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
24 use MediaWiki\MediaWikiServices
;
25 use Wikimedia\Rdbms\Database
;
26 use Wikimedia\Rdbms\IDatabase
;
27 use Wikimedia\Rdbms\DBError
;
28 use Wikimedia\Rdbms\DBQueryError
;
29 use Wikimedia\Rdbms\DBConnectionError
;
30 use Wikimedia\Rdbms\IMaintainableDatabase
;
31 use Wikimedia\Rdbms\LoadBalancer
;
32 use Wikimedia\ScopedCallback
;
33 use Wikimedia\WaitConditionLoop
;
36 * Class to store objects in the database
40 class SqlBagOStuff
extends MediumSpecificBagOStuff
{
41 /** @var array[] (server index => server config) */
42 protected $serverInfos;
43 /** @var string[] (server index => tag/host name) */
44 protected $serverTags;
46 protected $numServerShards;
47 /** @var int UNIX timestamp */
48 protected $lastGarbageCollect = 0;
50 protected $purgePeriod = 10;
52 protected $purgeLimit = 100;
54 protected $numTableShards = 1;
56 protected $tableName = 'objectcache';
58 protected $replicaOnly = false;
60 /** @var LoadBalancer|null */
61 protected $separateMainLB;
64 /** @var array UNIX timestamps */
65 protected $connFailureTimes = [];
66 /** @var array Exceptions */
67 protected $connFailureErrors = [];
70 private static $GC_DELAY_SEC = 1;
73 private static $OP_SET = 'set';
75 private static $OP_ADD = 'add';
77 private static $OP_TOUCH = 'touch';
79 private static $OP_DELETE = 'delete';
82 * Constructor. Parameters are:
83 * - server: A server info structure in the format required by each
84 * element in $wgDBServers.
86 * - servers: An array of server info structures describing a set of database servers
87 * to distribute keys to. If this is specified, the "server" option will be
88 * ignored. If string keys are used, then they will be used for consistent
89 * hashing *instead* of the host name (from the server config). This is useful
90 * when a cluster is replicated to another site (with different host names)
91 * but each server has a corresponding replica in the other cluster.
93 * - purgePeriod: The average number of object cache writes in between
94 * garbage collection operations, where expired entries
95 * are removed from the database. Or in other words, the
96 * reciprocal of the probability of purging on any given
97 * write. If this is set to zero, purging will never be done.
99 * - purgeLimit: Maximum number of rows to purge at once.
101 * - tableName: The table name to use, default is "objectcache".
103 * - shards: The number of tables to use for data storage on each server.
104 * If this is more than 1, table names will be formed in the style
105 * objectcacheNNN where NNN is the shard index, between 0 and
106 * shards-1. The number of digits will be the minimum number
107 * required to hold the largest shard index. Data will be
108 * distributed across all tables by key hash. This is for
109 * MySQL bugs 61735 <https://bugs.mysql.com/bug.php?id=61735>
110 * and 61736 <https://bugs.mysql.com/bug.php?id=61736>.
112 * - replicaOnly: Whether to only use replica DBs and avoid triggering
113 * garbage collection logic of expired items. This only
114 * makes sense if the primary DB is used and only if get()
115 * calls will be used. This is used by ReplicatedBagOStuff.
116 * - syncTimeout: Max seconds to wait for replica DBs to catch up for WRITE_SYNC.
118 * @param array $params
120 public function __construct( $params ) {
121 parent
::__construct( $params );
123 $this->attrMap
[self
::ATTR_EMULATION
] = self
::QOS_EMULATION_SQL
;
124 $this->attrMap
[self
::ATTR_SYNCWRITES
] = self
::QOS_SYNCWRITES_NONE
;
126 if ( isset( $params['servers'] ) ) {
127 $this->serverInfos
= [];
128 $this->serverTags
= [];
129 $this->numServerShards
= count( $params['servers'] );
131 foreach ( $params['servers'] as $tag => $info ) {
132 $this->serverInfos
[$index] = $info;
133 if ( is_string( $tag ) ) {
134 $this->serverTags
[$index] = $tag;
136 $this->serverTags
[$index] = $info['host'] ??
