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 Wikimedia\ScopedCallback;
  31 use Wikimedia\Timestamp\ConvertibleTimestamp;
  32 use Wikimedia;
  33 use BagOStuff;
  34 use HashBagOStuff;
  35 use InvalidArgumentException;
  36 use Exception;
  37 use RuntimeException;
  38
  39 /**
  40  * Relational database abstraction object
  41  *
  42  * @ingroup Database
  43  * @since 1.28
  44  */
  45 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  46         /** Number of times to re-try an operation in case of deadlock */
  47         const DEADLOCK_TRIES = 4;
  48         /** Minimum time to wait before retry, in microseconds */
  49         const DEADLOCK_DELAY_MIN = 500000;
  50         /** Maximum time to wait before retry */
  51         const DEADLOCK_DELAY_MAX = 1500000;
  52
  53         /** How long before it is worth doing a dummy query to test the connection */
  54         const PING_TTL = 1.0;
  55         const PING_QUERY = 'SELECT 1 AS ping';
  56
  57         const TINY_WRITE_SEC = 0.010;
  58         const SLOW_WRITE_SEC = 0.500;
  59         const SMALL_WRITE_ROWS = 100;
  60
  61         /** @var string SQL query */
  62         protected $lastQuery = '';
  63         /** @var float|bool UNIX timestamp of last write query */
  64         protected $lastWriteTime = false;
  65         /** @var string|bool */
  66         protected $phpError = false;
  67         /** @var string */
  68         protected $server;
  69         /** @var string */
  70         protected $user;
  71         /** @var string */
  72         protected $password;
  73         /** @var string */
  74         protected $dbName;
  75         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  76         protected $tableAliases = [];
  77         /** @var bool Whether this PHP instance is for a CLI script */
  78         protected $cliMode;
  79         /** @var string Agent name for query profiling */
  80         protected $agent;
  81
  82         /** @var BagOStuff APC cache */
  83         protected $srvCache;
  84         /** @var LoggerInterface */
  85         protected $connLogger;
  86         /** @var LoggerInterface */
  87         protected $queryLogger;
  88         /** @var callback Error logging callback */
  89         protected $errorLogger;
  90
  91         /** @var resource|null Database connection */
  92         protected $conn = null;
  93         /** @var bool */
  94         protected $opened = false;
  95
  96         /** @var array[] List of (callable, method name) */
  97         protected $trxIdleCallbacks = [];
  98         /** @var array[] List of (callable, method name) */
  99         protected $trxPreCommitCallbacks = [];
 100         /** @var array[] List of (callable, method name) */
 101         protected $trxEndCallbacks = [];
 102         /** @var callable[] Map of (name => callable) */
 103         protected $trxRecurringCallbacks = [];
 104         /** @var bool Whether to suppress triggering of transaction end callbacks */
 105         protected $trxEndCallbacksSuppressed = false;
 106
 107         /** @var string */
 108         protected $tablePrefix = '';
 109         /** @var string */
 110         protected $schema = '';
 111         /** @var int */
 112         protected $flags;
 113         /** @var array */
 114         protected $lbInfo = [];
 115         /** @var array|bool */
 116         protected $schemaVars = false;
 117         /** @var array */
 118         protected $sessionVars = [];
 119         /** @var array|null */
 120         protected $preparedArgs;
 121         /** @var string|bool|null Stashed value of html_errors INI setting */
 122         protected $htmlErrors;
 123         /** @var string */
 124         protected $delimiter = ';';
 125         /** @var DatabaseDomain */
 126         protected $currentDomain;
 127         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 128         protected $affectedRowCount;
 129
 130         /**
 131          * Either 1 if a transaction is active or 0 otherwise.
 132          * The other Trx fields may not be meaningfull if this is 0.
 133          *
 134          * @var int
 135          */
 136         protected $trxLevel = 0;
 137         /**
 138          * Either a short hexidecimal string if a transaction is active or ""
 139          *
 140          * @var string
 141          * @see Database::trxLevel
 142          */
 143         protected $trxShortId = '';
 144         /**
 145          * The UNIX time that the transaction started. Callers can assume that if
 146          * snapshot isolation is used, then the data is *at least* up to date to that
 147          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 148          *
 149          * @var float|null
 150          * @see Database::trxLevel
 151          */
 152         private $trxTimestamp = null;
 153         /** @var float Lag estimate at the time of BEGIN */
 154         private $trxReplicaLag = null;
 155         /**
 156          * Remembers the function name given for starting the most recent transaction via begin().
 157          * Used to provide additional context for error reporting.
 158          *
 159          * @var string
 160          * @see Database::trxLevel
 161          */
 162         private $trxFname = null;
 163         /**
 164          * Record if possible write queries were done in the last transaction started
 165          *
 166          * @var bool
 167          * @see Database::trxLevel
 168          */
 169         private $trxDoneWrites = false;
 170         /**
 171          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 172          *
 173          * @var bool
 174          * @see Database::trxLevel
 175          */
 176         private $trxAutomatic = false;
 177         /**
 178          * Array of levels of atomicity within transactions
 179          *
 180          * @var array
 181          */
 182         private $trxAtomicLevels = [];
 183         /**
 184          * Record if the current transaction was started implicitly by Database::startAtomic
 185          *
 186          * @var bool
 187          */
 188         private $trxAutomaticAtomic = false;
 189         /**
 190          * Track the write query callers of the current transaction
 191          *
 192          * @var string[]
 193          */
 194         private $trxWriteCallers = [];
 195         /**
 196          * @var float Seconds spent in write queries for the current transaction
 197          */
 198         private $trxWriteDuration = 0.0;
 199         /**
 200          * @var int Number of write queries for the current transaction
 201          */
 202         private $trxWriteQueryCount = 0;
 203         /**
 204          * @var int Number of rows affected by write queries for the current transaction
 205          */
 206         private $trxWriteAffectedRows = 0;
 207         /**
 208          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 209          */
 210         private $trxWriteAdjDuration = 0.0;
 211         /**
 212          * @var int Number of write queries counted in trxWriteAdjDuration
 213          */
 214         private $trxWriteAdjQueryCount = 0;
 215         /**
 216          * @var float RTT time estimate
 217          */
 218         private $rttEstimate = 0.0;
 219
 220         /** @var array Map of (name => 1) for locks obtained via lock() */
 221         private $namedLocksHeld = [];
 222         /** @var array Map of (table name => 1) for TEMPORARY tables */
 223         protected $sessionTempTables = [];
 224
 225         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 226         private $lazyMasterHandle;
 227
 228         /** @var float UNIX timestamp */
 229         protected $lastPing = 0.0;
 230
 231         /** @var int[] Prior flags member variable values */
 232         private $priorFlags = [];
 233
 234         /** @var object|string Class name or object With profileIn/profileOut methods */
 235         protected $profiler;
 236         /** @var TransactionProfiler */
 237         protected $trxProfiler;
 238
 239         /** @var int */
 240         protected $nonNativeInsertSelectBatchSize = 10000;
 241
 242         /**
 243          * Constructor and database handle and attempt to connect to the DB server
 244          *
 245          * IDatabase classes should not be constructed directly in external
 246          * code. Database::factory() should be used instead.
 247          *
 248          * @param array $params Parameters passed from Database::factory()
 249          */
 250         function __construct( array $params ) {
 251                 $server = $params['host'];
 252                 $user = $params['user'];
 253                 $password = $params['password'];
 254                 $dbName = $params['dbname'];
 255
 256                 $this->schema = $params['schema'];
 257                 $this->tablePrefix = $params['tablePrefix'];
 258
 259                 $this->cliMode = $params['cliMode'];
 260                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 261                 $this->agent = str_replace( '/', '-', $params['agent'] );
 262
 263                 $this->flags = $params['flags'];
 264                 if ( $this->flags & self::DBO_DEFAULT ) {
 265                         if ( $this->cliMode ) {
 266                                 $this->flags &= ~self::DBO_TRX;
 267                         } else {
 268                                 $this->flags |= self::DBO_TRX;
 269                         }
 270                 }
 271
 272                 $this->sessionVars = $params['variables'];
 273
 274                 $this->srvCache = isset( $params['srvCache'] )
 275                         ? $params['srvCache']
 276                         : new HashBagOStuff();
 277
 278                 $this->profiler = $params['profiler'];
 279                 $this->trxProfiler = $params['trxProfiler'];
 280                 $this->connLogger = $params['connLogger'];
 281                 $this->queryLogger = $params['queryLogger'];
 282                 $this->errorLogger = $params['errorLogger'];
 283
 284                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 285                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 286                 }
 287
 288                 // Set initial dummy domain until open() sets the final DB/prefix
 289                 $this->currentDomain = DatabaseDomain::newUnspecified();
 290
 291                 if ( $user ) {
 292                         $this->open( $server, $user, $password, $dbName );
 293                 } elseif ( $this->requiresDatabaseUser() ) {
 294                         throw new InvalidArgumentException( "No database user provided." );
 295                 }
 296
 297                 // Set the domain object after open() sets the relevant fields
 298                 if ( $this->dbName != '' ) {
 299                         // Domains with server scope but a table prefix are not used by IDatabase classes
 300                         $this->currentDomain = new DatabaseDomain( $this->dbName, null, $this->tablePrefix );
 301                 }
 302         }
 303
 304         /**
 305          * Construct a Database subclass instance given a database type and parameters
 306          *
 307          * This also connects to the database immediately upon object construction
 308          *
 309          * @param string $dbType A possible DB type (sqlite, mysql, postgres)
 310          * @param array $p Parameter map with keys:
 311          *   - host : The hostname of the DB server
 312          *   - user : The name of the database user the client operates under
 313          *   - password : The password for the database user
 314          *   - dbname : The name of the database to use where queries do not specify one.
 315          *      The database must exist or an error might be thrown. Setting this to the empty string
 316          *      will avoid any such errors and make the handle have no implicit database scope. This is
 317          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 318          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 319          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 320          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 321          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 322          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 323          *      recognized in queries. This can be used in place of schemas for handle site farms.
 324          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 325          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 326          *      flag in place UNLESS this this database simply acts as a key/value store.
 327          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 328          *      'mysqli' driver; the old one 'mysql' has been removed.
 329          *   - variables: Optional map of session variables to set after connecting. This can be
 330          *      used to adjust lock timeouts or encoding modes and the like.
 331          *   - connLogger: Optional PSR-3 logger interface instance.
 332          *   - queryLogger: Optional PSR-3 logger interface instance.
 333          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 334          *      These will be called in query(), using a simplified version of the SQL that also
 335          *      includes the agent as a SQL comment.
 336          *   - trxProfiler: Optional TransactionProfiler instance.
 337          *   - errorLogger: Optional callback that takes an Exception and logs it.
 338          *   - cliMode: Whether to consider the execution context that of a CLI script.
 339          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 340          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 341          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 342          * @return Database|null If the database driver or extension cannot be found
 343          * @throws InvalidArgumentException If the database driver or extension cannot be found
 344          * @since 1.18
 345          */
 346         final public static function factory( $dbType, $p = [] ) {
 347                 // For database types with built-in support, the below maps type to IDatabase
 348                 // implementations. For types with multipe driver implementations (PHP extensions),
 349                 // an array can be used, keyed by extension name. In case of an array, the
 350                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 351                 // we auto-detect the first available driver. For types without built-in support,
 352                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 353                 static $builtinTypes = [
 354                         'mssql' => DatabaseMssql::class,
 355                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 356                         'sqlite' => DatabaseSqlite::class,
 357                         'postgres' => DatabasePostgres::class,
 358                 ];
 359
 360                 $dbType = strtolower( $dbType );
 361                 $class = false;
 362                 if ( isset( $builtinTypes[$dbType] ) ) {
 363                         $possibleDrivers = $builtinTypes[$dbType];
 364                         if ( is_string( $possibleDrivers ) ) {
 365                                 $class = $possibleDrivers;
 366                         } else {
 367                                 if ( !empty( $p['driver'] ) ) {
 368                                         if ( !isset( $possibleDrivers[$p['driver']] ) ) {
 369                                                 throw new InvalidArgumentException( __METHOD__ .
 370                                                         " type '$dbType' does not support driver '{$p['driver']}'" );
 371                                         } else {
 372                                                 $class = $possibleDrivers[$p['driver']];
 373                                         }
 374                                 } else {
 375                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 376                                                 if ( extension_loaded( $posDriver ) ) {
 377                                                         $class = $possibleClass;
 378                                                         break;
 379                                                 }
 380                                         }
 381                                 }
 382                         }
 383                 } else {
 384                         $class = 'Database' . ucfirst( $dbType );
 385                 }
 386
 387                 if ( $class === false ) {
 388                         throw new InvalidArgumentException( __METHOD__ .
 389                                 " no viable database extension found for type '$dbType'" );
 390                 }
 391
 392                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 393                         // Resolve some defaults for b/c
 394                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 395                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 396                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 397                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 398                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 399                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 400                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 401                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 402                         $p['cliMode'] = isset( $p['cliMode'] )
 403                                 ? $p['cliMode']
 404                                 : ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 405                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 406                         if ( !isset( $p['connLogger'] ) ) {
 407                                 $p['connLogger'] = new \Psr\Log\NullLogger();
 408                         }
 409                         if ( !isset( $p['queryLogger'] ) ) {
 410                                 $p['queryLogger'] = new \Psr\Log\NullLogger();
 411                         }
 412                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 413                         if ( !isset( $p['trxProfiler'] ) ) {
 414                                 $p['trxProfiler'] = new TransactionProfiler();
 415                         }
 416                         if ( !isset( $p['errorLogger'] ) ) {
 417                                 $p['errorLogger'] = function ( Exception $e ) {
 418                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 419                                 };
 420                         }
 421
 422                         $conn = new $class( $p );
 423                 } else {
 424                         $conn = null;
 425                 }
 426
 427                 return $conn;
 428         }
 429
 430         /**
 431          * Set the PSR-3 logger interface to use for query logging. (The logger
 432          * interfaces for connection logging and error logging can be set with the
 433          * constructor.)
