
2578          * @param string $index
2579          * @return string
2580          */
2581         public function useIndexClause( $index ) {
2582                 return '';
2583         }
2584
2585         /**
2586          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2587          * is only needed because a) MySQL must be as efficient as possible due to
2588          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2589          * which index to pick. Anyway, other databases might have different
2590          * indexes on a given table. So don't bother overriding this unless you're
2591          * MySQL.
2592          * @param string $index
2593          * @return string
2594          */
2595         public function ignoreIndexClause( $index ) {
2596                 return '';
2597         }
2598
2599         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2600                 if ( count( $rows ) == 0 ) {
2601                         return;
2602                 }
2603
2604                 // Single row case
2605                 if ( !is_array( reset( $rows ) ) ) {
2606                         $rows = [ $rows ];
2607                 }
2608
2609                 try {
2610                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2611                         $affectedRowCount = 0;
2612                         foreach ( $rows as $row ) {
2613                                 // Delete rows which collide with this one
2614                                 $indexWhereClauses = [];
2615                                 foreach ( $uniqueIndexes as $index ) {
2616                                         $indexColumns = (array)$index;
2617                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2618                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2619                                                 throw new DBUnexpectedError(
2620                                                         $this,
2621                                                         'New record does not provide all values for unique key (' .
2622                                                         implode( ', ', $indexColumns ) . ')'
2623                                                 );
2624                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2625                                                 throw new DBUnexpectedError(
2626                                                         $this,
2627                                                         'New record has a null value for unique key (' .
2628                                                         implode( ', ', $indexColumns ) . ')'
2629                                                 );
2630                                         }
2631                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2632                                 }
2633
2634                                 if ( $indexWhereClauses ) {
2635                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2636                                         $affectedRowCount += $this->affectedRows();
2637                                 }
2638
2639                                 // Now insert the row
2640                                 $this->insert( $table, $row, $fname );
2641                                 $affectedRowCount += $this->affectedRows();
2642                         }
2643                         $this->endAtomic( $fname );
2644                         $this->affectedRowCount = $affectedRowCount;
2645                 } catch ( Exception $e ) {
2646                         $this->cancelAtomic( $fname );
2647                         throw $e;
2648                 }
2649         }
2650
2651         /**
2652          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2653          * statement.
2654          *
2655          * @param string $table Table name
2656          * @param array|string $rows Row(s) to insert
2657          * @param string $fname Caller function name
2658          *
2659          * @return ResultWrapper
2660          */
2661         protected function nativeReplace( $table, $rows, $fname ) {
2662                 $table = $this->tableName( $table );
2663
2664                 # Single row case
2665                 if ( !is_array( reset( $rows ) ) ) {
2666                         $rows = [ $rows ];
2667                 }
2668
2669                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2670                 $first = true;
2671
2672                 foreach ( $rows as $row ) {
2673                         if ( $first ) {
2674                                 $first = false;
2675                         } else {
2676                                 $sql .= ',';
2677                         }
2678
2679                         $sql .= '(' . $this->makeList( $row ) . ')';
2680                 }
2681
2682                 return $this->query( $sql, $fname );
2683         }
2684
2685         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2686                 $fname = __METHOD__
2687         ) {
2688                 if ( !count( $rows ) ) {
2689                         return true; // nothing to do
2690                 }
2691
2692                 if ( !is_array( reset( $rows ) ) ) {
2693                         $rows = [ $rows ];
2694                 }
2695
2696                 if ( count( $uniqueIndexes ) ) {
2697                         $clauses = []; // list WHERE clauses that each identify a single row
2698                         foreach ( $rows as $row ) {
2699                                 foreach ( $uniqueIndexes as $index ) {
2700                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2701                                         $rowKey = []; // unique key to this row
2702                                         foreach ( $index as $column ) {
2703                                                 $rowKey[$column] = $row[$column];
2704                                         }
2705                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2706                                 }
2707                         }
2708                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2709                 } else {
2710                         $where = false;
2711                 }
2712
2713                 $affectedRowCount = 0;
2714                 try {
2715                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2716                         # Update any existing conflicting row(s)
2717                         if ( $where !== false ) {
2718                                 $ok = $this->update( $table, $set, $where, $fname );
2719                                 $affectedRowCount += $this->affectedRows();
2720                         } else {
2721                                 $ok = true;
2722                         }
2723                         # Now insert any non-conflicting row(s)
2724                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2725                         $affectedRowCount += $this->affectedRows();
2726                         $this->endAtomic( $fname );
2727                         $this->affectedRowCount = $affectedRowCount;
2728                 } catch ( Exception $e ) {
2729                         $this->cancelAtomic( $fname );
2730                         throw $e;
2731                 }
2732
2733                 return $ok;
2734         }
2735
2736         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2737                 $fname = __METHOD__
2738         ) {
2739                 if ( !$conds ) {
2740                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2741                 }
2742
2743                 $delTable = $this->tableName( $delTable );
2744                 $joinTable = $this->tableName( $joinTable );
2745                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2746                 if ( $conds != '*' ) {
2747                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2748                 }
2749                 $sql .= ')';
2750
2751                 $this->query( $sql, $fname );
2752         }
2753
2754         public function textFieldSize( $table, $field ) {
2755                 $table = $this->tableName( $table );
2756                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2757                 $res = $this->query( $sql, __METHOD__ );
2758                 $row = $this->fetchObject( $res );
2759
2760                 $m = [];
2761
2762                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2763                         $size = $m[1];
2764                 } else {
2765                         $size = -1;
2766                 }
2767
2768                 return $size;
2769         }
2770
2771         public function delete( $table, $conds, $fname = __METHOD__ ) {
2772                 if ( !$conds ) {
2773                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2774                 }
2775
2776                 $table = $this->tableName( $table );
2777                 $sql = "DELETE FROM $table";
2778
2779                 if ( $conds != '*' ) {
2780                         if ( is_array( $conds ) ) {
2781                                 $conds = $this->makeList( $conds, self::LIST_AND );
2782                         }
2783                         $sql .= ' WHERE ' . $conds;
2784                 }
2785
2786                 return $this->query( $sql, $fname );
2787         }
2788
2789         final public function insertSelect(
2790                 $destTable, $srcTable, $varMap, $conds,
2791                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2792         ) {
2793                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2794
2795                 $insertOptions = (array)$insertOptions;
2796                 $selectOptions = (array)$selectOptions;
2797
2798                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2799                         // For massive migrations with downtime, we don't want to select everything
2800                         // into memory and OOM, so do all this native on the server side if possible.
