3 * Database load balancing manager
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
23 use Psr\Log\LoggerInterface
;
26 * Database connection, tracking, load balancing, and transaction manager for a cluster
30 class LoadBalancer
implements ILoadBalancer
{
31 /** @var array[] Map of (server index => server config array) */
33 /** @var array[] Map of (local/foreignUsed/foreignFree => server index => IDatabase array) */
35 /** @var float[] Map of (server index => weight) */
37 /** @var array[] Map of (group => server index => weight) */
39 /** @var bool Whether to disregard replica DB lag as a factor in replica DB selection */
40 private $mAllowLagged;
41 /** @var integer Seconds to spend waiting on replica DB lag to resolve */
42 private $mWaitTimeout;
43 /** @var array The LoadMonitor configuration */
44 private $loadMonitorConfig;
45 /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
46 private $tableAliases = [];
48 /** @var ILoadMonitor */
54 /** @var WANObjectCache */
56 /** @var object|string Class name or object With profileIn/profileOut methods */
58 /** @var TransactionProfiler */
59 protected $trxProfiler;
60 /** @var LoggerInterface */
61 protected $replLogger;
62 /** @var LoggerInterface */
63 protected $connLogger;
64 /** @var LoggerInterface */
65 protected $queryLogger;
66 /** @var LoggerInterface */
67 protected $perfLogger;
69 /** @var bool|IDatabase Database connection that caused a problem */
70 private $mErrorConnection;
71 /** @var integer The generic (not query grouped) replica DB index (of $mServers) */
73 /** @var bool|DBMasterPos False if not set */
75 /** @var bool Whether the generic reader fell back to a lagged replica DB */
76 private $laggedReplicaMode = false;
77 /** @var bool Whether the generic reader fell back to a lagged replica DB */
78 private $allReplicasDownMode = false;
79 /** @var string The last DB selection or connection error */
80 private $mLastError = 'Unknown error';
81 /** @var string|bool Reason the LB is read-only or false if not */
82 private $readOnlyReason = false;
83 /** @var integer Total connections opened */
84 private $connsOpened = 0;
85 /** @var string|bool String if a requested DBO_TRX transaction round is active */
86 private $trxRoundId = false;
87 /** @var array[] Map of (name => callable) */
88 private $trxRecurringCallbacks = [];
89 /** @var DatabaseDomain Local Domain ID and default for selectDB() calls */
91 /** @var string Alternate ID string for the domain instead of DatabaseDomain::getId() */
92 private $localDomainIdAlias;
93 /** @var string Current server name */
95 /** @var bool Whether this PHP instance is for a CLI script */
97 /** @var string Agent name for query profiling */
100 /** @var callable Exception logger */
101 private $errorLogger;
104 private $disabled = false;
106 /** @var integer Warn when this many connection are held */
107 const CONN_HELD_WARN_THRESHOLD
= 10;
109 /** @var integer Default 'max lag' when unspecified */
110 const MAX_LAG_DEFAULT
= 10;
111 /** @var integer Seconds to cache master server read-only status */
112 const TTL_CACHE_READONLY
= 5;
114 public function __construct( array $params ) {
115 if ( !isset( $params['servers'] ) ) {
116 throw new InvalidArgumentException( __CLASS__
. ': missing servers parameter' );
118 $this->mServers
= $params['servers'];
120 $this->localDomain
= isset( $params['localDomain'] )
121 ? DatabaseDomain
::newFromId( $params['localDomain'] )
122 : DatabaseDomain
::newUnspecified();
123 // In case a caller assumes that the domain ID is simply <db>-<prefix>, which is almost
124 // always true, gracefully handle the case when they fail to account for escaping.
125 if ( $this->localDomain
->getTablePrefix() != '' ) {
126 $this->localDomainIdAlias
=
127 $this->localDomain
->getDatabase() . '-' . $this->localDomain
->getTablePrefix();
129 $this->localDomainIdAlias
= $this->localDomain
->getDatabase();
132 $this->mWaitTimeout
= isset( $params['waitTimeout'] ) ?
$params['waitTimeout'] : 10;
134 $this->mReadIndex
= -1;
141 $this->mWaitForPos
= false;
142 $this->mErrorConnection
= false;
143 $this->mAllowLagged
= false;
145 if ( isset( $params['readOnlyReason'] ) && is_string( $params['readOnlyReason'] ) ) {
146 $this->readOnlyReason
= $params['readOnlyReason'];
149 if ( isset( $params['loadMonitor'] ) ) {
150 $this->loadMonitorConfig
= $params['loadMonitor'];
152 $this->loadMonitorConfig
= [ 'class' => 'LoadMonitorNull' ];
155 foreach ( $params['servers'] as $i => $server ) {
156 $this->mLoads
[$i] = $server['load'];
157 if ( isset( $server['groupLoads'] ) ) {
158 foreach ( $server['groupLoads'] as $group => $ratio ) {
159 if ( !isset( $this->mGroupLoads
[$group] ) ) {
160 $this->mGroupLoads
[$group] = [];
162 $this->mGroupLoads
[$group][$i] = $ratio;
167 if ( isset( $params['srvCache'] ) ) {
168 $this->srvCache
= $params['srvCache'];
170 $this->srvCache
= new EmptyBagOStuff();
172 if ( isset( $params['memCache'] ) ) {
173 $this->memCache
= $params['memCache'];
175 $this->memCache
= new EmptyBagOStuff();
177 if ( isset( $params['wanCache'] ) ) {
178 $this->wanCache
= $params['wanCache'];
180 $this->wanCache
= WANObjectCache
::newEmpty();
182 $this->profiler
= isset( $params['profiler'] ) ?
$params['profiler'] : null;
183 if ( isset( $params['trxProfiler'] ) ) {
184 $this->trxProfiler
= $params['trxProfiler'];
186 $this->trxProfiler
= new TransactionProfiler();
189 $this->errorLogger
= isset( $params['errorLogger'] )
190 ?
$params['errorLogger']
191 : function ( Exception
$e ) {
192 trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING
);
195 foreach ( [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ] as $key ) {
196 $this->$key = isset( $params[$key] ) ?
$params[$key] : new \Psr\Log\
NullLogger();
199 $this->host
= isset( $params['hostname'] )
200 ?
$params['hostname']
201 : ( gethostname() ?
