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
;
24 use Wikimedia\ScopedCallback
;
27 * Database connection, tracking, load balancing, and transaction manager for a cluster
31 class LoadBalancer
implements ILoadBalancer
{
32 /** @var array[] Map of (server index => server config array) */
34 /** @var IDatabase[][] Map of (local/foreignUsed/foreignFree => server index => IDatabase array) */
36 /** @var float[] Map of (server index => weight) */
38 /** @var array[] Map of (group => server index => weight) */
40 /** @var bool Whether to disregard replica DB lag as a factor in replica DB selection */
41 private $mAllowLagged;
42 /** @var integer Seconds to spend waiting on replica DB lag to resolve */
43 private $mWaitTimeout;
44 /** @var array The LoadMonitor configuration */
45 private $loadMonitorConfig;
46 /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
47 private $tableAliases = [];
49 /** @var ILoadMonitor */
55 /** @var WANObjectCache */
57 /** @var object|string Class name or object With profileIn/profileOut methods */
59 /** @var TransactionProfiler */
60 protected $trxProfiler;
61 /** @var LoggerInterface */
62 protected $replLogger;
63 /** @var LoggerInterface */
64 protected $connLogger;
65 /** @var LoggerInterface */
66 protected $queryLogger;
67 /** @var LoggerInterface */
68 protected $perfLogger;
70 /** @var bool|IDatabase Database connection that caused a problem */
71 private $mErrorConnection;
72 /** @var integer The generic (not query grouped) replica DB index (of $mServers) */
74 /** @var bool|DBMasterPos False if not set */
76 /** @var bool Whether the generic reader fell back to a lagged replica DB */
77 private $laggedReplicaMode = false;
78 /** @var bool Whether the generic reader fell back to a lagged replica DB */
79 private $allReplicasDownMode = false;
80 /** @var string The last DB selection or connection error */
81 private $mLastError = 'Unknown error';
82 /** @var string|bool Reason the LB is read-only or false if not */
83 private $readOnlyReason = false;
84 /** @var integer Total connections opened */
85 private $connsOpened = 0;
86 /** @var string|bool String if a requested DBO_TRX transaction round is active */
87 private $trxRoundId = false;
88 /** @var array[] Map of (name => callable) */
89 private $trxRecurringCallbacks = [];
90 /** @var DatabaseDomain Local Domain ID and default for selectDB() calls */
92 /** @var string Alternate ID string for the domain instead of DatabaseDomain::getId() */
93 private $localDomainIdAlias;
94 /** @var string Current server name */
96 /** @var bool Whether this PHP instance is for a CLI script */
98 /** @var string Agent name for query profiling */
101 /** @var callable Exception logger */
102 private $errorLogger;
105 private $disabled = false;
107 /** @var integer Warn when this many connection are held */
108 const CONN_HELD_WARN_THRESHOLD
= 10;
110 /** @var integer Default 'max lag' when unspecified */
111 const MAX_LAG_DEFAULT
= 10;
112 /** @var integer Seconds to cache master server read-only status */
113 const TTL_CACHE_READONLY
= 5;
115 public function __construct( array $params ) {
116 if ( !isset( $params['servers'] ) ) {
117 throw new InvalidArgumentException( __CLASS__
. ': missing servers parameter' );
119 $this->mServers
= $params['servers'];
121 $this->localDomain
= isset( $params['localDomain'] )
122 ? DatabaseDomain
::newFromId( $params['localDomain'] )
123 : DatabaseDomain
::newUnspecified();
124 // In case a caller assumes that the domain ID is simply <db>-<prefix>, which is almost
125 // always true, gracefully handle the case when they fail to account for escaping.
126 if ( $this->localDomain
->getTablePrefix() != '' ) {
127 $this->localDomainIdAlias
=
128 $this->localDomain
->getDatabase() . '-' . $this->localDomain
->getTablePrefix();
130 $this->localDomainIdAlias
= $this->localDomain
->getDatabase();
133 $this->mWaitTimeout
= isset( $params['waitTimeout'] ) ?
$params['waitTimeout'] : 10;
135 $this->mReadIndex
= -1;
142 $this->mWaitForPos
= false;
143 $this->mErrorConnection
= false;
144 $this->mAllowLagged
= false;
146 if ( isset( $params['readOnlyReason'] ) && is_string( $params['readOnlyReason'] ) ) {
147 $this->readOnlyReason
= $params['readOnlyReason'];
150 if ( isset( $params['loadMonitor'] ) ) {
151 $this->loadMonitorConfig
= $params['loadMonitor'];
153 $this->loadMonitorConfig
= [ 'class' => 'LoadMonitorNull' ];
156 foreach ( $params['servers'] as $i => $server ) {
157 $this->mLoads
[$i] = $server['load'];
158 if ( isset( $server['groupLoads'] ) ) {
159 foreach ( $server['groupLoads'] as $group => $ratio ) {
160 if ( !isset( $this->mGroupLoads
[$group] ) ) {
161 $this->mGroupLoads
[$group] = [];
163 $this->mGroupLoads
[$group][$i] = $ratio;
168 if ( isset( $params['srvCache'] ) ) {
169 $this->srvCache
= $params['srvCache'];
171 $this->srvCache
= new EmptyBagOStuff();
173 if ( isset( $params['memCache'] ) ) {
174 $this->memCache
= $params['memCache'];
176 $this->memCache
= new EmptyBagOStuff();
178 if ( isset( $params['wanCache'] ) ) {
179 $this->wanCache
= $params['wanCache'];
181 $this->wanCache
= WANObjectCache
::newEmpty();
183 $this->profiler
= isset( $params['profiler'] ) ?
$params['profiler'] : null;
184 if ( isset( $params['trxProfiler'] ) ) {
185 $this->trxProfiler
= $params['trxProfiler'];
187 $this->trxProfiler
= new TransactionProfiler();
190 $this->errorLogger
= isset( $params['errorLogger'] )
191 ?
$params['errorLogger']
192 : function ( Exception
$e ) {
193 trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING
);
196 foreach ( [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ] as $key ) {
197 $this->$key = isset( $params[$key] ) ?
$params[$key] : new \Psr\Log\
NullLogger();
200 $this->host
= isset( $params['hostname'] )
201 ?
$params['hostname']
202 : ( gethostname() ?
: 'unknown' );
203 $this->cliMode
= isset( $params['cliMode'] ) ?