2801                         return $this->nativeInsertSelect(
2802                                 $destTable,
2803                                 $srcTable,
2804                                 $varMap,
2805                                 $conds,
2806                                 $fname,
2807                                 array_diff( $insertOptions, $hints ),
2808                                 $selectOptions,
2809                                 $selectJoinConds
2810                         );
2811                 }
2812
2813                 return $this->nonNativeInsertSelect(
2814                         $destTable,
2815                         $srcTable,
2816                         $varMap,
2817                         $conds,
2818                         $fname,
2819                         array_diff( $insertOptions, $hints ),
2820                         $selectOptions,
2821                         $selectJoinConds
2822                 );
2823         }
2824
2825         /**
2826          * @param array $insertOptions INSERT options
2827          * @param array $selectOptions SELECT options
2828          * @return bool Whether an INSERT SELECT with these options will be replication safe
2829          * @since 1.31
2830          */
2831         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
2832                 return true;
2833         }
2834
2835         /**
2836          * Implementation of insertSelect() based on select() and insert()
2837          *
2838          * @see IDatabase::insertSelect()
2839          * @since 1.30
2840          * @param string $destTable
2841          * @param string|array $srcTable
2842          * @param array $varMap
2843          * @param array $conds
2844          * @param string $fname
2845          * @param array $insertOptions
2846          * @param array $selectOptions
2847          * @param array $selectJoinConds
2848          * @return bool
2849          */
2850         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2851                 $fname = __METHOD__,
2852                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2853         ) {
2854                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2855                 // on only the master (without needing row-based-replication). It also makes it easy to
2856                 // know how big the INSERT is going to be.
2857                 $fields = [];
2858                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2859                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2860                 }
2861                 $selectOptions[] = 'FOR UPDATE';
2862                 $res = $this->select(
2863                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2864                 );
2865                 if ( !$res ) {
2866                         return false;
2867                 }
2868
2869                 try {
2870                         $affectedRowCount = 0;
2871                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2872                         $rows = [];
2873                         $ok = true;
2874                         foreach ( $res as $row ) {
2875                                 $rows[] = (array)$row;
2876
2877                                 // Avoid inserts that are too huge
2878                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
2879                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2880                                         if ( !$ok ) {
2881                                                 break;
2882                                         }
2883                                         $affectedRowCount += $this->affectedRows();
2884                                         $rows = [];
2885                                 }
2886                         }
2887                         if ( $rows && $ok ) {
2888                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2889                                 if ( $ok ) {
2890                                         $affectedRowCount += $this->affectedRows();
2891                                 }
2892                         }
2893                         if ( $ok ) {
2894                                 $this->endAtomic( $fname );
2895                                 $this->affectedRowCount = $affectedRowCount;
2896                         } else {
2897                                 $this->cancelAtomic( $fname );
2898                         }
2899                         return $ok;
2900                 } catch ( Exception $e ) {
2901                         $this->cancelAtomic( $fname );
2902                         throw $e;
2903                 }
2904         }
2905
2906         /**
2907          * Native server-side implementation of insertSelect() for situations where
2908          * we don't want to select everything into memory
2909          *
2910          * @see IDatabase::insertSelect()
2911          * @param string $destTable
2912          * @param string|array $srcTable
2913          * @param array $varMap
2914          * @param array $conds
2915          * @param string $fname
2916          * @param array $insertOptions
2917          * @param array $selectOptions
2918          * @param array $selectJoinConds
2919          * @return bool
2920          */
2921         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2922                 $fname = __METHOD__,
2923                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2924         ) {
2925                 $destTable = $this->tableName( $destTable );
2926
2927                 if ( !is_array( $insertOptions ) ) {
2928                         $insertOptions = [ $insertOptions ];
2929                 }
2930
2931                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2932
2933                 $selectSql = $this->selectSQLText(
2934                         $srcTable,
2935                         array_values( $varMap ),
2936                         $conds,
2937                         $fname,
2938                         $selectOptions,
2939                         $selectJoinConds
2940                 );
2941
2942                 $sql = "INSERT $insertOptions" .
2943                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
2944                         $selectSql;
2945
2946                 return $this->query( $sql, $fname );
2947         }
2948
2949         /**
2950          * Construct a LIMIT query with optional offset. This is used for query
2951          * pages. The SQL should be adjusted so that only the first $limit rows
2952          * are returned. If $offset is provided as well, then the first $offset
2953          * rows should be discarded, and the next $limit rows should be returned.
2954          * If the result of the query is not ordered, then the rows to be returned
2955          * are theoretically arbitrary.
2956          *
2957          * $sql is expected to be a SELECT, if that makes a difference.
2958          *
2959          * The version provided by default works in MySQL and SQLite. It will very
2960          * likely need to be overridden for most other DBMSes.
2961          *
2962          * @param string $sql SQL query we will append the limit too
2963          * @param int $limit The SQL limit
2964          * @param int|bool $offset The SQL offset (default false)
2965          * @throws DBUnexpectedError
2966          * @return string
2967          */
2968         public function limitResult( $sql, $limit, $offset = false ) {
2969                 if ( !is_numeric( $limit ) ) {
2970                         throw new DBUnexpectedError( $this,
2971                                 "Invalid non-numeric limit passed to limitResult()\n" );
2972                 }
2973
2974                 return "$sql LIMIT "
2975                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2976                 . "{$limit} ";
2977         }
2978
2979         public function unionSupportsOrderAndLimit() {
2980                 return true; // True for almost every DB supported
2981         }
2982
2983         public function unionQueries( $sqls, $all ) {
2984                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2985
2986                 return '(' . implode( $glue, $sqls ) . ')';
2987         }
2988
2989         public function unionConditionPermutations(
2990                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
2991                 $options = [], $join_conds = []
2992         ) {
2993                 // First, build the Cartesian product of $permute_conds
2994                 $conds = [ [] ];
2995                 foreach ( $permute_conds as $field => $values ) {
2996                         if ( !$values ) {
2997                                 // Skip empty $values
2998                                 continue;
2999                         }
3000                         $values = array_unique( $values ); // For sanity
3001                         $newConds = [];
3002                         foreach ( $conds as $cond ) {
3003                                 foreach ( $values as $value ) {
3004                                         $cond[$field] = $value;
3005                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3006                                 }
3007                         }
3008                         $conds = $newConds;
3009                 }
3010
3011                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3012
3013                 // If there's just one condition and no subordering, hand off to
3014                 // selectSQLText directly.
3015                 if ( count( $conds ) === 1 &&
3016                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3017                 ) {
3018                         return $this->selectSQLText(
3019                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3020                         );
3021                 }
3022
3023                 // Otherwise, we need to pull out the order and limit to apply after
3024                 // the union. Then build the SQL queries for each set of conditions in
3025                 // $conds. Then union them together (using UNION ALL, because the
3026                 // product *should* already be distinct).
