objectcache: deleteObjectsExpiringBefore() signature and code improvements
[lhc/web/wiklou.git] / includes / objectcache / SqlBagOStuff.php
index 2ef94c4..c3a5897 100644 (file)
@@ -43,8 +43,8 @@ class SqlBagOStuff extends BagOStuff {
        protected $serverTags;
        /** @var int */
        protected $numServers;
-       /** @var int */
-       protected $lastExpireAll = 0;
+       /** @var int UNIX timestamp */
+       protected $lastGarbageCollect = 0;
        /** @var int */
        protected $purgePeriod = 10;
        /** @var int */
@@ -67,6 +67,9 @@ class SqlBagOStuff extends BagOStuff {
        /** @var array Exceptions */
        protected $connFailureErrors = [];
 
+       /** @var int */
+       const GARBAGE_COLLECT_DELAY_SEC = 1;
+
        /**
         * Constructor. Parameters are:
         *   - server:      A server info structure in the format required by each
@@ -338,8 +341,6 @@ class SqlBagOStuff extends BagOStuff {
                        $keysByTable[$serverIndex][$tableName][] = $key;
                }
 
-               $this->garbageCollect(); // expire old entries if any
-
                $result = true;
                $exptime = (int)$expiry;
                /** @noinspection PhpUnusedLocalVariableInspection */
@@ -348,6 +349,7 @@ class SqlBagOStuff extends BagOStuff {
                        $db = null;
                        try {
                                $db = $this->getDB( $serverIndex );
+                               $this->occasionallyGarbageCollect( $db );
                        } catch ( DBError $e ) {
                                $this->handleWriteError( $e, $db, $serverIndex );
                                $result = false;
@@ -601,7 +603,10 @@ class SqlBagOStuff extends BagOStuff {
         * @return bool
         */
        protected function isExpired( $db, $exptime ) {
-               return $exptime != $this->getMaxDateTime( $db ) && wfTimestamp( TS_UNIX, $exptime ) < time();
+               return (
+                       $exptime != $this->getMaxDateTime( $db ) &&
+                       wfTimestamp( TS_UNIX, $exptime ) < time()
+               );
        }
 
        /**
@@ -616,116 +621,147 @@ class SqlBagOStuff extends BagOStuff {
                }
        }
 
-       protected function garbageCollect() {
-               if ( !$this->purgePeriod || $this->replicaOnly ) {
-                       // Disabled
-                       return;
-               }
-               // Only purge on one in every $this->purgePeriod writes
-               if ( $this->purgePeriod !== 1 && mt_rand( 0, $this->purgePeriod - 1 ) ) {
-                       return;
-               }
-               $now = time();
-               // Avoid repeating the delete within a few seconds
-               if ( $now > ( $this->lastExpireAll + 1 ) ) {
-                       $this->lastExpireAll = $now;
-                       $this->deleteObjectsExpiringBefore(
-                               wfTimestamp( TS_MW, $now ),
-                               false,
-                               $this->purgeLimit
-                       );
+       /**
+        * @param IDatabase $db
+        * @throws DBError
+        */
+       protected function occasionallyGarbageCollect( IDatabase $db ) {
+               if (
+                       // Random purging is enabled
+                       $this->purgePeriod &&
+                       // This is not using a replica DB
+                       !$this->replicaOnly &&
+                       // Only purge on one in every $this->purgePeriod writes
+                       mt_rand( 0, $this->purgePeriod - 1 ) == 0 &&
+                       // Avoid repeating the delete within a few seconds
+                       ( time() - $this->lastGarbageCollect ) > self::GARBAGE_COLLECT_DELAY_SEC
+               ) {
+                       $garbageCollector = function () use ( $db ) {
+                               $this->deleteServerObjectsExpiringBefore( $db, time(), null, $this->purgeLimit );
+                               $this->lastGarbageCollect = time();
+                       };
+                       if ( $this->asyncHandler ) {
+                               $this->lastGarbageCollect = time(); // avoid duplicate enqueues
+                               ( $this->asyncHandler )( $garbageCollector );
+                       } else {
+                               $garbageCollector();
+                       }
                }
        }
 
        public function expireAll() {
-               $this->deleteObjectsExpiringBefore( wfTimestampNow() );
+               $this->deleteObjectsExpiringBefore( time() );
        }
 
        public function deleteObjectsExpiringBefore(
                $timestamp,
-               $progressCallback = false,
+               callable $progressCallback = null,
                $limit = INF
        ) {
                /** @noinspection PhpUnusedLocalVariableInspection */
                $silenceScope = $this->silenceTransactionProfiler();
 