"#$index";
140 } elseif ( isset( $params['server'] ) ) {
141 $this->serverInfos
= [ $params['server'] ];
142 $this->numServerShards
= count( $this->serverInfos
);
144 // Default to using the main wiki's database servers
145 $this->serverInfos
= false;
146 $this->numServerShards
= 1;
147 $this->attrMap
[self
::ATTR_SYNCWRITES
] = self
::QOS_SYNCWRITES_BE
;
149 if ( isset( $params['purgePeriod'] ) ) {
150 $this->purgePeriod
= intval( $params['purgePeriod'] );
152 if ( isset( $params['purgeLimit'] ) ) {
153 $this->purgeLimit
= intval( $params['purgeLimit'] );
155 if ( isset( $params['tableName'] ) ) {
156 $this->tableName
= $params['tableName'];
158 if ( isset( $params['shards'] ) ) {
159 $this->numTableShards
= intval( $params['shards'] );
161 // Backwards-compatibility for < 1.34
162 $this->replicaOnly
= $params['replicaOnly'] ??
( $params['slaveOnly'] ??
false );
166 * Get a connection to the specified database
168 * @param int $shardIndex
169 * @return IMaintainableDatabase
170 * @throws MWException
172 private function getDB( $shardIndex ) {
173 if ( $shardIndex >= $this->numServerShards
) {
174 throw new MWException( __METHOD__
. ": Invalid server index \"$shardIndex\"" );
177 # Don't keep timing out trying to connect for each call if the DB is down
179 isset( $this->connFailureErrors
[$shardIndex] ) &&
180 ( $this->getCurrentTime() - $this->connFailureTimes
[$shardIndex] ) < 60
182 throw $this->connFailureErrors
[$shardIndex];
185 if ( $this->serverInfos
) {
186 if ( !isset( $this->conns
[$shardIndex] ) ) {
187 // Use custom database defined by server connection info
188 $info = $this->serverInfos
[$shardIndex];
189 $type = $info['type'] ??
'mysql';
190 $host = $info['host'] ??
'[unknown]';
191 $this->logger
->debug( __CLASS__
. ": connecting to $host" );
192 $db = Database
::factory( $type, $info );
193 $db->clearFlag( DBO_TRX
); // auto-commit mode
194 $this->conns
[$shardIndex] = $db;
196 $db = $this->conns
[$shardIndex];
198 // Use the main LB database
199 $lb = MediaWikiServices
::getInstance()->getDBLoadBalancer();
200 $index = $this->replicaOnly ? DB_REPLICA
: DB_MASTER
;
201 if ( $lb->getServerType( $lb->getWriterIndex() ) !== 'sqlite' ) {
202 // Keep a separate connection to avoid contention and deadlocks
203 $db = $lb->getConnectionRef( $index, [], false, $lb::CONN_TRX_AUTOCOMMIT
);
205 // However, SQLite has the opposite behavior due to DB-level locking.
206 // Stock sqlite MediaWiki installs use a separate sqlite cache DB instead.
207 $db = $lb->getConnectionRef( $index );
211 $this->logger
->debug( sprintf( "Connection %s will be used for SqlBagOStuff", $db ) );
217 * Get the server index and table name for a given key
219 * @return array Server index and table name
221 private function getTableByKey( $key ) {
222 if ( $this->numTableShards
> 1 ) {
223 $hash = hexdec( substr( md5( $key ), 0, 8 ) ) & 0x7fffffff;
224 $tableIndex = $hash %
$this->numTableShards
;
228 if ( $this->numServerShards
> 1 ) {
229 $sortedServers = $this->serverTags
;
230 ArrayUtils
::consistentHashSort( $sortedServers, $key );
231 reset( $sortedServers );
232 $shardIndex = key( $sortedServers );
236 return [ $shardIndex, $this->getTableNameByShard( $tableIndex ) ];
240 * Get the table name for a given shard index
244 private function getTableNameByShard( $index ) {
245 if ( $this->numTableShards
> 1 ) {
246 $decimals = strlen( $this->numTableShards
- 1 );
247 return $this->tableName
.
248 sprintf( "%0{$decimals}d", $index );
250 return $this->tableName
;
254 protected function doGet( $key, $flags = 0, &$casToken = null ) {
257 $blobs = $this->fetchBlobMulti( [ $key ] );
258 if ( array_key_exists( $key, $blobs ) ) {
259 $blob = $blobs[$key];
260 $value = $this->unserialize( $blob );
262 $casToken = ( $value !== false ) ?