$params['cliMode'] : PHP_SAPI
=== 'cli';
204 $this->agent
= isset( $params['agent'] ) ?
$params['agent'] : '';
208 * Get a LoadMonitor instance
210 * @return ILoadMonitor
212 private function getLoadMonitor() {
213 if ( !isset( $this->loadMonitor
) ) {
214 $class = $this->loadMonitorConfig
['class'];
215 $this->loadMonitor
= new $class(
216 $this, $this->srvCache
, $this->memCache
, $this->loadMonitorConfig
);
217 $this->loadMonitor
->setLogger( $this->replLogger
);
220 return $this->loadMonitor
;
224 * @param array $loads
225 * @param bool|string $domain Domain to get non-lagged for
226 * @param int $maxLag Restrict the maximum allowed lag to this many seconds
227 * @return bool|int|string
229 private function getRandomNonLagged( array $loads, $domain = false, $maxLag = INF
) {
230 $lags = $this->getLagTimes( $domain );
232 # Unset excessively lagged servers
233 foreach ( $lags as $i => $lag ) {
235 # How much lag this server nominally is allowed to have
236 $maxServerLag = isset( $this->mServers
[$i]['max lag'] )
237 ?
$this->mServers
[$i]['max lag']
238 : self
::MAX_LAG_DEFAULT
; // default
239 # Constrain that futher by $maxLag argument
240 $maxServerLag = min( $maxServerLag, $maxLag );
242 $host = $this->getServerName( $i );
243 if ( $lag === false && !is_infinite( $maxServerLag ) ) {
244 $this->replLogger
->error( "Server $host (#$i) is not replicating?" );
246 } elseif ( $lag > $maxServerLag ) {
247 $this->replLogger
->warning( "Server $host (#$i) has >= $lag seconds of lag" );
253 # Find out if all the replica DBs with non-zero load are lagged
255 foreach ( $loads as $load ) {
259 # No appropriate DB servers except maybe the master and some replica DBs with zero load
260 # Do NOT use the master
261 # Instead, this function will return false, triggering read-only mode,
262 # and a lagged replica DB will be used instead.
266 if ( count( $loads ) == 0 ) {
270 # Return a random representative of the remainder
271 return ArrayUtils
::pickRandom( $loads );
274 public function getReaderIndex( $group = false, $domain = false ) {
275 if ( count( $this->mServers
) == 1 ) {
276 # Skip the load balancing if there's only one server
277 return $this->getWriterIndex();
278 } elseif ( $group === false && $this->mReadIndex
>= 0 ) {
279 # Shortcut if generic reader exists already
280 return $this->mReadIndex
;
283 # Find the relevant load array
284 if ( $group !== false ) {
285 if ( isset( $this->mGroupLoads
[$group] ) ) {
286 $nonErrorLoads = $this->mGroupLoads
[$group];
288 # No loads for this group, return false and the caller can use some other group
289 $this->connLogger
->info( __METHOD__
. ": no loads for group $group" );
294 $nonErrorLoads = $this->mLoads
;
297 if ( !count( $nonErrorLoads ) ) {
298 throw new InvalidArgumentException( "Empty server array given to LoadBalancer" );
301 # Scale the configured load ratios according to the dynamic load if supported
302 $this->getLoadMonitor()->scaleLoads( $nonErrorLoads, $domain );
304 $laggedReplicaMode = false;
306 # No server found yet
308 # First try quickly looking through the available servers for a server that
310 $currentLoads = $nonErrorLoads;
311 while ( count( $currentLoads ) ) {
312 if ( $this->mAllowLagged ||
$laggedReplicaMode ) {
313 $i = ArrayUtils
::pickRandom( $currentLoads );
316 if ( $this->mWaitForPos
&& $this->mWaitForPos
->asOfTime() ) {
317 # ChronologyProtecter causes mWaitForPos to be set via sessions.
318 # This triggers doWait() after connect, so it's especially good to
319 # avoid lagged servers so as to avoid just blocking in that method.
320 $ago = microtime( true ) - $this->mWaitForPos
->asOfTime();
321 # Aim for <= 1 second of waiting (being too picky can backfire)
322 $i = $this->getRandomNonLagged( $currentLoads, $domain, $ago +
1 );
324 if ( $i === false ) {
325 # Any server with less lag than it's 'max lag' param is preferable
326 $i = $this->getRandomNonLagged( $currentLoads, $domain );
328 if ( $i === false && count( $currentLoads ) != 0 ) {
329 # All replica DBs lagged. Switch to read-only mode
330 $this->replLogger
->error( "All replica DBs lagged. Switch to read-only mode" );
331 $i = ArrayUtils
::pickRandom( $currentLoads );
332 $laggedReplicaMode = true;
336 if ( $i === false ) {
337 # pickRandom() returned false
338 # This is permanent and means the configuration or the load monitor
339 # wants us to return false.
340 $this->connLogger
->debug( __METHOD__
. ": pickRandom() returned false" );
345 $serverName = $this->getServerName( $i );
346 $this->connLogger
->debug( __METHOD__
. ": Using reader #$i: $serverName..." );
348 $conn = $this->openConnection( $i, $domain );
350 $this->connLogger
->warning( __METHOD__
. ": Failed connecting to $i/$domain" );
351 unset( $nonErrorLoads[$i] );
352 unset( $currentLoads[$i] );
357 // Decrement reference counter, we are finished with this connection.
358 // It will be incremented for the caller later.
359 if ( $domain !== false ) {
360 $this->reuseConnection( $conn );
367 # If all servers were down, quit now
368 if ( !count( $nonErrorLoads ) ) {
369 $this->connLogger
->error( "All servers down" );
372 if ( $i !== false ) {
373 # Replica DB connection successful.
374 # Wait for the session master pos for a short time.