 434          *
 435          * @param LoggerInterface $logger
 436          */
 437         public function setLogger( LoggerInterface $logger ) {
 438                 $this->queryLogger = $logger;
 439         }
 440
 441         public function getServerInfo() {
 442                 return $this->getServerVersion();
 443         }
 444
 445         public function bufferResults( $buffer = null ) {
 446                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 447                 if ( $buffer !== null ) {
 448                         $buffer
 449                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 450                                 : $this->setFlag( self::DBO_NOBUFFER );
 451                 }
 452
 453                 return $res;
 454         }
 455
 456         /**
 457          * Turns on (false) or off (true) the automatic generation and sending
 458          * of a "we're sorry, but there has been a database error" page on
 459          * database errors. Default is on (false). When turned off, the
 460          * code should use lastErrno() and lastError() to handle the
 461          * situation as appropriate.
 462          *
 463          * Do not use this function outside of the Database classes.
 464          *
 465          * @param null|bool $ignoreErrors
 466          * @return bool The previous value of the flag.
 467          */
 468         protected function ignoreErrors( $ignoreErrors = null ) {
 469                 $res = $this->getFlag( self::DBO_IGNORE );
 470                 if ( $ignoreErrors !== null ) {
 471                         // setFlag()/clearFlag() do not allow DBO_IGNORE changes for sanity
 472                         if ( $ignoreErrors ) {
 473                                 $this->flags |= self::DBO_IGNORE;
 474                         } else {
 475                                 $this->flags &= ~self::DBO_IGNORE;
 476                         }
 477                 }
 478
 479                 return $res;
 480         }
 481
 482         public function trxLevel() {
 483                 return $this->trxLevel;
 484         }
 485
 486         public function trxTimestamp() {
 487                 return $this->trxLevel ? $this->trxTimestamp : null;
 488         }
 489
 490         public function tablePrefix( $prefix = null ) {
 491                 $old = $this->tablePrefix;
 492                 if ( $prefix !== null ) {
 493                         $this->tablePrefix = $prefix;
 494                         $this->currentDomain = ( $this->dbName != '' )
 495                                 ? new DatabaseDomain( $this->dbName, null, $this->tablePrefix )
 496                                 : DatabaseDomain::newUnspecified();
 497                 }
 498
 499                 return $old;
 500         }
 501
 502         public function dbSchema( $schema = null ) {
 503                 $old = $this->schema;
 504                 if ( $schema !== null ) {
 505                         $this->schema = $schema;
 506                 }
 507
 508                 return $old;
 509         }
 510
 511         public function getLBInfo( $name = null ) {
 512                 if ( is_null( $name ) ) {
 513                         return $this->lbInfo;
 514                 } else {
 515                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 516                                 return $this->lbInfo[$name];
 517                         } else {
 518                                 return null;
 519                         }
 520                 }
 521         }
 522
 523         public function setLBInfo( $name, $value = null ) {
 524                 if ( is_null( $value ) ) {
 525                         $this->lbInfo = $name;
 526                 } else {
 527                         $this->lbInfo[$name] = $value;
 528                 }
 529         }
 530
 531         public function setLazyMasterHandle( IDatabase $conn ) {
 532                 $this->lazyMasterHandle = $conn;
 533         }
 534
 535         /**
 536          * @return IDatabase|null
 537          * @see setLazyMasterHandle()
 538          * @since 1.27
 539          */
 540         protected function getLazyMasterHandle() {
 541                 return $this->lazyMasterHandle;
 542         }
 543
 544         public function implicitGroupby() {
 545                 return true;
 546         }
 547
 548         public function implicitOrderby() {
 549                 return true;
 550         }
 551
 552         public function lastQuery() {
 553                 return $this->lastQuery;
 554         }
 555
 556         public function doneWrites() {
 557                 return (bool)$this->lastWriteTime;
 558         }
 559
 560         public function lastDoneWrites() {
 561                 return $this->lastWriteTime ?: false;
 562         }
 563
 564         public function writesPending() {
 565                 return $this->trxLevel && $this->trxDoneWrites;
 566         }
 567
 568         public function writesOrCallbacksPending() {
 569                 return $this->trxLevel && (
 570                         $this->trxDoneWrites || $this->trxIdleCallbacks || $this->trxPreCommitCallbacks
 571                 );
 572         }
 573
 574         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 575                 if ( !$this->trxLevel ) {
 576                         return false;
 577                 } elseif ( !$this->trxDoneWrites ) {
 578                         return 0.0;
 579                 }
 580
 581                 switch ( $type ) {
 582                         case self::ESTIMATE_DB_APPLY:
 583                                 $this->ping( $rtt );
 584                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 585                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 586                                 // For omitted queries, make them count as something at least
 587                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 588                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 589
 590                                 return $applyTime;
 591                         default: // everything
 592                                 return $this->trxWriteDuration;
 593                 }
 594         }
 595
 596         public function pendingWriteCallers() {
 597                 return $this->trxLevel ? $this->trxWriteCallers : [];
 598         }
 599
 600         public function pendingWriteRowsAffected() {
 601                 return $this->trxWriteAffectedRows;
 602         }
 603
 604         /**
 605          * Get the list of method names that have pending write queries or callbacks
 606          * for this transaction
 607          *
 608          * @return array
 609          */
 610         protected function pendingWriteAndCallbackCallers() {
 611                 if ( !$this->trxLevel ) {
 612                         return [];
 613                 }
 614
 615                 $fnames = $this->trxWriteCallers;
 616                 foreach ( [
 617                         $this->trxIdleCallbacks,
 618                         $this->trxPreCommitCallbacks,
 619                         $this->trxEndCallbacks
 620                 ] as $callbacks ) {
 621                         foreach ( $callbacks as $callback ) {
 622                                 $fnames[] = $callback[1];
 623                         }
 624                 }
 625
 626                 return $fnames;
 627         }
 628
 629         public function isOpen() {
 630                 return $this->opened;
 631         }
 632
 633         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 634                 if ( ( $flag & self::DBO_IGNORE ) ) {
 635                         throw new \UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 636                 }
 637
 638                 if ( $remember === self::REMEMBER_PRIOR ) {
 639                         array_push( $this->priorFlags, $this->flags );
 640                 }
 641                 $this->flags |= $flag;
 642         }
 643
 644         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 645                 if ( ( $flag & self::DBO_IGNORE ) ) {
 646                         throw new \UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 647                 }
 648
 649                 if ( $remember === self::REMEMBER_PRIOR ) {
 650                         array_push( $this->priorFlags, $this->flags );
 651                 }
 652                 $this->flags &= ~$flag;
 653         }
 654
 655         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 656                 if ( !$this->priorFlags ) {
 657                         return;
 658                 }
 659
 660                 if ( $state === self::RESTORE_INITIAL ) {
 661                         $this->flags = reset( $this->priorFlags );
 662                         $this->priorFlags = [];
 663                 } else {
 664                         $this->flags = array_pop( $this->priorFlags );
 665                 }
 666         }
 667
 668         public function getFlag( $flag ) {
 669                 return !!( $this->flags & $flag );
 670         }
 671
 672         /**
 673          * @param string $name Class field name
 674          * @return mixed
 675          * @deprecated Since 1.28
 676          */
 677         public function getProperty( $name ) {
 678                 return $this->$name;
 679         }
 680
 681         public function getDomainID() {
 682                 return $this->currentDomain->getId();
 683         }
 684
 685         final public function getWikiID() {
 686                 return $this->getDomainID();
 687         }
 688
 689         /**
 690          * Get information about an index into an object
 691          * @param string $table Table name
 692          * @param string $index Index name
 693          * @param string $fname Calling function name
 694          * @return mixed Database-specific index description class or false if the index does not exist
 695          */
 696         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 697
 698         /**
 699          * Wrapper for addslashes()
 700          *
 701          * @param string $s String to be slashed.
 702          * @return string Slashed string.
 703          */
 704         abstract function strencode( $s );
 705
 706         /**
 707          * Set a custom error handler for logging errors during database connection
 708          */
 709         protected function installErrorHandler() {
 710                 $this->phpError = false;
 711                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 712                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 713         }
 714
 715         /**
 716          * Restore the previous error handler and return the last PHP error for this DB
 717          *
 718          * @return bool|string
 719          */
 720         protected function restoreErrorHandler() {
 721                 restore_error_handler();
 722                 if ( $this->htmlErrors !== false ) {
 723                         ini_set( 'html_errors', $this->htmlErrors );
 724                 }
 725
 726                 return $this->getLastPHPError();
 727         }
 728
 729         /**
 730          * @return string|bool Last PHP error for this DB (typically connection errors)
 731          */
 732         protected function getLastPHPError() {
 733                 if ( $this->phpError ) {
 734                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 735                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 736
 737                         return $error;
 738                 }
 739
 740                 return false;
 741         }
 742
 743         /**
 744          * Error handler for logging errors during database connection
 745          * This method should not be used outside of Database classes
 746          *
 747          * @param int $errno
 748          * @param string $errstr
 749          */
 750         public function connectionErrorLogger( $errno, $errstr ) {
 751                 $this->phpError = $errstr;
 752         }
 753
 754         /**
 755          * Create a log context to pass to PSR-3 logger functions.
 756          *
 757          * @param array $extras Additional data to add to context
 758          * @return array
 759          */
 760         protected function getLogContext( array $extras = [] ) {
 761                 return array_merge(
 762                         [
 763                                 'db_server' => $this->server,
 764                                 'db_name' => $this->dbName,
 765                                 'db_user' => $this->user,
 766                         ],
 767                         $extras
 768                 );
 769         }
 770
 771         public function close() {
 772                 if ( $this->conn ) {
 773                         if ( $this->trxLevel() ) {
 774                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 775                         }
 776
 777                         $closed = $this->closeConnection();
 778                         $this->conn = false;
 779                 } elseif (
 780                         $this->trxIdleCallbacks ||
 781                         $this->trxPreCommitCallbacks ||
 782                         $this->trxEndCallbacks
 783                 ) { // sanity
 784                         throw new RuntimeException( "Transaction callbacks still pending." );
 785                 } else {
 786                         $closed = true;
 787                 }
 788                 $this->opened = false;
 789
 790                 return $closed;
 791         }
 792
 793         /**
 794          * Make sure isOpen() returns true as a sanity check
 795          *
 796          * @throws DBUnexpectedError
 797          */
 798         protected function assertOpen() {
 799                 if ( !$this->isOpen() ) {
 800                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 801                 }
 802         }
 803
 804         /**
 805          * Closes underlying database connection
 806          * @since 1.20
 807          * @return bool Whether connection was closed successfully
 808          */
 809         abstract protected function closeConnection();
 810
 811         public function reportConnectionError( $error = 'Unknown error' ) {
 812                 $myError = $this->lastError();
 813                 if ( $myError ) {
 814                         $error = $myError;
 815                 }
 816
 817                 # New method
 818                 throw new DBConnectionError( $this, $error );
 819         }
 820
 821         /**
 822          * The DBMS-dependent part of query()
 823          *
 824          * @param string $sql SQL query.
 825          * @return ResultWrapper|bool Result object to feed to fetchObject,
 826          *   fetchRow, ...; or false on failure
 827          */
 828         abstract protected function doQuery( $sql );
 829
 830         /**
 831          * Determine whether a query writes to the DB.
 832          * Should return true if unsure.
 833          *
 834          * @param string $sql
 835          * @return bool
 836          */
 837         protected function isWriteQuery( $sql ) {
 838                 return !preg_match(
 839                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 840         }
 841
 842         /**
 843          * @param string $sql
 844          * @return string|null
 845          */
 846         protected function getQueryVerb( $sql ) {
 847                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 848         }
 849
 850         /**
 851          * Determine whether a SQL statement is sensitive to isolation level.
 852          * A SQL statement is considered transactable if its result could vary
 853          * depending on the transaction isolation level. Operational commands
 854          * such as 'SET' and 'SHOW' are not considered to be transactable.
 855          *
 856          * @param string $sql
 857          * @return bool
 858          */
 859         protected function isTransactableQuery( $sql ) {
 860                 return !in_array(
 861                         $this->getQueryVerb( $sql ),
 862                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 863                         true
 864                 );
 865         }
 866
 867         /**
 868          * @param string $sql A SQL query
 869          * @return bool Whether $sql is SQL for TEMPORARY table operation
 870          */
 871         protected function registerTempTableOperation( $sql ) {
 872                 if ( preg_match(
 873                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 874                         $sql,
 875                         $matches
 876                 ) ) {
 877                         $this->sessionTempTables[$matches[1]] = 1;
 878
 879                         return true;
 880                 } elseif ( preg_match(
 881                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 882                         $sql,
 883                         $matches
 884                 ) ) {
 885                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
 886                         unset( $this->sessionTempTables[$matches[1]] );
 887
 888                         return $isTemp;
 889                 } elseif ( preg_match(
 890                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 891                         $sql,
 892                         $matches
 893                 ) ) {
 894                         return isset( $this->sessionTempTables[$matches[1]] );
 895                 } elseif ( preg_match(
 896                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 897                         $sql,
 898                         $matches
 899                 ) ) {
 900                         return isset( $this->sessionTempTables[$matches[1]] );
 901                 }
 902
 903                 return false;
 904         }
 905
 906         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 907                 $priorWritesPending = $this->writesOrCallbacksPending();
 908                 $this->lastQuery = $sql;
 909
 910                 $isWrite = $this->isWriteQuery( $sql );
 911                 if ( $isWrite ) {
 912                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
 913                 } else {
 914                         $isNonTempWrite = false;
 915                 }
 916
 917                 if ( $isWrite ) {
 918                         if ( $this->getLBInfo( 'replica' ) === true ) {
 919                                 throw new DBError(
 920                                         $this,
 921                                         'Write operations are not allowed on replica database connections.'
 922                                 );
 923                         }
 924                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
 925                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
 926                         $reason = $this->getReadOnlyReason();
 927                         if ( $reason !== false ) {
 928                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 929                         }
 930                         # Set a flag indicating that writes have been done
 931                         $this->lastWriteTime = microtime( true );
 932                 }
 933
 934                 # Add trace comment to the begin of the sql string, right after the operator.
