1 files changed, 275 insertions, 0 deletions
diff --git a/www/wiki/extensions/SemanticMediaWiki/src/MediaWiki/Deferred/TransactionalCallableUpdate.php b/www/wiki/extensions/SemanticMediaWiki/src/MediaWiki/Deferred/TransactionalCallableUpdate.php
new file mode 100644
index 00000000..d98d6983
--- /dev/null
+++ b/www/wiki/extensions/SemanticMediaWiki/src/MediaWiki/Deferred/TransactionalCallableUpdate.php
@@ -0,0 +1,275 @@
+<?php
+
+namespace SMW\MediaWiki\Deferred;
+
+use Closure;
+use SMW\MediaWiki\Database;
+
+/**
+ * Extends DeferredCallableUpdate to allow handling of transaction related tasks
+ * or isolations to ensure an undisturbed update process before and after
+ * MediaWiki::preOutputCommit.
+ *
+ * @license GNU GPL v2+
+ * @since 3.0
+ *
+ * @author mwjames
+ */
+class TransactionalCallableUpdate extends CallableUpdate {
+
+	/**
+	 * @var Database|null
+	 */
+	private $connection;
+
+	/**
+	 * @var boolean
+	 */
+	private $onTransactionIdle = false;
+
+	/**
+	 * @var int|null
+	 */
+	private $transactionTicket = null;
+
+	/**
+	 * @var array
+	 */
+	private $preCommitableCallbacks = [];
+
+	/**
+	 * @var array
+	 */
+	private $postCommitableCallbacks = [];
+
+	/**
+	 * @var boolean
+	 */
+	private $autoCommit = false;
+
+	/**
+	 * @since 3.0
+	 *
+	 * @param callable $callback|null
+	 * @param Database|null $connection
+	 */
+	public function __construct( callable $callback = null, Database $connection ) {
+		parent::__construct( $callback );
+		$this->connection = $connection;
+		$this->connection->onTransactionResolution( [ $this, 'cancelOnRollback' ], __METHOD__ );
+	}
+
+	/**
+	 * @note MW 1.29+ showed transaction collisions (Exception thrown with
+	 * an uncommitted database transaction), use 'onTransactionIdle' to isolate
+	 * the update execution.
+	 *
+	 * @since 2.5
+	 */
+	public function waitOnTransactionIdle() {
+		$this->onTransactionIdle = !$this->isCommandLineMode;
+	}
+
+	/**
+	 * @since 3.0
+	 */
+	public function runAsAutoCommit() {
+		$this->autoCommit = true;
+	}
+
+ 	/**
+	 * It tries to fetch a transactionTicket to assert whether transaction writes
+	 * are active or not and if available will process Database::commitAndWaitForReplication
+	 * during DeferredCallableUpdate::doUpdate to safely post commits to the
+	 * master.
+	 *
+	 * @note If the commandLine is active then continue an update without a ticket
+	 * to avoid any update lag or possible transaction lock.
+	 *
+	 * @since 3.0
+	 */
+	public function commitWithTransactionTicket() {
+		if ( $this->isCommandLineMode === false && $this->isDeferrableUpdate === true ) {
+			$this->transactionTicket = $this->connection->getEmptyTransactionTicket( $this->getOrigin() );
+		}
+	}
+
+	/**
+	 * Attaches a callback pre-execution of the source callback and is scheduled
+	 * to be executed before the source callback.
+	 *
+	 * @since 3.0
+	 *
+	 * @param string $fname
+	 * @param Closure $callback
+	 */
+	public function addPreCommitableCallback( $fname, callable $callback ) {
+		if ( is_callable( $callback ) ) {
+			$this->preCommitableCallbacks[$fname] = $callback;
+		}
+	}
+
+	/**
+	 * Attaches a callback post execution of the source callback and is scheduled
+	 * to be executed after the source callback.