375 if ( $this->mWaitForPos
&& $i > 0 ) {
378 if ( $this->mReadIndex
<= 0 && $this->mLoads
[$i] > 0 && $group === false ) {
379 $this->mReadIndex
= $i;
380 # Record if the generic reader index is in "lagged replica DB" mode
381 if ( $laggedReplicaMode ) {
382 $this->laggedReplicaMode
= true;
385 $serverName = $this->getServerName( $i );
386 $this->connLogger
->debug(
387 __METHOD__
. ": using server $serverName for group '$group'" );
394 * @param DBMasterPos|false $pos
396 public function waitFor( $pos ) {
397 $this->mWaitForPos
= $pos;
398 $i = $this->mReadIndex
;
401 if ( !$this->doWait( $i ) ) {
402 $this->laggedReplicaMode
= true;
407 public function waitForOne( $pos, $timeout = null ) {
408 $this->mWaitForPos
= $pos;
410 $i = $this->mReadIndex
;
412 // Pick a generic replica DB if there isn't one yet
413 $readLoads = $this->mLoads
;
414 unset( $readLoads[$this->getWriterIndex()] ); // replica DBs only
415 $readLoads = array_filter( $readLoads ); // with non-zero load
416 $i = ArrayUtils
::pickRandom( $readLoads );
420 $ok = $this->doWait( $i, true, $timeout );
422 $ok = true; // no applicable loads
428 public function waitForAll( $pos, $timeout = null ) {
429 $this->mWaitForPos
= $pos;
430 $serverCount = count( $this->mServers
);
433 for ( $i = 1; $i < $serverCount; $i++
) {
434 if ( $this->mLoads
[$i] > 0 ) {
435 $ok = $this->doWait( $i, true, $timeout ) && $ok;
446 public function getAnyOpenConnection( $i ) {
447 foreach ( $this->mConns
as $connsByServer ) {
448 if ( !empty( $connsByServer[$i] ) ) {
449 return reset( $connsByServer[$i] );
457 * Wait for a given replica DB to catch up to the master pos stored in $this
458 * @param int $index Server index
459 * @param bool $open Check the server even if a new connection has to be made
460 * @param int $timeout Max seconds to wait; default is mWaitTimeout
463 protected function doWait( $index, $open = false, $timeout = null ) {
464 $close = false; // close the connection afterwards
466 // Check if we already know that the DB has reached this point
467 $server = $this->getServerName( $index );
468 $key = $this->srvCache
->makeGlobalKey( __CLASS__
, 'last-known-pos', $server );
469 /** @var DBMasterPos $knownReachedPos */
470 $knownReachedPos = $this->srvCache
->get( $key );
471 if ( $knownReachedPos && $knownReachedPos->hasReached( $this->mWaitForPos
) ) {
472 $this->replLogger
->debug( __METHOD__
.
473 ": replica DB $server known to be caught up (pos >= $knownReachedPos)." );
477 // Find a connection to wait on, creating one if needed and allowed
478 $conn = $this->getAnyOpenConnection( $index );
481 $this->replLogger
->debug( __METHOD__
. ": no connection open for $server" );
485 $conn = $this->openConnection( $index, self
::DOMAIN_ANY
);
487 $this->replLogger
->warning( __METHOD__
. ": failed to connect to $server" );
491 // Avoid connection spam in waitForAll() when connections
492 // are made just for the sake of doing this lag check.
497 $this->replLogger
->info( __METHOD__
. ": Waiting for replica DB $server to catch up..." );
498 $timeout = $timeout ?
: $this->mWaitTimeout
;
499 $result = $conn->masterPosWait( $this->mWaitForPos
, $timeout );
501 if ( $result == -1 ||
is_null( $result ) ) {
502 // Timed out waiting for replica DB, use master instead
503 $msg = __METHOD__
. ": Timed out waiting on $server pos {$this->mWaitForPos}";
504 $this->replLogger
->warning( "$msg" );
507 $this->replLogger
->info( __METHOD__
. ": Done" );
509 // Remember that the DB reached this point
510 $this->srvCache
->set( $key, $this->mWaitForPos
, BagOStuff
::TTL_DAY
);
514 $this->closeConnection( $conn );
521 * @see ILoadBalancer::getConnection()
524 * @param array $groups
525 * @param bool $domain
527 * @throws DBConnectionError
529 public function getConnection( $i, $groups = [], $domain = false ) {
530 if ( $i === null ||
$i === false ) {
531 throw new InvalidArgumentException( 'Attempt to call ' . __METHOD__
.
532 ' with invalid server index' );
535 if ( $this->localDomain
->equals( $domain ) ||
$domain === $this->localDomainIdAlias
) {
536 $domain = false; // local connection requested
539 $groups = ( $groups === false ||
$groups === [] )
540 ?
[ false ] // check one "group": the generic pool
543 $masterOnly = ( $i == self
::DB_MASTER ||
$i == $this->getWriterIndex() );
544 $oldConnsOpened = $this->connsOpened
; // connections open now
546 if ( $i == self
::DB_MASTER
) {
547 $i = $this->getWriterIndex();
549 # Try to find an available server in any the query groups (in order)
550 foreach ( $groups as $group ) {
551 $groupIndex = $this->getReaderIndex( $group, $domain );
552 if ( $groupIndex !== false ) {
559 # Operation-based index
560 if ( $i == self
::DB_REPLICA
) {
561 $this->mLastError
= 'Unknown error'; // reset error string
562 # Try the general server pool if $groups are unavailable.
563 $i = ( $groups === [ false ] )
564 ?
false // don't bother with this if that is what was tried above
565 : $this->getReaderIndex( false, $domain );
566 # Couldn't find a working server in getReaderIndex()?
567 if ( $i === false ) {
568 $this->mLastError
= 'No working replica DB server: ' . $this->mLastError
;
569 // Throw an exception
570 $this->reportConnectionError();
571 return null; // not reached
575 # Now we have an explicit index into the servers array
576 $conn = $this->openConnection( $i, $domain );
578 // Throw an exception
579 $this->reportConnectionError();
580 return null; // not reached
583 # Profile any new connections that happen
584 if ( $this->connsOpened
> $oldConnsOpened ) {
585 $host = $conn->getServer();
586 $dbname = $conn->getDBname();
587 $this->trxProfiler
->recordConnection( $host, $dbname, $masterOnly );
591 # Make master-requested DB handles inherit any read-only mode setting
592 $conn->setLBInfo( 'readOnlyReason', $this->getReadOnlyReason( $domain, $conn ) );
598 public function reuseConnection( $conn ) {
599 $serverIndex = $conn->getLBInfo( 'serverIndex' );
600 $refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
601 if ( $serverIndex === null ||
$refCount === null ) {
603 * This can happen in code like:
604 * foreach ( $dbs as $db ) {
605 * $conn = $lb->getConnection( $lb::DB_REPLICA, [], $db );
607 * $lb->reuseConnection( $conn );
609 * When a connection to the local DB is opened in this way, reuseConnection()
613 } elseif ( $conn instanceof DBConnRef
) {
614 // DBConnRef already handles calling reuseConnection() and only passes the live
615 // Database instance to this method. Any caller passing in a DBConnRef is broken.
