DeferredUpdates::pendingUpdatesCount() - Code Metrics - wikimedia/mediawiki - Measure and Improve Code Quality continuously with Scrutinizer

DeferredUpdates::pendingUpdatesCount() A
last analyzed 2016-11-13 17:42 UTC

↳ Parent: DeferredUpdates

Complexity

Conditions	1
Paths	1

Size

Total Lines	3
Code Lines	2

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	1
eloc	2
c	0
b	0
f	0
nc	1
nop	0
dl	0
loc	3
rs	10

<?php
/**
 * Interface and manager for deferred updates.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */
use MediaWiki\MediaWikiServices;

/**
 * Class for managing the deferred updates
 *
 * In web request mode, deferred updates can be run at the end of the request, either before or
 * after the HTTP response has been sent. In either case, they run after the DB commit step. If
 * an update runs after the response is sent, it will not block clients. If sent before, it will
 * run synchronously. These two modes are defined via PRESEND and POSTSEND constants, the latter
 * being the default for addUpdate() and addCallableUpdate().
 *
 * Updates that work through this system will be more likely to complete by the time the client
 * makes their next request after this one than with the JobQueue system.
 *
 * In CLI mode, updates run immediately if no DB writes are pending. Otherwise, they run when:
 *   - a) Any waitForReplication() call if no writes are pending on any DB
 *   - b) A commit happens on Maintenance::getDB( DB_MASTER ) if no writes are pending on any DB
 *   - c) EnqueueableDataUpdate tasks may enqueue on commit of Maintenance::getDB( DB_MASTER )
 *   - d) At the completion of Maintenance::execute()
 *
 * When updates are deferred, they go into one two FIFO "top-queues" (one for pre-send and one
 * for post-send). Updates enqueued *during* doUpdate() of a "top" update go into the "sub-queue"
 * for that update. After that method finishes, the sub-queue is run until drained. This continues
 * for each top-queue job until the entire top queue is drained. This happens for the pre-send
 * top-queue, and later on, the post-send top-queue, in execute().
 *
 * @since 1.19
 */
class DeferredUpdates {
	/** @var DeferrableUpdate[] Updates to be deferred until before request end */
	private static $preSendUpdates = [];
	/** @var DeferrableUpdate[] Updates to be deferred until after request end */
	private static $postSendUpdates = [];
	/** @var bool Whether to just run updates in addUpdate() */
	private static $immediateMode = false;

	const ALL = 0; // all updates; in web requests, use only after flushing the output buffer
	const PRESEND = 1; // for updates that should run before flushing output buffer
	const POSTSEND = 2; // for updates that should run after flushing output buffer

	const BIG_QUEUE_SIZE = 100;

	/** @var array|null Information about the current execute() call or null if not running */
	private static $executeContext;

	/**
	 * Add an update to the deferred list to be run later by execute()
	 *
	 * In CLI mode, callback magic will also be used to run updates when safe
	 *
	 * @param DeferrableUpdate $update Some object that implements doUpdate()
	 * @param integer $stage DeferredUpdates constant (PRESEND or POSTSEND) (since 1.27)
	 */
	public static function addUpdate( DeferrableUpdate $update, $stage = self::POSTSEND ) {
		global $wgCommandLineMode;

		// This is a sub-DeferredUpdate, run it right after its parent update
		if ( self::$executeContext && self::$executeContext['stage'] >= $stage ) {
			self::$executeContext['subqueue'][] = $update;
			return;
		}

		if ( $stage === self::PRESEND ) {
			self::push( self::$preSendUpdates, $update );
		} else {
			self::push( self::$postSendUpdates, $update );
		}

		if ( self::$immediateMode ) {
			// No more explicit doUpdates() calls will happen, so run this now
			self::doUpdates( 'run' );
			return;
		}

