Merge "DatabaseMssql: Don't duplicate body of makeList()"
[mediawiki.git] / includes / objectcache / SqlBagOStuff.php
blobb9a99853de6c498445b59bc82924a21d9f6db8f8
1 <?php
2 /**
3 * Object caching using a SQL database.
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
18 * http://www.gnu.org/copyleft/gpl.html
20 * @file
21 * @ingroup Cache
24 /**
25 * Class to store objects in the database
27 * @ingroup Cache
29 class SqlBagOStuff extends BagOStuff {
30 /** @var LoadBalancer */
31 protected $lb;
33 protected $serverInfos;
35 /** @var array */
36 protected $serverNames;
38 /** @var int */
39 protected $numServers;
41 /** @var array */
42 protected $conns;
44 /** @var int */
45 protected $lastExpireAll = 0;
47 /** @var int */
48 protected $purgePeriod = 100;
50 /** @var int */
51 protected $shards = 1;
53 /** @var string */
54 protected $tableName = 'objectcache';
56 /** @var array UNIX timestamps */
57 protected $connFailureTimes = array();
59 /** @var array Exceptions */
60 protected $connFailureErrors = array();
62 /**
63 * Constructor. Parameters are:
64 * - server: A server info structure in the format required by each
65 * element in $wgDBServers.
67 * - servers: An array of server info structures describing a set of
68 * database servers to distribute keys to. If this is
69 * specified, the "server" option will be ignored.
71 * - purgePeriod: The average number of object cache requests in between
72 * garbage collection operations, where expired entries
73 * are removed from the database. Or in other words, the
74 * reciprocal of the probability of purging on any given
75 * request. If this is set to zero, purging will never be
76 * done.
78 * - tableName: The table name to use, default is "objectcache".
80 * - shards: The number of tables to use for data storage on each server.
81 * If this is more than 1, table names will be formed in the style
82 * objectcacheNNN where NNN is the shard index, between 0 and
83 * shards-1. The number of digits will be the minimum number
84 * required to hold the largest shard index. Data will be
85 * distributed across all tables by key hash. This is for
86 * MySQL bugs 61735 and 61736.
88 * @param array $params
90 public function __construct( $params ) {
91 parent::__construct( $params );
92 if ( isset( $params['servers'] ) ) {
93 $this->serverInfos = $params['servers'];
94 $this->numServers = count( $this->serverInfos );
95 $this->serverNames = array();
96 foreach ( $this->serverInfos as $i => $info ) {
97 $this->serverNames[$i] = isset( $info['host'] ) ? $info['host'] : "#$i";
99 } elseif ( isset( $params['server'] ) ) {
100 $this->serverInfos = array( $params['server'] );
101 $this->numServers = count( $this->serverInfos );
102 } else {
103 $this->serverInfos = false;
104 $this->numServers = 1;
106 if ( isset( $params['purgePeriod'] ) ) {
107 $this->purgePeriod = intval( $params['purgePeriod'] );
109 if ( isset( $params['tableName'] ) ) {
110 $this->tableName = $params['tableName'];
112 if ( isset( $params['shards'] ) ) {
113 $this->shards = intval( $params['shards'] );
118 * Get a connection to the specified database
120 * @param int $serverIndex
121 * @return DatabaseBase
122 * @throws MWException
124 protected function getDB( $serverIndex ) {
125 global $wgDebugDBTransactions;
127 if ( !isset( $this->conns[$serverIndex] ) ) {
128 if ( $serverIndex >= $this->numServers ) {
129 throw new MWException( __METHOD__ . ": Invalid server index \"$serverIndex\"" );
132 # Don't keep timing out trying to connect for each call if the DB is down
133 if ( isset( $this->connFailureErrors[$serverIndex] )
134 && ( time() - $this->connFailureTimes[$serverIndex] ) < 60
136 throw $this->connFailureErrors[$serverIndex];
139 # If server connection info was given, use that