3027                 $orderBy = $this->makeOrderBy( $options );
3028                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
3029                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
3030                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3031                 if ( !$this->unionSupportsOrderAndLimit() ) {
3032                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3033                 } else {
3034                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3035                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3036                         }
3037                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3038                                 // We need to increase the limit by the offset rather than
3039                                 // using the offset directly, otherwise it'll skip incorrectly
3040                                 // in the subqueries.
3041                                 $options['LIMIT'] = $limit + $offset;
3042                                 unset( $options['OFFSET'] );
3043                         }
3044                 }
3045
3046                 $sqls = [];
3047                 foreach ( $conds as $cond ) {
3048                         $sqls[] = $this->selectSQLText(
3049                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3050                         );
3051                 }
3052                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3053                 if ( $limit !== null ) {
3054                         $sql = $this->limitResult( $sql, $limit, $offset );
3055                 }
3056
3057                 return $sql;
3058         }
3059
3060         public function conditional( $cond, $trueVal, $falseVal ) {
3061                 if ( is_array( $cond ) ) {
3062                         $cond = $this->makeList( $cond, self::LIST_AND );
3063                 }
3064
3065                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3066         }
3067
3068         public function strreplace( $orig, $old, $new ) {
3069                 return "REPLACE({$orig}, {$old}, {$new})";
3070         }
3071
3072         public function getServerUptime() {
3073                 return 0;
3074         }
3075
3076         public function wasDeadlock() {
3077                 return false;
3078         }
3079
3080         public function wasLockTimeout() {
3081                 return false;
3082         }
3083
3084         public function wasConnectionLoss() {
3085                 return $this->wasConnectionError( $this->lastErrno() );
3086         }
3087
3088         public function wasReadOnlyError() {
3089                 return false;
3090         }
3091
3092         public function wasErrorReissuable() {
3093                 return (
3094                         $this->wasDeadlock() ||
3095                         $this->wasLockTimeout() ||
3096                         $this->wasConnectionLoss()
3097                 );
3098         }
3099
3100         /**
3101          * Do not use this method outside of Database/DBError classes
3102          *
3103          * @param int|string $errno
3104          * @return bool Whether the given query error was a connection drop
3105          */
3106         public function wasConnectionError( $errno ) {
3107                 return false;
3108         }
3109
3110         /**
3111          * @return bool Whether it is safe to assume the given error only caused statement rollback
3112          * @note This is for backwards compatibility for callers catching DBError exceptions in
3113          *   order to ignore problems like duplicate key errors or foriegn key violations
3114          * @since 1.31
3115          */
3116         protected function wasKnownStatementRollbackError() {
3117                 return false; // don't know; it could have caused a transaction rollback
3118         }
3119
3120         public function deadlockLoop() {
3121                 $args = func_get_args();
3122                 $function = array_shift( $args );
3123                 $tries = self::DEADLOCK_TRIES;
3124
3125                 $this->begin( __METHOD__ );
3126
3127                 $retVal = null;
3128                 /** @var Exception $e */
3129                 $e = null;
3130                 do {
3131                         try {
3132                                 $retVal = call_user_func_array( $function, $args );
3133                                 break;
3134                         } catch ( DBQueryError $e ) {
3135                                 if ( $this->wasDeadlock() ) {
3136                                         // Retry after a randomized delay
3137                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3138                                 } else {
3139                                         // Throw the error back up
3140                                         throw $e;
3141                                 }
3142                         }
3143                 } while ( --$tries > 0 );
3144
3145                 if ( $tries <= 0 ) {
3146                         // Too many deadlocks; give up
3147                         $this->rollback( __METHOD__ );
3148                         throw $e;
3149                 } else {
3150                         $this->commit( __METHOD__ );
3151
3152                         return $retVal;
3153                 }
3154         }
3155
3156         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3157                 # Real waits are implemented in the subclass.
3158                 return 0;
3159         }
3160
3161         public function getReplicaPos() {
3162                 # Stub
3163                 return false;
3164         }
3165
3166         public function getMasterPos() {
3167                 # Stub
3168                 return false;
3169         }
3170
3171         public function serverIsReadOnly() {
3172                 return false;
3173         }
3174
3175         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3176                 if ( !$this->trxLevel ) {
3177                         throw new DBUnexpectedError( $this, "No transaction is active." );
3178                 }
3179                 $this->trxEndCallbacks[] = [ $callback, $fname ];
3180         }
3181
3182         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3183                 $this->trxIdleCallbacks[] = [ $callback, $fname ];
3184                 if ( !$this->trxLevel ) {
3185                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3186                 }
3187         }
3188
3189         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3190                 if ( $this->trxLevel || $this->getFlag( self::DBO_TRX ) ) {
3191                         // As long as DBO_TRX is set, writes will accumulate until the load balancer issues
3192                         // an implicit commit of all peer databases. This is true even if a transaction has
3193                         // not yet been triggered by writes; make sure $callback runs *after* any such writes.
3194                         $this->trxPreCommitCallbacks[] = [ $callback, $fname ];
3195                 } else {
3196                         // No transaction is active nor will start implicitly, so make one for this callback
3197                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3198                         try {
3199                                 call_user_func( $callback );
3200                                 $this->endAtomic( __METHOD__ );
3201                         } catch ( Exception $e ) {
3202                                 $this->cancelAtomic( __METHOD__ );
3203                                 throw $e;
3204                         }
3205                 }
3206         }
3207
3208         final public function setTransactionListener( $name, callable $callback = null ) {
3209                 if ( $callback ) {
3210                         $this->trxRecurringCallbacks[$name] = $callback;
3211                 } else {
3212                         unset( $this->trxRecurringCallbacks[$name] );
3213                 }
3214         }
3215
3216         /**
3217          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3218          *
3219          * This method should not be used outside of Database/LoadBalancer
3220          *
3221          * @param bool $suppress
3222          * @since 1.28
3223          */
3224         final public function setTrxEndCallbackSuppression( $suppress ) {
3225                 $this->trxEndCallbacksSuppressed = $suppress;
3226         }
3227
3228         /**
3229          * Actually run and consume any "on transaction idle/resolution" callbacks.