		// Try to run the updates now if in CLI mode and no transaction is active.
		// This covers scripts that don't/barely use the DB but make updates to other stores.
		if ( $wgCommandLineMode ) {
			self::tryOpportunisticExecute( 'run' );
		}
	}

	/**
	 * Add a callable update. In a lot of cases, we just need a callback/closure,
	 * defining a new DeferrableUpdate object is not necessary
	 *
	 * @see MWCallableUpdate::__construct()
	 *
	 * @param callable $callable
	 * @param integer $stage DeferredUpdates constant (PRESEND or POSTSEND) (since 1.27)
	 * @param IDatabase|null $dbw Abort if this DB is rolled back [optional] (since 1.28)
	 */
	public static function addCallableUpdate(
		$callable, $stage = self::POSTSEND, IDatabase $dbw = null
	) {
		self::addUpdate( new MWCallableUpdate( $callable, wfGetCaller(), $dbw ), $stage );
	}

	/**
	 * Do any deferred updates and clear the list
	 *
	 * @param string $mode Use "enqueue" to use the job queue when possible [Default: "run"]
	 * @param integer $stage DeferredUpdates constant (PRESEND, POSTSEND, or ALL) (since 1.27)
	 */
	public static function doUpdates( $mode = 'run', $stage = self::ALL ) {
		$stageEffective = ( $stage === self::ALL ) ? self::POSTSEND : $stage;

		if ( $stage === self::ALL || $stage === self::PRESEND ) {
			self::execute( self::$preSendUpdates, $mode, $stageEffective );
		}

		if ( $stage === self::ALL || $stage == self::POSTSEND ) {
			self::execute( self::$postSendUpdates, $mode, $stageEffective );
		}
	}

	/**
	 * @param bool $value Whether to just immediately run updates in addUpdate()
	 * @since 1.28
	 */
	public static function setImmediateMode( $value ) {
		self::$immediateMode = (bool)$value;
	}

	/**
	 * @param DeferrableUpdate[] $queue
	 * @param DeferrableUpdate $update
	 */
	private static function push( array &$queue, DeferrableUpdate $update ) {
		if ( $update instanceof MergeableUpdate ) {
			$class = get_class( $update ); // fully-qualified class
			if ( isset( $queue[$class] ) ) {
				/** @var $existingUpdate MergeableUpdate */
				$existingUpdate = $queue[$class];
				$existingUpdate->merge( $update );
			} else {
				$queue[$class] = $update;
			}
		} else {
			$queue[] = $update;
		}
	}

	/**
	 * Immediately run/queue a list of updates
	 *
	 * @param DeferrableUpdate[] &$queue List of DeferrableUpdate objects
	 * @param string $mode Use "enqueue" to use the job queue when possible
	 * @param integer $stage Class constant (PRESEND, POSTSEND) (since 1.28)
	 * @throws ErrorPageError Happens on top-level calls
	 * @throws Exception Happens on second-level calls
	 */
	protected static function execute( array &$queue, $mode, $stage ) {
		$services = MediaWikiServices::getInstance();
		$stats = $services->getStatsdDataFactory();
		$lbFactory = $services->getDBLoadBalancerFactory();
		$method = RequestContext::getMain()->getRequest()->getMethod();

		$ticket = $lbFactory->getEmptyTransactionTicket( __METHOD__ );

		/** @var ErrorPageError $reportableError */
		$reportableError = null;
		/** @var DeferrableUpdate[] $updates Snapshot of queue */
		$updates = $queue;

		// Keep doing rounds of updates until none get enqueued...
		while ( $updates ) {
			$queue = []; // clear the queue

			if ( $mode === 'enqueue' ) {
				try {
					// Push enqueuable updates to the job queue and get the rest
					$updates = self::enqueueUpdates( $updates );
				} catch ( Exception $e ) {
					// Let other updates have a chance to run if this failed
					MWExceptionHandler::rollbackMasterChangesAndLog( $e );
				}
			}