: 'unknown' );
202 $this->cliMode
= isset( $params['cliMode'] ) ?
$params['cliMode'] : PHP_SAPI
=== 'cli';
203 $this->agent
= isset( $params['agent'] ) ?
$params['agent'] : '';
207 * Get a LoadMonitor instance
209 * @return ILoadMonitor
211 private function getLoadMonitor() {
212 if ( !isset( $this->loadMonitor
) ) {
213 $class = $this->loadMonitorConfig
['class'];
214 $this->loadMonitor
= new $class(
215 $this, $this->srvCache
, $this->memCache
, $this->loadMonitorConfig
);
216 $this->loadMonitor
->setLogger( $this->replLogger
);
219 return $this->loadMonitor
;
223 * @param array $loads
224 * @param bool|string $domain Domain to get non-lagged for
225 * @param int $maxLag Restrict the maximum allowed lag to this many seconds
226 * @return bool|int|string
228 private function getRandomNonLagged( array $loads, $domain = false, $maxLag = INF
) {
229 $lags = $this->getLagTimes( $domain );
231 # Unset excessively lagged servers
232 foreach ( $lags as $i => $lag ) {
234 # How much lag this server nominally is allowed to have
235 $maxServerLag = isset( $this->mServers
[$i]['max lag'] )
236 ?
$this->mServers
[$i]['max lag']
237 : self
::MAX_LAG_DEFAULT
; // default
238 # Constrain that futher by $maxLag argument
239 $maxServerLag = min( $maxServerLag, $maxLag );
241 $host = $this->getServerName( $i );
242 if ( $lag === false && !is_infinite( $maxServerLag ) ) {
243 $this->replLogger
->error( "Server $host (#$i) is not replicating?" );
245 } elseif ( $lag > $maxServerLag ) {
246 $this->replLogger
->warning( "Server $host (#$i) has >= $lag seconds of lag" );
252 # Find out if all the replica DBs with non-zero load are lagged
254 foreach ( $loads as $load ) {
258 # No appropriate DB servers except maybe the master and some replica DBs with zero load
259 # Do NOT use the master
260 # Instead, this function will return false, triggering read-only mode,
261 # and a lagged replica DB will be used instead.
265 if ( count( $loads ) == 0 ) {
269 # Return a random representative of the remainder
270 return ArrayUtils
::pickRandom( $loads );
273 public function getReaderIndex( $group = false, $domain = false ) {
274 if ( count( $this->mServers
) == 1 ) {
275 # Skip the load balancing if there's only one server
276 return $this->getWriterIndex();
277 } elseif ( $group === false && $this->mReadIndex
>= 0 ) {
278 # Shortcut if generic reader exists already
279 return $this->mReadIndex
;
282 # Find the relevant load array
283 if ( $group !== false ) {
284 if ( isset( $this->mGroupLoads
[$group] ) ) {
285 $nonErrorLoads = $this->mGroupLoads
[$group];
287 # No loads for this group, return false and the caller can use some other group
288 $this->connLogger
->info( __METHOD__
. ": no loads for group $group" );
293 $nonErrorLoads = $this->mLoads
;
296 if ( !count( $nonErrorLoads ) ) {
297 throw new InvalidArgumentException( "Empty server array given to LoadBalancer" );
300 # Scale the configured load ratios according to the dynamic load if supported
301 $this->getLoadMonitor()->scaleLoads( $nonErrorLoads, $domain );
303 $laggedReplicaMode = false;
305 # No server found yet
307 # First try quickly looking through the available servers for a server that
309 $currentLoads = $nonErrorLoads;
310 while ( count( $currentLoads ) ) {
311 if ( $this->mAllowLagged ||
$laggedReplicaMode ) {
312 $i = ArrayUtils
::pickRandom( $currentLoads );
315 if ( $this->mWaitForPos
&& $this->mWaitForPos
->asOfTime() ) {
316 # ChronologyProtecter causes mWaitForPos to be set via sessions.
317 # This triggers doWait() after connect, so it's especially good to
318 # avoid lagged servers so as to avoid just blocking in that method.
319 $ago = microtime( true ) - $this->mWaitForPos
->asOfTime();
320 # Aim for <= 1 second of waiting (being too picky can backfire)
321 $i = $this->getRandomNonLagged( $currentLoads, $domain, $ago +
1 );
323 if ( $i === false ) {
324 # Any server with less lag than it's 'max lag' param is preferable
325 $i = $this->getRandomNonLagged( $currentLoads, $domain );
327 if ( $i === false && count( $currentLoads ) != 0 ) {
328 # All replica DBs lagged. Switch to read-only mode
329 $this->replLogger
->error( "All replica DBs lagged. Switch to read-only mode" );
330 $i = ArrayUtils
::pickRandom( $currentLoads );
331 $laggedReplicaMode = true;
335 if ( $i === false ) {
336 # pickRandom() returned false
337 # This is permanent and means the configuration or the load monitor
338 # wants us to return false.
339 $this->connLogger
->debug( __METHOD__
. ": pickRandom() returned false" );
344 $serverName = $this->getServerName( $i );
345 $this->connLogger
->debug( __METHOD__
. ": Using reader #$i: $serverName..." );
347 $conn = $this->openConnection( $i, $domain );
349 $this->connLogger
->warning( __METHOD__
. ": Failed connecting to $i/$domain" );
350 unset( $nonErrorLoads[$i] );
351 unset( $currentLoads[$i] );
356 // Decrement reference counter, we are finished with this connection.
357 // It will be incremented for the caller later.
358 if ( $domain !== false ) {
359 $this->reuseConnection( $conn );
366 # If all servers were down, quit now
367 if ( !count( $nonErrorLoads ) ) {
368 $this->connLogger
->error( "All servers down" );
371 if ( $i !== false ) {
372 # Replica DB connection successful.
373 # Wait for the session master pos for a short time.