140 if ( $this->serverInfos ) {
141 if ( $wgDebugDBTransactions ) {
142 $this->logger->debug( "Using provided serverInfo for SqlBagOStuff" );
144 $info = $this->serverInfos[$serverIndex];
145 $type = isset( $info['type'] ) ? $info['type'] : 'mysql';
146 $host = isset( $info['host'] ) ? $info['host'] : '[unknown]';
147 $this->logger->debug( __CLASS__ . ": connecting to $host" );
148 $db = DatabaseBase::factory( $type, $info );
149 $db->clearFlag( DBO_TRX );
150 } else {
152 * We must keep a separate connection to MySQL in order to avoid deadlocks
153 * However, SQLite has an opposite behavior. And PostgreSQL needs to know
154 * if we are in transaction or no
156 if ( wfGetDB( DB_MASTER )->getType() == 'mysql' ) {
157 $this->lb = wfGetLBFactory()->newMainLB();
158 $db = $this->lb->getConnection( DB_MASTER );
159 $db->clearFlag( DBO_TRX ); // auto-commit mode
160 } else {
161 $db = wfGetDB( DB_MASTER );
164 if ( $wgDebugDBTransactions ) {
165 $this->logger->debug( sprintf( "Connection %s will be used for SqlBagOStuff", $db ) );
167 $this->conns[$serverIndex] = $db;
170 return $this->conns[$serverIndex];
174 * Get the server index and table name for a given key
175 * @param string $key
176 * @return array Server index and table name
178 protected function getTableByKey( $key ) {
179 if ( $this->shards > 1 ) {
180 $hash = hexdec( substr( md5( $key ), 0, 8 ) ) & 0x7fffffff;
181 $tableIndex = $hash % $this->shards;
182 } else {
183 $tableIndex = 0;
185 if ( $this->numServers > 1 ) {
186 $sortedServers = $this->serverNames;
187 ArrayUtils::consistentHashSort( $sortedServers, $key );
188 reset( $sortedServers );
189 $serverIndex = key( $sortedServers );
190 } else {
191 $serverIndex = 0;
193 return array( $serverIndex, $this->getTableNameByShard( $tableIndex ) );
197 * Get the table name for a given shard index
198 * @param int $index
199 * @return string
201 protected function getTableNameByShard( $index ) {
202 if ( $this->shards > 1 ) {
203 $decimals = strlen( $this->shards - 1 );
204 return $this->tableName .
205 sprintf( "%0{$decimals}d", $index );
206 } else {
207 return $this->tableName;
212 * @param string $key
213 * @param mixed $casToken [optional]
214 * @return mixed
216 public function get( $key, &$casToken = null ) {
217 $values = $this->getMulti( array( $key ) );
218 if ( array_key_exists( $key, $values ) ) {
219 $casToken = $values[$key];
220 return $values[$key];
222 return false;
226 * @param array $keys
227 * @return array
229 public function getMulti( array $keys ) {
230 $values = array(); // array of (key => value)
232 $keysByTable = array();
233 foreach ( $keys as $key ) {
234 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
235 $keysByTable[$serverIndex][$tableName][] = $key;
238 $this->garbageCollect(); // expire old entries if any
240 $dataRows = array();
241 foreach ( $keysByTable as $serverIndex => $serverKeys ) {
242 try {
243 $db = $this->getDB( $serverIndex );
244 foreach ( $serverKeys as $tableName => $tableKeys ) {
245 $res = $db->select( $tableName,
246 array( 'keyname', 'value', 'exptime' ),
247 array( 'keyname' => $tableKeys ),
248 __METHOD__,
249 // Approximate write-on-the-fly BagOStuff API via blocking.
250 // This approximation fails if a ROLLBACK happens (which is rare).
251 // We do not want to flush the TRX as that can break callers.
252 $db->trxLevel() ? array( 'LOCK IN SHARE MODE' ) : array()
254 if ( $res === false ) {
255 continue;
257 foreach ( $res as $row ) {
258 $row->serverIndex = $serverIndex;
259 $row->tableName = $tableName;
260 $dataRows[$row->keyname] = $row;
263 } catch ( DBError $e ) {
264 $this->handleReadError( $e, $serverIndex );
268 foreach ( $keys as $key ) {
269 if ( isset( $dataRows[$key] ) ) { // HIT?