			// Order will be DataUpdate followed by generic DeferrableUpdate tasks
			$updatesByType = [ 'data' => [], 'generic' => [] ];
			foreach ( $updates as $du ) {
				if ( $du instanceof DataUpdate ) {
					$du->setTransactionTicket( $ticket );
					$updatesByType['data'][] = $du;
				} else {
					$updatesByType['generic'][] = $du;
				}

				$name = ( $du instanceof DeferrableCallback )
					? get_class( $du ) . '-' . $du->getOrigin()
					: get_class( $du );
				$stats->increment( 'deferred_updates.' . $method . '.' . $name );
			}

			// Execute all remaining tasks...
			foreach ( $updatesByType as $updatesForType ) {
				foreach ( $updatesForType as $update ) {
					self::$executeContext = [
						'update' => $update,
						'stage' => $stage,
						'subqueue' => []
					];
					/** @var DeferrableUpdate $update */
					$guiError = self::runUpdate( $update, $lbFactory, $stage );
					$reportableError = $reportableError ?: $guiError;
					// Do the subqueue updates for $update until there are none
					while ( self::$executeContext['subqueue'] ) {
						$subUpdate = reset( self::$executeContext['subqueue'] );
						$firstKey = key( self::$executeContext['subqueue'] );
						unset( self::$executeContext['subqueue'][$firstKey] );

						if ( $subUpdate instanceof DataUpdate ) {
							$subUpdate->setTransactionTicket( $ticket );
						}

						$guiError = self::runUpdate( $subUpdate, $lbFactory, $stage );
						$reportableError = $reportableError ?: $guiError;
					}
					self::$executeContext = null;
				}
			}

			$updates = $queue; // new snapshot of queue (check for new entries)
		}

		if ( $reportableError ) {
			throw $reportableError; // throw the first of any GUI errors
		}
	}

	/**
	 * @param DeferrableUpdate $update
	 * @param LBFactory $lbFactory
	 * @param integer $stage
	 * @return ErrorPageError|null
	 */
	private static function runUpdate( DeferrableUpdate $update, LBFactory $lbFactory, $stage ) {
		$guiError = null;
		try {
			$fnameTrxOwner = get_class( $update ) . '::doUpdate';
			$lbFactory->beginMasterChanges( $fnameTrxOwner );
			$update->doUpdate();
			$lbFactory->commitMasterChanges( $fnameTrxOwner );
		} catch ( Exception $e ) {
			// Reporting GUI exceptions does not work post-send
			if ( $e instanceof ErrorPageError && $stage === self::PRESEND ) {
				$guiError = $e;
			}
			MWExceptionHandler::rollbackMasterChangesAndLog( $e );
		}

		return $guiError;
	}

	/**
	 * Run all deferred updates immediately if there are no DB writes active
	 *
	 * If $mode is 'run' but there are busy databates, EnqueueableDataUpdate
	 * tasks will be enqueued anyway for the sake of progress.
	 *
	 * @param string $mode Use "enqueue" to use the job queue when possible
	 * @return bool Whether updates were allowed to run
	 * @since 1.28
	 */
	public static function tryOpportunisticExecute( $mode = 'run' ) {
		// execute() loop is already running
		if ( self::$executeContext ) {
			return false;
		}

		// Avoiding running updates without them having outer scope
		if ( !self::getBusyDbConnections() ) {
			self::doUpdates( $mode );
			return true;
		}

		if ( self::pendingUpdatesCount() >= self::BIG_QUEUE_SIZE ) {
			// If we cannot run the updates with outer transaction context, try to
			// at least enqueue all the updates that support queueing to job queue
			self::$preSendUpdates = self::enqueueUpdates( self::$preSendUpdates );
			self::$postSendUpdates = self::enqueueUpdates( self::$postSendUpdates );
		}