616 $this->connLogger
->error( __METHOD__
. ": got DBConnRef instance.\n" .
617 ( new RuntimeException() )->getTraceAsString() );
622 if ( $this->disabled
) {
623 return; // DBConnRef handle probably survived longer than the LoadBalancer
626 $domain = $conn->getDomainID();
627 if ( !isset( $this->mConns
['foreignUsed'][$serverIndex][$domain] ) ) {
628 throw new InvalidArgumentException( __METHOD__
.
629 ": connection $serverIndex/$domain not found; it may have already been freed." );
630 } elseif ( $this->mConns
['foreignUsed'][$serverIndex][$domain] !== $conn ) {
631 throw new InvalidArgumentException( __METHOD__
.
632 ": connection $serverIndex/$domain mismatched; it may have already been freed." );
634 $conn->setLBInfo( 'foreignPoolRefCount', --$refCount );
635 if ( $refCount <= 0 ) {
636 $this->mConns
['foreignFree'][$serverIndex][$domain] = $conn;
637 unset( $this->mConns
['foreignUsed'][$serverIndex][$domain] );
638 if ( !$this->mConns
['foreignUsed'][$serverIndex] ) {
639 unset( $this->mConns
[ 'foreignUsed' ][$serverIndex] ); // clean up
641 $this->connLogger
->debug( __METHOD__
. ": freed connection $serverIndex/$domain" );
643 $this->connLogger
->debug( __METHOD__
.
644 ": reference count for $serverIndex/$domain reduced to $refCount" );
648 public function getConnectionRef( $db, $groups = [], $domain = false ) {
649 $domain = ( $domain !== false ) ?
$domain : $this->localDomain
;
651 return new DBConnRef( $this, $this->getConnection( $db, $groups, $domain ) );
654 public function getLazyConnectionRef( $db, $groups = [], $domain = false ) {
655 $domain = ( $domain !== false ) ?
$domain : $this->localDomain
;
657 return new DBConnRef( $this, [ $db, $groups, $domain ] );
661 * @see ILoadBalancer::openConnection()
664 * @param bool $domain
665 * @return bool|Database
666 * @throws DBAccessError
668 public function openConnection( $i, $domain = false ) {
669 if ( $this->localDomain
->equals( $domain ) ||
$domain === $this->localDomainIdAlias
) {
670 $domain = false; // local connection requested
673 if ( $domain !== false ) {
674 $conn = $this->openForeignConnection( $i, $domain );
675 } elseif ( isset( $this->mConns
['local'][$i][0] ) ) {
676 $conn = $this->mConns
['local'][$i][0];
678 if ( !isset( $this->mServers
[$i] ) ||
!is_array( $this->mServers
[$i] ) ) {
679 throw new InvalidArgumentException( "No server with index '$i'." );
681 // Open a new connection
682 $server = $this->mServers
[$i];
683 $server['serverIndex'] = $i;
684 $conn = $this->reallyOpenConnection( $server, false );
685 $serverName = $this->getServerName( $i );
686 if ( $conn->isOpen() ) {
687 $this->connLogger
->debug( "Connected to database $i at '$serverName'." );
688 $this->mConns
['local'][$i][0] = $conn;
690 $this->connLogger
->warning( "Failed to connect to database $i at '$serverName'." );
691 $this->mErrorConnection
= $conn;
696 if ( $conn && !$conn->isOpen() ) {
697 // Connection was made but later unrecoverably lost for some reason.
698 // Do not return a handle that will just throw exceptions on use,
699 // but let the calling code (e.g. getReaderIndex) try another server.
700 // See DatabaseMyslBase::ping() for how this can happen.
701 $this->mErrorConnection
= $conn;
709 * Open a connection to a foreign DB, or return one if it is already open.
711 * Increments a reference count on the returned connection which locks the
712 * connection to the requested domain. This reference count can be
713 * decremented by calling reuseConnection().
715 * If a connection is open to the appropriate server already, but with the wrong
716 * database, it will be switched to the right database and returned, as long as
717 * it has been freed first with reuseConnection().
719 * On error, returns false, and the connection which caused the
720 * error will be available via $this->mErrorConnection.
722 * @note If disable() was called on this LoadBalancer, this method will throw a DBAccessError.
724 * @param int $i Server index
725 * @param string $domain Domain ID to open
728 private function openForeignConnection( $i, $domain ) {
729 $domainInstance = DatabaseDomain
::newFromId( $domain );
730 $dbName = $domainInstance->getDatabase();
731 $prefix = $domainInstance->getTablePrefix();
733 if ( isset( $this->mConns
['foreignUsed'][$i][$domain] ) ) {
734 // Reuse an already-used connection
735 $conn = $this->mConns
['foreignUsed'][$i][$domain];
736 $this->connLogger
->debug( __METHOD__
. ": reusing connection $i/$domain" );
737 } elseif ( isset( $this->mConns
['foreignFree'][$i][$domain] ) ) {
738 // Reuse a free connection for the same domain
739 $conn = $this->mConns
['foreignFree'][$i][$domain];
740 unset( $this->mConns
['foreignFree'][$i][$domain] );
741 $this->mConns
['foreignUsed'][$i][$domain] = $conn;
742 $this->connLogger
->debug( __METHOD__
. ": reusing free connection $i/$domain" );
743 } elseif ( !empty( $this->mConns
['foreignFree'][$i] ) ) {
744 // Reuse a connection from another domain
745 $conn = reset( $this->mConns
['foreignFree'][$i] );
746 $oldDomain = key( $this->mConns
['foreignFree'][$i] );
747 // The empty string as a DB name means "don't care".
748 // DatabaseMysqlBase::open() already handle this on connection.
749 if ( strlen( $dbName ) && !$conn->selectDB( $dbName ) ) {
750 $this->mLastError
= "Error selecting database '$dbName' on server " .
751 $conn->getServer() . " from client host {$this->host}";
752 $this->mErrorConnection
= $conn;
755 $conn->tablePrefix( $prefix );
756 unset( $this->mConns
['foreignFree'][$i][$oldDomain] );
757 $this->mConns
['foreignUsed'][$i][$domain] = $conn;
758 $this->connLogger
->debug( __METHOD__
.