3230          *
3231          * This method should not be used outside of Database/LoadBalancer
3232          *
3233          * @param int $trigger IDatabase::TRIGGER_* constant
3234          * @since 1.20
3235          * @throws Exception
3236          */
3237         public function runOnTransactionIdleCallbacks( $trigger ) {
3238                 if ( $this->trxEndCallbacksSuppressed ) {
3239                         return;
3240                 }
3241
3242                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3243                 /** @var Exception $e */
3244                 $e = null; // first exception
3245                 do { // callbacks may add callbacks :)
3246                         $callbacks = array_merge(
3247                                 $this->trxIdleCallbacks,
3248                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3249                         );
3250                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3251                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3252                         foreach ( $callbacks as $callback ) {
3253                                 try {
3254                                         list( $phpCallback ) = $callback;
3255                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3256                                         call_user_func_array( $phpCallback, [ $trigger ] );
3257                                         if ( $autoTrx ) {
3258                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3259                                         } else {
3260                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3261                                         }
3262                                 } catch ( Exception $ex ) {
3263                                         call_user_func( $this->errorLogger, $ex );
3264                                         $e = $e ?: $ex;
3265                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3266                                         // their transactions are ended so other callbacks don't fail
3267                                         if ( $this->trxLevel() ) {
3268                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3269                                         }
3270                                 }
3271                         }
3272                 } while ( count( $this->trxIdleCallbacks ) );
3273
3274                 if ( $e instanceof Exception ) {
3275                         throw $e; // re-throw any first exception
3276                 }
3277         }
3278
3279         /**
3280          * Actually run and consume any "on transaction pre-commit" callbacks.
3281          *
3282          * This method should not be used outside of Database/LoadBalancer
3283          *
3284          * @since 1.22
3285          * @throws Exception
3286          */
3287         public function runOnTransactionPreCommitCallbacks() {
3288                 $e = null; // first exception
3289                 do { // callbacks may add callbacks :)
3290                         $callbacks = $this->trxPreCommitCallbacks;
3291                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3292                         foreach ( $callbacks as $callback ) {
3293                                 try {
3294                                         list( $phpCallback ) = $callback;
3295                                         call_user_func( $phpCallback );
3296                                 } catch ( Exception $ex ) {
3297                                         call_user_func( $this->errorLogger, $ex );
3298                                         $e = $e ?: $ex;
3299                                 }
3300                         }
3301                 } while ( count( $this->trxPreCommitCallbacks ) );
3302
3303                 if ( $e instanceof Exception ) {
3304                         throw $e; // re-throw any first exception
3305                 }
3306         }
3307
3308         /**
3309          * Actually run any "transaction listener" callbacks.
3310          *
3311          * This method should not be used outside of Database/LoadBalancer
3312          *
3313          * @param int $trigger IDatabase::TRIGGER_* constant
3314          * @throws Exception
3315          * @since 1.20
3316          */
3317         public function runTransactionListenerCallbacks( $trigger ) {
3318                 if ( $this->trxEndCallbacksSuppressed ) {
3319                         return;
3320                 }
3321
3322                 /** @var Exception $e */
3323                 $e = null; // first exception
3324
3325                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3326                         try {
3327                                 $phpCallback( $trigger, $this );
3328                         } catch ( Exception $ex ) {
3329                                 call_user_func( $this->errorLogger, $ex );
3330                                 $e = $e ?: $ex;
3331                         }
3332                 }
3333
3334                 if ( $e instanceof Exception ) {
3335                         throw $e; // re-throw any first exception
3336                 }
3337         }
3338
3339         /**
3340          * Create a savepoint
3341          *
3342          * This is used internally to implement atomic sections. It should not be
3343          * used otherwise.
3344          *
3345          * @since 1.31
3346          * @param string $identifier Identifier for the savepoint
3347          * @param string $fname Calling function name
3348          */
3349         protected function doSavepoint( $identifier, $fname ) {
3350                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3351         }
3352
3353         /**
3354          * Release a savepoint
3355          *
3356          * This is used internally to implement atomic sections. It should not be
3357          * used otherwise.
3358          *
3359          * @since 1.31
3360          * @param string $identifier Identifier for the savepoint
3361          * @param string $fname Calling function name
3362          */
3363         protected function doReleaseSavepoint( $identifier, $fname ) {
3364                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3365         }
3366
3367         /**
3368          * Rollback to a savepoint
3369          *
3370          * This is used internally to implement atomic sections. It should not be
3371          * used otherwise.
3372          *
3373          * @since 1.31
3374          * @param string $identifier Identifier for the savepoint
3375          * @param string $fname Calling function name
3376          */
3377         protected function doRollbackToSavepoint( $identifier, $fname ) {
3378                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3379         }
3380
3381         final public function startAtomic(
3382                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3383         ) {
3384                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? 'n/a' : null;
3385                 if ( !$this->trxLevel ) {
3386                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
3387                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3388                         // in all changes being in one transaction to keep requests transactional.
3389                         if ( !$this->getFlag( self::DBO_TRX ) ) {
3390                                 $this->trxAutomaticAtomic = true;
3391                         }
3392                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3393                         $savepointId = 'wikimedia_rdbms_atomic' . ++$this->trxAtomicCounter;
3394                         if ( strlen( $savepointId ) > 30 ) { // 30 == Oracle's identifier length limit (pre 12c)
3395                                 $this->queryLogger->warning(
3396                                         'There have been an excessively large number of atomic sections in a transaction'
3397                                         . " started by $this->trxFname, reusing IDs (at $fname)",
3398                                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
3399                                 );
3400                                 $this->trxAtomicCounter = 0;
3401                                 $savepointId = 'wikimedia_rdbms_atomic' . ++$this->trxAtomicCounter;
3402                         }
3403                         $this->doSavepoint( $savepointId, $fname );
3404                 }
3405
3406                 $this->trxAtomicLevels[] = [ $fname, $savepointId ];
3407         }
3408
3409         final public function endAtomic( $fname = __METHOD__ ) {
3410                 if ( !$this->trxLevel ) {
3411                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
3412                 }
3413
3414                 list( $savedFname, $savepointId ) = $this->trxAtomicLevels
3415                         ? array_pop( $this->trxAtomicLevels ) : [ null, null ];
3416                 if ( $savedFname !== $fname ) {
3417                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
3418                 }
3419
3420                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3421                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3422                 } elseif ( $savepointId && $savepointId !== 'n/a' ) {
3423                         $this->doReleaseSavepoint( $savepointId, $fname );
3424                 }
3425         }
3426
3427         final public function cancelAtomic( $fname = __METHOD__ ) {
3428                 if ( !$this->trxLevel ) {
3429                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
3430                 }
3431
3432                 list( $savedFname, $savepointId ) = $this->trxAtomicLevels
3433                         ? array_pop( $this->trxAtomicLevels ) : [ null, null ];
3434                 if ( $savedFname !== $fname ) {
3435                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
