JobQueueFederated.php

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<?php
class JobQueueFederated extends JobQueue {
    protected $partitionRing;
    protected $partitionQueues = [];

    protected $maxPartitionsTry;

    protected function __construct( array $params ) {
        parent::__construct( $params );
        $section = $params['sectionsByWiki'][$this->domain] ?? 'default';
        if ( !isset( $params['partitionsBySection'][$section] ) ) {
            throw new MWException( "No configuration for section '$section'." );
        }
        $this->maxPartitionsTry = $params['maxPartitionsTry'] ?? 2;
        // Get the full partition map
        $partitionMap = $params['partitionsBySection'][$section];
        arsort( $partitionMap, SORT_NUMERIC );
        // Get the config to pass to merge into each partition queue config
        $baseConfig = $params;
        foreach ( [ 'class', 'sectionsByWiki', 'maxPartitionsTry',
            'partitionsBySection', 'configByPartition', ] as $o
        ) {
            unset( $baseConfig[$o] ); // partition queue doesn't care about this
        }
        // Get the partition queue objects
        foreach ( $partitionMap as $partition => $w ) {
            if ( !isset( $params['configByPartition'][$partition] ) ) {
                throw new MWException( "No configuration for partition '$partition'." );
            }
            $this->partitionQueues[$partition] = JobQueue::factory(
                $baseConfig + $params['configByPartition'][$partition] );
        }
        // Ring of all partitions
        $this->partitionRing = new HashRing( $partitionMap );
    }

    protected function supportedOrders() {
        // No FIFO due to partitioning, though "rough timestamp order" is supported
        return [ 'undefined', 'random', 'timestamp' ];
    }

    protected function optimalOrder() {
        return 'undefined'; // defer to the partitions
    }

    protected function supportsDelayedJobs() {
        foreach ( $this->partitionQueues as $queue ) {
            if ( !$queue->supportsDelayedJobs() ) {
                return false;
            }
        }

        return true;
    }

    protected function doIsEmpty() {
        $empty = true;
        $failed = 0;
        foreach ( $this->partitionQueues as $queue ) {
            try {
                $empty = $empty && $queue->doIsEmpty();
            } catch ( JobQueueError $e ) {
                ++$failed;
                $this->logException( $e );
            }
        }
        $this->throwErrorIfAllPartitionsDown( $failed );

        return $empty;
    }

    protected function doGetSize() {
        return $this->getCrossPartitionSum( 'size', 'doGetSize' );
    }

    protected function doGetAcquiredCount() {
        return $this->getCrossPartitionSum( 'acquiredcount', 'doGetAcquiredCount' );
    }

    protected function doGetDelayedCount() {
        return $this->getCrossPartitionSum( 'delayedcount', 'doGetDelayedCount' );
    }

    protected function doGetAbandonedCount() {
        return $this->getCrossPartitionSum( 'abandonedcount', 'doGetAbandonedCount' );
    }

    protected function getCrossPartitionSum( $type, $method ) {
        $count = 0;
        $failed = 0;
        foreach ( $this->partitionQueues as $queue ) {
            try {
                $count += $queue->$method();
            } catch ( JobQueueError $e ) {
                ++$failed;
                $this->logException( $e );
            }
        }
        $this->throwErrorIfAllPartitionsDown( $failed );

        return $count;
    }

    protected function doBatchPush( array $jobs, $flags ) {
        // Local ring variable that may be changed to point to a new ring on failure
        $partitionRing = $this->partitionRing;
        // Try to insert the jobs and update $partitionsTry on any failures.
        // Retry to insert any remaning jobs again, ignoring the bad partitions.
        $jobsLeft = $jobs;
        for ( $i = $this->maxPartitionsTry; $i > 0 && count( $jobsLeft ); --$i ) {
            try {
                $partitionRing->getLiveLocationWeights();
            } catch ( UnexpectedValueException $e ) {
                break; // all servers down; nothing to insert to
            }
            $jobsLeft = $this->tryJobInsertions( $jobsLeft, $partitionRing, $flags );
        }
        if ( count( $jobsLeft ) ) {
            throw new JobQueueError(
                "Could not insert job(s), {$this->maxPartitionsTry} partitions tried." );
        }
    }

    protected function tryJobInsertions( array $jobs, HashRing &$partitionRing, $flags ) {
        $jobsLeft = [];