 935                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 936                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 937
 938                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 939                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
 940                         && $this->isTransactableQuery( $sql )
 941                 ) {
 942                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 943                         $this->trxAutomatic = true;
 944                 }
 945
 946                 # Keep track of whether the transaction has write queries pending
 947                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
 948                         $this->trxDoneWrites = true;
 949                         $this->trxProfiler->transactionWritingIn(
 950                                 $this->server, $this->dbName, $this->trxShortId );
 951                 }
 952
 953                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 954                         $this->queryLogger->debug( "{$this->dbName} {$commentedSql}" );
 955                 }
 956
 957                 # Avoid fatals if close() was called
 958                 $this->assertOpen();
 959
 960                 # Send the query to the server
 961                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 962
 963                 # Try reconnecting if the connection was lost
 964                 if ( false === $ret && $this->wasErrorReissuable() ) {
 965                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 966                         # Stash the last error values before anything might clear them
 967                         $lastError = $this->lastError();
 968                         $lastErrno = $this->lastErrno();
 969                         # Update state tracking to reflect transaction loss due to disconnection
 970                         $this->handleSessionLoss();
 971                         if ( $this->reconnect() ) {
 972                                 $msg = __METHOD__ . ': lost connection to {dbserver}; reconnected';
 973                                 $params = [ 'dbserver' => $this->getServer() ];
 974                                 $this->connLogger->warning( $msg, $params );
 975                                 $this->queryLogger->warning( $msg, $params +
 976                                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ] );
 977
 978                                 if ( !$recoverable ) {
 979                                         # Callers may catch the exception and continue to use the DB
 980                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 981                                 } else {
 982                                         # Should be safe to silently retry the query
 983                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 984                                 }
 985                         } else {
 986                                 $msg = __METHOD__ . ': lost connection to {dbserver} permanently';
 987                                 $this->connLogger->error( $msg, [ 'dbserver' => $this->getServer() ] );
 988                         }
 989                 }
 990
 991                 if ( false === $ret ) {
 992                         # Deadlocks cause the entire transaction to abort, not just the statement.
 993                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 994                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 995                         if ( $this->wasDeadlock() ) {
 996                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 997                                         $tempIgnore = false; // not recoverable
 998                                 }
 999                                 # Update state tracking to reflect transaction loss
1000                                 $this->handleSessionLoss();
1001                         }
1002
1003                         $this->reportQueryError(
1004                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
1005                 }
1006
1007                 $res = $this->resultObject( $ret );
1008
1009                 return $res;
1010         }
1011
1012         /**
1013          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1014          *
1015          * @param string $sql Original SQL query
1016          * @param string $commentedSql SQL query with debugging/trace comment
1017          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1018          * @param string $fname Name of the calling function
1019          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1020          *     object for a successful read query, or false on failure
1021          */
1022         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1023                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1024                 # generalizeSQL() will probably cut down the query to reasonable
1025                 # logging size most of the time. The substr is really just a sanity check.
1026                 if ( $isMaster ) {
1027                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1028                 } else {
1029                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1030                 }
1031
1032                 # Include query transaction state
1033                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1034
1035                 $startTime = microtime( true );
1036                 if ( $this->profiler ) {
1037                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1038                 }
1039                 $this->affectedRowCount = null;
1040                 $ret = $this->doQuery( $commentedSql );
1041                 $this->affectedRowCount = $this->affectedRows();
1042                 if ( $this->profiler ) {
1043                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1044                 }
1045                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1046
1047                 unset( $queryProfSection ); // profile out (if set)
1048
1049                 if ( $ret !== false ) {
1050                         $this->lastPing = $startTime;
1051                         if ( $isWrite && $this->trxLevel ) {
1052                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1053                                 $this->trxWriteCallers[] = $fname;
1054                         }
1055                 }
1056
1057                 if ( $sql === self::PING_QUERY ) {
1058                         $this->rttEstimate = $queryRuntime;
1059                 }
1060
1061                 $this->trxProfiler->recordQueryCompletion(
1062                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1063                 );
1064                 $this->queryLogger->debug( $sql, [
1065                         'method' => $fname,
1066                         'master' => $isMaster,
1067                         'runtime' => $queryRuntime,
1068                 ] );
1069
1070                 return $ret;
1071         }
1072
1073         /**
1074          * Update the estimated run-time of a query, not counting large row lock times
1075          *
1076          * LoadBalancer can be set to rollback transactions that will create huge replication
1077          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1078          * queries, like inserting a row can take a long time due to row locking. This method
1079          * uses some simple heuristics to discount those cases.
1080          *
1081          * @param string $sql A SQL write query
1082          * @param float $runtime Total runtime, including RTT
1083          * @param int $affected Affected row count
1084          */
1085         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1086                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1087                 $indicativeOfReplicaRuntime = true;
1088                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1089                         $verb = $this->getQueryVerb( $sql );
1090                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1091                         if ( $verb === 'INSERT' ) {
1092                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1093                         } elseif ( $verb === 'REPLACE' ) {
1094                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1095                         }
1096                 }
1097
1098                 $this->trxWriteDuration += $runtime;
1099                 $this->trxWriteQueryCount += 1;
1100                 $this->trxWriteAffectedRows += $affected;
1101                 if ( $indicativeOfReplicaRuntime ) {
1102                         $this->trxWriteAdjDuration += $runtime;
1103                         $this->trxWriteAdjQueryCount += 1;
1104                 }
1105         }
1106
1107         /**
1108          * Determine whether or not it is safe to retry queries after a database
1109          * connection is lost
1110          *
1111          * @param string $sql SQL query
1112          * @param bool $priorWritesPending Whether there is a transaction open with
1113          *     possible write queries or transaction pre-commit/idle callbacks
1114          *     waiting on it to finish.
1115          * @return bool True if it is safe to retry the query, false otherwise
1116          */
1117         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1118                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1119                 # Dropped connections also mean that named locks are automatically released.
1120                 # Only allow error suppression in autocommit mode or when the lost transaction
1121                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1122                 if ( $this->namedLocksHeld ) {
1123                         return false; // possible critical section violation
1124                 } elseif ( $sql === 'COMMIT' ) {
1125                         return !$priorWritesPending; // nothing written anyway? (T127428)
1126                 } elseif ( $sql === 'ROLLBACK' ) {
1127                         return true; // transaction lost...which is also what was requested :)
1128                 } elseif ( $this->explicitTrxActive() ) {
1129                         return false; // don't drop atomocity
1130                 } elseif ( $priorWritesPending ) {
1131                         return false; // prior writes lost from implicit transaction
1132                 }
1133
1134                 return true;
1135         }
1136
1137         /**
1138          * Clean things up after transaction loss due to disconnection
1139          *
1140          * @return null|Exception
1141          */
1142         private function handleSessionLoss() {
1143                 $this->trxLevel = 0;
1144                 $this->trxIdleCallbacks = []; // T67263
1145                 $this->trxPreCommitCallbacks = []; // T67263
1146                 $this->sessionTempTables = [];
1147                 $this->namedLocksHeld = [];
1148                 try {
1149                         // Handle callbacks in trxEndCallbacks
1150                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1151                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1152                         return null;
1153                 } catch ( Exception $e ) {
1154                         // Already logged; move on...
1155                         return $e;
1156                 }
1157         }
1158
1159         /**
1160          * Checks whether the cause of the error is detected to be a timeout.
1161          *
1162          * It returns false by default, and not all engines support detecting this yet.
1163          * If this returns false, it will be treated as a generic query error.
1164          *
1165          * @param string $error Error text
1166          * @param int $errno Error number
1167          * @return bool
1168          */
1169         protected function wasQueryTimeout( $error, $errno ) {
1170                 return false;
1171         }
1172
1173         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1174                 if ( $this->ignoreErrors() || $tempIgnore ) {
1175                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1176                 } else {
1177                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1178                         $this->queryLogger->error(
1179                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1180                                 $this->getLogContext( [
1181                                         'method' => __METHOD__,
1182                                         'errno' => $errno,
1183                                         'error' => $error,
1184                                         'sql1line' => $sql1line,
1185                                         'fname' => $fname,
1186                                 ] )
1187                         );
1188                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1189                         $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1190                         if ( $wasQueryTimeout ) {
1191                                 throw new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1192                         } else {
1193                                 throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1194                         }
1195                 }
1196         }
1197
1198         public function freeResult( $res ) {
1199         }
1200
1201         public function selectField(
1202                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1203         ) {
1204                 if ( $var === '*' ) { // sanity
1205                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1206                 }
1207
1208                 if ( !is_array( $options ) ) {
1209                         $options = [ $options ];
1210                 }
1211
1212                 $options['LIMIT'] = 1;
1213
1214                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1215                 if ( $res === false || !$this->numRows( $res ) ) {
1216                         return false;
1217                 }
1218
1219                 $row = $this->fetchRow( $res );
1220
1221                 if ( $row !== false ) {
1222                         return reset( $row );
1223                 } else {
1224                         return false;
1225                 }
1226         }
1227
1228         public function selectFieldValues(
1229                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1230         ) {
1231                 if ( $var === '*' ) { // sanity
1232                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1233                 } elseif ( !is_string( $var ) ) { // sanity
1234                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1235                 }
1236
1237                 if ( !is_array( $options ) ) {
1238                         $options = [ $options ];
1239                 }
1240
1241                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1242                 if ( $res === false ) {
1243                         return false;
1244                 }
1245
1246                 $values = [];
1247                 foreach ( $res as $row ) {
1248                         $values[] = $row->$var;
1249                 }
1250
1251                 return $values;
1252         }
1253
1254         /**
1255          * Returns an optional USE INDEX clause to go after the table, and a
1256          * string to go at the end of the query.
1257          *
1258          * @param array $options Associative array of options to be turned into
1259          *   an SQL query, valid keys are listed in the function.
1260          * @return array
1261          * @see Database::select()
1262          */
1263         protected function makeSelectOptions( $options ) {
1264                 $preLimitTail = $postLimitTail = '';
1265                 $startOpts = '';
1266
1267                 $noKeyOptions = [];
1268
1269                 foreach ( $options as $key => $option ) {
1270                         if ( is_numeric( $key ) ) {
1271                                 $noKeyOptions[$option] = true;
1272                         }
1273                 }
1274
1275                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1276
1277                 $preLimitTail .= $this->makeOrderBy( $options );
1278
1279                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1280                         $postLimitTail .= ' FOR UPDATE';
1281                 }
1282
1283                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1284                         $postLimitTail .= ' LOCK IN SHARE MODE';
1285                 }
1286
1287                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1288                         $startOpts .= 'DISTINCT';
1289                 }
1290
1291                 # Various MySQL extensions
1292                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1293                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1294                 }
1295
1296                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1297                         $startOpts .= ' HIGH_PRIORITY';
1298                 }
1299
1300                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1301                         $startOpts .= ' SQL_BIG_RESULT';
1302                 }
1303
1304                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1305                         $startOpts .= ' SQL_BUFFER_RESULT';
1306                 }
1307
1308                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1309                         $startOpts .= ' SQL_SMALL_RESULT';
1310                 }
1311
1312                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1313                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1314                 }
1315
1316                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1317                         $startOpts .= ' SQL_CACHE';
1318                 }
1319
1320                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1321                         $startOpts .= ' SQL_NO_CACHE';
1322                 }
1323
1324                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1325                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1326                 } else {
1327                         $useIndex = '';
1328                 }
1329                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1330                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1331                 } else {
1332                         $ignoreIndex = '';
1333                 }
1334
1335                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1336         }
1337
1338         /**
1339          * Returns an optional GROUP BY with an optional HAVING
1340          *
1341          * @param array $options Associative array of options
1342          * @return string
1343          * @see Database::select()
1344          * @since 1.21
1345          */
1346         protected function makeGroupByWithHaving( $options ) {
1347                 $sql = '';
1348                 if ( isset( $options['GROUP BY'] ) ) {
1349                         $gb = is_array( $options['GROUP BY'] )
1350                                 ? implode( ',', $options['GROUP BY'] )
1351                                 : $options['GROUP BY'];
1352                         $sql .= ' GROUP BY ' . $gb;
1353                 }
1354                 if ( isset( $options['HAVING'] ) ) {
1355                         $having = is_array( $options['HAVING'] )
1356                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1357                                 : $options['HAVING'];
1358                         $sql .= ' HAVING ' . $having;
1359                 }
1360
1361                 return $sql;
1362         }
1363
1364         /**
1365          * Returns an optional ORDER BY
1366          *
1367          * @param array $options Associative array of options
1368          * @return string
1369          * @see Database::select()
1370          * @since 1.21
1371          */
1372         protected function makeOrderBy( $options ) {
1373                 if ( isset( $options['ORDER BY'] ) ) {
1374                         $ob = is_array( $options['ORDER BY'] )
1375                                 ? implode( ',', $options['ORDER BY'] )
1376                                 : $options['ORDER BY'];
1377
1378                         return ' ORDER BY ' . $ob;
1379                 }
1380
1381                 return '';
1382         }
1383
1384         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1385                 $options = [], $join_conds = [] ) {
1386                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1387
1388                 return $this->query( $sql, $fname );
1389         }
1390
1391         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1392                 $options = [], $join_conds = []
1393         ) {
1394                 if ( is_array( $vars ) ) {
1395                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1396                 }
1397
1398                 $options = (array)$options;
1399                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1400                         ? $options['USE INDEX']
1401                         : [];
1402                 $ignoreIndexes = (
1403                         isset( $options['IGNORE INDEX'] ) &&
1404                         is_array( $options['IGNORE INDEX'] )
1405                 )
1406                         ? $options['IGNORE INDEX']
1407                         : [];
1408
1409                 if ( is_array( $table ) ) {
1410                         $from = ' FROM ' .
1411                                 $this->tableNamesWithIndexClauseOrJOIN(
1412                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1413                 } elseif ( $table != '' ) {
1414                         $from = ' FROM ' .