		return !self::pendingUpdatesCount();
	}

	/**
	 * Enqueue a job for each EnqueueableDataUpdate item and return the other items
	 *
	 * @param DeferrableUpdate[] $updates A list of deferred update instances
	 * @return DeferrableUpdate[] Remaining updates that do not support being queued
	 */
	private static function enqueueUpdates( array $updates ) {
		$remaining = [];

		foreach ( $updates as $update ) {
			if ( $update instanceof EnqueueableDataUpdate ) {
				$spec = $update->getAsJobSpecification();
				JobQueueGroup::singleton( $spec['wiki'] )->push( $spec['job'] );
			} else {
				$remaining[] = $update;
			}
		}

		return $remaining;
	}

	/**
	 * @return integer Number of enqueued updates
	 * @since 1.28
	 */
	public static function pendingUpdatesCount() {
		return count( self::$preSendUpdates ) + count( self::$postSendUpdates );
	}

	/**
	 * Clear all pending updates without performing them. Generally, you don't
	 * want or need to call this. Unit tests need it though.
	 */
	public static function clearPendingUpdates() {
		self::$preSendUpdates = [];
		self::$postSendUpdates = [];
	}

	/**
	 * @return IDatabase[] Connection where commit() cannot be called yet
	 */
	private static function getBusyDbConnections() {
		$connsBusy = [];

		$lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
		$lbFactory->forEachLB( function ( LoadBalancer $lb ) use ( &$connsBusy ) {
			$lb->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$connsBusy ) {
				if ( $conn->writesOrCallbacksPending() || $conn->explicitTrxActive() ) {
					$connsBusy[] = $conn;
				}
			} );
		} );