759 ": reusing free connection from $oldDomain for $domain" );
762 if ( !isset( $this->mServers
[$i] ) ||
!is_array( $this->mServers
[$i] ) ) {
763 throw new InvalidArgumentException( "No server with index '$i'." );
765 // Open a new connection
766 $server = $this->mServers
[$i];
767 $server['serverIndex'] = $i;
768 $server['foreignPoolRefCount'] = 0;
769 $server['foreign'] = true;
770 $conn = $this->reallyOpenConnection( $server, $dbName );
771 if ( !$conn->isOpen() ) {
772 $this->connLogger
->warning( __METHOD__
. ": connection error for $i/$domain" );
773 $this->mErrorConnection
= $conn;
776 $conn->tablePrefix( $prefix );
777 $this->mConns
['foreignUsed'][$i][$domain] = $conn;
778 $this->connLogger
->debug( __METHOD__
. ": opened new connection for $i/$domain" );
782 // Increment reference count
784 $refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
785 $conn->setLBInfo( 'foreignPoolRefCount', $refCount +
1 );
792 * Test if the specified index represents an open connection
794 * @param int $index Server index
798 private function isOpen( $index ) {
799 if ( !is_integer( $index ) ) {
803 return (bool)$this->getAnyOpenConnection( $index );
807 * Really opens a connection. Uncached.
808 * Returns a Database object whether or not the connection was successful.
811 * @param array $server
812 * @param string|bool $dbNameOverride Use "" to not select any database
814 * @throws DBAccessError
815 * @throws InvalidArgumentException
817 protected function reallyOpenConnection( array $server, $dbNameOverride = false ) {
818 if ( $this->disabled
) {
819 throw new DBAccessError();
822 if ( $dbNameOverride !== false ) {
823 $server['dbname'] = $dbNameOverride;
826 // Let the handle know what the cluster master is (e.g. "db1052")
827 $masterName = $this->getServerName( $this->getWriterIndex() );
828 $server['clusterMasterHost'] = $masterName;
830 // Log when many connection are made on requests
831 if ( ++
$this->connsOpened
>= self
::CONN_HELD_WARN_THRESHOLD
) {
832 $this->perfLogger
->warning( __METHOD__
. ": " .
833 "{$this->connsOpened}+ connections made (master=$masterName)" );
836 $server['srvCache'] = $this->srvCache
;
837 // Set loggers and profilers
838 $server['connLogger'] = $this->connLogger
;
839 $server['queryLogger'] = $this->queryLogger
;
840 $server['errorLogger'] = $this->errorLogger
;
841 $server['profiler'] = $this->profiler
;
842 $server['trxProfiler'] = $this->trxProfiler
;
843 // Use the same agent and PHP mode for all DB handles
844 $server['cliMode'] = $this->cliMode
;
845 $server['agent'] = $this->agent
;
846 // Use DBO_DEFAULT flags by default for LoadBalancer managed databases. Assume that the
847 // application calls LoadBalancer::commitMasterChanges() before the PHP script completes.
848 $server['flags'] = isset( $server['flags'] ) ?
$server['flags'] : IDatabase
::DBO_DEFAULT
;
850 // Create a live connection object
852 $db = Database
::factory( $server['type'], $server );
853 } catch ( DBConnectionError
$e ) {
854 // FIXME: This is probably the ugliest thing I have ever done to
855 // PHP. I'm half-expecting it to segfault, just out of disgust. -- TS
859 $db->setLBInfo( $server );
860 $db->setLazyMasterHandle(
861 $this->getLazyConnectionRef( self
::DB_MASTER
, [], $db->getDomainID() )
863 $db->setTableAliases( $this->tableAliases
);
865 if ( $server['serverIndex'] === $this->getWriterIndex() ) {
866 if ( $this->trxRoundId
!== false ) {
867 $this->applyTransactionRoundFlags( $db );
869 foreach ( $this->trxRecurringCallbacks
as $name => $callback ) {
870 $db->setTransactionListener( $name, $callback );
878 * @throws DBConnectionError
880 private function reportConnectionError() {
881 $conn = $this->mErrorConnection
; // the connection which caused the error
883 'method' => __METHOD__
,
884 'last_error' => $this->mLastError
,
887 if ( !is_object( $conn ) ) {
888 // No last connection, probably due to all servers being too busy
889 $this->connLogger
->error(
890 "LB failure with no last connection. Connection error: {last_error}",
894 // If all servers were busy, mLastError will contain something sensible
895 throw new DBConnectionError( null, $this->mLastError
);
897 $context['db_server'] = $conn->getServer();
898 $this->connLogger
->warning(
899 "Connection error: {last_error} ({db_server})",
903 // throws DBConnectionError
904 $conn->reportConnectionError( "{$this->mLastError} ({$context['db_server']})" );
908 public function getWriterIndex() {
912 public function haveIndex( $i ) {
913 return array_key_exists( $i, $this->mServers
);
916 public function isNonZeroLoad( $i ) {
917 return array_key_exists( $i, $this->mServers
) && $this->mLoads
[$i] != 0;
920 public function getServerCount() {
921 return count( $this->mServers
);
924 public function getServerName( $i ) {
925 if ( isset( $this->mServers
[$i]['hostName'] ) ) {
926 $name = $this->mServers
[$i]['hostName'];
927 } elseif ( isset( $this->mServers
[$i]['host'] ) ) {
928 $name = $this->mServers
[$i]['host'];
933 return ( $name != '' ) ?
$name : 'localhost';
936 public function getServerInfo( $i ) {
937 if ( isset( $this->mServers
[$i] ) ) {
938 return $this->mServers
[$i];
944 public function setServerInfo( $i, array $serverInfo ) {
945 $this->mServers
[$i] = $serverInfo;
948 public function getMasterPos() {
949 # If this entire request was served from a replica DB without opening a connection to the
950 # master (however unlikely that may be), then we can fetch the position from the replica DB.