+	 *
+	 * @since 3.0
+	 *
+	 * @param string $fname
+	 * @param Closure $callback
+	 */
+	public function addPostCommitableCallback( $fname, callable $callback ) {
+		if ( is_callable( $callback ) ) {
+			$this->postCommitableCallbacks[$fname] = $callback;
+		}
+	}
+
+	/**
+	 * @see DeferrableUpdate::doUpdate
+	 *
+	 * @since 3.0
+	 */
+	public function doUpdate() {
+
+		if ( $this->onTransactionIdle ) {
+			return $this->runOnTransactionIdle();
+		}
+
+		$this->runPreCommitCallbacks();
+
+		$e = null;
+		$autoTrx = null;
+
+		if ( $this->autoCommit ) {
+			$this->logger->info( [ 'DeferrableUpdate', 'Transactional, as auto commit', 'Update' ] );
+			$autoTrx = $this->connection->getFlag( DBO_TRX );
+			$this->connection->clearFlag( DBO_TRX );
+		}
+
+		try {
+			parent::doUpdate();
+		} catch ( \Exception $e ) {
+		}
+
+		if ( $this->autoCommit && $autoTrx ) {
+			$this->connection->setFlag( DBO_TRX );
+		}
+
+		if ( $e ) {
+			throw $e;
+		}
+
+		$this->runPostCommitCallbacks();
+
+		if ( $this->transactionTicket !== null ) {
+			$this->connection->commitAndWaitForReplication( $this->getOrigin(), $this->transactionTicket );
+		}
+	}
+
+	/**
+	 * @since 3.0
+	 */
+	public function cancelOnRollback( $trigger ) {
+		if ( $trigger === Database::TRIGGER_ROLLBACK ) {
+			$this->callback = [ $this, 'emptyCancelCallback' ];
+		}
+	}
+
+	protected function addUpdate( $update ) {
+
+		if ( $this->onTransactionIdle ) {
+			$this->logger->info(
+				[
+					'DeferrableUpdate',
+					'Transactional',
+					'Added: {origin} (onTransactionIdle)'
+				],
+				[
+					'method' => __METHOD__,
+					'role' => 'developer',
+					'origin' => $this->getOrigin()
+				]
+			);
+
+			return $this->connection->onTransactionIdle( function() use( $update ) {
+				$update->onTransactionIdle = false;
+				parent::addUpdate( $update );
+			} );
+		}
+
+		parent::addUpdate( $update );
+	}
+
+	protected function getLoggableContext() {
+		return parent::getLoggableContext() + [
+			'transactionTicket' => $this->transactionTicket
+		];
+	}
+
+	private function runOnTransactionIdle() {
+		$this->connection->onTransactionIdle( function() {
+			$this->logger->info(
+				[
+					'DeferrableUpdate',
+					'Transactional',
+					'Update: {origin} (onTransactionIdle)'
+				],
+				[
+					'method' => __METHOD__,
+					'role' => 'developer',
+					'origin' => $this->getOrigin()
+				]
+			);
+			$this->onTransactionIdle = false;
+			$this->doUpdate();
+		} );
+	}
+
+	private function runPreCommitCallbacks() {
+		foreach ( $this->preCommitableCallbacks as $fname => $preCallback ) {
+			$this->logger->info(
+				[
+					'DeferrableUpdate',
+					'Transactional',
+					'Update: {origin} (pre-commitable callback: {fname})'
+				],
+				[
+					'method' => __METHOD__,
+					'role' => 'developer',
+					'origin' => $this->getOrigin(),
+					'fname' => $fname
+				]
+			);
+
+			call_user_func( $preCallback, $this->transactionTicket );
+		}
+	}
+
+	private function runPostCommitCallbacks() {
+		foreach ( $this->postCommitableCallbacks as $fname => $postCallback ) {
+			$this->logger->info(
+				[
+					'DeferrableUpdate',
+					'Transactional',
+					'Update: {origin} (post-commitable callback: {fname})'
+				],
+				[
+					'method' => __METHOD__,
+					'role' => 'developer',
+					'origin' => $this->getOrigin(),
+					'fname' => $fname
+				]
+			);
+
+			call_user_func( $postCallback, $this->transactionTicket );
+		}
+	}
+
+	protected function emptyCancelCallback() {
+		$this->logger->info(
+			[ 'DeferrableUpdate', 'cancelOnRollback' ],
+			[ 'role' => 'developer', 'method' => __METHOD__ ]
+		);
+	}
+
+}