374 if ( $this->mWaitForPos
&& $i > 0 ) {
377 if ( $this->mReadIndex
<= 0 && $this->mLoads
[$i] > 0 && $group === false ) {
378 $this->mReadIndex
= $i;
379 # Record if the generic reader index is in "lagged replica DB" mode
380 if ( $laggedReplicaMode ) {
381 $this->laggedReplicaMode
= true;
384 $serverName = $this->getServerName( $i );
385 $this->connLogger
->debug(
386 __METHOD__
. ": using server $serverName for group '$group'" );
392 public function waitFor( $pos ) {
393 $this->mWaitForPos
= $pos;
394 $i = $this->mReadIndex
;
397 if ( !$this->doWait( $i ) ) {
398 $this->laggedReplicaMode
= true;
403 public function waitForOne( $pos, $timeout = null ) {
404 $this->mWaitForPos
= $pos;
406 $i = $this->mReadIndex
;
408 // Pick a generic replica DB if there isn't one yet
409 $readLoads = $this->mLoads
;
410 unset( $readLoads[$this->getWriterIndex()] ); // replica DBs only
411 $readLoads = array_filter( $readLoads ); // with non-zero load
412 $i = ArrayUtils
::pickRandom( $readLoads );
416 $ok = $this->doWait( $i, true, $timeout );
418 $ok = true; // no applicable loads
424 public function waitForAll( $pos, $timeout = null ) {
425 $this->mWaitForPos
= $pos;
426 $serverCount = count( $this->mServers
);
429 for ( $i = 1; $i < $serverCount; $i++
) {
430 if ( $this->mLoads
[$i] > 0 ) {
431 $ok = $this->doWait( $i, true, $timeout ) && $ok;
438 public function getAnyOpenConnection( $i ) {
439 foreach ( $this->mConns
as $connsByServer ) {
440 if ( !empty( $connsByServer[$i] ) ) {
441 return reset( $connsByServer[$i] );
449 * Wait for a given replica DB to catch up to the master pos stored in $this
450 * @param int $index Server index
451 * @param bool $open Check the server even if a new connection has to be made
452 * @param int $timeout Max seconds to wait; default is mWaitTimeout
455 protected function doWait( $index, $open = false, $timeout = null ) {
456 $close = false; // close the connection afterwards
458 // Check if we already know that the DB has reached this point
459 $server = $this->getServerName( $index );
460 $key = $this->srvCache
->makeGlobalKey( __CLASS__
, 'last-known-pos', $server );
461 /** @var DBMasterPos $knownReachedPos */
462 $knownReachedPos = $this->srvCache
->get( $key );
463 if ( $knownReachedPos && $knownReachedPos->hasReached( $this->mWaitForPos
) ) {
464 $this->replLogger
->debug( __METHOD__
.
465 ": replica DB $server known to be caught up (pos >= $knownReachedPos)." );
469 // Find a connection to wait on, creating one if needed and allowed
470 $conn = $this->getAnyOpenConnection( $index );
473 $this->replLogger
->debug( __METHOD__
. ": no connection open for $server" );
477 $conn = $this->openConnection( $index, self
::DOMAIN_ANY
);
479 $this->replLogger
->warning( __METHOD__
. ": failed to connect to $server" );
483 // Avoid connection spam in waitForAll() when connections
484 // are made just for the sake of doing this lag check.
489 $this->replLogger
->info( __METHOD__
. ": Waiting for replica DB $server to catch up..." );
490 $timeout = $timeout ?
: $this->mWaitTimeout
;
491 $result = $conn->masterPosWait( $this->mWaitForPos
, $timeout );
493 if ( $result == -1 ||
is_null( $result ) ) {
494 // Timed out waiting for replica DB, use master instead
495 $msg = __METHOD__
. ": Timed out waiting on $server pos {$this->mWaitForPos}";
496 $this->replLogger
->warning( "$msg" );
499 $this->replLogger
->info( __METHOD__
. ": Done" );
501 // Remember that the DB reached this point
502 $this->srvCache
->set( $key, $this->mWaitForPos
, BagOStuff
::TTL_DAY
);
506 $this->closeConnection( $conn );
513 * @see ILoadBalancer::getConnection()
516 * @param array $groups
517 * @param bool $domain
519 * @throws DBConnectionError
521 public function getConnection( $i, $groups = [], $domain = false ) {
522 if ( $i === null ||
$i === false ) {
523 throw new InvalidArgumentException( 'Attempt to call ' . __METHOD__
.
524 ' with invalid server index' );
527 if ( $this->localDomain
->equals( $domain ) ||
$domain === $this->localDomainIdAlias
) {
528 $domain = false; // local connection requested
531 $groups = ( $groups === false ||
$groups === [] )
532 ?
[ false ] // check one "group": the generic pool
535 $masterOnly = ( $i == self
::DB_MASTER ||
$i == $this->getWriterIndex() );
536 $oldConnsOpened = $this->connsOpened
; // connections open now
538 if ( $i == self
::DB_MASTER
) {
539 $i = $this->getWriterIndex();
541 # Try to find an available server in any the query groups (in order)
542 foreach ( $groups as $group ) {
543 $groupIndex = $this->getReaderIndex( $group, $domain );
544 if ( $groupIndex !== false ) {
551 # Operation-based index
552 if ( $i == self
::DB_REPLICA
) {
553 $this->mLastError
= 'Unknown error'; // reset error string
554 # Try the general server pool if $groups are unavailable.
555 $i = in_array( false, $groups, true )
556 ?
false // don't bother with this if that is what was tried above
557 : $this->getReaderIndex( false, $domain );
558 # Couldn't find a working server in getReaderIndex()?
559 if ( $i === false ) {
560 $this->mLastError
= 'No working replica DB server: ' . $this->mLastError
;
561 // Throw an exception
562 $this->reportConnectionError();
563 return null; // not reached
567 # Now we have an explicit index into the servers array
568 $conn = $this->openConnection( $i, $domain );
570 // Throw an exception
571 $this->reportConnectionError();
572 return null; // not reached
575 # Profile any new connections that happen
576 if ( $this->connsOpened
> $oldConnsOpened ) {
577 $host = $conn->getServer();
578 $dbname = $conn->getDBname();
579 $this->trxProfiler
->recordConnection( $host, $dbname, $masterOnly );
583 # Make master-requested DB handles inherit any read-only mode setting
584 $conn->setLBInfo( 'readOnlyReason', $this->getReadOnlyReason( $domain, $conn ) );
590 public function reuseConnection( $conn ) {
591 $serverIndex = $conn->getLBInfo( 'serverIndex' );
592 $refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
593 if ( $serverIndex === null ||
$refCount === null ) {
595 * This can happen in code like:
596 * foreach ( $dbs as $db ) {
597 * $conn = $lb->getConnection( $lb::DB_REPLICA, [], $db );
599 * $lb->reuseConnection( $conn );
601 * When a connection to the local DB is opened in this way, reuseConnection()
605 } elseif ( $conn instanceof DBConnRef
) {
606 // DBConnRef already handles calling reuseConnection() and only passes the live
607 // Database instance to this method. Any caller passing in a DBConnRef is broken.