951 $masterConn = $this->getAnyOpenConnection( $this->getWriterIndex() );
952 if ( !$masterConn ) {
953 $serverCount = count( $this->mServers
);
954 for ( $i = 1; $i < $serverCount; $i++
) {
955 $conn = $this->getAnyOpenConnection( $i );
957 return $conn->getReplicaPos();
961 return $masterConn->getMasterPos();
967 public function disable() {
969 $this->disabled
= true;
972 public function closeAll() {
973 $this->forEachOpenConnection( function ( IDatabase
$conn ) {
974 $host = $conn->getServer();
975 $this->connLogger
->debug( "Closing connection to database '$host'." );
984 $this->connsOpened
= 0;
987 public function closeConnection( IDatabase
$conn ) {
988 $serverIndex = $conn->getLBInfo( 'serverIndex' ); // second index level of mConns
989 foreach ( $this->mConns
as $type => $connsByServer ) {
990 if ( !isset( $connsByServer[$serverIndex] ) ) {
994 foreach ( $connsByServer[$serverIndex] as $i => $trackedConn ) {
995 if ( $conn === $trackedConn ) {
996 $host = $this->getServerName( $i );
997 $this->connLogger
->debug( "Closing connection to database $i at '$host'." );
998 unset( $this->mConns
[$type][$serverIndex][$i] );
999 --$this->connsOpened
;
1008 public function commitAll( $fname = __METHOD__
) {
1011 $restore = ( $this->trxRoundId
!== false );
1012 $this->trxRoundId
= false;
1013 $this->forEachOpenConnection(
1014 function ( IDatabase
$conn ) use ( $fname, $restore, &$failures ) {
1016 $conn->commit( $fname, $conn::FLUSHING_ALL_PEERS
);
1017 } catch ( DBError
$e ) {
1018 call_user_func( $this->errorLogger
, $e );
1019 $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
1021 if ( $restore && $conn->getLBInfo( 'master' ) ) {
1022 $this->undoTransactionRoundFlags( $conn );
1028 throw new DBExpectedError(
1030 "Commit failed on server(s) " . implode( "\n", array_unique( $failures ) )
1035 public function finalizeMasterChanges() {
1036 $this->forEachOpenMasterConnection( function ( Database
$conn ) {
1037 // Any error should cause all DB transactions to be rolled back together
1038 $conn->setTrxEndCallbackSuppression( false );
1039 $conn->runOnTransactionPreCommitCallbacks();
1040 // Defer post-commit callbacks until COMMIT finishes for all DBs
1041 $conn->setTrxEndCallbackSuppression( true );
1045 public function approveMasterChanges( array $options ) {
1046 $limit = isset( $options['maxWriteDuration'] ) ?
$options['maxWriteDuration'] : 0;
1047 $this->forEachOpenMasterConnection( function ( IDatabase
$conn ) use ( $limit ) {
1048 // If atomic sections or explicit transactions are still open, some caller must have
1049 // caught an exception but failed to properly rollback any changes. Detect that and
1050 // throw and error (causing rollback).
1051 if ( $conn->explicitTrxActive() ) {
1052 throw new DBTransactionError(
1054 "Explicit transaction still active. A caller may have caught an error."
1057 // Assert that the time to replicate the transaction will be sane.
1058 // If this fails, then all DB transactions will be rollback back together.
1059 $time = $conn->pendingWriteQueryDuration( $conn::ESTIMATE_DB_APPLY
);
1060 if ( $limit > 0 && $time > $limit ) {
1061 throw new DBTransactionSizeError(
1063 "Transaction spent $time second(s) in writes, exceeding the $limit limit.",
1067 // If a connection sits idle while slow queries execute on another, that connection
1068 // may end up dropped before the commit round is reached. Ping servers to detect this.
1069 if ( $conn->writesOrCallbacksPending() && !$conn->ping() ) {
1070 throw new DBTransactionError(
1072 "A connection to the {$conn->getDBname()} database was lost before commit."
1078 public function beginMasterChanges( $fname = __METHOD__
) {
1079 if ( $this->trxRoundId
!== false ) {
1080 throw new DBTransactionError(
1082 "$fname: Transaction round '{$this->trxRoundId}' already started."
1085 $this->trxRoundId
= $fname;
1088 $this->forEachOpenMasterConnection(
1089 function ( Database
$conn ) use ( $fname, &$failures ) {
1090 $conn->setTrxEndCallbackSuppression( true );
1092 $conn->flushSnapshot( $fname );
1093 } catch ( DBError
$e ) {
1094 call_user_func( $this->errorLogger
, $e );
1095 $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
1097 $conn->setTrxEndCallbackSuppression( false );
1098 $this->applyTransactionRoundFlags( $conn );
1103 throw new DBExpectedError(
1105 "$fname: Flush failed on server(s) " . implode( "\n", array_unique( $failures ) )
1110 public function commitMasterChanges( $fname = __METHOD__
) {
1113 /** @noinspection PhpUnusedLocalVariableInspection */
1114 $scope = $this->getScopedPHPBehaviorForCommit(); // try to ignore client aborts
1116 $restore = ( $this->trxRoundId
!== false );
1117 $this->trxRoundId
= false;
1118 $this->forEachOpenMasterConnection(
1119 function ( IDatabase
$conn ) use ( $fname, $restore, &$failures ) {
1121 if ( $conn->writesOrCallbacksPending() ) {
1122 $conn->commit( $fname, $conn::FLUSHING_ALL_PEERS
);
1123 } elseif ( $restore ) {
1124 $conn->flushSnapshot( $fname );
1126 } catch ( DBError
$e ) {
1127 call_user_func( $this->errorLogger
, $e );
1128 $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
1131 $this->undoTransactionRoundFlags( $conn );
1137 throw new DBExpectedError(
1139 "$fname: Commit failed on server(s) " . implode( "\n", array_unique( $failures ) )
1144 public function runMasterPostTrxCallbacks( $type ) {
1145 $e = null; // first exception
1146 $this->forEachOpenMasterConnection( function ( Database
$conn ) use ( $type, &$e ) {
1147 $conn->setTrxEndCallbackSuppression( false );
1148 if ( $conn->writesOrCallbacksPending() ) {
1149 // This happens if onTransactionIdle() callbacks leave callbacks on *another* DB
1150 // (which finished its callbacks already). Warn and recover in this case. Let the
1151 // callbacks run in the final commitMasterChanges() in LBFactory::shutdown().
1152 $this->queryLogger
->error( __METHOD__
. ": found writes/callbacks pending." );
1154 } elseif ( $conn->trxLevel() ) {
1155 // This happens for single-DB setups where DB_REPLICA uses the master DB,
1156 // thus leaving an implicit read-only transaction open at this point. It
1157 // also happens if onTransactionIdle() callbacks leave implicit transactions
1158 // open on *other* DBs (which is slightly improper). Let these COMMIT on the
1159 // next call to commitMasterChanges(), possibly in LBFactory::shutdown().