        // Because jobs are spread across partitions, per-job de-duplication needs
        // to use a consistent hash to avoid allowing duplicate jobs per partition.
        // When inserting a batch of de-duplicated jobs, QOS_ATOMIC is disregarded.
        $uJobsByPartition = []; // (partition name => job list)
        foreach ( $jobs as $key => $job ) {
            if ( $job->ignoreDuplicates() ) {
                $sha1 = sha1( serialize( $job->getDeduplicationInfo() ) );
                $uJobsByPartition[$partitionRing->getLiveLocation( $sha1 )][] = $job;
                unset( $jobs[$key] );
            }
        }
        // Get the batches of jobs that are not de-duplicated
        if ( $flags & self::QOS_ATOMIC ) {
            $nuJobBatches = [ $jobs ]; // all or nothing
        } else {
            // Split the jobs into batches and spread them out over servers if there
            // are many jobs. This helps keep the partitions even. Otherwise, send all
            // the jobs to a single partition queue to avoids the extra connections.
            $nuJobBatches = array_chunk( $jobs, 300 );
        }

        // Insert the de-duplicated jobs into the queues...
        foreach ( $uJobsByPartition as $partition => $jobBatch ) {
            $queue = $this->partitionQueues[$partition];
            try {
                $ok = true;
                $queue->doBatchPush( $jobBatch, $flags | self::QOS_ATOMIC );
            } catch ( JobQueueError $e ) {
                $ok = false;
                $this->logException( $e );
            }
            if ( !$ok ) {
                if ( !$partitionRing->ejectFromLiveRing( $partition, 5 ) ) { // blacklist
                    throw new JobQueueError( "Could not insert job(s), no partitions available." );
                }
                $jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
            }
        }

        // Insert the jobs that are not de-duplicated into the queues...
        foreach ( $nuJobBatches as $jobBatch ) {
            $partition = ArrayUtils::pickRandom( $partitionRing->getLiveLocationWeights() );
            $queue = $this->partitionQueues[$partition];
            try {
                $ok = true;
                $queue->doBatchPush( $jobBatch, $flags | self::QOS_ATOMIC );
            } catch ( JobQueueError $e ) {
                $ok = false;
                $this->logException( $e );
            }
            if ( !$ok ) {
                if ( !$partitionRing->ejectFromLiveRing( $partition, 5 ) ) { // blacklist
                    throw new JobQueueError( "Could not insert job(s), no partitions available." );
                }
                $jobsLeft = array_merge( $jobsLeft, $jobBatch ); // not inserted
            }
        }

        return $jobsLeft;
    }

    protected function doPop() {
        $partitionsTry = $this->partitionRing->getLiveLocationWeights(); // (partition => weight)

        $failed = 0;
        while ( count( $partitionsTry ) ) {
            $partition = ArrayUtils::pickRandom( $partitionsTry );
            if ( $partition === false ) {
                break; // all partitions at 0 weight
            }

            $queue = $this->partitionQueues[$partition];
            try {
                $job = $queue->pop();
            } catch ( JobQueueError $e ) {
                ++$failed;
                $this->logException( $e );
                $job = false;
            }
            if ( $job ) {
                $job->setMetadata( 'QueuePartition', $partition );

                return $job;
            } else {
                unset( $partitionsTry[$partition] ); // blacklist partition
            }
        }
        $this->throwErrorIfAllPartitionsDown( $failed );

        return false;
    }

    protected function doAck( RunnableJob $job ) {
        $partition = $job->getMetadata( 'QueuePartition' );
        if ( $partition === null ) {
            throw new MWException( "The given job has no defined partition name." );
        }

        $this->partitionQueues[$partition]->ack( $job );
    }

    protected function doIsRootJobOldDuplicate( IJobSpecification $job ) {
        $signature = $job->getRootJobParams()['rootJobSignature'];
        $partition = $this->partitionRing->getLiveLocation( $signature );
        try {
            return $this->partitionQueues[$partition]->doIsRootJobOldDuplicate( $job );
        } catch ( JobQueueError $e ) {
            if ( $this->partitionRing->ejectFromLiveRing( $partition, 5 ) ) {
                $partition = $this->partitionRing->getLiveLocation( $signature );
                return $this->partitionQueues[$partition]->doIsRootJobOldDuplicate( $job );
            }
        }