		return $connsBusy;
	}
}


1			<?php
2			/**
3			* Interface and manager for deferred updates.
4			*
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.
9			*
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.
14			*
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
19			*
20			* @file
21			*/
22			use MediaWiki\MediaWikiServices;
23
24			/**
25			* Class for managing the deferred updates
26			*
27			* In web request mode, deferred updates can be run at the end of the request, either before or
28			* after the HTTP response has been sent. In either case, they run after the DB commit step. If
29			* an update runs after the response is sent, it will not block clients. If sent before, it will
30			* run synchronously. These two modes are defined via PRESEND and POSTSEND constants, the latter
31			* being the default for addUpdate() and addCallableUpdate().
32			*
33			* Updates that work through this system will be more likely to complete by the time the client
34			* makes their next request after this one than with the JobQueue system.
35			*
36			* In CLI mode, updates run immediately if no DB writes are pending. Otherwise, they run when:
37			* - a) Any waitForReplication() call if no writes are pending on any DB
38			* - b) A commit happens on Maintenance::getDB( DB_MASTER ) if no writes are pending on any DB
39			* - c) EnqueueableDataUpdate tasks may enqueue on commit of Maintenance::getDB( DB_MASTER )
40			* - d) At the completion of Maintenance::execute()
41			*
42			* When updates are deferred, they go into one two FIFO "top-queues" (one for pre-send and one
43			* for post-send). Updates enqueued during doUpdate() of a "top" update go into the "sub-queue"
44			* for that update. After that method finishes, the sub-queue is run until drained. This continues
45			* for each top-queue job until the entire top queue is drained. This happens for the pre-send
46			* top-queue, and later on, the post-send top-queue, in execute().
47			*
48			* @since 1.19
49			*/
50			class DeferredUpdates {
51			/** @var DeferrableUpdate[] Updates to be deferred until before request end */
52			private static $preSendUpdates = [];
53			/** @var DeferrableUpdate[] Updates to be deferred until after request end */
54			private static $postSendUpdates = [];
55			/** @var bool Whether to just run updates in addUpdate() */
56			private static $immediateMode = false;
57
58			const ALL = 0; // all updates; in web requests, use only after flushing the output buffer
59			const PRESEND = 1; // for updates that should run before flushing output buffer
60			const POSTSEND = 2; // for updates that should run after flushing output buffer
61
62			const BIG_QUEUE_SIZE = 100;
63
64			/** @var array\|null Information about the current execute() call or null if not running */
65			private static $executeContext;
66
67			/**
68			* Add an update to the deferred list to be run later by execute()
69			*
70			* In CLI mode, callback magic will also be used to run updates when safe
71			*
72			* @param DeferrableUpdate $update Some object that implements doUpdate()
73			* @param integer $stage DeferredUpdates constant (PRESEND or POSTSEND) (since 1.27)
74			*/
75			public static function addUpdate( DeferrableUpdate $update, $stage = self::POSTSEND ) {
76			global $wgCommandLineMode;
77
78			// This is a sub-DeferredUpdate, run it right after its parent update
79			if ( self::$executeContext && self::$executeContext['stage'] >= $stage ) {
80			self::$executeContext['subqueue'][] = $update;
81			return;
82			}
83
84			if ( $stage === self::PRESEND ) {
85			self::push( self::$preSendUpdates, $update );
86			} else {
87			self::push( self::$postSendUpdates, $update );
88			}
89
90			if ( self::$immediateMode ) {
91			// No more explicit doUpdates() calls will happen, so run this now
92			self::doUpdates( 'run' );
93			return;
94			}
95
96			// Try to run the updates now if in CLI mode and no transaction is active.
97			// This covers scripts that don't/barely use the DB but make updates to other stores.
98			if ( $wgCommandLineMode ) {
99			self::tryOpportunisticExecute( 'run' );
100			}
101			}
102
103			/**
104			* Add a callable update. In a lot of cases, we just need a callback/closure,
105			* defining a new DeferrableUpdate object is not necessary
106			*
107			* @see MWCallableUpdate::__construct()
108			*
109			* @param callable $callable
110			* @param integer $stage DeferredUpdates constant (PRESEND or POSTSEND) (since 1.27)
111			* @param IDatabase\|null $dbw Abort if this DB is rolled back [optional] (since 1.28)