608 $this->connLogger
->error( __METHOD__
. ": got DBConnRef instance.\n" .
609 ( new RuntimeException() )->getTraceAsString() );
614 if ( $this->disabled
) {
615 return; // DBConnRef handle probably survived longer than the LoadBalancer
618 $domain = $conn->getDomainID();
619 if ( !isset( $this->mConns
['foreignUsed'][$serverIndex][$domain] ) ) {
620 throw new InvalidArgumentException( __METHOD__
.
621 ": connection $serverIndex/$domain not found; it may have already been freed." );
622 } elseif ( $this->mConns
['foreignUsed'][$serverIndex][$domain] !== $conn ) {
623 throw new InvalidArgumentException( __METHOD__
.
624 ": connection $serverIndex/$domain mismatched; it may have already been freed." );
626 $conn->setLBInfo( 'foreignPoolRefCount', --$refCount );
627 if ( $refCount <= 0 ) {
628 $this->mConns
['foreignFree'][$serverIndex][$domain] = $conn;
629 unset( $this->mConns
['foreignUsed'][$serverIndex][$domain] );
630 if ( !$this->mConns
['foreignUsed'][$serverIndex] ) {
631 unset( $this->mConns
[ 'foreignUsed' ][$serverIndex] ); // clean up
633 $this->connLogger
->debug( __METHOD__
. ": freed connection $serverIndex/$domain" );
635 $this->connLogger
->debug( __METHOD__
.
636 ": reference count for $serverIndex/$domain reduced to $refCount" );
640 public function getConnectionRef( $db, $groups = [], $domain = false ) {
641 $domain = ( $domain !== false ) ?
$domain : $this->localDomain
;
643 return new DBConnRef( $this, $this->getConnection( $db, $groups, $domain ) );
646 public function getLazyConnectionRef( $db, $groups = [], $domain = false ) {
647 $domain = ( $domain !== false ) ?
$domain : $this->localDomain
;
649 return new DBConnRef( $this, [ $db, $groups, $domain ] );
653 * @see ILoadBalancer::openConnection()
656 * @param bool $domain
657 * @return bool|Database
658 * @throws DBAccessError
660 public function openConnection( $i, $domain = false ) {
661 if ( $this->localDomain
->equals( $domain ) ||
$domain === $this->localDomainIdAlias
) {
662 $domain = false; // local connection requested
665 if ( $domain !== false ) {
666 $conn = $this->openForeignConnection( $i, $domain );
667 } elseif ( isset( $this->mConns
['local'][$i][0] ) ) {
668 $conn = $this->mConns
['local'][$i][0];
670 $server = $this->mServers
[$i];
671 $server['serverIndex'] = $i;
672 $conn = $this->reallyOpenConnection( $server, false );
673 $serverName = $this->getServerName( $i );
674 if ( $conn->isOpen() ) {
675 $this->connLogger
->debug( "Connected to database $i at '$serverName'." );
676 $this->mConns
['local'][$i][0] = $conn;
678 $this->connLogger
->warning( "Failed to connect to database $i at '$serverName'." );
679 $this->mErrorConnection
= $conn;
684 if ( $conn && !$conn->isOpen() ) {
685 // Connection was made but later unrecoverably lost for some reason.
686 // Do not return a handle that will just throw exceptions on use,
687 // but let the calling code (e.g. getReaderIndex) try another server.
688 // See DatabaseMyslBase::ping() for how this can happen.
689 $this->mErrorConnection
= $conn;
697 * Open a connection to a foreign DB, or return one if it is already open.
699 * Increments a reference count on the returned connection which locks the
700 * connection to the requested domain. This reference count can be
701 * decremented by calling reuseConnection().
703 * If a connection is open to the appropriate server already, but with the wrong
704 * database, it will be switched to the right database and returned, as long as
705 * it has been freed first with reuseConnection().
707 * On error, returns false, and the connection which caused the
708 * error will be available via $this->mErrorConnection.
710 * @note If disable() was called on this LoadBalancer, this method will throw a DBAccessError.
712 * @param int $i Server index
713 * @param string $domain Domain ID to open
716 private function openForeignConnection( $i, $domain ) {
717 $domainInstance = DatabaseDomain
::newFromId( $domain );
718 $dbName = $domainInstance->getDatabase();
719 $prefix = $domainInstance->getTablePrefix();
721 if ( isset( $this->mConns
['foreignUsed'][$i][$domain] ) ) {
722 // Reuse an already-used connection
723 $conn = $this->mConns
['foreignUsed'][$i][$domain];
724 $this->connLogger
->debug( __METHOD__
. ": reusing connection $i/$domain" );
725 } elseif ( isset( $this->mConns
['foreignFree'][$i][$domain] ) ) {
726 // Reuse a free connection for the same domain
727 $conn = $this->mConns
['foreignFree'][$i][$domain];
728 unset( $this->mConns
['foreignFree'][$i][$domain] );
729 $this->mConns
['foreignUsed'][$i][$domain] = $conn;
730 $this->connLogger
->debug( __METHOD__
. ": reusing free connection $i/$domain" );
731 } elseif ( !empty( $this->mConns
['foreignFree'][$i] ) ) {
732 // Reuse a connection from another domain
733 $conn = reset( $this->mConns
['foreignFree'][$i] );
734 $oldDomain = key( $this->mConns
['foreignFree'][$i] );
735 // The empty string as a DB name means "don't care".
736 // DatabaseMysqlBase::open() already handle this on connection.
737 if ( strlen( $dbName ) && !$conn->selectDB( $dbName ) ) {
738 $this->mLastError
= "Error selecting database '$dbName' on server " .
739 $conn->getServer() . " from client host {$this->host}";
740 $this->mErrorConnection
= $conn;
743 $conn->tablePrefix( $prefix );
744 unset( $this->mConns
['foreignFree'][$i][$oldDomain] );
745 $this->mConns
['foreignUsed'][$i][$domain] = $conn;
746 $this->connLogger
->debug( __METHOD__
.