270 $row = $dataRows[$key];
271 $this->debug( "get: retrieved data; expiry time is " . $row->exptime );
272 try {
273 $db = $this->getDB( $row->serverIndex );
274 if ( $this->isExpired( $db, $row->exptime ) ) { // MISS
275 $this->debug( "get: key has expired, deleting" );
276 # Put the expiry time in the WHERE condition to avoid deleting a
277 # newly-inserted value
278 $db->delete( $row->tableName,
279 array( 'keyname' => $key, 'exptime' => $row->exptime ),
280 __METHOD__ );
281 } else { // HIT
282 $values[$key] = $this->unserialize( $db->decodeBlob( $row->value ) );
284 } catch ( DBQueryError $e ) {
285 $this->handleWriteError( $e, $row->serverIndex );
287 } else { // MISS
288 $this->debug( 'get: no matching rows' );
292 return $values;
296 * @param array $data
297 * @param int $expiry
298 * @return bool
300 public function setMulti( array $data, $expiry = 0 ) {
301 $keysByTable = array();
302 foreach ( $data as $key => $value ) {
303 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
304 $keysByTable[$serverIndex][$tableName][] = $key;
307 $this->garbageCollect(); // expire old entries if any
309 $result = true;
310 $exptime = (int)$expiry;
311 foreach ( $keysByTable as $serverIndex => $serverKeys ) {
312 try {
313 $db = $this->getDB( $serverIndex );
314 } catch ( DBError $e ) {
315 $this->handleWriteError( $e, $serverIndex );
316 $result = false;
317 continue;
320 if ( $exptime < 0 ) {
321 $exptime = 0;
324 if ( $exptime == 0 ) {
325 $encExpiry = $this->getMaxDateTime( $db );
326 } else {
327 $exptime = $this->convertExpiry( $exptime );
328 $encExpiry = $db->timestamp( $exptime );
330 foreach ( $serverKeys as $tableName => $tableKeys ) {
331 $rows = array();
332 foreach ( $tableKeys as $key ) {
333 $rows[] = array(
334 'keyname' => $key,
335 'value' => $db->encodeBlob( $this->serialize( $data[$key] ) ),
336 'exptime' => $encExpiry,
340 try {
341 $db->replace(
342 $tableName,
343 array( 'keyname' ),
344 $rows,
345 __METHOD__
347 } catch ( DBError $e ) {
348 $this->handleWriteError( $e, $serverIndex );
349 $result = false;
356 return $result;
362 * @param string $key
363 * @param mixed $value
364 * @param int $exptime
365 * @return bool
367 public function set( $key, $value, $exptime = 0 ) {
368 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
369 try {
370 $db = $this->getDB( $serverIndex );
371 $exptime = intval( $exptime );
373 if ( $exptime < 0 ) {
374 $exptime = 0;
377 if ( $exptime == 0 ) {
378 $encExpiry = $this->getMaxDateTime( $db );
379 } else {
380 $exptime = $this->convertExpiry( $exptime );
381 $encExpiry = $db->timestamp( $exptime );
383 // (bug 24425) use a replace if the db supports it instead of
384 // delete/insert to avoid clashes with conflicting keynames
385 $db->replace(
386 $tableName,
387 array( 'keyname' ),
388 array(
389 'keyname' => $key,
390 'value' => $db->encodeBlob( $this->serialize( $value ) ),
391 'exptime' => $encExpiry
392 ), __METHOD__ );
393 } catch ( DBError $e ) {
394 $this->handleWriteError( $e, $serverIndex );
395 return false;
398 return true;
402 * @param mixed $casToken
403 * @param string $key
404 * @param mixed $value
405 * @param int $exptime
406 * @return bool
408 protected function cas( $casToken, $key, $value, $exptime = 0 ) {
409 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
410 try {
411 $db = $this->getDB( $serverIndex );
412 $exptime = intval( $exptime );
414 if ( $exptime < 0 ) {
415 $exptime = 0;
418 if ( $exptime == 0 ) {
419 $encExpiry = $this->getMaxDateTime( $db );
420 } else {
421 $exptime = $this->convertExpiry( $exptime );
422 $encExpiry = $db->timestamp( $exptime );
424 // (bug 24425) use a replace if the db supports it instead of
425 // delete/insert to avoid clashes with conflicting keynames
426 $db->update(
427 $tableName,
428 array(
429 'keyname' => $key,
430 'value' => $db->encodeBlob( $this->serialize( $value ) ),
431 'exptime' => $encExpiry
433 array(
434 'keyname' => $key,
435 'value' => $db->encodeBlob( $this->serialize( $casToken ) )
437 __METHOD__
439 } catch ( DBQueryError $e ) {
440 $this->handleWriteError( $e, $serverIndex );
442 return false;
445 return (bool)$db->affectedRows();
449 * @param string $key
450 * @return bool
452 public function delete( $key ) {
453 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
454 try {
455 $db = $this->getDB( $serverIndex );
456 $db->delete(
457 $tableName,
458 array( 'keyname' => $key ),
459 __METHOD__ );
460 } catch ( DBError $e ) {