$blob : null;
270 protected function doGetMulti( array $keys, $flags = 0 ) {
273 $blobs = $this->fetchBlobMulti( $keys );
274 foreach ( $blobs as $key => $blob ) {
275 $values[$key] = $this->unserialize( $blob );
281 private function fetchBlobMulti( array $keys, $flags = 0 ) {
282 $values = []; // array of (key => value)
285 foreach ( $keys as $key ) {
286 list( $shardIndex, $tableName ) = $this->getTableByKey( $key );
287 $keysByTable[$shardIndex][$tableName][] = $key;
291 foreach ( $keysByTable as $shardIndex => $serverKeys ) {
293 $db = $this->getDB( $shardIndex );
294 foreach ( $serverKeys as $tableName => $tableKeys ) {
295 $res = $db->select( $tableName,
296 [ 'keyname', 'value', 'exptime' ],
297 [ 'keyname' => $tableKeys ],
299 // Approximate write-on-the-fly BagOStuff API via blocking.
300 // This approximation fails if a ROLLBACK happens (which is rare).
301 // We do not want to flush the TRX as that can break callers.
302 $db->trxLevel() ?
[ 'LOCK IN SHARE MODE' ] : []
304 if ( $res === false ) {
307 foreach ( $res as $row ) {
308 $row->shardIndex
= $shardIndex;
309 $row->tableName
= $tableName;
310 $dataRows[$row->keyname
] = $row;
313 } catch ( DBError
$e ) {
314 $this->handleReadError( $e, $shardIndex );
318 foreach ( $keys as $key ) {
319 if ( isset( $dataRows[$key] ) ) { // HIT?
320 $row = $dataRows[$key];
321 $this->debug( "get: retrieved data; expiry time is " . $row->exptime
);
322 $db = null; // in case of connection failure
324 $db = $this->getDB( $row->shardIndex
);
325 if ( $this->isExpired( $db, $row->exptime
) ) { // MISS
326 $this->debug( "get: key has expired" );
328 $values[$key] = $db->decodeBlob( $row->value
);
330 } catch ( DBQueryError
$e ) {
331 $this->handleWriteError( $e, $db, $row->shardIndex
);
334 $this->debug( 'get: no matching rows' );
341 protected function doSetMulti( array $data, $exptime = 0, $flags = 0 ) {
342 return $this->modifyMulti( $data, $exptime, $flags, self
::$OP_SET );
346 * @param mixed[]|null[] $data Map of (key => new value or null)
347 * @param int $exptime UNIX timestamp, TTL in seconds, or 0 (no expiration)
348 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
349 * @param string $op Cache operation
352 private function modifyMulti( array $data, $exptime, $flags, $op ) {
354 foreach ( $data as $key => $value ) {
355 list( $shardIndex, $tableName ) = $this->getTableByKey( $key );
356 $keysByTable[$shardIndex][$tableName][] = $key;
359 $exptime = $this->getExpirationAsTimestamp( $exptime );
362 /** @noinspection PhpUnusedLocalVariableInspection */
363 $silenceScope = $this->silenceTransactionProfiler();
364 foreach ( $keysByTable as $shardIndex => $serverKeys ) {
365 $db = null; // in case of connection failure
367 $db = $this->getDB( $shardIndex );
368 $this->occasionallyGarbageCollect( $db ); // expire old entries if any
369 $dbExpiry = $exptime ?