747 ": reusing free connection from $oldDomain for $domain" );
750 // Open a new connection
751 $server = $this->mServers
[$i];
752 $server['serverIndex'] = $i;
753 $server['foreignPoolRefCount'] = 0;
754 $server['foreign'] = true;
755 $conn = $this->reallyOpenConnection( $server, $dbName );
756 if ( !$conn->isOpen() ) {
757 $this->connLogger
->warning( __METHOD__
. ": connection error for $i/$domain" );
758 $this->mErrorConnection
= $conn;
761 $conn->tablePrefix( $prefix );
762 $this->mConns
['foreignUsed'][$i][$domain] = $conn;
763 $this->connLogger
->debug( __METHOD__
. ": opened new connection for $i/$domain" );
767 // Increment reference count
769 $refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
770 $conn->setLBInfo( 'foreignPoolRefCount', $refCount +
1 );
777 * Test if the specified index represents an open connection
779 * @param int $index Server index
783 private function isOpen( $index ) {
784 if ( !is_integer( $index ) ) {
788 return (bool)$this->getAnyOpenConnection( $index );
792 * Really opens a connection. Uncached.
793 * Returns a Database object whether or not the connection was successful.
796 * @param array $server
797 * @param string|bool $dbNameOverride Use "" to not select any database
799 * @throws DBAccessError
800 * @throws InvalidArgumentException
802 protected function reallyOpenConnection( $server, $dbNameOverride = false ) {
803 if ( $this->disabled
) {
804 throw new DBAccessError();
807 if ( !is_array( $server ) ) {
808 throw new InvalidArgumentException(
809 'You must update your load-balancing configuration. ' .
810 'See DefaultSettings.php entry for $wgDBservers.' );
813 if ( $dbNameOverride !== false ) {
814 $server['dbname'] = $dbNameOverride;
817 // Let the handle know what the cluster master is (e.g. "db1052")
818 $masterName = $this->getServerName( $this->getWriterIndex() );
819 $server['clusterMasterHost'] = $masterName;
821 // Log when many connection are made on requests
822 if ( ++
$this->connsOpened
>= self
::CONN_HELD_WARN_THRESHOLD
) {
823 $this->perfLogger
->warning( __METHOD__
. ": " .
824 "{$this->connsOpened}+ connections made (master=$masterName)" );
827 $server['srvCache'] = $this->srvCache
;
828 // Set loggers and profilers
829 $server['connLogger'] = $this->connLogger
;
830 $server['queryLogger'] = $this->queryLogger
;
831 $server['errorLogger'] = $this->errorLogger
;
832 $server['profiler'] = $this->profiler
;
833 $server['trxProfiler'] = $this->trxProfiler
;
834 // Use the same agent and PHP mode for all DB handles
835 $server['cliMode'] = $this->cliMode
;
836 $server['agent'] = $this->agent
;
837 // Use DBO_DEFAULT flags by default for LoadBalancer managed databases. Assume that the
838 // application calls LoadBalancer::commitMasterChanges() before the PHP script completes.
839 $server['flags'] = isset( $server['flags'] ) ?
$server['flags'] : IDatabase
::DBO_DEFAULT
;
841 // Create a live connection object
843 $db = Database
::factory( $server['type'], $server );
844 } catch ( DBConnectionError
$e ) {
845 // FIXME: This is probably the ugliest thing I have ever done to
846 // PHP. I'm half-expecting it to segfault, just out of disgust. -- TS
850 $db->setLBInfo( $server );
851 $db->setLazyMasterHandle(
852 $this->getLazyConnectionRef( self
::DB_MASTER
, [], $db->getDomainID() )
854 $db->setTableAliases( $this->tableAliases
);
856 if ( $server['serverIndex'] === $this->getWriterIndex() ) {
857 if ( $this->trxRoundId
!== false ) {
858 $this->applyTransactionRoundFlags( $db );
860 foreach ( $this->trxRecurringCallbacks
as $name => $callback ) {
861 $db->setTransactionListener( $name, $callback );
869 * @throws DBConnectionError
871 private function reportConnectionError() {
872 $conn = $this->mErrorConnection
; // the connection which caused the error
874 'method' => __METHOD__
,
875 'last_error' => $this->mLastError
,
878 if ( !is_object( $conn ) ) {
879 // No last connection, probably due to all servers being too busy
880 $this->connLogger
->error(
881 "LB failure with no last connection. Connection error: {last_error}",
885 // If all servers were busy, mLastError will contain something sensible
886 throw new DBConnectionError( null, $this->mLastError
);
888 $context['db_server'] = $conn->getProperty( 'mServer' );
889 $this->connLogger
->warning(
890 "Connection error: {last_error} ({db_server})",
894 // throws DBConnectionError
895 $conn->reportConnectionError( "{$this->mLastError} ({$context['db_server']})" );
899 public function getWriterIndex() {
903 public function haveIndex( $i ) {
904 return array_key_exists( $i, $this->mServers
);
907 public function isNonZeroLoad( $i ) {
908 return array_key_exists( $i, $this->mServers
) && $this->mLoads
[$i] != 0;
911 public function getServerCount() {
912 return count( $this->mServers
);
915 public function getServerName( $i ) {
916 if ( isset( $this->mServers
[$i]['hostName'] ) ) {
917 $name = $this->mServers
[$i]['hostName'];
918 } elseif ( isset( $this->mServers
[$i]['host'] ) ) {
919 $name = $this->mServers
[$i]['host'];
924 return ( $name != '' ) ?
$name : 'localhost';
927 public function getServerInfo( $i ) {
928 if ( isset( $this->mServers
[$i] ) ) {
929 return $this->mServers
[$i];
935 public function setServerInfo( $i, array $serverInfo ) {
936 $this->mServers
[$i] = $serverInfo;
939 public function getMasterPos() {
940 # If this entire request was served from a replica DB without opening a connection to the
941 # master (however unlikely that may be), then we can fetch the position from the replica DB.