112			*/
113			public static function addCallableUpdate(
114			$callable, $stage = self::POSTSEND, IDatabase $dbw = null
115			) {
116			self::addUpdate( new MWCallableUpdate( $callable, wfGetCaller(), $dbw ), $stage );
117			}
118
119			/**
120			* Do any deferred updates and clear the list
121			*
122			* @param string $mode Use "enqueue" to use the job queue when possible [Default: "run"]
123			* @param integer $stage DeferredUpdates constant (PRESEND, POSTSEND, or ALL) (since 1.27)
124			*/
125			public static function doUpdates( $mode = 'run', $stage = self::ALL ) {
126			$stageEffective = ( $stage === self::ALL ) ? self::POSTSEND : $stage;
127
128			if ( $stage === self::ALL \|\| $stage === self::PRESEND ) {
129			self::execute( self::$preSendUpdates, $mode, $stageEffective );
130			}
131
132			if ( $stage === self::ALL \|\| $stage == self::POSTSEND ) {
133			self::execute( self::$postSendUpdates, $mode, $stageEffective );
134			}
135			}
136
137			/**
138			* @param bool $value Whether to just immediately run updates in addUpdate()
139			* @since 1.28
140			*/
141			public static function setImmediateMode( $value ) {
142			self::$immediateMode = (bool)$value;
143			}
144
145			/**
146			* @param DeferrableUpdate[] $queue
147			* @param DeferrableUpdate $update
148			*/
149			private static function push( array &$queue, DeferrableUpdate $update ) {
150			if ( $update instanceof MergeableUpdate ) {
151			$class = get_class( $update ); // fully-qualified class
152			if ( isset( $queue[$class] ) ) {
153			/** @var $existingUpdate MergeableUpdate */
154			$existingUpdate = $queue[$class];
155			$existingUpdate->merge( $update );
156			} else {
157			$queue[$class] = $update;
158			}
159			} else {
160			$queue[] = $update;
161			}
162			}
163
164			/**
165			* Immediately run/queue a list of updates
166			*
167			* @param DeferrableUpdate[] &$queue List of DeferrableUpdate objects
168			* @param string $mode Use "enqueue" to use the job queue when possible
169			* @param integer $stage Class constant (PRESEND, POSTSEND) (since 1.28)
170			* @throws ErrorPageError Happens on top-level calls
171			* @throws Exception Happens on second-level calls
172			*/
173			protected static function execute( array &$queue, $mode, $stage ) {
174			$services = MediaWikiServices::getInstance();
175			$stats = $services->getStatsdDataFactory();
176			$lbFactory = $services->getDBLoadBalancerFactory();
177			$method = RequestContext::getMain()->getRequest()->getMethod();
178
179			$ticket = $lbFactory->getEmptyTransactionTicket( __METHOD__ );
180
181			/** @var ErrorPageError $reportableError */
182			$reportableError = null;
183			/** @var DeferrableUpdate[] $updates Snapshot of queue */
184			$updates = $queue;
185
186			// Keep doing rounds of updates until none get enqueued...
187			while ( $updates ) {
188			$queue = []; // clear the queue
189
190			if ( $mode === 'enqueue' ) {
191			try {
192			// Push enqueuable updates to the job queue and get the rest
193			$updates = self::enqueueUpdates( $updates );
194			} catch ( Exception $e ) {
195			// Let other updates have a chance to run if this failed
196			MWExceptionHandler::rollbackMasterChangesAndLog( $e );
197			}
198			}
199
200			// Order will be DataUpdate followed by generic DeferrableUpdate tasks
201			$updatesByType = [ 'data' => [], 'generic' => [] ];
202			foreach ( $updates as $du ) {
203			if ( $du instanceof DataUpdate ) {
204			$du->setTransactionTicket( $ticket );
205			$updatesByType['data'][] = $du;
206			} else {
207			$updatesByType['generic'][] = $du;
208			}
209
210			$name = ( $du instanceof DeferrableCallback )
211			? get_class( $du ) . '-' . $du->getOrigin()
212			: get_class( $du );
213			$stats->increment( 'deferred_updates.' . $method . '.' . $name );
214			}
215
216			// Execute all remaining tasks...
217			foreach ( $updatesByType as $updatesForType ) {
218			foreach ( $updatesForType as $update ) {
219			self::$executeContext = [
220			'update' => $update,
221			'stage' => $stage,
222			'subqueue' => []
223			];
224			/** @var DeferrableUpdate $update */
225			$guiError = self::runUpdate( $update, $lbFactory, $stage );
226			$reportableError = $reportableError ?: $guiError;
227			// Do the subqueue updates for $update until there are none
228			while ( self::$executeContext['subqueue'] ) {
229			$subUpdate = reset( self::$executeContext['subqueue'] );
230			$firstKey = key( self::$executeContext['subqueue'] );
231			unset( self::$executeContext['subqueue'][$firstKey] );