1415                                 $this->tableNamesWithIndexClauseOrJOIN(
1416                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1417                 } else {
1418                         $from = '';
1419                 }
1420
1421                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1422                         $this->makeSelectOptions( $options );
1423
1424                 if ( !empty( $conds ) ) {
1425                         if ( is_array( $conds ) ) {
1426                                 $conds = $this->makeList( $conds, self::LIST_AND );
1427                         }
1428                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1429                                 "WHERE $conds $preLimitTail";
1430                 } else {
1431                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1432                 }
1433
1434                 if ( isset( $options['LIMIT'] ) ) {
1435                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1436                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1437                 }
1438                 $sql = "$sql $postLimitTail";
1439
1440                 if ( isset( $options['EXPLAIN'] ) ) {
1441                         $sql = 'EXPLAIN ' . $sql;
1442                 }
1443
1444                 return $sql;
1445         }
1446
1447         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1448                 $options = [], $join_conds = []
1449         ) {
1450                 $options = (array)$options;
1451                 $options['LIMIT'] = 1;
1452                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1453
1454                 if ( $res === false ) {
1455                         return false;
1456                 }
1457
1458                 if ( !$this->numRows( $res ) ) {
1459                         return false;
1460                 }
1461
1462                 $obj = $this->fetchObject( $res );
1463
1464                 return $obj;
1465         }
1466
1467         public function estimateRowCount(
1468                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1469         ) {
1470                 $rows = 0;
1471                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1472
1473                 if ( $res ) {
1474                         $row = $this->fetchRow( $res );
1475                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1476                 }
1477
1478                 return $rows;
1479         }
1480
1481         public function selectRowCount(
1482                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1483         ) {
1484                 $rows = 0;
1485                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1486                 // The identifier quotes is primarily for MSSQL.
1487                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1488                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1489                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1490
1491                 if ( $res ) {
1492                         $row = $this->fetchRow( $res );
1493                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1494                 }
1495
1496                 return $rows;
1497         }
1498
1499         /**
1500          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1501          * It's only slightly flawed. Don't use for anything important.
1502          *
1503          * @param string $sql A SQL Query
1504          *
1505          * @return string
1506          */
1507         protected static function generalizeSQL( $sql ) {
1508                 # This does the same as the regexp below would do, but in such a way
1509                 # as to avoid crashing php on some large strings.
1510                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1511
1512                 $sql = str_replace( "\\\\", '', $sql );
1513                 $sql = str_replace( "\\'", '', $sql );
1514                 $sql = str_replace( "\\\"", '', $sql );
1515                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1516                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1517
1518                 # All newlines, tabs, etc replaced by single space
1519                 $sql = preg_replace( '/\s+/', ' ', $sql );
1520
1521                 # All numbers => N,
1522                 # except the ones surrounded by characters, e.g. l10n
1523                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1524                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1525
1526                 return $sql;
1527         }
1528
1529         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1530                 $info = $this->fieldInfo( $table, $field );
1531
1532                 return (bool)$info;
1533         }
1534
1535         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1536                 if ( !$this->tableExists( $table ) ) {
1537                         return null;
1538                 }
1539
1540                 $info = $this->indexInfo( $table, $index, $fname );
1541                 if ( is_null( $info ) ) {
1542                         return null;
1543                 } else {
1544                         return $info !== false;
1545                 }
1546         }
1547
1548         public function tableExists( $table, $fname = __METHOD__ ) {
1549                 $tableRaw = $this->tableName( $table, 'raw' );
1550                 if ( isset( $this->sessionTempTables[$tableRaw] ) ) {
1551                         return true; // already known to exist
1552                 }
1553
1554                 $table = $this->tableName( $table );
1555                 $ignoreErrors = true;
1556                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1557
1558                 return (bool)$res;
1559         }
1560
1561         public function indexUnique( $table, $index ) {
1562                 $indexInfo = $this->indexInfo( $table, $index );
1563
1564                 if ( !$indexInfo ) {
1565                         return null;
1566                 }
1567
1568                 return !$indexInfo[0]->Non_unique;
1569         }
1570
1571         /**
1572          * Helper for Database::insert().
1573          *
1574          * @param array $options
1575          * @return string
1576          */
1577         protected function makeInsertOptions( $options ) {
1578                 return implode( ' ', $options );
1579         }
1580
1581         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1582                 # No rows to insert, easy just return now
1583                 if ( !count( $a ) ) {
1584                         return true;
1585                 }
1586
1587                 $table = $this->tableName( $table );
1588
1589                 if ( !is_array( $options ) ) {
1590                         $options = [ $options ];
1591                 }
1592
1593                 $fh = null;
1594                 if ( isset( $options['fileHandle'] ) ) {
1595                         $fh = $options['fileHandle'];
1596                 }
1597                 $options = $this->makeInsertOptions( $options );
1598
1599                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1600                         $multi = true;
1601                         $keys = array_keys( $a[0] );
1602                 } else {
1603                         $multi = false;
1604                         $keys = array_keys( $a );
1605                 }
1606
1607                 $sql = 'INSERT ' . $options .
1608                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1609
1610                 if ( $multi ) {
1611                         $first = true;
1612                         foreach ( $a as $row ) {
1613                                 if ( $first ) {
1614                                         $first = false;
1615                                 } else {
1616                                         $sql .= ',';
1617                                 }
1618                                 $sql .= '(' . $this->makeList( $row ) . ')';
1619                         }
1620                 } else {
1621                         $sql .= '(' . $this->makeList( $a ) . ')';
1622                 }
1623
1624                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1625                         return false;
1626                 } elseif ( $fh !== null ) {
1627                         return true;
1628                 }
1629
1630                 return (bool)$this->query( $sql, $fname );
1631         }
1632
1633         /**
1634          * Make UPDATE options array for Database::makeUpdateOptions
1635          *
1636          * @param array $options
1637          * @return array
1638          */
1639         protected function makeUpdateOptionsArray( $options ) {
1640                 if ( !is_array( $options ) ) {
1641                         $options = [ $options ];
1642                 }
1643
1644                 $opts = [];
1645
1646                 if ( in_array( 'IGNORE', $options ) ) {
1647                         $opts[] = 'IGNORE';
1648                 }
1649
1650                 return $opts;
1651         }
1652
1653         /**
1654          * Make UPDATE options for the Database::update function
1655          *
1656          * @param array $options The options passed to Database::update
1657          * @return string
1658          */
1659         protected function makeUpdateOptions( $options ) {
1660                 $opts = $this->makeUpdateOptionsArray( $options );
1661
1662                 return implode( ' ', $opts );
1663         }
1664
1665         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1666                 $table = $this->tableName( $table );
1667                 $opts = $this->makeUpdateOptions( $options );
1668                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1669
1670                 if ( $conds !== [] && $conds !== '*' ) {
1671                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1672                 }
1673
1674                 return (bool)$this->query( $sql, $fname );
1675         }
1676
1677         public function makeList( $a, $mode = self::LIST_COMMA ) {
1678                 if ( !is_array( $a ) ) {
1679                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1680                 }
1681
1682                 $first = true;
1683                 $list = '';
1684
1685                 foreach ( $a as $field => $value ) {
1686                         if ( !$first ) {
1687                                 if ( $mode == self::LIST_AND ) {
1688                                         $list .= ' AND ';
1689                                 } elseif ( $mode == self::LIST_OR ) {
1690                                         $list .= ' OR ';
1691                                 } else {
1692                                         $list .= ',';
1693                                 }
1694                         } else {
1695                                 $first = false;
1696                         }
1697
1698                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1699                                 $list .= "($value)";
1700                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1701                                 $list .= "$value";
1702                         } elseif (
1703                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1704                         ) {
1705                                 // Remove null from array to be handled separately if found
1706                                 $includeNull = false;
1707                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1708                                         $includeNull = true;
1709                                         unset( $value[$nullKey] );
1710                                 }
1711                                 if ( count( $value ) == 0 && !$includeNull ) {
1712                                         throw new InvalidArgumentException(
1713                                                 __METHOD__ . ": empty input for field $field" );
1714                                 } elseif ( count( $value ) == 0 ) {
1715                                         // only check if $field is null
1716                                         $list .= "$field IS NULL";
1717                                 } else {
1718                                         // IN clause contains at least one valid element
1719                                         if ( $includeNull ) {
1720                                                 // Group subconditions to ensure correct precedence
1721                                                 $list .= '(';
1722                                         }
1723                                         if ( count( $value ) == 1 ) {
1724                                                 // Special-case single values, as IN isn't terribly efficient
1725                                                 // Don't necessarily assume the single key is 0; we don't
1726                                                 // enforce linear numeric ordering on other arrays here.
1727                                                 $value = array_values( $value )[0];
1728                                                 $list .= $field . " = " . $this->addQuotes( $value );
1729                                         } else {
1730                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1731                                         }
1732                                         // if null present in array, append IS NULL
1733                                         if ( $includeNull ) {
1734                                                 $list .= " OR $field IS NULL)";
1735                                         }
1736                                 }
1737                         } elseif ( $value === null ) {
1738                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1739                                         $list .= "$field IS ";
1740                                 } elseif ( $mode == self::LIST_SET ) {
1741                                         $list .= "$field = ";
1742                                 }
1743                                 $list .= 'NULL';
1744                         } else {
1745                                 if (
1746                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1747                                 ) {
1748                                         $list .= "$field = ";
1749                                 }
1750                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1751                         }
1752                 }
1753
1754                 return $list;
1755         }
1756
1757         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1758                 $conds = [];
1759
1760                 foreach ( $data as $base => $sub ) {
1761                         if ( count( $sub ) ) {
1762                                 $conds[] = $this->makeList(
1763                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1764                                         self::LIST_AND );
1765                         }
1766                 }
1767
1768                 if ( $conds ) {
1769                         return $this->makeList( $conds, self::LIST_OR );
1770                 } else {
1771                         // Nothing to search for...
1772                         return false;
1773                 }
1774         }
1775
1776         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1777                 return $valuename;
1778         }
1779
1780         public function bitNot( $field ) {
1781                 return "(~$field)";
1782         }
1783
1784         public function bitAnd( $fieldLeft, $fieldRight ) {
1785                 return "($fieldLeft & $fieldRight)";
1786         }
1787
1788         public function bitOr( $fieldLeft, $fieldRight ) {
1789                 return "($fieldLeft | $fieldRight)";
1790         }
1791
1792         public function buildConcat( $stringList ) {
1793                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1794         }
1795
1796         public function buildGroupConcatField(
1797                 $delim, $table, $field, $conds = '', $join_conds = []
1798         ) {
1799                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1800
1801                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1802         }
1803
1804         public function buildStringCast( $field ) {
1805                 return $field;
1806         }
1807
1808         public function databasesAreIndependent() {
1809                 return false;
1810         }
1811
1812         public function selectDB( $db ) {
1813                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1814                 # if your database engine supports a concept similar to MySQL's
1815                 # databases you may as well.
1816                 $this->dbName = $db;
1817
1818                 return true;
1819         }
1820
1821         public function getDBname() {
1822                 return $this->dbName;
1823         }
1824
1825         public function getServer() {
1826                 return $this->server;
1827         }
1828
1829         public function tableName( $name, $format = 'quoted' ) {
1830                 # Skip the entire process when we have a string quoted on both ends.
1831                 # Note that we check the end so that we will still quote any use of
1832                 # use of `database`.table. But won't break things if someone wants
1833                 # to query a database table with a dot in the name.
1834                 if ( $this->isQuotedIdentifier( $name ) ) {
1835                         return $name;
1836                 }
1837
1838                 # Lets test for any bits of text that should never show up in a table
1839                 # name. Basically anything like JOIN or ON which are actually part of
1840                 # SQL queries, but may end up inside of the table value to combine
1841                 # sql. Such as how the API is doing.
1842                 # Note that we use a whitespace test rather than a \b test to avoid
1843                 # any remote case where a word like on may be inside of a table name
1844                 # surrounded by symbols which may be considered word breaks.
1845                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1846                         return $name;
1847                 }
1848
1849                 # Split database and table into proper variables.
1850                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
1851
1852                 # Quote $table and apply the prefix if not quoted.
1853                 # $tableName might be empty if this is called from Database::replaceVars()
1854                 $tableName = "{$prefix}{$table}";
1855                 if ( $format === 'quoted'
1856                         && !$this->isQuotedIdentifier( $tableName )
1857                         && $tableName !== ''
1858                 ) {
1859                         $tableName = $this->addIdentifierQuotes( $tableName );
1860                 }
1861
1862                 # Quote $schema and $database and merge them with the table name if needed
1863                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1864                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1865
1866                 return $tableName;
1867         }
1868
1869         /**
1870          * Get the table components needed for a query given the currently selected database
1871          *
1872          * @param string $name Table name in the form of db.schema.table, db.table, or table
1873          * @return array (DB name or "" for default, schema name, table prefix, table name)
1874          */
1875         protected function qualifiedTableComponents( $name ) {
1876                 # We reverse the explode so that database.table and table both output the correct table.
1877                 $dbDetails = explode( '.', $name, 3 );
1878                 if ( count( $dbDetails ) == 3 ) {
1879                         list( $database, $schema, $table ) = $dbDetails;
1880                         # We don't want any prefix added in this case
1881                         $prefix = '';
1882                 } elseif ( count( $dbDetails ) == 2 ) {
1883                         list( $database, $table ) = $dbDetails;
1884                         # We don't want any prefix added in this case
1885                         $prefix = '';
1886                         # In dbs that support it, $database may actually be the schema
1887                         # but that doesn't affect any of the functionality here
1888                         $schema = '';
1889                 } else {
1890                         list( $table ) = $dbDetails;
1891                         if ( isset( $this->tableAliases[$table] ) ) {
1892                                 $database = $this->tableAliases[$table]['dbname'];
1893                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1894                                         ? $this->tableAliases[$table]['schema']
1895                                         : $this->schema;
1896                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1897                                         ? $this->tableAliases[$table]['prefix']
1898                                         : $this->tablePrefix;
1899                         } else {
1900                                 $database = '';
1901                                 $schema = $this->schema; # Default schema
1902                                 $prefix = $this->tablePrefix; # Default prefix
1903                         }
1904                 }
1905
1906                 return [ $database, $schema, $prefix, $table ];
1907         }
1908
1909         /**
1910          * @param string|null $namespace Database or schema
1911          * @param string $relation Name of table, view, sequence, etc...