3436                 }
3437                 if ( !$savepointId ) {
3438                         throw new DBUnexpectedError( $this, "Uncancelable atomic section canceled (got $fname)." );
3439                 }
3440
3441                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3442                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
3443                 } elseif ( $savepointId !== 'n/a' ) {
3444                         $this->doRollbackToSavepoint( $savepointId, $fname );
3445                         $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3446                 }
3447
3448                 $this->affectedRowCount = 0; // for the sake of consistency
3449         }
3450
3451         final public function doAtomicSection( $fname, callable $callback ) {
3452                 $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3453                 try {
3454                         $res = call_user_func_array( $callback, [ $this, $fname ] );
3455                 } catch ( Exception $e ) {
3456                         $this->cancelAtomic( $fname );
3457                         throw $e;
3458                 }
3459                 $this->endAtomic( $fname );
3460
3461                 return $res;
3462         }
3463
3464         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3465                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3466                 if ( $this->trxLevel ) {
3467                         if ( $this->trxAtomicLevels ) {
3468                                 $levels = $this->flatAtomicSectionList();
3469                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3470                                 throw new DBUnexpectedError( $this, $msg );
3471                         } elseif ( !$this->trxAutomatic ) {
3472                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3473                                 throw new DBUnexpectedError( $this, $msg );
3474                         } else {
3475                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3476                                 throw new DBUnexpectedError( $this, $msg );
3477                         }
3478                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3479                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3480                         throw new DBUnexpectedError( $this, $msg );
3481                 }
3482
3483                 // Avoid fatals if close() was called
3484                 $this->assertOpen();
3485
3486                 $this->doBegin( $fname );
3487                 $this->trxStatus = self::STATUS_TRX_OK;
3488                 $this->trxAtomicCounter = 0;
3489                 $this->trxTimestamp = microtime( true );
3490                 $this->trxFname = $fname;
3491                 $this->trxDoneWrites = false;
3492                 $this->trxAutomaticAtomic = false;
3493                 $this->trxAtomicLevels = [];
3494                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3495                 $this->trxWriteDuration = 0.0;
3496                 $this->trxWriteQueryCount = 0;
3497                 $this->trxWriteAffectedRows = 0;
3498                 $this->trxWriteAdjDuration = 0.0;
3499                 $this->trxWriteAdjQueryCount = 0;
3500                 $this->trxWriteCallers = [];
3501                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3502                 // Get an estimate of the replication lag before any such queries.
3503                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3504                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3505                 // caller will think its OK to muck around with the transaction just because startAtomic()
3506                 // has not yet completed (e.g. setting trxAtomicLevels).
3507                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3508         }
3509
3510         /**
3511          * Issues the BEGIN command to the database server.
3512          *
3513          * @see Database::begin()
3514          * @param string $fname
3515          */
3516         protected function doBegin( $fname ) {
3517                 $this->query( 'BEGIN', $fname );
3518                 $this->trxLevel = 1;
3519         }
3520
3521         final public function commit( $fname = __METHOD__, $flush = '' ) {
3522                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3523                         // There are still atomic sections open. This cannot be ignored
3524                         $levels = $this->flatAtomicSectionList();
3525                         throw new DBUnexpectedError(
3526                                 $this,
3527                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3528                         );
3529                 }
3530
3531                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3532                         if ( !$this->trxLevel ) {
3533                                 return; // nothing to do
3534                         } elseif ( !$this->trxAutomatic ) {
3535                                 throw new DBUnexpectedError(
3536                                         $this,
3537                                         "$fname: Flushing an explicit transaction, getting out of sync."
3538                                 );
3539                         }
3540                 } else {
3541                         if ( !$this->trxLevel ) {
3542                                 $this->queryLogger->error(
3543                                         "$fname: No transaction to commit, something got out of sync." );
3544                                 return; // nothing to do
3545                         } elseif ( $this->trxAutomatic ) {
3546                                 throw new DBUnexpectedError(
3547                                         $this,
3548                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3549                                 );
3550                         }
3551                 }
3552
3553                 // Avoid fatals if close() was called
3554                 $this->assertOpen();
3555
3556                 $this->runOnTransactionPreCommitCallbacks();
3557                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3558                 $this->doCommit( $fname );
3559                 $this->trxStatus = self::STATUS_TRX_NONE;
3560                 if ( $this->trxDoneWrites ) {
3561                         $this->lastWriteTime = microtime( true );
3562                         $this->trxProfiler->transactionWritingOut(
3563                                 $this->server,
3564                                 $this->dbName,
3565                                 $this->trxShortId,
3566                                 $writeTime,
3567                                 $this->trxWriteAffectedRows
3568                         );
3569                 }
3570
3571                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3572                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3573         }
3574
3575         /**
3576          * Issues the COMMIT command to the database server.
3577          *
3578          * @see Database::commit()
3579          * @param string $fname
3580          */
3581         protected function doCommit( $fname ) {
3582                 if ( $this->trxLevel ) {
3583                         $this->query( 'COMMIT', $fname );
3584                         $this->trxLevel = 0;
3585                 }
3586         }
3587
3588         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3589                 $trxActive = $this->trxLevel;
3590
3591                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3592                         if ( $this->getFlag( self::DBO_TRX ) ) {
3593                                 throw new DBUnexpectedError(
3594                                         $this,
3595                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3596                                 );
3597                         }
3598                 }
3599
3600                 if ( $trxActive ) {
3601                         // Avoid fatals if close() was called
3602                         $this->assertOpen();
3603
3604                         $this->doRollback( $fname );
3605                         $this->trxStatus = self::STATUS_TRX_NONE;
3606                         $this->trxAtomicLevels = [];
3607                         if ( $this->trxDoneWrites ) {
3608                                 $this->trxProfiler->transactionWritingOut(
3609                                         $this->server,
3610                                         $this->dbName,
3611                                         $this->trxShortId
3612                                 );
3613                         }
3614                 }
3615
3616                 // Clear any commit-dependant callbacks. They might even be present
3617                 // only due to transaction rounds, with no SQL transaction being active
3618                 $this->trxIdleCallbacks = [];
3619                 $this->trxPreCommitCallbacks = [];
3620
3621                 if ( $trxActive ) {
3622                         try {
3623                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3624                         } catch ( Exception $e ) {
3625                                 // already logged; finish and let LoadBalancer move on during mass-rollback
3626                         }
3627                         try {
3628                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3629                         } catch ( Exception $e ) {
3630                                 // already logged; let LoadBalancer move on during mass-rollback
3631                         }
3632
3633                         $this->affectedRowCount = 0; // for the sake of consistency
3634                 }
3635         }
3636
3637         /**
3638          * Issues the ROLLBACK command to the database server.