1163 $conn->runOnTransactionIdleCallbacks( $type );
1164 } catch ( Exception
$ex ) {
1168 $conn->runTransactionListenerCallbacks( $type );
1169 } catch ( Exception
$ex ) {
1177 public function rollbackMasterChanges( $fname = __METHOD__
) {
1178 $restore = ( $this->trxRoundId
!== false );
1179 $this->trxRoundId
= false;
1180 $this->forEachOpenMasterConnection(
1181 function ( IDatabase
$conn ) use ( $fname, $restore ) {
1182 if ( $conn->writesOrCallbacksPending() ) {
1183 $conn->rollback( $fname, $conn::FLUSHING_ALL_PEERS
);
1186 $this->undoTransactionRoundFlags( $conn );
1192 public function suppressTransactionEndCallbacks() {
1193 $this->forEachOpenMasterConnection( function ( Database
$conn ) {
1194 $conn->setTrxEndCallbackSuppression( true );
1199 * @param IDatabase $conn
1201 private function applyTransactionRoundFlags( IDatabase
$conn ) {
1202 if ( $conn->getFlag( $conn::DBO_DEFAULT
) ) {
1203 // DBO_TRX is controlled entirely by CLI mode presence with DBO_DEFAULT.
1204 // Force DBO_TRX even in CLI mode since a commit round is expected soon.
1205 $conn->setFlag( $conn::DBO_TRX
, $conn::REMEMBER_PRIOR
);
1206 // If config has explicitly requested DBO_TRX be either on or off by not
1207 // setting DBO_DEFAULT, then respect that. Forcing no transactions is useful
1208 // for things like blob stores (ExternalStore) which want auto-commit mode.
1213 * @param IDatabase $conn
1215 private function undoTransactionRoundFlags( IDatabase
$conn ) {
1216 if ( $conn->getFlag( $conn::DBO_DEFAULT
) ) {
1217 $conn->restoreFlags( $conn::RESTORE_PRIOR
);
1221 public function flushReplicaSnapshots( $fname = __METHOD__
) {
1222 $this->forEachOpenReplicaConnection( function ( IDatabase
$conn ) {
1223 $conn->flushSnapshot( __METHOD__
);
1227 public function hasMasterConnection() {
1228 return $this->isOpen( $this->getWriterIndex() );
1231 public function hasMasterChanges() {
1233 $this->forEachOpenMasterConnection( function ( IDatabase
$conn ) use ( &$pending ) {
1234 $pending |
= $conn->writesOrCallbacksPending();
1237 return (bool)$pending;
1240 public function lastMasterChangeTimestamp() {
1242 $this->forEachOpenMasterConnection( function ( IDatabase
$conn ) use ( &$lastTime ) {
1243 $lastTime = max( $lastTime, $conn->lastDoneWrites() );
1249 public function hasOrMadeRecentMasterChanges( $age = null ) {
1250 $age = ( $age === null ) ?
$this->mWaitTimeout
: $age;
1252 return ( $this->hasMasterChanges()
1253 ||
$this->lastMasterChangeTimestamp() > microtime( true ) - $age );
1256 public function pendingMasterChangeCallers() {
1258 $this->forEachOpenMasterConnection( function ( IDatabase
$conn ) use ( &$fnames ) {
1259 $fnames = array_merge( $fnames, $conn->pendingWriteCallers() );
1265 public function getLaggedReplicaMode( $domain = false ) {
1266 // No-op if there is only one DB (also avoids recursion)
1267 if ( !$this->laggedReplicaMode
&& $this->getServerCount() > 1 ) {
1269 // See if laggedReplicaMode gets set
1270 $conn = $this->getConnection( self
::DB_REPLICA
, false, $domain );
1271 $this->reuseConnection( $conn );
1272 } catch ( DBConnectionError
$e ) {
1273 // Avoid expensive re-connect attempts and failures
1274 $this->allReplicasDownMode
= true;
1275 $this->laggedReplicaMode
= true;
1279 return $this->laggedReplicaMode
;
1283 * @param bool $domain
1285 * @deprecated 1.28; use getLaggedReplicaMode()
1287 public function getLaggedSlaveMode( $domain = false ) {
1288 return $this->getLaggedReplicaMode( $domain );
1291 public function laggedReplicaUsed() {
1292 return $this->laggedReplicaMode
;
1298 * @deprecated Since 1.28; use laggedReplicaUsed()
1300 public function laggedSlaveUsed() {
1301 return $this->laggedReplicaUsed();
1304 public function getReadOnlyReason( $domain = false, IDatabase
$conn = null ) {
1305 if ( $this->readOnlyReason
!== false ) {
1306 return $this->readOnlyReason
;
1307 } elseif ( $this->getLaggedReplicaMode( $domain ) ) {
1308 if ( $this->allReplicasDownMode
) {
1309 return 'The database has been automatically locked ' .
1310 'until the replica database servers become available';
1312 return 'The database has been automatically locked ' .
1313 'while the replica database servers catch up to the master.';
1315 } elseif ( $this->masterRunningReadOnly( $domain, $conn ) ) {
1316 return 'The database master is running in read-only mode.';
1323 * @param string $domain Domain ID, or false for the current domain
1324 * @param IDatabase|null DB master connectionl used to avoid loops [optional]
1327 private function masterRunningReadOnly( $domain, IDatabase
$conn = null ) {
1328 $cache = $this->wanCache
;
1329 $masterServer = $this->getServerName( $this->getWriterIndex() );
1331 return (bool)$cache->getWithSetCallback(
1332 $cache->makeGlobalKey( __CLASS__
, 'server-read-only', $masterServer ),
1333 self
::TTL_CACHE_READONLY
,
1334 function () use ( $domain, $conn ) {
1335 $old = $this->trxProfiler
->setSilenced( true );
1337 $dbw = $conn ?