232
233			if ( $subUpdate instanceof DataUpdate ) {
234			$subUpdate->setTransactionTicket( $ticket );
235			}
236
237			$guiError = self::runUpdate( $subUpdate, $lbFactory, $stage );
238			$reportableError = $reportableError ?: $guiError;
239			}
240			self::$executeContext = null;
241			}
242			}
243
244			$updates = $queue; // new snapshot of queue (check for new entries)
245			}
246
247			if ( $reportableError ) {
248			throw $reportableError; // throw the first of any GUI errors
249			}
250			}
251
252			/**
253			* @param DeferrableUpdate $update
254			* @param LBFactory $lbFactory
255			* @param integer $stage
256			* @return ErrorPageError\|null
257			*/
258			private static function runUpdate( DeferrableUpdate $update, LBFactory $lbFactory, $stage ) {
259			$guiError = null;
260			try {
261			$fnameTrxOwner = get_class( $update ) . '::doUpdate';
262			$lbFactory->beginMasterChanges( $fnameTrxOwner );
263			$update->doUpdate();
264			$lbFactory->commitMasterChanges( $fnameTrxOwner );
265			} catch ( Exception $e ) {
266			// Reporting GUI exceptions does not work post-send
267			if ( $e instanceof ErrorPageError && $stage === self::PRESEND ) {
268			$guiError = $e;
269			}
270			MWExceptionHandler::rollbackMasterChangesAndLog( $e );
271			}
272
273			return $guiError;
274			}
275
276			/**
277			* Run all deferred updates immediately if there are no DB writes active
278			*
279			* If $mode is 'run' but there are busy databates, EnqueueableDataUpdate
280			* tasks will be enqueued anyway for the sake of progress.
281			*
282			* @param string $mode Use "enqueue" to use the job queue when possible
283			* @return bool Whether updates were allowed to run
284			* @since 1.28
285			*/
286			public static function tryOpportunisticExecute( $mode = 'run' ) {
287			// execute() loop is already running
288			if ( self::$executeContext ) {
289			return false;
290			}
291
292			// Avoiding running updates without them having outer scope
293			if ( !self::getBusyDbConnections() ) {
294			self::doUpdates( $mode );
295			return true;
296			}
297
298			if ( self::pendingUpdatesCount() >= self::BIG_QUEUE_SIZE ) {
299			// If we cannot run the updates with outer transaction context, try to
300			// at least enqueue all the updates that support queueing to job queue
301			self::$preSendUpdates = self::enqueueUpdates( self::$preSendUpdates );
302			self::$postSendUpdates = self::enqueueUpdates( self::$postSendUpdates );
303			}
304
305			return !self::pendingUpdatesCount();
306			}
307
308			/**
309			* Enqueue a job for each EnqueueableDataUpdate item and return the other items
310			*
311			* @param DeferrableUpdate[] $updates A list of deferred update instances
312			* @return DeferrableUpdate[] Remaining updates that do not support being queued
313			*/
314			private static function enqueueUpdates( array $updates ) {
315			$remaining = [];
316
317			foreach ( $updates as $update ) {
318			if ( $update instanceof EnqueueableDataUpdate ) {
319			$spec = $update->getAsJobSpecification();
320			JobQueueGroup::singleton( $spec['wiki'] )->push( $spec['job'] );
321			} else {
322			$remaining[] = $update;
323			}
324			}
325
326			return $remaining;
327			}
328
329			/**
330			* @return integer Number of enqueued updates
331			* @since 1.28
332			*/
333			public static function pendingUpdatesCount() {
334			return count( self::$preSendUpdates ) + count( self::$postSendUpdates );
335			}
336
337			/**
338			* Clear all pending updates without performing them. Generally, you don't
339			* want or need to call this. Unit tests need it though.
340			*/
341			public static function clearPendingUpdates() {
342			self::$preSendUpdates = [];
343			self::$postSendUpdates = [];
344			}
345
346			/**
347			* @return IDatabase[] Connection where commit() cannot be called yet
348			*/
349			private static function getBusyDbConnections() {
350			$connsBusy = [];
351
352			$lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
353			$lbFactory->forEachLB( function ( LoadBalancer $lb ) use ( &$connsBusy ) {
354			$lb->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$connsBusy ) {
355			if ( $conn->writesOrCallbacksPending() \|\| $conn->explicitTrxActive() ) {
356			$connsBusy[] = $conn;
357			}
358			} );
359			} );
360
361			return $connsBusy;
362			}
363			}
364

wikimedia / mediawiki

DeferredUpdates::pendingUpdatesCount() A last analyzed 2016-11-13 17:42 UTC

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DeferredUpdates::pendingUpdatesCount() A
last analyzed 2016-11-13 17:42 UTC