1912          * @param string $format One of (raw, quoted)
1913          * @return string Relation name with quoted and merged $namespace as needed
1914          */
1915         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1916                 if ( strlen( $namespace ) ) {
1917                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1918                                 $namespace = $this->addIdentifierQuotes( $namespace );
1919                         }
1920                         $relation = $namespace . '.' . $relation;
1921                 }
1922
1923                 return $relation;
1924         }
1925
1926         public function tableNames() {
1927                 $inArray = func_get_args();
1928                 $retVal = [];
1929
1930                 foreach ( $inArray as $name ) {
1931                         $retVal[$name] = $this->tableName( $name );
1932                 }
1933
1934                 return $retVal;
1935         }
1936
1937         public function tableNamesN() {
1938                 $inArray = func_get_args();
1939                 $retVal = [];
1940
1941                 foreach ( $inArray as $name ) {
1942                         $retVal[] = $this->tableName( $name );
1943                 }
1944
1945                 return $retVal;
1946         }
1947
1948         /**
1949          * Get an aliased table name
1950          * e.g. tableName AS newTableName
1951          *
1952          * @param string $name Table name, see tableName()
1953          * @param string|bool $alias Alias (optional)
1954          * @return string SQL name for aliased table. Will not alias a table to its own name
1955          */
1956         protected function tableNameWithAlias( $name, $alias = false ) {
1957                 if ( !$alias || $alias == $name ) {
1958                         return $this->tableName( $name );
1959                 } else {
1960                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1961                 }
1962         }
1963
1964         /**
1965          * Gets an array of aliased table names
1966          *
1967          * @param array $tables [ [alias] => table ]
1968          * @return string[] See tableNameWithAlias()
1969          */
1970         protected function tableNamesWithAlias( $tables ) {
1971                 $retval = [];
1972                 foreach ( $tables as $alias => $table ) {
1973                         if ( is_numeric( $alias ) ) {
1974                                 $alias = $table;
1975                         }
1976                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1977                 }
1978
1979                 return $retval;
1980         }
1981
1982         /**
1983          * Get an aliased field name
1984          * e.g. fieldName AS newFieldName
1985          *
1986          * @param string $name Field name
1987          * @param string|bool $alias Alias (optional)
1988          * @return string SQL name for aliased field. Will not alias a field to its own name
1989          */
1990         protected function fieldNameWithAlias( $name, $alias = false ) {
1991                 if ( !$alias || (string)$alias === (string)$name ) {
1992                         return $name;
1993                 } else {
1994                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1995                 }
1996         }
1997
1998         /**
1999          * Gets an array of aliased field names
2000          *
2001          * @param array $fields [ [alias] => field ]
2002          * @return string[] See fieldNameWithAlias()
2003          */
2004         protected function fieldNamesWithAlias( $fields ) {
2005                 $retval = [];
2006                 foreach ( $fields as $alias => $field ) {
2007                         if ( is_numeric( $alias ) ) {
2008                                 $alias = $field;
2009                         }
2010                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2011                 }
2012
2013                 return $retval;
2014         }
2015
2016         /**
2017          * Get the aliased table name clause for a FROM clause
2018          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2019          *
2020          * @param array $tables ( [alias] => table )
2021          * @param array $use_index Same as for select()
2022          * @param array $ignore_index Same as for select()
2023          * @param array $join_conds Same as for select()
2024          * @return string
2025          */
2026         protected function tableNamesWithIndexClauseOrJOIN(
2027                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2028         ) {
2029                 $ret = [];
2030                 $retJOIN = [];
2031                 $use_index = (array)$use_index;
2032                 $ignore_index = (array)$ignore_index;
2033                 $join_conds = (array)$join_conds;
2034
2035                 foreach ( $tables as $alias => $table ) {
2036                         if ( !is_string( $alias ) ) {
2037                                 // No alias? Set it equal to the table name
2038                                 $alias = $table;
2039                         }
2040
2041                         if ( is_array( $table ) ) {
2042                                 // A parenthesized group
2043                                 if ( count( $table ) > 1 ) {
2044                                         $joinedTable = '('
2045                                                 . $this->tableNamesWithIndexClauseOrJOIN( $table, $use_index, $ignore_index, $join_conds )
2046                                                 . ')';
2047                                 } else {
2048                                         // Degenerate case
2049                                         $innerTable = reset( $table );
2050                                         $innerAlias = key( $table );
2051                                         $joinedTable = $this->tableNameWithAlias(
2052                                                 $innerTable,
2053                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2054                                         );
2055                                 }
2056                         } else {
2057                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2058                         }
2059
2060                         // Is there a JOIN clause for this table?
2061                         if ( isset( $join_conds[$alias] ) ) {
2062                                 list( $joinType, $conds ) = $join_conds[$alias];
2063                                 $tableClause = $joinType;
2064                                 $tableClause .= ' ' . $joinedTable;
2065                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2066                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2067                                         if ( $use != '' ) {
2068                                                 $tableClause .= ' ' . $use;
2069                                         }
2070                                 }
2071                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2072                                         $ignore = $this->ignoreIndexClause(
2073                                                 implode( ',', (array)$ignore_index[$alias] ) );
2074                                         if ( $ignore != '' ) {
2075                                                 $tableClause .= ' ' . $ignore;
2076                                         }
2077                                 }
2078                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2079                                 if ( $on != '' ) {
2080                                         $tableClause .= ' ON (' . $on . ')';
2081                                 }
2082
2083                                 $retJOIN[] = $tableClause;
2084                         } elseif ( isset( $use_index[$alias] ) ) {
2085                                 // Is there an INDEX clause for this table?
2086                                 $tableClause = $joinedTable;
2087                                 $tableClause .= ' ' . $this->useIndexClause(
2088                                                 implode( ',', (array)$use_index[$alias] )
2089                                         );
2090
2091                                 $ret[] = $tableClause;
2092                         } elseif ( isset( $ignore_index[$alias] ) ) {
2093                                 // Is there an INDEX clause for this table?
2094                                 $tableClause = $joinedTable;
2095                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2096                                                 implode( ',', (array)$ignore_index[$alias] )
2097                                         );
2098
2099                                 $ret[] = $tableClause;
2100                         } else {
2101                                 $tableClause = $joinedTable;
2102
2103                                 $ret[] = $tableClause;
2104                         }
2105                 }
2106
2107                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2108                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2109                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2110
2111                 // Compile our final table clause
2112                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2113         }
2114
2115         /**
2116          * Allows for index remapping in queries where this is not consistent across DBMS
2117          *
2118          * @param string $index
2119          * @return string
2120          */
2121         protected function indexName( $index ) {
2122                 return $index;
2123         }
2124
2125         public function addQuotes( $s ) {
2126                 if ( $s instanceof Blob ) {
2127                         $s = $s->fetch();
2128                 }
2129                 if ( $s === null ) {
2130                         return 'NULL';
2131                 } elseif ( is_bool( $s ) ) {
2132                         return (int)$s;
2133                 } else {
2134                         # This will also quote numeric values. This should be harmless,
2135                         # and protects against weird problems that occur when they really
2136                         # _are_ strings such as article titles and string->number->string
2137                         # conversion is not 1:1.
2138                         return "'" . $this->strencode( $s ) . "'";
2139                 }
2140         }
2141
2142         /**
2143          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2144          * MySQL uses `backticks` while basically everything else uses double quotes.
2145          * Since MySQL is the odd one out here the double quotes are our generic
2146          * and we implement backticks in DatabaseMysqlBase.
2147          *
2148          * @param string $s
2149          * @return string
2150          */
2151         public function addIdentifierQuotes( $s ) {
2152                 return '"' . str_replace( '"', '""', $s ) . '"';
2153         }
2154
2155         /**
2156          * Returns if the given identifier looks quoted or not according to
2157          * the database convention for quoting identifiers .
2158          *
2159          * @note Do not use this to determine if untrusted input is safe.
2160          *   A malicious user can trick this function.
2161          * @param string $name
2162          * @return bool
2163          */
2164         public function isQuotedIdentifier( $name ) {
2165                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2166         }
2167
2168         /**
2169          * @param string $s
2170          * @param string $escapeChar
2171          * @return string
2172          */
2173         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2174                 return str_replace( [ $escapeChar, '%', '_' ],
2175                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2176                         $s );
2177         }
2178
2179         public function buildLike() {
2180                 $params = func_get_args();
2181
2182                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2183                         $params = $params[0];
2184                 }
2185
2186                 $s = '';
2187
2188                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2189                 // may escape backslashes, creating problems of double escaping. The `
2190                 // character has good cross-DBMS compatibility, avoiding special operators
2191                 // in MS SQL like ^ and %
2192                 $escapeChar = '`';
2193
2194                 foreach ( $params as $value ) {
2195                         if ( $value instanceof LikeMatch ) {
2196                                 $s .= $value->toString();
2197                         } else {
2198                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2199                         }
2200                 }
2201
2202                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2203         }
2204
2205         public function anyChar() {
2206                 return new LikeMatch( '_' );
2207         }
2208
2209         public function anyString() {
2210                 return new LikeMatch( '%' );
2211         }
2212
2213         public function nextSequenceValue( $seqName ) {
2214                 return null;
2215         }
2216
2217         /**
2218          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2219          * is only needed because a) MySQL must be as efficient as possible due to
2220          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2221          * which index to pick. Anyway, other databases might have different
2222          * indexes on a given table. So don't bother overriding this unless you're
2223          * MySQL.
2224          * @param string $index
2225          * @return string
2226          */
2227         public function useIndexClause( $index ) {
2228                 return '';
2229         }
2230
2231         /**
2232          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2233          * is only needed because a) MySQL must be as efficient as possible due to
2234          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2235          * which index to pick. Anyway, other databases might have different
2236          * indexes on a given table. So don't bother overriding this unless you're
2237          * MySQL.
2238          * @param string $index
2239          * @return string
2240          */
2241         public function ignoreIndexClause( $index ) {
2242                 return '';
2243         }
2244
2245         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2246                 if ( count( $rows ) == 0 ) {
2247                         return;
2248                 }
2249
2250                 // Single row case
2251                 if ( !is_array( reset( $rows ) ) ) {
2252                         $rows = [ $rows ];
2253                 }
2254
2255                 $useTrx = !$this->trxLevel;
2256                 if ( $useTrx ) {
2257                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2258                 }
2259                 try {
2260                         $affectedRowCount = 0;
2261                         foreach ( $rows as $row ) {
2262                                 // Delete rows which collide with this one
2263                                 $indexWhereClauses = [];
2264                                 foreach ( $uniqueIndexes as $index ) {
2265                                         $indexColumns = (array)$index;
2266                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2267                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2268                                                 throw new DBUnexpectedError(
2269                                                         $this,
2270                                                         'New record does not provide all values for unique key (' .
2271                                                         implode( ', ', $indexColumns ) . ')'
2272                                                 );
2273                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2274                                                 throw new DBUnexpectedError(
2275                                                         $this,
2276                                                         'New record has a null value for unique key (' .
2277                                                         implode( ', ', $indexColumns ) . ')'
2278                                                 );
2279                                         }
2280                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2281                                 }
2282
2283                                 if ( $indexWhereClauses ) {
2284                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2285                                         $affectedRowCount += $this->affectedRows();
2286                                 }
2287
2288                                 // Now insert the row
2289                                 $this->insert( $table, $row, $fname );
2290                                 $affectedRowCount += $this->affectedRows();
2291                         }
2292                 } catch ( Exception $e ) {
2293                         if ( $useTrx ) {
2294                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2295                         }
2296                         throw $e;
2297                 }
2298                 if ( $useTrx ) {
2299                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2300                 }
2301
2302                 $this->affectedRowCount = $affectedRowCount;
2303         }
2304
2305         /**
2306          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2307          * statement.
2308          *
2309          * @param string $table Table name
2310          * @param array|string $rows Row(s) to insert
2311          * @param string $fname Caller function name
2312          *
2313          * @return ResultWrapper
2314          */
2315         protected function nativeReplace( $table, $rows, $fname ) {
2316                 $table = $this->tableName( $table );
2317
2318                 # Single row case
2319                 if ( !is_array( reset( $rows ) ) ) {
2320                         $rows = [ $rows ];
2321                 }
2322
2323                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2324                 $first = true;
2325
2326                 foreach ( $rows as $row ) {
2327                         if ( $first ) {
2328                                 $first = false;
2329                         } else {
2330                                 $sql .= ',';
2331                         }
2332
2333                         $sql .= '(' . $this->makeList( $row ) . ')';
2334                 }
2335
2336                 return $this->query( $sql, $fname );
2337         }
2338
2339         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2340                 $fname = __METHOD__
2341         ) {
2342                 if ( !count( $rows ) ) {
2343                         return true; // nothing to do
2344                 }
2345
2346                 if ( !is_array( reset( $rows ) ) ) {
2347                         $rows = [ $rows ];
2348                 }
2349
2350                 if ( count( $uniqueIndexes ) ) {
2351                         $clauses = []; // list WHERE clauses that each identify a single row
2352                         foreach ( $rows as $row ) {
2353                                 foreach ( $uniqueIndexes as $index ) {
2354                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2355                                         $rowKey = []; // unique key to this row
2356                                         foreach ( $index as $column ) {
2357                                                 $rowKey[$column] = $row[$column];
2358                                         }
2359                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2360                                 }
2361                         }
2362                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2363                 } else {
2364                         $where = false;
2365                 }
2366
2367                 $affectedRowCount = 0;
2368                 $useTrx = !$this->trxLevel;
2369                 if ( $useTrx ) {
2370                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2371                 }
2372                 try {
2373                         # Update any existing conflicting row(s)
2374                         if ( $where !== false ) {
2375                                 $ok = $this->update( $table, $set, $where, $fname );
2376                                 $affectedRowCount += $this->affectedRows();
2377                         } else {
2378                                 $ok = true;
2379                         }
2380                         # Now insert any non-conflicting row(s)
2381                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2382                         $affectedRowCount += $this->affectedRows();
2383                 } catch ( Exception $e ) {
2384                         if ( $useTrx ) {
2385                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2386                         }
2387                         throw $e;
2388                 }
2389                 if ( $useTrx ) {
2390                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2391                 }
2392                 $this->affectedRowCount = $affectedRowCount;
2393
2394                 return $ok;
2395         }
2396
2397         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2398                 $fname = __METHOD__
2399         ) {
2400                 if ( !$conds ) {
2401                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2402                 }
2403
2404                 $delTable = $this->tableName( $delTable );
2405                 $joinTable = $this->tableName( $joinTable );
2406                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2407                 if ( $conds != '*' ) {
2408                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2409                 }
2410                 $sql .= ')';
2411
2412                 $this->query( $sql, $fname );
2413         }
2414
2415         public function textFieldSize( $table, $field ) {
2416                 $table = $this->tableName( $table );
2417                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2418                 $res = $this->query( $sql, __METHOD__ );
2419                 $row = $this->fetchObject( $res );
2420
2421                 $m = [];
2422
2423                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2424                         $size = $m[1];
2425                 } else {
2426                         $size = -1;
2427                 }
2428
2429                 return $size;
2430         }
2431
2432         public function delete( $table, $conds, $fname = __METHOD__ ) {
2433                 if ( !$conds ) {
2434                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2435                 }
2436
2437                 $table = $this->tableName( $table );
2438                 $sql = "DELETE FROM $table";
2439
2440                 if ( $conds != '*' ) {
2441                         if ( is_array( $conds ) ) {
2442                                 $conds = $this->makeList( $conds, self::LIST_AND );
2443                         }
2444                         $sql .= ' WHERE ' . $conds;
2445                 }
2446
2447                 return $this->query( $sql, $fname );
2448         }
2449
2450         public function insertSelect(
2451                 $destTable, $srcTable, $varMap, $conds,
2452                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2453         ) {
2454                 if ( $this->cliMode ) {
2455                         // For massive migrations with downtime, we don't want to select everything
2456                         // into memory and OOM, so do all this native on the server side if possible.