3639          *
3640          * @see Database::rollback()
3641          * @param string $fname
3642          */
3643         protected function doRollback( $fname ) {
3644                 if ( $this->trxLevel ) {
3645                         # Disconnects cause rollback anyway, so ignore those errors
3646                         $ignoreErrors = true;
3647                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3648                         $this->trxLevel = 0;
3649                 }
3650         }
3651
3652         public function flushSnapshot( $fname = __METHOD__ ) {
3653                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3654                         // This only flushes transactions to clear snapshots, not to write data
3655                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3656                         throw new DBUnexpectedError(
3657                                 $this,
3658                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3659                         );
3660                 }
3661
3662                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3663         }
3664
3665         public function explicitTrxActive() {
3666                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
3667         }
3668
3669         public function duplicateTableStructure(
3670                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3671         ) {
3672                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3673         }
3674
3675         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3676                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3677         }
3678
3679         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3680                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3681         }
3682
3683         public function timestamp( $ts = 0 ) {
3684                 $t = new ConvertibleTimestamp( $ts );
3685                 // Let errors bubble up to avoid putting garbage in the DB
3686                 return $t->getTimestamp( TS_MW );
3687         }
3688
3689         public function timestampOrNull( $ts = null ) {
3690                 if ( is_null( $ts ) ) {
3691                         return null;
3692                 } else {
3693                         return $this->timestamp( $ts );
3694                 }
3695         }
3696
3697         public function affectedRows() {
3698                 return ( $this->affectedRowCount === null )
3699                         ? $this->fetchAffectedRowCount() // default to driver value
3700                         : $this->affectedRowCount;
3701         }
3702
3703         /**
3704          * @return int Number of retrieved rows according to the driver
3705          */
3706         abstract protected function fetchAffectedRowCount();
3707
3708         /**
3709          * Take the result from a query, and wrap it in a ResultWrapper if
3710          * necessary. Boolean values are passed through as is, to indicate success
3711          * of write queries or failure.
3712          *
3713          * Once upon a time, Database::query() returned a bare MySQL result
3714          * resource, and it was necessary to call this function to convert it to
3715          * a wrapper. Nowadays, raw database objects are never exposed to external
3716          * callers, so this is unnecessary in external code.
3717          *
3718          * @param bool|ResultWrapper|resource|object $result
3719          * @return bool|ResultWrapper
3720          */
3721         protected function resultObject( $result ) {
3722                 if ( !$result ) {
3723                         return false;
3724                 } elseif ( $result instanceof ResultWrapper ) {
3725                         return $result;
3726                 } elseif ( $result === true ) {
3727                         // Successful write query
3728                         return $result;
3729                 } else {
3730                         return new ResultWrapper( $this, $result );
3731                 }
3732         }
3733
3734         public function ping( &$rtt = null ) {
3735                 // Avoid hitting the server if it was hit recently
3736                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3737                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
3738                                 $rtt = $this->rttEstimate;
3739                                 return true; // don't care about $rtt
3740                         }
3741                 }
3742
3743                 // This will reconnect if possible or return false if not
3744                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3745                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3746                 $this->restoreFlags( self::RESTORE_PRIOR );
3747
3748                 if ( $ok ) {
3749                         $rtt = $this->rttEstimate;
3750                 }
3751
3752                 return $ok;
3753         }
3754
3755         /**
3756          * Close any existing (dead) database connection and open a new connection
3757          *
3758          * @param string $fname
3759          * @return bool True if new connection is opened successfully, false if error
3760          */
3761         protected function replaceLostConnection( $fname ) {
3762                 $this->closeConnection();
3763                 $this->opened = false;
3764                 $this->conn = false;
3765                 try {
3766                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
3767                         $this->lastPing = microtime( true );
3768                         $ok = true;
3769
3770                         $this->connLogger->warning(
3771                                 $fname . ': lost connection to {dbserver}; reconnected',
3772                                 [
3773                                         'dbserver' => $this->getServer(),
3774                                         'trace' => ( new RuntimeException() )->getTraceAsString()
3775                                 ]
3776                         );
3777                 } catch ( DBConnectionError $e ) {
3778                         $ok = false;
3779
3780                         $this->connLogger->error(
3781                                 $fname . ': lost connection to {dbserver} permanently',
3782                                 [ 'dbserver' => $this->getServer() ]
3783                         );
3784                 }
3785
3786                 $this->handleSessionLoss();
3787
3788                 return $ok;
3789         }
3790
3791         public function getSessionLagStatus() {
3792                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3793         }
3794
3795         /**
3796          * Get the replica DB lag when the current transaction started
3797          *
3798          * This is useful when transactions might use snapshot isolation
3799          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3800          * is this lag plus transaction duration. If they don't, it is still
3801          * safe to be pessimistic. This returns null if there is no transaction.