-               $count = 0;
-               for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
+               $serverIndexes = range( 0, $this->numServers - 1 );
+               shuffle( $serverIndexes );
+
+               $ok = true;
+
+               $keysDeletedCount = 0;
+               foreach ( $serverIndexes as $numServersDone => $serverIndex ) {
                        $db = null;
                        try {
                                $db = $this->getDB( $serverIndex );
-                               $dbTimestamp = $db->timestamp( $timestamp );
-                               $totalSeconds = false;
-                               $baseConds = [ 'exptime < ' . $db->addQuotes( $dbTimestamp ) ];
-                               for ( $i = 0; $i < $this->shards; $i++ ) {
-                                       $maxExpTime = false;
-                                       while ( true ) {
-                                               $conds = $baseConds;
-                                               if ( $maxExpTime !== false ) {
-                                                       $conds[] = 'exptime >= ' . $db->addQuotes( $maxExpTime );
-                                               }
-                                               $rows = $db->select(
-                                                       $this->getTableNameByShard( $i ),
-                                                       [ 'keyname', 'exptime' ],
-                                                       $conds,
-                                                       __METHOD__,
-                                                       [ 'LIMIT' => 100, 'ORDER BY' => 'exptime' ]
-                                               );
-                                               if ( $rows === false || !$rows->numRows() ) {
-                                                       break;
-                                               }
-                                               $keys = [];
-                                               $row = $rows->current();
-                                               $minExpTime = $row->exptime;
-                                               if ( $totalSeconds === false ) {
-                                                       $totalSeconds = wfTimestamp( TS_UNIX, $timestamp )
-                                                               - wfTimestamp( TS_UNIX, $minExpTime );
-                                               }
-                                               foreach ( $rows as $row ) {
-                                                       $keys[] = $row->keyname;
-                                                       $maxExpTime = $row->exptime;
-                                               }
-
-                                               $db->delete(
-                                                       $this->getTableNameByShard( $i ),
-                                                       [
-                                                               'exptime >= ' . $db->addQuotes( $minExpTime ),
-                                                               'exptime < ' . $db->addQuotes( $dbTimestamp ),
-                                                               'keyname' => $keys
-                                                       ],
-                                                       __METHOD__
-                                               );
-                                               $count += $db->affectedRows();
-                                               if ( $count >= $limit ) {
-                                                       return true;
-                                               }
-
-                                               if ( is_callable( $progressCallback ) ) {
-                                                       if ( intval( $totalSeconds ) === 0 ) {
-                                                               $percent = 0;
-                                                       } else {
-                                                               $remainingSeconds = wfTimestamp( TS_UNIX, $timestamp )
-                                                                       - wfTimestamp( TS_UNIX, $maxExpTime );
-                                                               if ( $remainingSeconds > $totalSeconds ) {
-                                                                       $totalSeconds = $remainingSeconds;
-                                                               }
-                                                               $processedSeconds = $totalSeconds - $remainingSeconds;
-                                                               $percent = ( $i + $processedSeconds / $totalSeconds )
-                                                                       / $this->shards * 100;
-                                                       }
-                                                       $percent = ( $percent / $this->numServers )
-                                                               + ( $serverIndex / $this->numServers * 100 );
-                                                       call_user_func( $progressCallback, $percent );
-                                               }
-                                       }
-                               }
+                               $this->deleteServerObjectsExpiringBefore(
+                                       $db,
+                                       $timestamp,
+                                       $progressCallback,
+                                       $limit,
+                                       $numServersDone,
+                                       $keysDeletedCount
+                               );
                        } catch ( DBError $e ) {
                                $this->handleWriteError( $e, $db, $serverIndex );
-                               return false;
+                               $ok = false;
                        }
                }
 