2457                         return $this->nativeInsertSelect(
2458                                 $destTable,
2459                                 $srcTable,
2460                                 $varMap,
2461                                 $conds,
2462                                 $fname,
2463                                 $insertOptions,
2464                                 $selectOptions,
2465                                 $selectJoinConds
2466                         );
2467                 }
2468
2469                 return $this->nonNativeInsertSelect(
2470                         $destTable,
2471                         $srcTable,
2472                         $varMap,
2473                         $conds,
2474                         $fname,
2475                         $insertOptions,
2476                         $selectOptions,
2477                         $selectJoinConds
2478                 );
2479         }
2480
2481         /**
2482          * Implementation of insertSelect() based on select() and insert()
2483          *
2484          * @see IDatabase::insertSelect()
2485          * @since 1.30
2486          * @param string $destTable
2487          * @param string|array $srcTable
2488          * @param array $varMap
2489          * @param array $conds
2490          * @param string $fname
2491          * @param array $insertOptions
2492          * @param array $selectOptions
2493          * @param array $selectJoinConds
2494          * @return bool
2495          */
2496         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2497                 $fname = __METHOD__,
2498                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2499         ) {
2500                 $insertOptions = array_diff( (array)$insertOptions, [ 'NO_AUTO_COLUMNS' ] );
2501
2502                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2503                 // on only the master (without needing row-based-replication). It also makes it easy to
2504                 // know how big the INSERT is going to be.
2505                 $fields = [];
2506                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2507                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2508                 }
2509                 $selectOptions[] = 'FOR UPDATE';
2510                 $res = $this->select(
2511                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2512                 );
2513                 if ( !$res ) {
2514                         return false;
2515                 }
2516
2517                 try {
2518                         $affectedRowCount = 0;
2519                         $this->startAtomic( $fname );
2520                         $rows = [];
2521                         $ok = true;
2522                         foreach ( $res as $row ) {
2523                                 $rows[] = (array)$row;
2524
2525                                 // Avoid inserts that are too huge
2526                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
2527                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2528                                         if ( !$ok ) {
2529                                                 break;
2530                                         }
2531                                         $affectedRowCount += $this->affectedRows();
2532                                         $rows = [];
2533                                 }
2534                         }
2535                         if ( $rows && $ok ) {
2536                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2537                                 if ( $ok ) {
2538                                         $affectedRowCount += $this->affectedRows();
2539                                 }
2540                         }
2541                         if ( $ok ) {
2542                                 $this->endAtomic( $fname );
2543                                 $this->affectedRowCount = $affectedRowCount;
2544                         } else {
2545                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2546                                 $this->affectedRowCount = 0;
2547                         }
2548                         return $ok;
2549                 } catch ( Exception $e ) {
2550                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2551                         $this->affectedRowCount = 0;
2552                         throw $e;
2553                 }
2554         }
2555
2556         /**
2557          * Native server-side implementation of insertSelect() for situations where
2558          * we don't want to select everything into memory
2559          *
2560          * @see IDatabase::insertSelect()
2561          * @param string $destTable
2562          * @param string|array $srcTable
2563          * @param array $varMap
2564          * @param array $conds
2565          * @param string $fname
2566          * @param array $insertOptions
2567          * @param array $selectOptions
2568          * @param array $selectJoinConds
2569          * @return bool
2570          */
2571         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2572                 $fname = __METHOD__,
2573                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2574         ) {
2575                 $destTable = $this->tableName( $destTable );
2576
2577                 if ( !is_array( $insertOptions ) ) {
2578                         $insertOptions = [ $insertOptions ];
2579                 }
2580                 $insertOptions = array_diff( (array)$insertOptions, [ 'NO_AUTO_COLUMNS' ] );
2581
2582                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2583
2584                 $selectSql = $this->selectSQLText(
2585                         $srcTable,
2586                         array_values( $varMap ),
2587                         $conds,
2588                         $fname,
2589                         $selectOptions,
2590                         $selectJoinConds
2591                 );
2592
2593                 $sql = "INSERT $insertOptions" .
2594                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
2595                         $selectSql;
2596
2597                 return $this->query( $sql, $fname );
2598         }
2599
2600         /**
2601          * Construct a LIMIT query with optional offset. This is used for query
2602          * pages. The SQL should be adjusted so that only the first $limit rows
2603          * are returned. If $offset is provided as well, then the first $offset
2604          * rows should be discarded, and the next $limit rows should be returned.
2605          * If the result of the query is not ordered, then the rows to be returned
2606          * are theoretically arbitrary.
2607          *
2608          * $sql is expected to be a SELECT, if that makes a difference.
2609          *
2610          * The version provided by default works in MySQL and SQLite. It will very
2611          * likely need to be overridden for most other DBMSes.
2612          *
2613          * @param string $sql SQL query we will append the limit too
2614          * @param int $limit The SQL limit
2615          * @param int|bool $offset The SQL offset (default false)
2616          * @throws DBUnexpectedError
2617          * @return string
2618          */
2619         public function limitResult( $sql, $limit, $offset = false ) {
2620                 if ( !is_numeric( $limit ) ) {
2621                         throw new DBUnexpectedError( $this,
2622                                 "Invalid non-numeric limit passed to limitResult()\n" );
2623                 }
2624
2625                 return "$sql LIMIT "
2626                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2627                 . "{$limit} ";
2628         }
2629
2630         public function unionSupportsOrderAndLimit() {
2631                 return true; // True for almost every DB supported
2632         }
2633
2634         public function unionQueries( $sqls, $all ) {
2635                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2636
2637                 return '(' . implode( $glue, $sqls ) . ')';
2638         }
2639
2640         public function unionConditionPermutations(
2641                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
2642                 $options = [], $join_conds = []
2643         ) {
2644                 // First, build the Cartesian product of $permute_conds
2645                 $conds = [ [] ];
2646                 foreach ( $permute_conds as $field => $values ) {
2647                         if ( !$values ) {
2648                                 // Skip empty $values
2649                                 continue;
2650                         }
2651                         $values = array_unique( $values ); // For sanity
2652                         $newConds = [];
2653                         foreach ( $conds as $cond ) {
2654                                 foreach ( $values as $value ) {
2655                                         $cond[$field] = $value;
2656                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
2657                                 }
2658                         }
2659                         $conds = $newConds;
2660                 }
2661
2662                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
2663
2664                 // If there's just one condition and no subordering, hand off to
2665                 // selectSQLText directly.
2666                 if ( count( $conds ) === 1 &&
2667                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
2668                 ) {
2669                         return $this->selectSQLText(
2670                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
2671                         );
2672                 }
2673
2674                 // Otherwise, we need to pull out the order and limit to apply after
2675                 // the union. Then build the SQL queries for each set of conditions in
2676                 // $conds. Then union them together (using UNION ALL, because the
2677                 // product *should* already be distinct).
2678                 $orderBy = $this->makeOrderBy( $options );
2679                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
2680                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
2681                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
2682                 if ( !$this->unionSupportsOrderAndLimit() ) {
2683                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
2684                 } else {
2685                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
2686                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
2687                         }
2688                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
2689                                 // We need to increase the limit by the offset rather than
2690                                 // using the offset directly, otherwise it'll skip incorrectly
2691                                 // in the subqueries.
2692                                 $options['LIMIT'] = $limit + $offset;
2693                                 unset( $options['OFFSET'] );
2694                         }
2695                 }
2696
2697                 $sqls = [];
2698                 foreach ( $conds as $cond ) {
2699                         $sqls[] = $this->selectSQLText(
2700                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
2701                         );
2702                 }
2703                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
2704                 if ( $limit !== null ) {
2705                         $sql = $this->limitResult( $sql, $limit, $offset );
2706                 }
2707
2708                 return $sql;
2709         }
2710
2711         public function conditional( $cond, $trueVal, $falseVal ) {
2712                 if ( is_array( $cond ) ) {
2713                         $cond = $this->makeList( $cond, self::LIST_AND );
2714                 }
2715
2716                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2717         }
2718
2719         public function strreplace( $orig, $old, $new ) {
2720                 return "REPLACE({$orig}, {$old}, {$new})";
2721         }
2722
2723         public function getServerUptime() {
2724                 return 0;
2725         }
2726
2727         public function wasDeadlock() {
2728                 return false;
2729         }
2730
2731         public function wasLockTimeout() {
2732                 return false;
2733         }
2734
2735         public function wasErrorReissuable() {
2736                 return false;
2737         }
2738
2739         public function wasReadOnlyError() {
2740                 return false;
2741         }
2742
2743         /**
2744          * Do not use this method outside of Database/DBError classes
2745          *
2746          * @param int|string $errno
2747          * @return bool Whether the given query error was a connection drop
2748          */
2749         public function wasConnectionError( $errno ) {
2750                 return false;
2751         }
2752
2753         public function deadlockLoop() {
2754                 $args = func_get_args();
2755                 $function = array_shift( $args );
2756                 $tries = self::DEADLOCK_TRIES;
2757
2758                 $this->begin( __METHOD__ );
2759
2760                 $retVal = null;
2761                 /** @var Exception $e */
2762                 $e = null;
2763                 do {
2764                         try {
2765                                 $retVal = call_user_func_array( $function, $args );
2766                                 break;
2767                         } catch ( DBQueryError $e ) {
2768                                 if ( $this->wasDeadlock() ) {
2769                                         // Retry after a randomized delay
2770                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2771                                 } else {
2772                                         // Throw the error back up
2773                                         throw $e;
2774                                 }
2775                         }
2776                 } while ( --$tries > 0 );
2777
2778                 if ( $tries <= 0 ) {
2779                         // Too many deadlocks; give up
2780                         $this->rollback( __METHOD__ );
2781                         throw $e;
2782                 } else {
2783                         $this->commit( __METHOD__ );
2784
2785                         return $retVal;
2786                 }
2787         }
2788
2789         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2790                 # Real waits are implemented in the subclass.
2791                 return 0;
2792         }
2793
2794         public function getReplicaPos() {
2795                 # Stub
2796                 return false;
2797         }
2798
2799         public function getMasterPos() {
2800                 # Stub
2801                 return false;
2802         }
2803
2804         public function serverIsReadOnly() {
2805                 return false;
2806         }
2807
2808         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2809                 if ( !$this->trxLevel ) {
2810                         throw new DBUnexpectedError( $this, "No transaction is active." );
2811                 }
2812                 $this->trxEndCallbacks[] = [ $callback, $fname ];
2813         }
2814
2815         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2816                 $this->trxIdleCallbacks[] = [ $callback, $fname ];
2817                 if ( !$this->trxLevel ) {
2818                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2819                 }
2820         }
2821
2822         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2823                 if ( $this->trxLevel || $this->getFlag( self::DBO_TRX ) ) {
2824                         // As long as DBO_TRX is set, writes will accumulate until the load balancer issues
2825                         // an implicit commit of all peer databases. This is true even if a transaction has
2826                         // not yet been triggered by writes; make sure $callback runs *after* any such writes.
2827                         $this->trxPreCommitCallbacks[] = [ $callback, $fname ];
2828                 } else {
2829                         // No transaction is active nor will start implicitly, so make one for this callback
2830                         $this->startAtomic( __METHOD__ );
2831                         try {
2832                                 call_user_func( $callback );
2833                                 $this->endAtomic( __METHOD__ );
2834                         } catch ( Exception $e ) {
2835                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2836                                 throw $e;
2837                         }
2838                 }
2839         }
2840
2841         final public function setTransactionListener( $name, callable $callback = null ) {
2842                 if ( $callback ) {
2843                         $this->trxRecurringCallbacks[$name] = $callback;
2844                 } else {
2845                         unset( $this->trxRecurringCallbacks[$name] );
2846                 }
2847         }
2848
2849         /**
2850          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2851          *
2852          * This method should not be used outside of Database/LoadBalancer
2853          *
2854          * @param bool $suppress
2855          * @since 1.28
2856          */
2857         final public function setTrxEndCallbackSuppression( $suppress ) {
2858                 $this->trxEndCallbacksSuppressed = $suppress;
2859         }
2860
2861         /**
2862          * Actually run and consume any "on transaction idle/resolution" callbacks.
2863          *
2864          * This method should not be used outside of Database/LoadBalancer
2865          *
2866          * @param int $trigger IDatabase::TRIGGER_* constant
2867          * @since 1.20
2868          * @throws Exception
2869          */
2870         public function runOnTransactionIdleCallbacks( $trigger ) {
2871                 if ( $this->trxEndCallbacksSuppressed ) {
2872                         return;
2873                 }
2874
2875                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2876                 /** @var Exception $e */
2877                 $e = null; // first exception
2878                 do { // callbacks may add callbacks :)
2879                         $callbacks = array_merge(
2880                                 $this->trxIdleCallbacks,
2881                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
2882                         );
2883                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
2884                         $this->trxEndCallbacks = []; // consumed (recursion guard)
2885                         foreach ( $callbacks as $callback ) {
2886                                 try {
2887                                         list( $phpCallback ) = $callback;
2888                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2889                                         call_user_func_array( $phpCallback, [ $trigger ] );
2890                                         if ( $autoTrx ) {
2891                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2892                                         } else {
2893                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2894                                         }
2895                                 } catch ( Exception $ex ) {
2896                                         call_user_func( $this->errorLogger, $ex );
2897                                         $e = $e ?: $ex;
2898                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2899                                         // their transactions are ended so other callbacks don't fail
2900                                         if ( $this->trxLevel() ) {
2901                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2902                                         }
2903                                 }
2904                         }
2905                 } while ( count( $this->trxIdleCallbacks ) );
2906
2907                 if ( $e instanceof Exception ) {
2908                         throw $e; // re-throw any first exception
2909                 }
2910         }
2911
2912         /**
2913          * Actually run and consume any "on transaction pre-commit" callbacks.