$db->timestamp( $exptime ) : $this->getMaxDateTime( $db );
370 } catch ( DBError
$e ) {
371 $this->handleWriteError( $e, $db, $shardIndex );
376 foreach ( $serverKeys as $tableName => $tableKeys ) {
378 $result = $this->updateTableKeys(
386 } catch ( DBError
$e ) {
387 $this->handleWriteError( $e, $db, $shardIndex );
394 if ( $this->fieldHasFlags( $flags, self
::WRITE_SYNC
) ) {
395 $result = $this->waitForReplication() && $result;
403 * @param IDatabase $db
404 * @param string $table
405 * @param string[] $tableKeys Keys in $data to update
406 * @param mixed[]|null[] $data Map of (key => new value or null)
407 * @param string $dbExpiry DB-encoded expiry
410 * @throws InvalidArgumentException
412 private function updateTableKeys( $op, $db, $table, $tableKeys, $data, $dbExpiry ) {
415 if ( $op === self
::$OP_ADD ) {
417 foreach ( $tableKeys as $key ) {
420 'value' => $db->encodeBlob( $this->serialize( $data[$key] ) ),
421 'exptime' => $dbExpiry
427 'keyname' => $tableKeys,
428 'exptime <= ' . $db->addQuotes( $db->timestamp() )
432 $db->insert( $table, $rows, __METHOD__
, [ 'IGNORE' ] );
434 $success = ( $db->affectedRows() == count( $rows ) );
435 } elseif ( $op === self
::$OP_SET ) {
437 foreach ( $tableKeys as $key ) {
440 'value' => $db->encodeBlob( $this->serialize( $data[$key] ) ),
441 'exptime' => $dbExpiry
444 $db->replace( $table, [ 'keyname' ], $rows, __METHOD__
);
445 } elseif ( $op === self
::$OP_DELETE ) {
446 $db->delete( $table, [ 'keyname' => $tableKeys ], __METHOD__
);
447 } elseif ( $op === self
::$OP_TOUCH ) {
450 [ 'exptime' => $dbExpiry ],
452 'keyname' => $tableKeys,
453 'exptime > ' . $db->addQuotes( $db->timestamp() )
458 $success = ( $db->affectedRows() == count( $tableKeys ) );
460 throw new InvalidArgumentException( "Invalid operation '$op'" );
466 protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
467 return $this->modifyMulti( [ $key => $value ], $exptime, $flags, self
::$OP_SET );
470 protected function doAdd( $key, $value, $exptime = 0, $flags = 0 ) {
471 return $this->modifyMulti( [ $key => $value ], $exptime, $flags, self
::$OP_ADD );
474 protected function doCas( $casToken, $key, $value, $exptime = 0, $flags = 0 ) {
475 list( $shardIndex, $tableName ) = $this->getTableByKey( $key );
476 $exptime = $this->getExpirationAsTimestamp( $exptime );
478 /** @noinspection PhpUnusedLocalVariableInspection */
479 $silenceScope = $this->silenceTransactionProfiler();
480 $db = null; // in case of connection failure
482 $db = $this->getDB( $shardIndex );
483 // (T26425) use a replace if the db supports it instead of
484 // delete/insert to avoid clashes with conflicting keynames
489 'value' => $db->encodeBlob( $this->serialize( $value ) ),
490 'exptime' => $exptime
491 ?
$db->timestamp( $exptime )
492 : $this->getMaxDateTime( $db )
496 'value' => $db->encodeBlob( $casToken ),
497 'exptime > ' . $db->addQuotes( $db->timestamp() )
501 } catch ( DBQueryError
$e ) {
502 $this->handleWriteError( $e, $db, $shardIndex );
507 $success = (bool)$db->affectedRows();
508 if ( $this->fieldHasFlags( $flags, self
::WRITE_SYNC
) ) {
509 $success = $this->waitForReplication() && $success;
515 protected function doDeleteMulti( array $keys, $flags = 0 ) {
516 return $this->modifyMulti(
517 array_fill_keys( $keys, null ),
524 protected function doDelete( $key, $flags = 0 ) {
525 return $this->modifyMulti( [ $key => null ], 0, $flags, self
::$OP_DELETE );
528 public function incr( $key, $step = 1 ) {
529 list( $shardIndex, $tableName ) = $this->getTableByKey( $key );