461 $this->handleWriteError( $e, $serverIndex );
462 return false;
465 return true;
469 * @param string $key
470 * @param int $step
471 * @return int|null
473 public function incr( $key, $step = 1 ) {
474 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
475 try {
476 $db = $this->getDB( $serverIndex );
477 $step = intval( $step );
478 $row = $db->selectRow(
479 $tableName,
480 array( 'value', 'exptime' ),
481 array( 'keyname' => $key ),
482 __METHOD__,
483 array( 'FOR UPDATE' ) );
484 if ( $row === false ) {
485 // Missing
487 return null;
489 $db->delete( $tableName, array( 'keyname' => $key ), __METHOD__ );
490 if ( $this->isExpired( $db, $row->exptime ) ) {
491 // Expired, do not reinsert
493 return null;
496 $oldValue = intval( $this->unserialize( $db->decodeBlob( $row->value ) ) );
497 $newValue = $oldValue + $step;
498 $db->insert( $tableName,
499 array(
500 'keyname' => $key,
501 'value' => $db->encodeBlob( $this->serialize( $newValue ) ),
502 'exptime' => $row->exptime
503 ), __METHOD__, 'IGNORE' );
505 if ( $db->affectedRows() == 0 ) {
506 // Race condition. See bug 28611
507 $newValue = null;
509 } catch ( DBError $e ) {
510 $this->handleWriteError( $e, $serverIndex );
511 return null;
514 return $newValue;
518 * @param DatabaseBase $db
519 * @param string $exptime
520 * @return bool
522 protected function isExpired( $db, $exptime ) {
523 return $exptime != $this->getMaxDateTime( $db ) && wfTimestamp( TS_UNIX, $exptime ) < time();
527 * @param DatabaseBase $db
528 * @return string
530 protected function getMaxDateTime( $db ) {
531 if ( time() > 0x7fffffff ) {
532 return $db->timestamp( 1 << 62 );
533 } else {
534 return $db->timestamp( 0x7fffffff );
538 protected function garbageCollect() {
539 if ( !$this->purgePeriod ) {
540 // Disabled
541 return;
543 // Only purge on one in every $this->purgePeriod requests.
544 if ( $this->purgePeriod !== 1 && mt_rand( 0, $this->purgePeriod - 1 ) ) {
545 return;
547 $now = time();
548 // Avoid repeating the delete within a few seconds
549 if ( $now > ( $this->lastExpireAll + 1 ) ) {
550 $this->lastExpireAll = $now;
551 $this->expireAll();
555 public function expireAll() {
556 $this->deleteObjectsExpiringBefore( wfTimestampNow() );
560 * Delete objects from the database which expire before a certain date.
561 * @param string $timestamp
562 * @param bool|callable $progressCallback
563 * @return bool
565 public function deleteObjectsExpiringBefore( $timestamp, $progressCallback = false ) {
566 for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
567 try {
568 $db = $this->getDB( $serverIndex );
569 $dbTimestamp = $db->timestamp( $timestamp );
570 $totalSeconds = false;
571 $baseConds = array( 'exptime < ' . $db->addQuotes( $dbTimestamp ) );
572 for ( $i = 0; $i < $this->shards; $i++ ) {
573 $maxExpTime = false;
574 while ( true ) {
575 $conds = $baseConds;
576 if ( $maxExpTime !== false ) {
577 $conds[] = 'exptime > ' . $db->addQuotes( $maxExpTime );
579 $rows = $db->select(
580 $this->getTableNameByShard( $i ),
581 array( 'keyname', 'exptime' ),
582 $conds,
583 __METHOD__,
584 array( 'LIMIT' => 100, 'ORDER BY' => 'exptime' ) );
585 if ( $rows === false || !$rows->numRows() ) {
586 break;
588 $keys = array();
589 $row = $rows->current();
590 $minExpTime = $row->exptime;
591 if ( $totalSeconds === false ) {
592 $totalSeconds = wfTimestamp( TS_UNIX, $timestamp )
593 - wfTimestamp( TS_UNIX, $minExpTime );
595 foreach ( $rows as $row ) {
596 $keys[] = $row->keyname;
597 $maxExpTime = $row->exptime;
600 $db->delete(
601 $this->getTableNameByShard( $i ),
602 array(
603 'exptime >= ' . $db->addQuotes( $minExpTime ),
604 'exptime < ' . $db->addQuotes( $dbTimestamp ),
605 'keyname' => $keys
607 __METHOD__ );
609 if ( $progressCallback ) {
610 if ( intval( $totalSeconds ) === 0 ) {
611 $percent = 0;
612 } else {
613 $remainingSeconds = wfTimestamp( TS_UNIX, $timestamp )
614 - wfTimestamp( TS_UNIX, $maxExpTime );
615 if ( $remainingSeconds > $totalSeconds ) {
616 $totalSeconds = $remainingSeconds;
618 $processedSeconds = $totalSeconds - $remainingSeconds;
619 $percent = ( $i + $processedSeconds / $totalSeconds )
620 / $this->shards * 100;
622 $percent = ( $percent / $this->numServers )
623 + ( $serverIndex / $this->numServers * 100 );
624 call_user_func( $progressCallback, $percent );
628 } catch ( DBError $e ) {
629 $this->handleWriteError( $e, $serverIndex );
630 return false;
633 return true;
637 * Delete content of shard tables in every server.