-               return true;
+               return $ok;
+       }
+
+       /**
+        * @param IDatabase $db
+        * @param string|int $timestamp
+        * @param callable|null $progressCallback
+        * @param int $limit
+        * @param int $serversDoneCount
+        * @param int &$keysDeletedCount
+        * @throws DBError
+        */
+       private function deleteServerObjectsExpiringBefore(
+               IDatabase $db,
+               $timestamp,
+               $progressCallback,
+               $limit,
+               $serversDoneCount = 0,
+               &$keysDeletedCount = 0
+       ) {
+               $cutoffUnix = wfTimestamp( TS_UNIX, $timestamp );
+               $shardIndexes = range( 0, $this->shards - 1 );
+               shuffle( $shardIndexes );
+
+               foreach ( $shardIndexes as $numShardsDone => $shardIndex ) {
+                       $continue = null; // last exptime
+                       $lag = null; // purge lag
+                       do {
+                               $res = $db->select(
+                                       $this->getTableNameByShard( $shardIndex ),
+                                       [ 'keyname', 'exptime' ],
+                                       array_merge(
+                                               [ 'exptime < ' . $db->addQuotes( $db->timestamp( $cutoffUnix ) ) ],
+                                               $continue ? [ 'exptime >= ' . $db->addQuotes( $continue ) ] : []
+                                       ),
+                                       __METHOD__,
+                                       [ 'LIMIT' => min( $limit, 100 ), 'ORDER BY' => 'exptime' ]
+                               );
+
+                               if ( $res->numRows() ) {
+                                       $row = $res->current();
+                                       if ( $lag === null ) {
+                                               $lag = max( $cutoffUnix - wfTimestamp( TS_UNIX, $row->exptime ), 1 );
+                                       }
+
+                                       $keys = [];
+                                       foreach ( $res as $row ) {
+                                               $keys[] = $row->keyname;
+                                               $continue = $row->exptime;
+                                       }
+
+                                       $db->delete(
+                                               $this->getTableNameByShard( $shardIndex ),
+                                               [
+                                                       'exptime < ' . $db->addQuotes( $db->timestamp( $cutoffUnix ) ),
+                                                       'keyname' => $keys
+                                               ],
+                                               __METHOD__
+                                       );
+                                       $keysDeletedCount += $db->affectedRows();
+                               }
+
+                               if ( is_callable( $progressCallback ) ) {
+                                       if ( $lag ) {
+                                               $remainingLag = $cutoffUnix - wfTimestamp( TS_UNIX, $continue );
+                                               $processedLag = max( $lag - $remainingLag, 0 );
+                                               $doneRatio = ( $numShardsDone + $processedLag / $lag ) / $this->shards;
+                                       } else {
+                                               $doneRatio = 1;
+                                       }
+
+                                       $overallRatio = ( $doneRatio / $this->numServers )
+                                               + ( $serversDoneCount / $this->numServers );
+                                       call_user_func( $progressCallback, $overallRatio * 100 );
+                               }
+                       } while ( $res->numRows() && $keysDeletedCount < $limit );
+               }
        }
 
        /**
@@ -763,6 +799,8 @@ class SqlBagOStuff extends BagOStuff {
                }
 
                list( $serverIndex ) = $this->getTableByKey( $key );
+
+               $db = null;
                try {
                        $db = $this->getDB( $serverIndex );
                        $ok = $db->lock( $key, __METHOD__, $timeout );
@@ -793,6 +831,8 @@ class SqlBagOStuff extends BagOStuff {
                        unset( $this->locks[$key] );
 
                        list( $serverIndex ) = $this->getTableByKey( $key );
+
+                       $db = null;
                        try {
                                $db = $this->getDB( $serverIndex );
                                $ok = $db->unlock( $key, __METHOD__ );