3802          *
3803          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3804          * @since 1.27
3805          */
3806         final protected function getTransactionLagStatus() {
3807                 return $this->trxLevel
3808                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
3809                         : null;
3810         }
3811
3812         /**
3813          * Get a replica DB lag estimate for this server
3814          *
3815          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3816          * @since 1.27
3817          */
3818         protected function getApproximateLagStatus() {
3819                 return [
3820                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3821                         'since' => microtime( true )
3822                 ];
3823         }
3824
3825         /**
3826          * Merge the result of getSessionLagStatus() for several DBs
3827          * using the most pessimistic values to estimate the lag of
3828          * any data derived from them in combination
3829          *
3830          * This is information is useful for caching modules
3831          *
3832          * @see WANObjectCache::set()
3833          * @see WANObjectCache::getWithSetCallback()
3834          *
3835          * @param IDatabase $db1
3836          * @param IDatabase $db2 [optional]
3837          * @return array Map of values:
3838          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3839          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3840          *   - pending: whether any of the DBs have uncommitted changes
3841          * @throws DBError
3842          * @since 1.27
3843          */
3844         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
3845                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3846                 foreach ( func_get_args() as $db ) {
3847                         /** @var IDatabase $db */
3848                         $status = $db->getSessionLagStatus();
3849                         if ( $status['lag'] === false ) {
3850                                 $res['lag'] = false;
3851                         } elseif ( $res['lag'] !== false ) {
3852                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3853                         }
3854                         $res['since'] = min( $res['since'], $status['since'] );
3855                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3856                 }
3857
3858                 return $res;
3859         }
3860
3861         public function getLag() {
3862                 return 0;
3863         }
3864
3865         public function maxListLen() {
3866                 return 0;
3867         }
3868
3869         public function encodeBlob( $b ) {
3870                 return $b;
3871         }
3872
3873         public function decodeBlob( $b ) {
3874                 if ( $b instanceof Blob ) {
3875                         $b = $b->fetch();
3876                 }
3877                 return $b;
3878         }
3879
3880         public function setSessionOptions( array $options ) {
3881         }
3882
3883         public function sourceFile(
3884                 $filename,
3885                 callable $lineCallback = null,
3886                 callable $resultCallback = null,
3887                 $fname = false,
3888                 callable $inputCallback = null
3889         ) {
3890                 Wikimedia\suppressWarnings();
3891                 $fp = fopen( $filename, 'r' );
3892                 Wikimedia\restoreWarnings();
3893
3894                 if ( false === $fp ) {
3895                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3896                 }
3897
3898                 if ( !$fname ) {
3899                         $fname = __METHOD__ . "( $filename )";
3900                 }
3901
3902                 try {
3903                         $error = $this->sourceStream(
3904                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3905                 } catch ( Exception $e ) {
3906                         fclose( $fp );
3907                         throw $e;
3908                 }
3909
3910                 fclose( $fp );
3911
3912                 return $error;
3913         }
3914
3915         public function setSchemaVars( $vars ) {
3916                 $this->schemaVars = $vars;
3917         }
3918
3919         public function sourceStream(
3920                 $fp,
3921                 callable $lineCallback = null,
3922                 callable $resultCallback = null,
3923                 $fname = __METHOD__,
3924                 callable $inputCallback = null
3925         ) {
3926                 $delimiterReset = new ScopedCallback(
3927                         function ( $delimiter ) {
3928                                 $this->delimiter = $delimiter;
3929                         },
3930                         [ $this->delimiter ]
3931                 );
3932                 $cmd = '';
3933
3934                 while ( !feof( $fp ) ) {
3935                         if ( $lineCallback ) {
3936                                 call_user_func( $lineCallback );
3937                         }
3938
3939                         $line = trim( fgets( $fp ) );
3940
3941                         if ( $line == '' ) {
3942                                 continue;
3943                         }
3944
3945                         if ( '-' == $line[0] && '-' == $line[1] ) {
3946                                 continue;
3947                         }
3948
3949                         if ( $cmd != '' ) {
3950                                 $cmd .= ' ';
3951                         }
3952
3953                         $done = $this->streamStatementEnd( $cmd, $line );
3954
3955                         $cmd .= "$line\n";
3956
3957                         if ( $done || feof( $fp ) ) {
3958                                 $cmd = $this->replaceVars( $cmd );
3959
3960                                 if ( $inputCallback ) {
3961                                         $callbackResult = call_user_func( $inputCallback, $cmd );
3962
3963                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
3964                                                 $cmd = $callbackResult;
3965                                         }
3966                                 }
3967
3968                                 if ( $cmd ) {
3969                                         $res = $this->query( $cmd, $fname );
3970
3971                                         if ( $resultCallback ) {
3972                                                 call_user_func( $resultCallback, $res, $this );
3973                                         }
3974
3975                                         if ( false === $res ) {
3976                                                 $err = $this->lastError();
3977
3978                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3979                                         }
3980                                 }
3981                                 $cmd = '';
3982                         }
3983                 }
3984
3985                 ScopedCallback::consume( $delimiterReset );
3986                 return true;
3987         }
3988
3989         /**
3990          * Called by sourceStream() to check if we've reached a statement end
3991          *
3992          * @param string &$sql SQL assembled so far
3993          * @param string &$newLine New line about to be added to $sql
3994          * @return bool Whether $newLine contains end of the statement
3995          */
3996         public function streamStatementEnd( &$sql, &$newLine ) {
3997                 if ( $this->delimiter ) {
3998                         $prev = $newLine;
3999                         $newLine = preg_replace(
4000                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4001                         if ( $newLine != $prev ) {
4002                                 return true;
4003                         }
4004                 }
4005
4006                 return false;
4007         }
4008
4009         /**
4010          * Database independent variable replacement. Replaces a set of variables
4011          * in an SQL statement with their contents as given by $this->getSchemaVars().
4012          *
4013          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4014          *
4015          * - '{$var}' should be used for text and is passed through the database's
4016          *   addQuotes method.
4017          * - `{$var}` should be used for identifiers (e.g. table and database names).
4018          *   It is passed through the database's addIdentifierQuotes method which
4019          *   can be overridden if the database uses something other than backticks.
4020          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4021          *   database's tableName method.
4022          * - / *i* / passes the name that follows through the database's indexName method.
4023          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4024          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4025          *
4026          * @param string $ins SQL statement to replace variables in
4027          * @return string The new SQL statement with variables replaced
4028          */
4029         protected function replaceVars( $ins ) {
4030                 $vars = $this->getSchemaVars();
4031                 return preg_replace_callback(
4032                         '!
4033                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4034                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4035                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4036                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4037                         !x',
4038                         function ( $m ) use ( $vars ) {
4039                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4040                                 // check for both nonexistent keys *and* the empty string.
4041                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4042                                         if ( $m[1] === 'i' ) {
4043                                                 return $this->indexName( $m[2] );
4044                                         } else {
4045                                                 return $this->tableName( $m[2] );
4046                                         }
4047                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4048                                         return $this->addQuotes( $vars[$m[3]] );
4049                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4050                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4051                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4052                                         return $vars[$m[5]];
4053                                 } else {
4054                                         return $m[0];
4055                                 }
4056                         },
4057                         $ins
4058                 );
4059         }
4060
4061         /**
4062          * Get schema variables. If none have been set via setSchemaVars(), then
4063          * use some defaults from the current object.
4064          *
4065          * @return array
4066          */
4067         protected function getSchemaVars() {
4068                 if ( $this->schemaVars ) {
4069                         return $this->schemaVars;
4070                 } else {
4071                         return $this->getDefaultSchemaVars();
4072                 }
4073         }
4074
4075         /**
4076          * Get schema variables to use if none have been set via setSchemaVars().
4077          *
4078          * Override this in derived classes to provide variables for tables.sql
4079          * and SQL patch files.
4080          *
4081          * @return array
4082          */
4083         protected function getDefaultSchemaVars() {
4084                 return [];
4085         }
4086
4087         public function lockIsFree( $lockName, $method ) {
4088                 // RDBMs methods for checking named locks may or may not count this thread itself.
4089                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4090                 // the behavior choosen by the interface for this method.