942 $masterConn = $this->getAnyOpenConnection( $this->getWriterIndex() );
943 if ( !$masterConn ) {
944 $serverCount = count( $this->mServers
);
945 for ( $i = 1; $i < $serverCount; $i++
) {
946 $conn = $this->getAnyOpenConnection( $i );
948 return $conn->getReplicaPos();
952 return $masterConn->getMasterPos();
958 public function disable() {
960 $this->disabled
= true;
963 public function closeAll() {
964 $this->forEachOpenConnection( function ( IDatabase
$conn ) {
965 $host = $conn->getServer();
966 $this->connLogger
->debug( "Closing connection to database '$host'." );
975 $this->connsOpened
= 0;
978 public function closeConnection( IDatabase
$conn ) {
979 $serverIndex = $conn->getLBInfo( 'serverIndex' ); // second index level of mConns
980 foreach ( $this->mConns
as $type => $connsByServer ) {
981 if ( !isset( $connsByServer[$serverIndex] ) ) {
985 foreach ( $connsByServer[$serverIndex] as $i => $trackedConn ) {
986 if ( $conn === $trackedConn ) {
987 $host = $this->getServerName( $i );
988 $this->connLogger
->debug( "Closing connection to database $i at '$host'." );
989 unset( $this->mConns
[$type][$serverIndex][$i] );
990 --$this->connsOpened
;
999 public function commitAll( $fname = __METHOD__
) {
1002 $restore = ( $this->trxRoundId
!== false );
1003 $this->trxRoundId
= false;
1004 $this->forEachOpenConnection(
1005 function ( IDatabase
$conn ) use ( $fname, $restore, &$failures ) {
1007 $conn->commit( $fname, $conn::FLUSHING_ALL_PEERS
);
1008 } catch ( DBError
$e ) {
1009 call_user_func( $this->errorLogger
, $e );
1010 $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
1012 if ( $restore && $conn->getLBInfo( 'master' ) ) {
1013 $this->undoTransactionRoundFlags( $conn );
1019 throw new DBExpectedError(
1021 "Commit failed on server(s) " . implode( "\n", array_unique( $failures ) )
1026 public function finalizeMasterChanges() {
1027 $this->forEachOpenMasterConnection( function ( Database
$conn ) {
1028 // Any error should cause all DB transactions to be rolled back together
1029 $conn->setTrxEndCallbackSuppression( false );
1030 $conn->runOnTransactionPreCommitCallbacks();
1031 // Defer post-commit callbacks until COMMIT finishes for all DBs
1032 $conn->setTrxEndCallbackSuppression( true );
1036 public function approveMasterChanges( array $options ) {
1037 $limit = isset( $options['maxWriteDuration'] ) ?
$options['maxWriteDuration'] : 0;
1038 $this->forEachOpenMasterConnection( function ( IDatabase
$conn ) use ( $limit ) {
1039 // If atomic sections or explicit transactions are still open, some caller must have
1040 // caught an exception but failed to properly rollback any changes. Detect that and
1041 // throw and error (causing rollback).
1042 if ( $conn->explicitTrxActive() ) {
1043 throw new DBTransactionError(
1045 "Explicit transaction still active. A caller may have caught an error."
1048 // Assert that the time to replicate the transaction will be sane.
1049 // If this fails, then all DB transactions will be rollback back together.
1050 $time = $conn->pendingWriteQueryDuration( $conn::ESTIMATE_DB_APPLY
);
1051 if ( $limit > 0 && $time > $limit ) {
1052 throw new DBTransactionSizeError(
1054 "Transaction spent $time second(s) in writes, exceeding the $limit limit.",
1058 // If a connection sits idle while slow queries execute on another, that connection
1059 // may end up dropped before the commit round is reached. Ping servers to detect this.
1060 if ( $conn->writesOrCallbacksPending() && !$conn->ping() ) {
1061 throw new DBTransactionError(
1063 "A connection to the {$conn->getDBname()} database was lost before commit."
1069 public function beginMasterChanges( $fname = __METHOD__
) {
1070 if ( $this->trxRoundId
!== false ) {
1071 throw new DBTransactionError(
1073 "$fname: Transaction round '{$this->trxRoundId}' already started."
1076 $this->trxRoundId
= $fname;
1079 $this->forEachOpenMasterConnection(
1080 function ( Database
$conn ) use ( $fname, &$failures ) {
1081 $conn->setTrxEndCallbackSuppression( true );
1083 $conn->flushSnapshot( $fname );
1084 } catch ( DBError
$e ) {
1085 call_user_func( $this->errorLogger
, $e );
1086 $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
1088 $conn->setTrxEndCallbackSuppression( false );
1089 $this->applyTransactionRoundFlags( $conn );
1094 throw new DBExpectedError(
1096 "$fname: Flush failed on server(s) " . implode( "\n", array_unique( $failures ) )
1101 public function commitMasterChanges( $fname = __METHOD__
) {
1104 /** @noinspection PhpUnusedLocalVariableInspection */
1105 $scope = $this->getScopedPHPBehaviorForCommit(); // try to ignore client aborts
1107 $restore = ( $this->trxRoundId
!== false );
1108 $this->trxRoundId
= false;
1109 $this->forEachOpenMasterConnection(
1110 function ( IDatabase
$conn ) use ( $fname, $restore, &$failures ) {
1112 if ( $conn->writesOrCallbacksPending() ) {
1113 $conn->commit( $fname, $conn::FLUSHING_ALL_PEERS
);
1114 } elseif ( $restore ) {
1115 $conn->flushSnapshot( $fname );
1117 } catch ( DBError
$e ) {
1118 call_user_func( $this->errorLogger
, $e );
1119 $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
1122 $this->undoTransactionRoundFlags( $conn );
1128 throw new DBExpectedError(
1130 "$fname: Commit failed on server(s) " . implode( "\n", array_unique( $failures ) )
1135 public function runMasterPostTrxCallbacks( $type ) {
1136 $e = null; // first exception
1137 $this->forEachOpenMasterConnection( function ( Database
$conn ) use ( $type, &$e ) {
1138 $conn->setTrxEndCallbackSuppression( false );
1139 if ( $conn->writesOrCallbacksPending() ) {
1140 // This happens if onTransactionIdle() callbacks leave callbacks on *another* DB
1141 // (which finished its callbacks already). Warn and recover in this case. Let the
1142 // callbacks run in the final commitMasterChanges() in LBFactory::shutdown().
1143 $this->queryLogger
->error( __METHOD__
. ": found writes/callbacks pending." );
1145 } elseif ( $conn->trxLevel() ) {
1146 // This happens for single-DB setups where DB_REPLICA uses the master DB,
1147 // thus leaving an implicit read-only transaction open at this point. It
1148 // also happens if onTransactionIdle() callbacks leave implicit transactions
1149 // open on *other* DBs (which is slightly improper). Let these COMMIT on the
1150 // next call to commitMasterChanges(), possibly in LBFactory::shutdown().