638 * Return true if the operation is successful, false otherwise.
639 * @return bool
641 public function deleteAll() {
642 for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
643 try {
644 $db = $this->getDB( $serverIndex );
645 for ( $i = 0; $i < $this->shards; $i++ ) {
646 $db->delete( $this->getTableNameByShard( $i ), '*', __METHOD__ );
648 } catch ( DBError $e ) {
649 $this->handleWriteError( $e, $serverIndex );
650 return false;
653 return true;
657 * Serialize an object and, if possible, compress the representation.
658 * On typical message and page data, this can provide a 3X decrease
659 * in storage requirements.
661 * @param mixed $data
662 * @return string
664 protected function serialize( &$data ) {
665 $serial = serialize( $data );
667 if ( function_exists( 'gzdeflate' ) ) {
668 return gzdeflate( $serial );
669 } else {
670 return $serial;
675 * Unserialize and, if necessary, decompress an object.
676 * @param string $serial
677 * @return mixed
679 protected function unserialize( $serial ) {
680 if ( function_exists( 'gzinflate' ) ) {
681 wfSuppressWarnings();
682 $decomp = gzinflate( $serial );
683 wfRestoreWarnings();
685 if ( false !== $decomp ) {
686 $serial = $decomp;
690 $ret = unserialize( $serial );
692 return $ret;
696 * Handle a DBError which occurred during a read operation.
698 * @param DBError $exception
699 * @param int $serverIndex
701 protected function handleReadError( DBError $exception, $serverIndex ) {
702 if ( $exception instanceof DBConnectionError ) {
703 $this->markServerDown( $exception, $serverIndex );
705 $this->logger->error( "DBError: {$exception->getMessage()}" );
706 if ( $exception instanceof DBConnectionError ) {
707 $this->setLastError( BagOStuff::ERR_UNREACHABLE );
708 $this->logger->debug( __METHOD__ . ": ignoring connection error" );
709 } else {
710 $this->setLastError( BagOStuff::ERR_UNEXPECTED );
711 $this->logger->debug( __METHOD__ . ": ignoring query error" );
716 * Handle a DBQueryError which occurred during a write operation.
718 * @param DBError $exception
719 * @param int $serverIndex
721 protected function handleWriteError( DBError $exception, $serverIndex ) {
722 if ( $exception instanceof DBConnectionError ) {
723 $this->markServerDown( $exception, $serverIndex );
725 if ( $exception->db && $exception->db->wasReadOnlyError() ) {
726 try {
727 $exception->db->rollback( __METHOD__ );
728 } catch ( DBError $e ) {
732 $this->logger->error( "DBError: {$exception->getMessage()}" );
733 if ( $exception instanceof DBConnectionError ) {
734 $this->setLastError( BagOStuff::ERR_UNREACHABLE );
735 $this->logger->debug( __METHOD__ . ": ignoring connection error" );
736 } else {
737 $this->setLastError( BagOStuff::ERR_UNEXPECTED );
738 $this->logger->debug( __METHOD__ . ": ignoring query error" );
743 * Mark a server down due to a DBConnectionError exception
745 * @param DBError $exception
746 * @param int $serverIndex
748 protected function markServerDown( $exception, $serverIndex ) {
749 if ( isset( $this->connFailureTimes[$serverIndex] ) ) {
750 if ( time() - $this->connFailureTimes[$serverIndex] >= 60 ) {
751 unset( $this->connFailureTimes[$serverIndex] );
752 unset( $this->connFailureErrors[$serverIndex] );
753 } else {
754 $this->logger->debug( __METHOD__ . ": Server #$serverIndex already down" );
755 return;
758 $now = time();
759 $this->logger->info( __METHOD__ . ": Server #$serverIndex down until " . ( $now + 60 ) );
760 $this->connFailureTimes[$serverIndex] = $now;
761 $this->connFailureErrors[$serverIndex] = $exception;
765 * Create shard tables. For use from eval.php.
767 public function createTables() {
768 for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
769 $db = $this->getDB( $serverIndex );
770 if ( $db->getType() !== 'mysql' ) {
771 throw new MWException( __METHOD__ . ' is not supported on this DB server' );
774 for ( $i = 0; $i < $this->shards; $i++ ) {
775 $db->query(
776 'CREATE TABLE ' . $db->tableName( $this->getTableNameByShard( $i ) ) .
777 ' LIKE ' . $db->tableName( 'objectcache' ),
778 __METHOD__ );