        return false;
    }

    protected function doDeduplicateRootJob( IJobSpecification $job ) {
        $signature = $job->getRootJobParams()['rootJobSignature'];
        $partition = $this->partitionRing->getLiveLocation( $signature );
        try {
            return $this->partitionQueues[$partition]->doDeduplicateRootJob( $job );
        } catch ( JobQueueError $e ) {
            if ( $this->partitionRing->ejectFromLiveRing( $partition, 5 ) ) {
                $partition = $this->partitionRing->getLiveLocation( $signature );
                return $this->partitionQueues[$partition]->doDeduplicateRootJob( $job );
            }
        }

        return false;
    }

    protected function doDelete() {
        $failed = 0;
        foreach ( $this->partitionQueues as $queue ) {
            try {
                $queue->doDelete();
            } catch ( JobQueueError $e ) {
                ++$failed;
                $this->logException( $e );
            }
        }
        $this->throwErrorIfAllPartitionsDown( $failed );
        return true;
    }

    protected function doWaitForBackups() {
        $failed = 0;
        foreach ( $this->partitionQueues as $queue ) {
            try {
                $queue->waitForBackups();
            } catch ( JobQueueError $e ) {
                ++$failed;
                $this->logException( $e );
            }
        }
        $this->throwErrorIfAllPartitionsDown( $failed );
    }

    protected function doFlushCaches() {
        foreach ( $this->partitionQueues as $queue ) {
            $queue->doFlushCaches();
        }
    }

    public function getAllQueuedJobs() {
        $iterator = new AppendIterator();

        foreach ( $this->partitionQueues as $queue ) {
            $iterator->append( $queue->getAllQueuedJobs() );
        }

        return $iterator;
    }

    public function getAllDelayedJobs() {
        $iterator = new AppendIterator();

        foreach ( $this->partitionQueues as $queue ) {
            $iterator->append( $queue->getAllDelayedJobs() );
        }

        return $iterator;
    }

    public function getAllAcquiredJobs() {
        $iterator = new AppendIterator();

        foreach ( $this->partitionQueues as $queue ) {
            $iterator->append( $queue->getAllAcquiredJobs() );
        }

        return $iterator;
    }

    public function getAllAbandonedJobs() {
        $iterator = new AppendIterator();

        foreach ( $this->partitionQueues as $queue ) {
            $iterator->append( $queue->getAllAbandonedJobs() );
        }

        return $iterator;
    }

    public function getCoalesceLocationInternal() {
        return "JobQueueFederated:wiki:{$this->domain}" .
            sha1( serialize( array_keys( $this->partitionQueues ) ) );
    }

    protected function doGetSiblingQueuesWithJobs( array $types ) {
        $result = [];

        $failed = 0;
        foreach ( $this->partitionQueues as $queue ) {
            try {
                $nonEmpty = $queue->doGetSiblingQueuesWithJobs( $types );
                if ( is_array( $nonEmpty ) ) {
                    $result = array_unique( array_merge( $result, $nonEmpty ) );
                } else {
                    return null; // not supported on all partitions; bail
                }
                if ( count( $result ) == count( $types ) ) {
                    break; // short-circuit
                }
            } catch ( JobQueueError $e ) {
                ++$failed;
                $this->logException( $e );
            }
        }
        $this->throwErrorIfAllPartitionsDown( $failed );

        return array_values( $result );
    }

    protected function doGetSiblingQueueSizes( array $types ) {
        $result = [];
        $failed = 0;
        foreach ( $this->partitionQueues as $queue ) {
            try {
                $sizes = $queue->doGetSiblingQueueSizes( $types );
                if ( is_array( $sizes ) ) {
                    foreach ( $sizes as $type => $size ) {
                        $result[$type] = isset( $result[$type] ) ? $result[$type] + $size : $size;
                    }
                } else {
                    return null; // not supported on all partitions; bail
                }
            } catch ( JobQueueError $e ) {
                ++$failed;
                $this->logException( $e );
            }
        }
        $this->throwErrorIfAllPartitionsDown( $failed );

        return $result;
    }

    protected function logException( Exception $e ) {
        wfDebugLog( 'JobQueueFederated', $e->getMessage() . "\n" . $e->getTraceAsString() );
    }

    protected function throwErrorIfAllPartitionsDown( $down ) {
        if ( $down >= count( $this->partitionQueues ) ) {
            throw new JobQueueError( 'No queue partitions available.' );
        }
    }
}