1154 $conn->runOnTransactionIdleCallbacks( $type );
1155 } catch ( Exception
$ex ) {
1159 $conn->runTransactionListenerCallbacks( $type );
1160 } catch ( Exception
$ex ) {
1168 public function rollbackMasterChanges( $fname = __METHOD__
) {
1169 $restore = ( $this->trxRoundId
!== false );
1170 $this->trxRoundId
= false;
1171 $this->forEachOpenMasterConnection(
1172 function ( IDatabase
$conn ) use ( $fname, $restore ) {
1173 if ( $conn->writesOrCallbacksPending() ) {
1174 $conn->rollback( $fname, $conn::FLUSHING_ALL_PEERS
);
1177 $this->undoTransactionRoundFlags( $conn );
1183 public function suppressTransactionEndCallbacks() {
1184 $this->forEachOpenMasterConnection( function ( Database
$conn ) {
1185 $conn->setTrxEndCallbackSuppression( true );
1190 * @param IDatabase $conn
1192 private function applyTransactionRoundFlags( IDatabase
$conn ) {
1193 if ( $conn->getFlag( $conn::DBO_DEFAULT
) ) {
1194 // DBO_TRX is controlled entirely by CLI mode presence with DBO_DEFAULT.
1195 // Force DBO_TRX even in CLI mode since a commit round is expected soon.
1196 $conn->setFlag( $conn::DBO_TRX
, $conn::REMEMBER_PRIOR
);
1197 // If config has explicitly requested DBO_TRX be either on or off by not
1198 // setting DBO_DEFAULT, then respect that. Forcing no transactions is useful
1199 // for things like blob stores (ExternalStore) which want auto-commit mode.
1204 * @param IDatabase $conn
1206 private function undoTransactionRoundFlags( IDatabase
$conn ) {
1207 if ( $conn->getFlag( $conn::DBO_DEFAULT
) ) {
1208 $conn->restoreFlags( $conn::RESTORE_PRIOR
);
1212 public function flushReplicaSnapshots( $fname = __METHOD__
) {
1213 $this->forEachOpenReplicaConnection( function ( IDatabase
$conn ) {
1214 $conn->flushSnapshot( __METHOD__
);
1218 public function hasMasterConnection() {
1219 return $this->isOpen( $this->getWriterIndex() );
1222 public function hasMasterChanges() {
1224 $this->forEachOpenMasterConnection( function ( IDatabase
$conn ) use ( &$pending ) {
1225 $pending |
= $conn->writesOrCallbacksPending();
1228 return (bool)$pending;
1231 public function lastMasterChangeTimestamp() {
1233 $this->forEachOpenMasterConnection( function ( IDatabase
$conn ) use ( &$lastTime ) {
1234 $lastTime = max( $lastTime, $conn->lastDoneWrites() );
1240 public function hasOrMadeRecentMasterChanges( $age = null ) {
1241 $age = ( $age === null ) ?
$this->mWaitTimeout
: $age;
1243 return ( $this->hasMasterChanges()
1244 ||
$this->lastMasterChangeTimestamp() > microtime( true ) - $age );
1247 public function pendingMasterChangeCallers() {
1249 $this->forEachOpenMasterConnection( function ( IDatabase
$conn ) use ( &$fnames ) {
1250 $fnames = array_merge( $fnames, $conn->pendingWriteCallers() );
1256 public function getLaggedReplicaMode( $domain = false ) {
1257 // No-op if there is only one DB (also avoids recursion)
1258 if ( !$this->laggedReplicaMode
&& $this->getServerCount() > 1 ) {
1260 // See if laggedReplicaMode gets set
1261 $conn = $this->getConnection( self
::DB_REPLICA
, false, $domain );
1262 $this->reuseConnection( $conn );
1263 } catch ( DBConnectionError
$e ) {
1264 // Avoid expensive re-connect attempts and failures
1265 $this->allReplicasDownMode
= true;
1266 $this->laggedReplicaMode
= true;
1270 return $this->laggedReplicaMode
;
1274 * @param bool $domain
1276 * @deprecated 1.28; use getLaggedReplicaMode()
1278 public function getLaggedSlaveMode( $domain = false ) {
1279 return $this->getLaggedReplicaMode( $domain );
1282 public function laggedReplicaUsed() {
1283 return $this->laggedReplicaMode
;
1289 * @deprecated Since 1.28; use laggedReplicaUsed()
1291 public function laggedSlaveUsed() {
1292 return $this->laggedReplicaUsed();
1295 public function getReadOnlyReason( $domain = false, IDatabase
$conn = null ) {
1296 if ( $this->readOnlyReason
!== false ) {
1297 return $this->readOnlyReason
;
1298 } elseif ( $this->getLaggedReplicaMode( $domain ) ) {
1299 if ( $this->allReplicasDownMode
) {
1300 return 'The database has been automatically locked ' .
1301 'until the replica database servers become available';
1303 return 'The database has been automatically locked ' .
1304 'while the replica database servers catch up to the master.';
1306 } elseif ( $this->masterRunningReadOnly( $domain, $conn ) ) {
1307 return 'The database master is running in read-only mode.';
1314 * @param string $domain Domain ID, or false for the current domain
1315 * @param IDatabase|null DB master connectionl used to avoid loops [optional]
1318 private function masterRunningReadOnly( $domain, IDatabase
$conn = null ) {
1319 $cache = $this->wanCache
;
1320 $masterServer = $this->getServerName( $this->getWriterIndex() );
1322 return (bool)$cache->getWithSetCallback(
1323 $cache->makeGlobalKey( __CLASS__
, 'server-read-only', $masterServer ),
1324 self
::TTL_CACHE_READONLY
,
1325 function () use ( $domain, $conn ) {
1326 $this->trxProfiler
->setSilenced( true );
1328 $dbw = $conn ?
