objectcache: Add BagOStuff::READ_VERIFIED flag to get()

[lhc/web/wiklou.git] / includes / objectcache / MultiWriteBagOStuff.php

diff --git a/includes/objectcache/MultiWriteBagOStuff.php b/includes/objectcache/MultiWriteBagOStuff.php
index b390659..b690772 100644 (file)
--- a/includes/objectcache/MultiWriteBagOStuff.php
+++ b/includes/objectcache/MultiWriteBagOStuff.php
@@ -32,9 +32,12 @@ class MultiWriteBagOStuff extends BagOStuff {
        /** @var BagOStuff[] */
        protected $caches;
        /** @var bool Use async secondary writes */
-       protected $asyncReplication = false;
-       /** @var array[] */
-       protected $asyncWrites = array();
+       protected $asyncWrites = false;
+
+       /** Idiom for "write to all backends" */
+       const ALL = INF;
+
+       const UPGRADE_TTL = 3600; // TTL when a key is copied to a higher cache tier
 
        /**
         * $params include:
@@ -61,8 +64,10 @@ class MultiWriteBagOStuff extends BagOStuff {
        public function __construct( $params ) {
                parent::__construct( $params );
 
-               if ( !isset( $params['caches'] ) ) {
-                       throw new InvalidArgumentException( __METHOD__ . ': "caches" parameter required' );
+               if ( empty( $params['caches'] ) || !is_array( $params['caches'] ) ) {
+                       throw new InvalidArgumentException(
+                               __METHOD__ . ': "caches" parameter must be an array of caches'
+                       );
                }
 
                $this->caches = array();
@@ -72,26 +77,35 @@ class MultiWriteBagOStuff extends BagOStuff {
                                : ObjectCache::newFromParams( $cacheInfo );
                }
 
-               if ( isset( $params['replication'] ) && $params['replication'] === 'async' ) {
-                       $this->asyncReplication = true;
-               }
+               $this->asyncWrites = isset( $params['replication'] ) && $params['replication'] === 'async';
        }
 
        /**
         * @param bool $debug
         */
        public function setDebug( $debug ) {
-               $this->doWrite( 'setDebug', $debug );
+               $this->doWrite( self::ALL, 'setDebug', $debug );
        }
 
        public function get( $key, &$casToken = null, $flags = 0 ) {
+               $misses = 0; // number backends checked
+               $value = false;
                foreach ( $this->caches as $cache ) {
                        $value = $cache->get( $key, $casToken, $flags );
                        if ( $value !== false ) {
-                               return $value;
+                               break;
                        }
+                       ++$misses;
                }
-               return false;
+
+               if ( $value !== false
+                       && $misses > 0
+                       && ( $flags & self::READ_VERIFIED ) == self::READ_VERIFIED
+               ) {
+                       $this->doWrite( $misses, 'set', $key, $value, self::UPGRADE_TTL );
+               }
+
+               return $value;
        }
 
        /**
@@ -101,7 +115,7 @@ class MultiWriteBagOStuff extends BagOStuff {
         * @return bool
         */
        public function set( $key, $value, $exptime = 0 ) {
-               return $this->doWrite( 'set', $key, $value, $exptime );
+               return $this->doWrite( self::ALL, 'set', $key, $value, $exptime );
        }
 
        /**
@@ -109,7 +123,7 @@ class MultiWriteBagOStuff extends BagOStuff {
         * @return bool
         */
        public function delete( $key ) {
-               return $this->doWrite( 'delete', $key );
+               return $this->doWrite( self::ALL, 'delete', $key );
        }
 
        /**
@@ -119,7 +133,7 @@ class MultiWriteBagOStuff extends BagOStuff {
         * @return bool
         */
        public function add( $key, $value, $exptime = 0 ) {
-               return $this->doWrite( 'add', $key, $value, $exptime );
+               return $this->doWrite( self::ALL, 'add', $key, $value, $exptime );
        }
 
        /**
@@ -128,7 +142,7 @@ class MultiWriteBagOStuff extends BagOStuff {
         * @return bool|null
         */
        public function incr( $key, $value = 1 ) {
-               return $this->doWrite( 'incr', $key, $value );
+               return $this->doWrite( self::ALL, 'incr', $key, $value );
        }
 
        /**
@@ -137,7 +151,7 @@ class MultiWriteBagOStuff extends BagOStuff {
         * @return bool
         */
        public function decr( $key, $value = 1 ) {
-               return $this->doWrite( 'decr', $key, $value );
+               return $this->doWrite( self::ALL, 'decr', $key, $value );
        }
 
        /**
@@ -149,11 +163,7 @@ class MultiWriteBagOStuff extends BagOStuff {
         */
        public function lock( $key, $timeout = 6, $expiry = 6, $rclass = '' ) {
                // Lock only the first cache, to avoid deadlocks
-               if ( isset( $this->caches[0] ) ) {
-                       return $this->caches[0]->lock( $key, $timeout, $expiry, $rclass );
-               } else {
-                       return true;
-               }
+               return $this->caches[0]->lock( $key, $timeout, $expiry, $rclass );
        }
 
        /**
@@ -161,11 +171,7 @@ class MultiWriteBagOStuff extends BagOStuff {
         * @return bool
         */
        public function unlock( $key ) {
-               if ( isset( $this->caches[0] ) ) {
-                       return $this->caches[0]->unlock( $key );
-               } else {
-                       return true;
-               }
+               return $this->caches[0]->unlock( $key );
        }
 
        /**
@@ -176,30 +182,35 @@ class MultiWriteBagOStuff extends BagOStuff {
         * @return bool Success
         */
        public function merge( $key, $callback, $exptime = 0, $attempts = 10 ) {
-               return $this->doWrite( 'merge', $key, $callback, $exptime );
+               return $this->doWrite( self::ALL, 'merge', $key, $callback, $exptime );
        }
 
        public function getLastError() {
-               return isset( $this->caches[0] ) ? $this->caches[0]->getLastError() : self::ERR_NONE;
+               return $this->caches[0]->getLastError();
        }
 
        public function clearLastError() {
-               if ( isset( $this->caches[0] ) ) {
-                       $this->caches[0]->clearLastError();
-               }
+               $this->caches[0]->clearLastError();
        }
 
        /**
+        * Apply a write method to the first $count backing caches
+        *
+        * @param integer $count
         * @param string $method
+        * @param mixed ...
         * @return bool
         */
-       protected function doWrite( $method /*, ... */ ) {
+       protected function doWrite( $count, $method /*, ... */ ) {
                $ret = true;
-               $args = func_get_args();
-               array_shift( $args );
+               $args = array_slice( func_get_args(), 2 );
 
                foreach ( $this->caches as $i => $cache ) {
-                       if ( $i == 0 || !$this->asyncReplication ) {
+                       if ( $i >= $count ) {
+                               break; // ignore the lower tiers
+                       }
+
+                       if ( $i == 0 || !$this->asyncWrites ) {
                                // First store or in sync mode: write now and get result
                                if ( !call_user_func_array( array( $cache, $method ), $args ) ) {
                                        $ret = false;
@@ -208,7 +219,7 @@ class MultiWriteBagOStuff extends BagOStuff {
                                // Secondary write in async mode: do not block this HTTP request
                                $logger = $this->logger;
                                DeferredUpdates::addCallableUpdate(
-                                       function() use ( $cache, $method, $args, $logger ) {
+                                       function () use ( $cache, $method, $args, $logger ) {
                                                if ( !call_user_func_array( array( $cache, $method ), $args ) ) {
                                                        $logger->warning( "Async $method op failed" );
                                                }