532 /** @noinspection PhpUnusedLocalVariableInspection */
533 $silenceScope = $this->silenceTransactionProfiler();
534 $db = null; // in case of connection failure
536 $db = $this->getDB( $shardIndex );
537 $encTimestamp = $db->addQuotes( $db->timestamp() );
540 [ 'value = value + ' . (int)$step ],
541 [ 'keyname' => $key, "exptime > $encTimestamp" ],
544 if ( $db->affectedRows() > 0 ) {
545 $newValue = $db->selectField(
548 [ 'keyname' => $key, "exptime > $encTimestamp" ],
551 if ( $this->isInteger( $newValue ) ) {
552 $newCount = (int)$newValue;
555 } catch ( DBError
$e ) {
556 $this->handleWriteError( $e, $db, $shardIndex );
562 public function changeTTLMulti( array $keys, $exptime, $flags = 0 ) {
563 return $this->modifyMulti(
564 array_fill_keys( $keys, null ),
571 protected function doChangeTTL( $key, $exptime, $flags ) {
572 return $this->modifyMulti( [ $key => null ], $exptime, $flags, self
::$OP_TOUCH );
576 * @param IDatabase $db
577 * @param string $exptime
580 private function isExpired( $db, $exptime ) {
582 $exptime != $this->getMaxDateTime( $db ) &&
583 wfTimestamp( TS_UNIX
, $exptime ) < $this->getCurrentTime()
588 * @param IDatabase $db
591 private function getMaxDateTime( $db ) {
592 if ( (int)$this->getCurrentTime() > 0x7fffffff ) {
593 return $db->timestamp( 1 << 62 );
595 return $db->timestamp( 0x7fffffff );
600 * @param IDatabase $db
603 private function occasionallyGarbageCollect( IDatabase
$db ) {
605 // Random purging is enabled
606 $this->purgePeriod
&&
607 // Only purge on one in every $this->purgePeriod writes
608 mt_rand( 0, $this->purgePeriod
- 1 ) == 0 &&
609 // Avoid repeating the delete within a few seconds
610 ( $this->getCurrentTime() - $this->lastGarbageCollect
) > self
::$GC_DELAY_SEC
612 $garbageCollector = function () use ( $db ) {
613 $this->deleteServerObjectsExpiringBefore(
614 $db, $this->getCurrentTime(),
618 $this->lastGarbageCollect
= time();
620 if ( $this->asyncHandler
) {
621 $this->lastGarbageCollect
= $this->getCurrentTime(); // avoid duplicate enqueues
622 ( $this->asyncHandler
)( $garbageCollector );
629 public function expireAll() {
630 $this->deleteObjectsExpiringBefore( $this->getCurrentTime() );
633 public function deleteObjectsExpiringBefore(
635 callable
$progress = null,
638 /** @noinspection PhpUnusedLocalVariableInspection */
639 $silenceScope = $this->silenceTransactionProfiler();
641 $shardIndexes = range( 0, $this->numServerShards
- 1 );
642 shuffle( $shardIndexes );
646 $keysDeletedCount = 0;
647 foreach ( $shardIndexes as $numServersDone => $shardIndex ) {
648 $db = null; // in case of connection failure
650 $db = $this->getDB( $shardIndex );
651 $this->deleteServerObjectsExpiringBefore(
659 } catch ( DBError
$e ) {
660 $this->handleWriteError( $e, $db, $shardIndex );
669 * @param IDatabase $db
670 * @param string|int $timestamp
671 * @param callable|null $progressCallback
673 * @param int $serversDoneCount
674 * @param int &$keysDeletedCount
677 private function deleteServerObjectsExpiringBefore(
682 $serversDoneCount = 0,
683 &$keysDeletedCount = 0
685 $cutoffUnix = wfTimestamp( TS_UNIX
, $timestamp );
686 $shardIndexes = range( 0, $this->numTableShards
- 1 );
687 shuffle( $shardIndexes );
689 foreach ( $shardIndexes as $numShardsDone => $shardIndex ) {
690 $continue = null; // last exptime
691 $lag = null; // purge lag
694 $this->getTableNameByShard( $shardIndex ),
695 [ 'keyname', 'exptime' ],
697 [ 'exptime < ' . $db->addQuotes( $db->timestamp( $cutoffUnix ) ) ],
698 $continue ?