: $this->getConnection( self
::DB_MASTER
, [], $domain );
1329 $readOnly = (int)$dbw->serverIsReadOnly();
1331 $this->reuseConnection( $dbw );
1333 } catch ( DBError
$e ) {
1336 $this->trxProfiler
->setSilenced( false );
1339 [ 'pcTTL' => $cache::TTL_PROC_LONG
, 'busyValue' => 0 ]
1343 public function allowLagged( $mode = null ) {
1344 if ( $mode === null ) {
1345 return $this->mAllowLagged
;
1347 $this->mAllowLagged
= $mode;
1349 return $this->mAllowLagged
;
1352 public function pingAll() {
1354 $this->forEachOpenConnection( function ( IDatabase
$conn ) use ( &$success ) {
1355 if ( !$conn->ping() ) {
1363 public function forEachOpenConnection( $callback, array $params = [] ) {
1364 foreach ( $this->mConns
as $connsByServer ) {
1365 foreach ( $connsByServer as $serverConns ) {
1366 foreach ( $serverConns as $conn ) {
1367 $mergedParams = array_merge( [ $conn ], $params );
1368 call_user_func_array( $callback, $mergedParams );
1374 public function forEachOpenMasterConnection( $callback, array $params = [] ) {
1375 $masterIndex = $this->getWriterIndex();
1376 foreach ( $this->mConns
as $connsByServer ) {
1377 if ( isset( $connsByServer[$masterIndex] ) ) {
1378 /** @var IDatabase $conn */
1379 foreach ( $connsByServer[$masterIndex] as $conn ) {
1380 $mergedParams = array_merge( [ $conn ], $params );
1381 call_user_func_array( $callback, $mergedParams );
1387 public function forEachOpenReplicaConnection( $callback, array $params = [] ) {
1388 foreach ( $this->mConns
as $connsByServer ) {
1389 foreach ( $connsByServer as $i => $serverConns ) {
1390 if ( $i === $this->getWriterIndex() ) {
1391 continue; // skip master
1393 foreach ( $serverConns as $conn ) {
1394 $mergedParams = array_merge( [ $conn ], $params );
1395 call_user_func_array( $callback, $mergedParams );
1401 public function getMaxLag( $domain = false ) {
1406 if ( $this->getServerCount() <= 1 ) {
1407 return [ $host, $maxLag, $maxIndex ]; // no replication = no lag
1410 $lagTimes = $this->getLagTimes( $domain );
1411 foreach ( $lagTimes as $i => $lag ) {
1412 if ( $this->mLoads
[$i] > 0 && $lag > $maxLag ) {
1414 $host = $this->mServers
[$i]['host'];
1419 return [ $host, $maxLag, $maxIndex ];
1422 public function getLagTimes( $domain = false ) {
1423 if ( $this->getServerCount() <= 1 ) {
1424 return [ $this->getWriterIndex() => 0 ]; // no replication = no lag
1427 $knownLagTimes = []; // map of (server index => 0 seconds)
1428 $indexesWithLag = [];
1429 foreach ( $this->mServers
as $i => $server ) {
1430 if ( empty( $server['is static'] ) ) {
1431 $indexesWithLag[] = $i; // DB server might have replication lag
1433 $knownLagTimes[$i] = 0; // DB server is a non-replicating and read-only archive
1437 return $this->getLoadMonitor()->getLagTimes( $indexesWithLag, $domain ) +
$knownLagTimes;
1440 public function safeGetLag( IDatabase
$conn ) {
1441 if ( $this->getServerCount() <= 1 ) {
1444 return $conn->getLag();
1448 public function safeWaitForMasterPos( IDatabase
$conn, $pos = false, $timeout = 10 ) {
1449 if ( $this->getServerCount() <= 1 ||
!$conn->getLBInfo( 'replica' ) ) {
1450 return true; // server is not a replica DB
1454 // Get the current master position, opening a connection if needed
1455 $masterConn = $this->getAnyOpenConnection( $this->getWriterIndex() );
1456 if ( $masterConn ) {
1457 $pos = $masterConn->getMasterPos();
1459 $masterConn = $this->openConnection( $this->getWriterIndex(), self
::DOMAIN_ANY
);
1460 $pos = $masterConn->getMasterPos();
1461 $this->closeConnection( $masterConn );
1465 if ( $pos instanceof DBMasterPos
) {
1466 $result = $conn->masterPosWait( $pos, $timeout );
1467 if ( $result == -1 ||
is_null( $result ) ) {
1468 $msg = __METHOD__
. ": Timed out waiting on {$conn->getServer()} pos {$pos}";
1469 $this->replLogger
->warning( "$msg" );
1472 $this->replLogger
->info( __METHOD__
. ": Done" );
1476 $ok = false; // something is misconfigured
1477 $this->replLogger
->error( "Could not get master pos for {$conn->getServer()}." );
1483 public function setTransactionListener( $name, callable
$callback = null ) {
1485 $this->trxRecurringCallbacks
[$name] = $callback;
1487 unset( $this->trxRecurringCallbacks
[$name] );
1489 $this->forEachOpenMasterConnection(
1490 function ( IDatabase
$conn ) use ( $name, $callback ) {
1491 $conn->setTransactionListener( $name, $callback );
1496 public function setTableAliases( array $aliases ) {
1497 $this->tableAliases
= $aliases;
1500 public function setDomainPrefix( $prefix ) {
1501 if ( $this->mConns
['foreignUsed'] ) {
1502 // Do not switch connections to explicit foreign domains unless marked as free
1504 foreach ( $this->mConns
['foreignUsed'] as $i => $connsByDomain ) {
1505 $domains = array_merge( $domains, array_keys( $connsByDomain ) );
1507 $domains = implode( ', ', $domains );
1508 throw new DBUnexpectedError( null,
1509 "Foreign domain connections are still in use ($domains)." );
1512 $this->localDomain
= new DatabaseDomain(
1513 $this->localDomain
->getDatabase(),
1518 $this->forEachOpenConnection( function ( IDatabase
$db ) use ( $prefix ) {
1519 $db->tablePrefix( $prefix );
1524 * Make PHP ignore user aborts/disconnects until the returned
1525 * value leaves scope. This returns null and does nothing in CLI mode.
1527 * @return ScopedCallback|null
1529 final protected function getScopedPHPBehaviorForCommit() {
1530 if ( PHP_SAPI
!= 'cli' ) { // http://bugs.php.net/bug.php?id=47540
1531 $old = ignore_user_abort( true ); // avoid half-finished operations
1532 return new ScopedCallback( function () use ( $old ) {
1533 ignore_user_abort( $old );
1540 function __destruct() {
1541 // Avoid connection leaks for sanity