2914          *
2915          * This method should not be used outside of Database/LoadBalancer
2916          *
2917          * @since 1.22
2918          * @throws Exception
2919          */
2920         public function runOnTransactionPreCommitCallbacks() {
2921                 $e = null; // first exception
2922                 do { // callbacks may add callbacks :)
2923                         $callbacks = $this->trxPreCommitCallbacks;
2924                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
2925                         foreach ( $callbacks as $callback ) {
2926                                 try {
2927                                         list( $phpCallback ) = $callback;
2928                                         call_user_func( $phpCallback );
2929                                 } catch ( Exception $ex ) {
2930                                         call_user_func( $this->errorLogger, $ex );
2931                                         $e = $e ?: $ex;
2932                                 }
2933                         }
2934                 } while ( count( $this->trxPreCommitCallbacks ) );
2935
2936                 if ( $e instanceof Exception ) {
2937                         throw $e; // re-throw any first exception
2938                 }
2939         }
2940
2941         /**
2942          * Actually run any "transaction listener" callbacks.
2943          *
2944          * This method should not be used outside of Database/LoadBalancer
2945          *
2946          * @param int $trigger IDatabase::TRIGGER_* constant
2947          * @throws Exception
2948          * @since 1.20
2949          */
2950         public function runTransactionListenerCallbacks( $trigger ) {
2951                 if ( $this->trxEndCallbacksSuppressed ) {
2952                         return;
2953                 }
2954
2955                 /** @var Exception $e */
2956                 $e = null; // first exception
2957
2958                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
2959                         try {
2960                                 $phpCallback( $trigger, $this );
2961                         } catch ( Exception $ex ) {
2962                                 call_user_func( $this->errorLogger, $ex );
2963                                 $e = $e ?: $ex;
2964                         }
2965                 }
2966
2967                 if ( $e instanceof Exception ) {
2968                         throw $e; // re-throw any first exception
2969                 }
2970         }
2971
2972         final public function startAtomic( $fname = __METHOD__ ) {
2973                 if ( !$this->trxLevel ) {
2974                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2975                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2976                         // in all changes being in one transaction to keep requests transactional.
2977                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2978                                 $this->trxAutomaticAtomic = true;
2979                         }
2980                 }
2981
2982                 $this->trxAtomicLevels[] = $fname;
2983         }
2984
2985         final public function endAtomic( $fname = __METHOD__ ) {
2986                 if ( !$this->trxLevel ) {
2987                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2988                 }
2989                 if ( !$this->trxAtomicLevels ||
2990                         array_pop( $this->trxAtomicLevels ) !== $fname
2991                 ) {
2992                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2993                 }
2994
2995                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
2996                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2997                 }
2998         }
2999
3000         final public function doAtomicSection( $fname, callable $callback ) {
3001                 $this->startAtomic( $fname );
3002                 try {
3003                         $res = call_user_func_array( $callback, [ $this, $fname ] );
3004                 } catch ( Exception $e ) {
3005                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
3006                         throw $e;
3007                 }
3008                 $this->endAtomic( $fname );
3009
3010                 return $res;
3011         }
3012
3013         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3014                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3015                 if ( $this->trxLevel ) {
3016                         if ( $this->trxAtomicLevels ) {
3017                                 $levels = implode( ', ', $this->trxAtomicLevels );
3018                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3019                                 throw new DBUnexpectedError( $this, $msg );
3020                         } elseif ( !$this->trxAutomatic ) {
3021                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3022                                 throw new DBUnexpectedError( $this, $msg );
3023                         } else {
3024                                 // @TODO: make this an exception at some point
3025                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3026                                 $this->queryLogger->error( $msg );
3027                                 return; // join the main transaction set
3028                         }
3029                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3030                         // @TODO: make this an exception at some point
3031                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3032                         $this->queryLogger->error( $msg );
3033                         return; // let any writes be in the main transaction
3034                 }
3035
3036                 // Avoid fatals if close() was called
3037                 $this->assertOpen();
3038
3039                 $this->doBegin( $fname );
3040                 $this->trxTimestamp = microtime( true );
3041                 $this->trxFname = $fname;
3042                 $this->trxDoneWrites = false;
3043                 $this->trxAutomaticAtomic = false;
3044                 $this->trxAtomicLevels = [];
3045                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3046                 $this->trxWriteDuration = 0.0;
3047                 $this->trxWriteQueryCount = 0;
3048                 $this->trxWriteAffectedRows = 0;
3049                 $this->trxWriteAdjDuration = 0.0;
3050                 $this->trxWriteAdjQueryCount = 0;
3051                 $this->trxWriteCallers = [];
3052                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3053                 // Get an estimate of the replica DB lag before then, treating estimate staleness
3054                 // as lag itself just to be safe
3055                 $status = $this->getApproximateLagStatus();
3056                 $this->trxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
3057                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3058                 // caller will think its OK to muck around with the transaction just because startAtomic()
3059                 // has not yet completed (e.g. setting trxAtomicLevels).
3060                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3061         }
3062
3063         /**
3064          * Issues the BEGIN command to the database server.
3065          *
3066          * @see Database::begin()
3067          * @param string $fname
3068          */
3069         protected function doBegin( $fname ) {
3070                 $this->query( 'BEGIN', $fname );
3071                 $this->trxLevel = 1;
3072         }
3073
3074         final public function commit( $fname = __METHOD__, $flush = '' ) {
3075                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3076                         // There are still atomic sections open. This cannot be ignored
3077                         $levels = implode( ', ', $this->trxAtomicLevels );
3078                         throw new DBUnexpectedError(
3079                                 $this,
3080                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3081                         );
3082                 }
3083
3084                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3085                         if ( !$this->trxLevel ) {
3086                                 return; // nothing to do
3087                         } elseif ( !$this->trxAutomatic ) {
3088                                 throw new DBUnexpectedError(
3089                                         $this,
3090                                         "$fname: Flushing an explicit transaction, getting out of sync."
3091                                 );
3092                         }
3093                 } else {
3094                         if ( !$this->trxLevel ) {
3095                                 $this->queryLogger->error(
3096                                         "$fname: No transaction to commit, something got out of sync." );
3097                                 return; // nothing to do
3098                         } elseif ( $this->trxAutomatic ) {
3099                                 // @TODO: make this an exception at some point
3100                                 $msg = "$fname: Explicit commit of implicit transaction.";
3101                                 $this->queryLogger->error( $msg );
3102                                 return; // wait for the main transaction set commit round
3103                         }
3104                 }
3105
3106                 // Avoid fatals if close() was called
3107                 $this->assertOpen();
3108
3109                 $this->runOnTransactionPreCommitCallbacks();
3110                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3111                 $this->doCommit( $fname );
3112                 if ( $this->trxDoneWrites ) {
3113                         $this->lastWriteTime = microtime( true );
3114                         $this->trxProfiler->transactionWritingOut(
3115                                 $this->server,
3116                                 $this->dbName,
3117                                 $this->trxShortId,
3118                                 $writeTime,
3119                                 $this->trxWriteAffectedRows
3120                         );
3121                 }
3122
3123                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3124                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3125         }
3126
3127         /**
3128          * Issues the COMMIT command to the database server.
3129          *
3130          * @see Database::commit()
3131          * @param string $fname
3132          */
3133         protected function doCommit( $fname ) {
3134                 if ( $this->trxLevel ) {
3135                         $this->query( 'COMMIT', $fname );
3136                         $this->trxLevel = 0;
3137                 }
3138         }
3139
3140         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3141                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3142                         if ( !$this->trxLevel ) {
3143                                 return; // nothing to do
3144                         }
3145                 } else {
3146                         if ( !$this->trxLevel ) {
3147                                 $this->queryLogger->error(
3148                                         "$fname: No transaction to rollback, something got out of sync." );
3149                                 return; // nothing to do
3150                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
3151                                 throw new DBUnexpectedError(
3152                                         $this,
3153                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3154                                 );
3155                         }
3156                 }
3157
3158                 // Avoid fatals if close() was called
3159                 $this->assertOpen();
3160
3161                 $this->doRollback( $fname );
3162                 $this->trxAtomicLevels = [];
3163                 if ( $this->trxDoneWrites ) {
3164                         $this->trxProfiler->transactionWritingOut(
3165                                 $this->server,
3166                                 $this->dbName,
3167                                 $this->trxShortId
3168                         );
3169                 }
3170
3171                 $this->trxIdleCallbacks = []; // clear
3172                 $this->trxPreCommitCallbacks = []; // clear
3173                 try {
3174                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3175                 } catch ( Exception $e ) {
3176                         // already logged; finish and let LoadBalancer move on during mass-rollback
3177                 }
3178                 try {
3179                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3180                 } catch ( Exception $e ) {
3181                         // already logged; let LoadBalancer move on during mass-rollback
3182                 }
3183         }
3184
3185         /**
3186          * Issues the ROLLBACK command to the database server.
3187          *
3188          * @see Database::rollback()
3189          * @param string $fname
3190          */
3191         protected function doRollback( $fname ) {
3192                 if ( $this->trxLevel ) {
3193                         # Disconnects cause rollback anyway, so ignore those errors
3194                         $ignoreErrors = true;
3195                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3196                         $this->trxLevel = 0;
3197                 }
3198         }
3199
3200         public function flushSnapshot( $fname = __METHOD__ ) {
3201                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3202                         // This only flushes transactions to clear snapshots, not to write data
3203                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3204                         throw new DBUnexpectedError(
3205                                 $this,
3206                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3207                         );
3208                 }
3209
3210                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3211         }
3212
3213         public function explicitTrxActive() {
3214                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
3215         }
3216
3217         public function duplicateTableStructure(
3218                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3219         ) {
3220                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3221         }
3222
3223         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3224                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3225         }
3226
3227         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3228                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3229         }
3230
3231         public function timestamp( $ts = 0 ) {
3232                 $t = new ConvertibleTimestamp( $ts );
3233                 // Let errors bubble up to avoid putting garbage in the DB
3234                 return $t->getTimestamp( TS_MW );
3235         }
3236
3237         public function timestampOrNull( $ts = null ) {
3238                 if ( is_null( $ts ) ) {
3239                         return null;
3240                 } else {
3241                         return $this->timestamp( $ts );
3242                 }
3243         }
3244
3245         public function affectedRows() {
3246                 return ( $this->affectedRowCount === null )
3247                         ? $this->fetchAffectedRowCount() // default to driver value
3248                         : $this->affectedRowCount;
3249         }
3250
3251         /**
3252          * @return int Number of retrieved rows according to the driver
3253          */
3254         abstract protected function fetchAffectedRowCount();
3255
3256         /**
3257          * Take the result from a query, and wrap it in a ResultWrapper if
3258          * necessary. Boolean values are passed through as is, to indicate success
3259          * of write queries or failure.
3260          *
3261          * Once upon a time, Database::query() returned a bare MySQL result
3262          * resource, and it was necessary to call this function to convert it to
3263          * a wrapper. Nowadays, raw database objects are never exposed to external
3264          * callers, so this is unnecessary in external code.
3265          *
3266          * @param bool|ResultWrapper|resource|object $result
3267          * @return bool|ResultWrapper
3268          */
3269         protected function resultObject( $result ) {
3270                 if ( !$result ) {
3271                         return false;
3272                 } elseif ( $result instanceof ResultWrapper ) {
3273                         return $result;
3274                 } elseif ( $result === true ) {
3275                         // Successful write query
3276                         return $result;
3277                 } else {
3278                         return new ResultWrapper( $this, $result );
3279                 }
3280         }
3281
3282         public function ping( &$rtt = null ) {
3283                 // Avoid hitting the server if it was hit recently
3284                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3285                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
3286                                 $rtt = $this->rttEstimate;
3287                                 return true; // don't care about $rtt
3288                         }
3289                 }
3290
3291                 // This will reconnect if possible or return false if not
3292                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3293                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3294                 $this->restoreFlags( self::RESTORE_PRIOR );
3295
3296                 if ( $ok ) {
3297                         $rtt = $this->rttEstimate;
3298                 }
3299
3300                 return $ok;
3301         }
3302
3303         /**
3304          * Close existing database connection and open a new connection
3305          *
3306          * @return bool True if new connection is opened successfully, false if error
3307          */
3308         protected function reconnect() {
3309                 $this->closeConnection();
3310                 $this->opened = false;
3311                 $this->conn = false;
3312                 try {
3313                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
3314                         $this->lastPing = microtime( true );
3315                         $ok = true;
3316                 } catch ( DBConnectionError $e ) {
3317                         $ok = false;
3318                 }
3319
3320                 return $ok;
3321         }
3322
3323         public function getSessionLagStatus() {
3324                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3325         }
3326
3327         /**
3328          * Get the replica DB lag when the current transaction started
3329          *
3330          * This is useful when transactions might use snapshot isolation
3331          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3332          * is this lag plus transaction duration. If they don't, it is still
3333          * safe to be pessimistic. This returns null if there is no transaction.