[ 'exptime >= ' . $db->addQuotes( $continue ) ] : []
701 [ 'LIMIT' => min( $limit, 100 ), 'ORDER BY' => 'exptime' ]
704 if ( $res->numRows() ) {
705 $row = $res->current();
706 if ( $lag === null ) {
707 $lag = max( $cutoffUnix - wfTimestamp( TS_UNIX
, $row->exptime
), 1 );
711 foreach ( $res as $row ) {
712 $keys[] = $row->keyname
;
713 $continue = $row->exptime
;
717 $this->getTableNameByShard( $shardIndex ),
719 'exptime < ' . $db->addQuotes( $db->timestamp( $cutoffUnix ) ),
724 $keysDeletedCount +
= $db->affectedRows();
727 if ( is_callable( $progressCallback ) ) {
729 $remainingLag = $cutoffUnix - wfTimestamp( TS_UNIX
, $continue );
730 $processedLag = max( $lag - $remainingLag, 0 );
731 $doneRatio = ( $numShardsDone +
$processedLag / $lag ) / $this->numTableShards
;
736 $overallRatio = ( $doneRatio / $this->numServerShards
)
737 +
( $serversDoneCount / $this->numServerShards
);
738 call_user_func( $progressCallback, $overallRatio * 100 );
740 } while ( $res->numRows() && $keysDeletedCount < $limit );
745 * Delete content of shard tables in every server.
746 * Return true if the operation is successful, false otherwise.
749 public function deleteAll() {
750 /** @noinspection PhpUnusedLocalVariableInspection */
751 $silenceScope = $this->silenceTransactionProfiler();
752 for ( $shardIndex = 0; $shardIndex < $this->numServerShards
; $shardIndex++
) {
753 $db = null; // in case of connection failure
755 $db = $this->getDB( $shardIndex );
756 for ( $i = 0; $i < $this->numTableShards
; $i++
) {
757 $db->delete( $this->getTableNameByShard( $i ), '*', __METHOD__
);
759 } catch ( DBError
$e ) {
760 $this->handleWriteError( $e, $db, $shardIndex );
767 public function lock( $key, $timeout = 6, $expiry = 6, $rclass = '' ) {
768 // Avoid deadlocks and allow lock reentry if specified
769 if ( isset( $this->locks
[$key] ) ) {
770 if ( $rclass != '' && $this->locks
[$key]['class'] === $rclass ) {
771 ++
$this->locks
[$key]['depth'];
778 list( $shardIndex ) = $this->getTableByKey( $key );
780 $db = null; // in case of connection failure
782 $db = $this->getDB( $shardIndex );
783 $ok = $db->lock( $key, __METHOD__
, $timeout );
785 $this->locks
[$key] = [ 'class' => $rclass, 'depth' => 1 ];
788 $this->logger
->warning(
789 __METHOD__
. " failed due to timeout for {key}.",
790 [ 'key' => $key, 'timeout' => $timeout ]
794 } catch ( DBError
$e ) {
795 $this->handleWriteError( $e, $db, $shardIndex );
802 public function unlock( $key ) {
803 if ( !isset( $this->locks
[$key] ) ) {
807 if ( --$this->locks
[$key]['depth'] <= 0 ) {
808 unset( $this->locks
[$key] );
810 list( $shardIndex ) = $this->getTableByKey( $key );
812 $db = null; // in case of connection failure
814 $db = $this->getDB( $shardIndex );
815 $ok = $db->unlock( $key, __METHOD__
);
817 $this->logger
->warning(
818 __METHOD__
. ' failed to release lock for {key}.',
822 } catch ( DBError
$e ) {
823 $this->handleWriteError( $e, $db, $shardIndex );
834 * Serialize an object and, if possible, compress the representation.
835 * On typical message and page data, this can provide a 3X decrease
836 * in storage requirements.
841 protected function serialize( $data ) {
842 if ( is_int( $data ) ) {
846 $serial = serialize( $data );
847 if ( function_exists( 'gzdeflate' ) ) {
848 $serial = gzdeflate( $serial );
855 * Unserialize and, if necessary, decompress an object.
856 * @param string $serial
859 protected function unserialize( $serial ) {
860 if ( $this->isInteger( $serial ) ) {
864 if ( function_exists( 'gzinflate' ) ) {
865 Wikimedia\
suppressWarnings();
866 $decomp = gzinflate( $serial );
867 Wikimedia\restoreWarnings
();
869 if ( $decomp !== false ) {
874 return unserialize( $serial );
878 * Handle a DBError which occurred during a read operation.
880 * @param DBError $exception
881 * @param int $shardIndex
883 private function handleReadError( DBError
$exception, $shardIndex ) {
884 if ( $exception instanceof DBConnectionError
) {
885 $this->markServerDown( $exception, $shardIndex );
888 $this->setAndLogDBError( $exception );
892 * Handle a DBQueryError which occurred during a write operation.