4091                 return !isset( $this->namedLocksHeld[$lockName] );
4092         }
4093
4094         public function lock( $lockName, $method, $timeout = 5 ) {
4095                 $this->namedLocksHeld[$lockName] = 1;
4096
4097                 return true;
4098         }
4099
4100         public function unlock( $lockName, $method ) {
4101                 unset( $this->namedLocksHeld[$lockName] );
4102
4103                 return true;
4104         }
4105
4106         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4107                 if ( $this->writesOrCallbacksPending() ) {
4108                         // This only flushes transactions to clear snapshots, not to write data
4109                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4110                         throw new DBUnexpectedError(
4111                                 $this,
4112                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4113                         );
4114                 }
4115
4116                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4117                         return null;
4118                 }
4119
4120                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4121                         if ( $this->trxLevel() ) {
4122                                 // There is a good chance an exception was thrown, causing any early return
4123                                 // from the caller. Let any error handler get a chance to issue rollback().
4124                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4125                                 $this->onTransactionResolution(
4126                                         function () use ( $lockKey, $fname ) {
4127                                                 $this->unlock( $lockKey, $fname );
4128                                         },
4129                                         $fname
4130                                 );
4131                         } else {
4132                                 $this->unlock( $lockKey, $fname );
4133                         }
4134                 } );
4135
4136                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4137
4138                 return $unlocker;
4139         }
4140
4141         public function namedLocksEnqueue() {
4142                 return false;
4143         }
4144
4145         public function tableLocksHaveTransactionScope() {
4146                 return true;
4147         }
4148
4149         final public function lockTables( array $read, array $write, $method ) {
4150                 if ( $this->writesOrCallbacksPending() ) {
4151                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4152                 }
4153
4154                 if ( $this->tableLocksHaveTransactionScope() ) {
4155                         $this->startAtomic( $method );
4156                 }
4157
4158                 return $this->doLockTables( $read, $write, $method );
4159         }
4160
4161         /**
4162          * Helper function for lockTables() that handles the actual table locking
4163          *
4164          * @param array $read Array of tables to lock for read access
4165          * @param array $write Array of tables to lock for write access
4166          * @param string $method Name of caller
4167          * @return true
4168          */
4169         protected function doLockTables( array $read, array $write, $method ) {
4170                 return true;
4171         }
4172
4173         final public function unlockTables( $method ) {
4174                 if ( $this->tableLocksHaveTransactionScope() ) {
4175                         $this->endAtomic( $method );
4176
4177                         return true; // locks released on COMMIT/ROLLBACK
4178                 }
4179
4180                 return $this->doUnlockTables( $method );
4181         }
4182
4183         /**
4184          * Helper function for unlockTables() that handles the actual table unlocking
4185          *
4186          * @param string $method Name of caller
4187          * @return true
4188          */
4189         protected function doUnlockTables( $method ) {
4190                 return true;
4191         }
4192
4193         /**
4194          * Delete a table
4195          * @param string $tableName
4196          * @param string $fName
4197          * @return bool|ResultWrapper
4198          * @since 1.18
4199          */
4200         public function dropTable( $tableName, $fName = __METHOD__ ) {
4201                 if ( !$this->tableExists( $tableName, $fName ) ) {
4202                         return false;
4203                 }
4204                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4205
4206                 return $this->query( $sql, $fName );
4207         }
4208
4209         public function getInfinity() {
4210                 return 'infinity';
4211         }
4212
4213         public function encodeExpiry( $expiry ) {
4214                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4215                         ? $this->getInfinity()
4216                         : $this->timestamp( $expiry );
4217         }
4218
4219         public function decodeExpiry( $expiry, $format = TS_MW ) {
4220                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4221                         return 'infinity';
4222                 }
4223
4224                 return ConvertibleTimestamp::convert( $format, $expiry );
4225         }
4226
4227         public function setBigSelects( $value = true ) {
4228                 // no-op
4229         }
4230
4231         public function isReadOnly() {
4232                 return ( $this->getReadOnlyReason() !== false );
4233         }
4234
4235         /**
4236          * @return string|bool Reason this DB is read-only or false if it is not
4237          */
4238         protected function getReadOnlyReason() {
4239                 $reason = $this->getLBInfo( 'readOnlyReason' );
4240
4241                 return is_string( $reason ) ? $reason : false;
4242         }
4243
4244         public function setTableAliases( array $aliases ) {
4245                 $this->tableAliases = $aliases;
4246         }
4247
4248         public function setIndexAliases( array $aliases ) {
4249                 $this->indexAliases = $aliases;
4250         }
4251
4252         /**
4253          * Get the underlying binding connection handle
4254          *
4255          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4256          * This catches broken callers than catch and ignore disconnection exceptions.
4257          * Unlike checking isOpen(), this is safe to call inside of open().
4258          *
4259          * @return mixed
4260          * @throws DBUnexpectedError
4261          * @since 1.26
4262          */
4263         protected function getBindingHandle() {
4264                 if ( !$this->conn ) {
4265                         throw new DBUnexpectedError(
4266                                 $this,
4267                                 'DB connection was already closed or the connection dropped.'
4268                         );
4269                 }
4270
4271                 return $this->conn;
4272         }
4273
4274         /**
4275          * @since 1.19
4276          * @return string
4277          */
4278         public function __toString() {
4279                 return (string)$this->conn;
4280         }
4281
4282         /**
4283          * Make sure that copies do not share the same client binding handle
4284          * @throws DBConnectionError
4285          */
4286         public function __clone() {
4287                 $this->connLogger->warning(
4288                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
4289                         ( new RuntimeException() )->getTraceAsString()
4290                 );
4291
4292                 if ( $this->isOpen() ) {
4293                         // Open a new connection resource without messing with the old one
4294                         $this->opened = false;
4295                         $this->conn = false;
4296                         $this->trxEndCallbacks = []; // don't copy
4297                         $this->handleSessionLoss(); // no trx or locks anymore
4298                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4299                         $this->lastPing = microtime( true );
4300                 }
4301         }
4302
4303         /**
4304          * Called by serialize. Throw an exception when DB connection is serialized.
4305          * This causes problems on some database engines because the connection is
4306          * not restored on unserialize.
4307          */
4308         public function __sleep() {
4309                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4310                         'the connection is not restored on wakeup.' );
4311         }
4312
4313         /**
4314          * Run a few simple sanity checks and close dangling connections
4315          */
4316         public function __destruct() {
4317                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4318                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4319                 }
4320
4321                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4322                 if ( $danglingWriters ) {
4323                         $fnames = implode( ', ', $danglingWriters );
4324                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4325                 }
4326
4327                 if ( $this->conn ) {
4328                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4329                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4330                         Wikimedia\suppressWarnings();
4331                         $this->closeConnection();
4332                         Wikimedia\restoreWarnings();
4333                         $this->conn = false;
4334                         $this->opened = false;
4335                 }
4336         }
4337 }
4338
4339 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
4340 class_alias( Database::class, 'Database' ); // b/c global alias