3334          *
3335          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3336          * @since 1.27
3337          */
3338         protected function getTransactionLagStatus() {
3339                 return $this->trxLevel
3340                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
3341                         : null;
3342         }
3343
3344         /**
3345          * Get a replica DB lag estimate for this server
3346          *
3347          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3348          * @since 1.27
3349          */
3350         protected function getApproximateLagStatus() {
3351                 return [
3352                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3353                         'since' => microtime( true )
3354                 ];
3355         }
3356
3357         /**
3358          * Merge the result of getSessionLagStatus() for several DBs
3359          * using the most pessimistic values to estimate the lag of
3360          * any data derived from them in combination
3361          *
3362          * This is information is useful for caching modules
3363          *
3364          * @see WANObjectCache::set()
3365          * @see WANObjectCache::getWithSetCallback()
3366          *
3367          * @param IDatabase $db1
3368          * @param IDatabase $db2 [optional]
3369          * @return array Map of values:
3370          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3371          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3372          *   - pending: whether any of the DBs have uncommitted changes
3373          * @throws DBError
3374          * @since 1.27
3375          */
3376         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
3377                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3378                 foreach ( func_get_args() as $db ) {
3379                         /** @var IDatabase $db */
3380                         $status = $db->getSessionLagStatus();
3381                         if ( $status['lag'] === false ) {
3382                                 $res['lag'] = false;
3383                         } elseif ( $res['lag'] !== false ) {
3384                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3385                         }
3386                         $res['since'] = min( $res['since'], $status['since'] );
3387                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3388                 }
3389
3390                 return $res;
3391         }
3392
3393         public function getLag() {
3394                 return 0;
3395         }
3396
3397         public function maxListLen() {
3398                 return 0;
3399         }
3400
3401         public function encodeBlob( $b ) {
3402                 return $b;
3403         }
3404
3405         public function decodeBlob( $b ) {
3406                 if ( $b instanceof Blob ) {
3407                         $b = $b->fetch();
3408                 }
3409                 return $b;
3410         }
3411
3412         public function setSessionOptions( array $options ) {
3413         }
3414
3415         public function sourceFile(
3416                 $filename,
3417                 callable $lineCallback = null,
3418                 callable $resultCallback = null,
3419                 $fname = false,
3420                 callable $inputCallback = null
3421         ) {
3422                 Wikimedia\suppressWarnings();
3423                 $fp = fopen( $filename, 'r' );
3424                 Wikimedia\restoreWarnings();
3425
3426                 if ( false === $fp ) {
3427                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3428                 }
3429
3430                 if ( !$fname ) {
3431                         $fname = __METHOD__ . "( $filename )";
3432                 }
3433
3434                 try {
3435                         $error = $this->sourceStream(
3436                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3437                 } catch ( Exception $e ) {
3438                         fclose( $fp );
3439                         throw $e;
3440                 }
3441
3442                 fclose( $fp );
3443
3444                 return $error;
3445         }
3446
3447         public function setSchemaVars( $vars ) {
3448                 $this->schemaVars = $vars;
3449         }
3450
3451         public function sourceStream(
3452                 $fp,
3453                 callable $lineCallback = null,
3454                 callable $resultCallback = null,
3455                 $fname = __METHOD__,
3456                 callable $inputCallback = null
3457         ) {
3458                 $delimiterReset = new ScopedCallback(
3459                         function ( $delimiter ) {
3460                                 $this->delimiter = $delimiter;
3461                         },
3462                         [ $this->delimiter ]
3463                 );
3464                 $cmd = '';
3465
3466                 while ( !feof( $fp ) ) {
3467                         if ( $lineCallback ) {
3468                                 call_user_func( $lineCallback );
3469                         }
3470
3471                         $line = trim( fgets( $fp ) );
3472
3473                         if ( $line == '' ) {
3474                                 continue;
3475                         }
3476
3477                         if ( '-' == $line[0] && '-' == $line[1] ) {
3478                                 continue;
3479                         }
3480
3481                         if ( $cmd != '' ) {
3482                                 $cmd .= ' ';
3483                         }
3484
3485                         $done = $this->streamStatementEnd( $cmd, $line );
3486
3487                         $cmd .= "$line\n";
3488
3489                         if ( $done || feof( $fp ) ) {
3490                                 $cmd = $this->replaceVars( $cmd );
3491
3492                                 if ( $inputCallback ) {
3493                                         $callbackResult = call_user_func( $inputCallback, $cmd );
3494
3495                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
3496                                                 $cmd = $callbackResult;
3497                                         }
3498                                 }
3499
3500                                 if ( $cmd ) {
3501                                         $res = $this->query( $cmd, $fname );
3502
3503                                         if ( $resultCallback ) {
3504                                                 call_user_func( $resultCallback, $res, $this );
3505                                         }
3506
3507                                         if ( false === $res ) {
3508                                                 $err = $this->lastError();
3509
3510                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3511                                         }
3512                                 }
3513                                 $cmd = '';
3514                         }
3515                 }
3516
3517                 ScopedCallback::consume( $delimiterReset );
3518                 return true;
3519         }
3520
3521         /**
3522          * Called by sourceStream() to check if we've reached a statement end
3523          *
3524          * @param string &$sql SQL assembled so far
3525          * @param string &$newLine New line about to be added to $sql
3526          * @return bool Whether $newLine contains end of the statement
3527          */
3528         public function streamStatementEnd( &$sql, &$newLine ) {
3529                 if ( $this->delimiter ) {
3530                         $prev = $newLine;
3531                         $newLine = preg_replace(
3532                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3533                         if ( $newLine != $prev ) {
3534                                 return true;
3535                         }
3536                 }
3537
3538                 return false;
3539         }
3540
3541         /**
3542          * Database independent variable replacement. Replaces a set of variables
3543          * in an SQL statement with their contents as given by $this->getSchemaVars().
3544          *
3545          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3546          *
3547          * - '{$var}' should be used for text and is passed through the database's
3548          *   addQuotes method.
3549          * - `{$var}` should be used for identifiers (e.g. table and database names).
3550          *   It is passed through the database's addIdentifierQuotes method which
3551          *   can be overridden if the database uses something other than backticks.
3552          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3553          *   database's tableName method.
3554          * - / *i* / passes the name that follows through the database's indexName method.
3555          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3556          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3557          *
3558          * @param string $ins SQL statement to replace variables in
3559          * @return string The new SQL statement with variables replaced
3560          */
3561         protected function replaceVars( $ins ) {
3562                 $vars = $this->getSchemaVars();
3563                 return preg_replace_callback(
3564                         '!
3565                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3566                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3567                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3568                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3569                         !x',
3570                         function ( $m ) use ( $vars ) {
3571                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3572                                 // check for both nonexistent keys *and* the empty string.
3573                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3574                                         if ( $m[1] === 'i' ) {
3575                                                 return $this->indexName( $m[2] );
3576                                         } else {
3577                                                 return $this->tableName( $m[2] );
3578                                         }
3579                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3580                                         return $this->addQuotes( $vars[$m[3]] );
3581                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3582                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3583                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3584                                         return $vars[$m[5]];
3585                                 } else {
3586                                         return $m[0];
3587                                 }
3588                         },
3589                         $ins
3590                 );
3591         }
3592
3593         /**
3594          * Get schema variables. If none have been set via setSchemaVars(), then
3595          * use some defaults from the current object.
3596          *
3597          * @return array
3598          */
3599         protected function getSchemaVars() {
3600                 if ( $this->schemaVars ) {
3601                         return $this->schemaVars;
3602                 } else {
3603                         return $this->getDefaultSchemaVars();
3604                 }
3605         }
3606
3607         /**
3608          * Get schema variables to use if none have been set via setSchemaVars().
3609          *
3610          * Override this in derived classes to provide variables for tables.sql
3611          * and SQL patch files.
3612          *
3613          * @return array
3614          */
3615         protected function getDefaultSchemaVars() {
3616                 return [];
3617         }
3618
3619         public function lockIsFree( $lockName, $method ) {
3620                 // RDBMs methods for checking named locks may or may not count this thread itself.
3621                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
3622                 // the behavior choosen by the interface for this method.
3623                 return !isset( $this->namedLocksHeld[$lockName] );
3624         }
3625
3626         public function lock( $lockName, $method, $timeout = 5 ) {
3627                 $this->namedLocksHeld[$lockName] = 1;
3628
3629                 return true;
3630         }
3631
3632         public function unlock( $lockName, $method ) {
3633                 unset( $this->namedLocksHeld[$lockName] );
3634
3635                 return true;
3636         }
3637
3638         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3639                 if ( $this->writesOrCallbacksPending() ) {
3640                         // This only flushes transactions to clear snapshots, not to write data
3641                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3642                         throw new DBUnexpectedError(
3643                                 $this,
3644                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3645                         );
3646                 }
3647
3648                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3649                         return null;
3650                 }
3651
3652                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3653                         if ( $this->trxLevel() ) {
3654                                 // There is a good chance an exception was thrown, causing any early return
3655                                 // from the caller. Let any error handler get a chance to issue rollback().
3656                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3657                                 $this->onTransactionResolution(
3658                                         function () use ( $lockKey, $fname ) {
3659                                                 $this->unlock( $lockKey, $fname );
3660                                         },
3661                                         $fname
3662                                 );
3663                         } else {
3664                                 $this->unlock( $lockKey, $fname );
3665                         }
3666                 } );
3667
3668                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3669
3670                 return $unlocker;
3671         }
3672
3673         public function namedLocksEnqueue() {
3674                 return false;
3675         }
3676
3677         public function tableLocksHaveTransactionScope() {
3678                 return true;
3679         }
3680
3681         final public function lockTables( array $read, array $write, $method ) {
3682                 if ( $this->writesOrCallbacksPending() ) {
3683                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3684                 }
3685
3686                 if ( $this->tableLocksHaveTransactionScope() ) {
3687                         $this->startAtomic( $method );
3688                 }
3689
3690                 return $this->doLockTables( $read, $write, $method );
3691         }
3692
3693         /**
3694          * Helper function for lockTables() that handles the actual table locking
3695          *
3696          * @param array $read Array of tables to lock for read access
3697          * @param array $write Array of tables to lock for write access
3698          * @param string $method Name of caller
3699          * @return true
3700          */
3701         protected function doLockTables( array $read, array $write, $method ) {
3702                 return true;
3703         }
3704
3705         final public function unlockTables( $method ) {
3706                 if ( $this->tableLocksHaveTransactionScope() ) {
3707                         $this->endAtomic( $method );
3708
3709                         return true; // locks released on COMMIT/ROLLBACK
3710                 }
3711
3712                 return $this->doUnlockTables( $method );
3713         }
3714
3715         /**
3716          * Helper function for unlockTables() that handles the actual table unlocking
3717          *
3718          * @param string $method Name of caller
3719          * @return true
3720          */
3721         protected function doUnlockTables( $method ) {
3722                 return true;
3723         }
3724
3725         /**
3726          * Delete a table
3727          * @param string $tableName
3728          * @param string $fName
3729          * @return bool|ResultWrapper
3730          * @since 1.18
3731          */
3732         public function dropTable( $tableName, $fName = __METHOD__ ) {
3733                 if ( !$this->tableExists( $tableName, $fName ) ) {
3734                         return false;
3735                 }
3736                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3737
3738                 return $this->query( $sql, $fName );
3739         }
3740
3741         public function getInfinity() {
3742                 return 'infinity';
3743         }
3744
3745         public function encodeExpiry( $expiry ) {
3746                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3747                         ? $this->getInfinity()
3748                         : $this->timestamp( $expiry );
3749         }
3750
3751         public function decodeExpiry( $expiry, $format = TS_MW ) {
3752                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3753                         return 'infinity';
3754                 }
3755
3756                 return ConvertibleTimestamp::convert( $format, $expiry );
3757         }
3758
3759         public function setBigSelects( $value = true ) {
3760                 // no-op
3761         }
3762
3763         public function isReadOnly() {
3764                 return ( $this->getReadOnlyReason() !== false );
3765         }
3766
3767         /**
3768          * @return string|bool Reason this DB is read-only or false if it is not
3769          */
3770         protected function getReadOnlyReason() {
3771                 $reason = $this->getLBInfo( 'readOnlyReason' );
3772
3773                 return is_string( $reason ) ? $reason : false;
3774         }
3775
3776         public function setTableAliases( array $aliases ) {
3777                 $this->tableAliases = $aliases;
3778         }
3779
3780         /**
3781          * @return bool Whether a DB user is required to access the DB
3782          * @since 1.28
3783          */
3784         protected function requiresDatabaseUser() {
3785                 return true;
3786         }
3787
3788         /**
3789          * Get the underlying binding connection handle
3790          *
3791          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
3792          * This catches broken callers than catch and ignore disconnection exceptions.
3793          * Unlike checking isOpen(), this is safe to call inside of open().
3794          *
3795          * @return resource|object
3796          * @throws DBUnexpectedError
3797          * @since 1.26
3798          */
3799         protected function getBindingHandle() {
3800                 if ( !$this->conn ) {
3801                         throw new DBUnexpectedError(
3802                                 $this,
3803                                 'DB connection was already closed or the connection dropped.'
3804                         );
3805                 }
3806
3807                 return $this->conn;
3808         }
3809
3810         /**
3811          * @since 1.19
3812          * @return string
3813          */
3814         public function __toString() {
3815                 return (string)$this->conn;
3816         }
3817
3818         /**
3819          * Make sure that copies do not share the same client binding handle
3820          * @throws DBConnectionError
3821          */
3822         public function __clone() {
3823                 $this->connLogger->warning(
3824                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3825                         ( new RuntimeException() )->getTraceAsString()
3826                 );
3827
3828                 if ( $this->isOpen() ) {
3829                         // Open a new connection resource without messing with the old one
3830                         $this->opened = false;
3831                         $this->conn = false;
3832                         $this->trxEndCallbacks = []; // don't copy
3833                         $this->handleSessionLoss(); // no trx or locks anymore
3834                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
3835                         $this->lastPing = microtime( true );
3836                 }
3837         }
3838
3839         /**
3840          * Called by serialize. Throw an exception when DB connection is serialized.
3841          * This causes problems on some database engines because the connection is
3842          * not restored on unserialize.
3843          */
3844         public function __sleep() {
3845                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3846                         'the connection is not restored on wakeup.' );
3847         }
3848
3849         /**
3850          * Run a few simple sanity checks and close dangling connections
3851          */
3852         public function __destruct() {
3853                 if ( $this->trxLevel && $this->trxDoneWrites ) {
3854                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
3855                 }
3856
3857                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3858                 if ( $danglingWriters ) {
3859                         $fnames = implode( ', ', $danglingWriters );
3860                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3861                 }
3862
3863                 if ( $this->conn ) {
3864                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3865                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3866                         Wikimedia\suppressWarnings();
3867                         $this->closeConnection();
3868                         Wikimedia\restoreWarnings();
3869                         $this->conn = false;
3870                         $this->opened = false;
3871                 }
3872         }
3873 }
3874
3875 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3876 class_alias( Database::class, 'Database' ); // b/c global alias