894 * @param DBError $exception
895 * @param IDatabase|null $db DB handle or null if connection failed
896 * @param int $shardIndex
899 private function handleWriteError( DBError
$exception, $db, $shardIndex ) {
900 if ( !( $db instanceof IDatabase
) ) {
901 $this->markServerDown( $exception, $shardIndex );
904 $this->setAndLogDBError( $exception );
908 * @param DBError $exception
910 private function setAndLogDBError( DBError
$exception ) {
911 $this->logger
->error( "DBError: {$exception->getMessage()}" );
912 if ( $exception instanceof DBConnectionError
) {
913 $this->setLastError( BagOStuff
::ERR_UNREACHABLE
);
914 $this->logger
->debug( __METHOD__
. ": ignoring connection error" );
916 $this->setLastError( BagOStuff
::ERR_UNEXPECTED
);
917 $this->logger
->debug( __METHOD__
. ": ignoring query error" );
922 * Mark a server down due to a DBConnectionError exception
924 * @param DBError $exception
925 * @param int $shardIndex
927 private function markServerDown( DBError
$exception, $shardIndex ) {
928 unset( $this->conns
[$shardIndex] ); // bug T103435
930 $now = $this->getCurrentTime();
931 if ( isset( $this->connFailureTimes
[$shardIndex] ) ) {
932 if ( $now - $this->connFailureTimes
[$shardIndex] >= 60 ) {
933 unset( $this->connFailureTimes
[$shardIndex] );
934 unset( $this->connFailureErrors
[$shardIndex] );
936 $this->logger
->debug( __METHOD__
. ": Server #$shardIndex already down" );
940 $this->logger
->info( __METHOD__
. ": Server #$shardIndex down until " . ( $now +
60 ) );
941 $this->connFailureTimes
[$shardIndex] = $now;
942 $this->connFailureErrors
[$shardIndex] = $exception;
946 * Create shard tables. For use from eval.php.
948 public function createTables() {
949 for ( $shardIndex = 0; $shardIndex < $this->numServerShards
; $shardIndex++
) {
950 $db = $this->getDB( $shardIndex );
951 if ( $db->getType() !== 'mysql' ) {
952 throw new MWException( __METHOD__
. ' is not supported on this DB server' );
955 for ( $i = 0; $i < $this->numTableShards
; $i++
) {
957 'CREATE TABLE ' . $db->tableName( $this->getTableNameByShard( $i ) ) .
958 ' LIKE ' . $db->tableName( 'objectcache' ),
965 * @return bool Whether the main DB is used, e.g. wfGetDB( DB_MASTER )
967 private function usesMainDB() {
968 return !$this->serverInfos
;
971 private function waitForReplication() {
972 if ( !$this->usesMainDB() ) {
973 // Custom DB server list; probably doesn't use replication
977 $lb = MediaWikiServices
::getInstance()->getDBLoadBalancer();
978 if ( $lb->getServerCount() <= 1 ) {
979 return true; // no replica DBs
982 // Main LB is used; wait for any replica DBs to catch up
984 $masterPos = $lb->getMasterPos();
986 return true; // not applicable
989 $loop = new WaitConditionLoop(
990 function () use ( $lb, $masterPos ) {
991 return $lb->waitForAll( $masterPos, 1 );
997 return ( $loop->invoke() === $loop::CONDITION_REACHED
);
998 } catch ( DBError
$e ) {
999 $this->setAndLogDBError( $e );
1006 * Silence the transaction profiler until the return value falls out of scope
1008 * @return ScopedCallback|null
1010 private function silenceTransactionProfiler() {
1011 if ( !$this->usesMainDB() ) {
1012 // Custom DB is configured which either has no TransactionProfiler injected,
1013 // or has one specific for cache use, which we shouldn't silence
1017 $trxProfiler = Profiler
::instance()->getTransactionProfiler();
1018 $oldSilenced = $trxProfiler->setSilenced( true );
1019 return new ScopedCallback( function () use ( $trxProfiler, $oldSilenced ) {
1020 $trxProfiler->setSilenced( $oldSilenced );