: $this->getConnection( self
::DB_MASTER
, [], $domain );
1338 $readOnly = (int)$dbw->serverIsReadOnly();
1340 $this->reuseConnection( $dbw );
1342 } catch ( DBError
$e ) {
1345 $this->trxProfiler
->setSilenced( $old );
1348 [ 'pcTTL' => $cache::TTL_PROC_LONG
, 'busyValue' => 0 ]
1352 public function allowLagged( $mode = null ) {
1353 if ( $mode === null ) {
1354 return $this->mAllowLagged
;
1356 $this->mAllowLagged
= $mode;
1358 return $this->mAllowLagged
;
1361 public function pingAll() {
1363 $this->forEachOpenConnection( function ( IDatabase
$conn ) use ( &$success ) {
1364 if ( !$conn->ping() ) {
1372 public function forEachOpenConnection( $callback, array $params = [] ) {
1373 foreach ( $this->mConns
as $connsByServer ) {
1374 foreach ( $connsByServer as $serverConns ) {
1375 foreach ( $serverConns as $conn ) {
1376 $mergedParams = array_merge( [ $conn ], $params );
1377 call_user_func_array( $callback, $mergedParams );
1383 public function forEachOpenMasterConnection( $callback, array $params = [] ) {
1384 $masterIndex = $this->getWriterIndex();
1385 foreach ( $this->mConns
as $connsByServer ) {
1386 if ( isset( $connsByServer[$masterIndex] ) ) {
1387 /** @var IDatabase $conn */
1388 foreach ( $connsByServer[$masterIndex] as $conn ) {
1389 $mergedParams = array_merge( [ $conn ], $params );
1390 call_user_func_array( $callback, $mergedParams );
1396 public function forEachOpenReplicaConnection( $callback, array $params = [] ) {
1397 foreach ( $this->mConns
as $connsByServer ) {
1398 foreach ( $connsByServer as $i => $serverConns ) {
1399 if ( $i === $this->getWriterIndex() ) {
1400 continue; // skip master
1402 foreach ( $serverConns as $conn ) {
1403 $mergedParams = array_merge( [ $conn ], $params );
1404 call_user_func_array( $callback, $mergedParams );
1410 public function getMaxLag( $domain = false ) {
1415 if ( $this->getServerCount() <= 1 ) {
1416 return [ $host, $maxLag, $maxIndex ]; // no replication = no lag
1419 $lagTimes = $this->getLagTimes( $domain );
1420 foreach ( $lagTimes as $i => $lag ) {
1421 if ( $this->mLoads
[$i] > 0 && $lag > $maxLag ) {
1423 $host = $this->mServers
[$i]['host'];
1428 return [ $host, $maxLag, $maxIndex ];
1431 public function getLagTimes( $domain = false ) {
1432 if ( $this->getServerCount() <= 1 ) {
1433 return [ $this->getWriterIndex() => 0 ]; // no replication = no lag
1436 $knownLagTimes = []; // map of (server index => 0 seconds)
1437 $indexesWithLag = [];
1438 foreach ( $this->mServers
as $i => $server ) {
1439 if ( empty( $server['is static'] ) ) {
1440 $indexesWithLag[] = $i; // DB server might have replication lag
1442 $knownLagTimes[$i] = 0; // DB server is a non-replicating and read-only archive
1446 return $this->getLoadMonitor()->getLagTimes( $indexesWithLag, $domain ) +
$knownLagTimes;
1449 public function safeGetLag( IDatabase
$conn ) {
1450 if ( $this->getServerCount() <= 1 ) {
1453 return $conn->getLag();
1458 * @param IDatabase $conn
1459 * @param DBMasterPos|false $pos
1460 * @param int $timeout
1462 public function safeWaitForMasterPos( IDatabase
$conn, $pos = false, $timeout = 10 ) {
1463 if ( $this->getServerCount() <= 1 ||
!$conn->getLBInfo( 'replica' ) ) {
1464 return true; // server is not a replica DB
1468 // Get the current master position, opening a connection if needed
1469 $masterConn = $this->getAnyOpenConnection( $this->getWriterIndex() );
1470 if ( $masterConn ) {
1471 $pos = $masterConn->getMasterPos();
1473 $masterConn = $this->openConnection( $this->getWriterIndex(), self
::DOMAIN_ANY
);
1474 $pos = $masterConn->getMasterPos();
1475 $this->closeConnection( $masterConn );
1479 if ( $pos instanceof DBMasterPos
) {
1480 $result = $conn->masterPosWait( $pos, $timeout );
1481 if ( $result == -1 ||
is_null( $result ) ) {
1482 $msg = __METHOD__
. ": Timed out waiting on {$conn->getServer()} pos {$pos}";
1483 $this->replLogger
->warning( "$msg" );
1486 $this->replLogger
->info( __METHOD__
. ": Done" );
1490 $ok = false; // something is misconfigured
1491 $this->replLogger
->error( "Could not get master pos for {$conn->getServer()}." );
1497 public function setTransactionListener( $name, callable
$callback = null ) {
1499 $this->trxRecurringCallbacks
[$name] = $callback;
1501 unset( $this->trxRecurringCallbacks
[$name] );
1503 $this->forEachOpenMasterConnection(
1504 function ( IDatabase
$conn ) use ( $name, $callback ) {
1505 $conn->setTransactionListener( $name, $callback );
1510 public function setTableAliases( array $aliases ) {
1511 $this->tableAliases
= $aliases;
1514 public function setDomainPrefix( $prefix ) {
1515 if ( $this->mConns
['foreignUsed'] ) {
1516 // Do not switch connections to explicit foreign domains unless marked as free
1518 foreach ( $this->mConns
['foreignUsed'] as $i => $connsByDomain ) {
1519 $domains = array_merge( $domains, array_keys( $connsByDomain ) );
1521 $domains = implode( ', ', $domains );
1522 throw new DBUnexpectedError( null,
1523 "Foreign domain connections are still in use ($domains)." );
1526 $this->localDomain
= new DatabaseDomain(
1527 $this->localDomain
->getDatabase(),
1532 $this->forEachOpenConnection( function ( IDatabase
$db ) use ( $prefix ) {
1533 $db->tablePrefix( $prefix );
1538 * Make PHP ignore user aborts/disconnects until the returned
1539 * value leaves scope. This returns null and does nothing in CLI mode.
1541 * @return ScopedCallback|null
1543 final protected function getScopedPHPBehaviorForCommit() {
1544 if ( PHP_SAPI
!= 'cli' ) { // https://bugs.php.net/bug.php?id=47540
1545 $old = ignore_user_abort( true ); // avoid half-finished operations
1546 return new ScopedCallback( function () use ( $old ) {
1547 ignore_user_abort( $old );
1554 function __destruct() {
1555 // Avoid connection leaks for sanity