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 1a52930..b690772 100644 (file)
--- a/includes/objectcache/MultiWriteBagOStuff.php
+++ b/includes/objectcache/MultiWriteBagOStuff.php
@@ -34,6 +34,11 @@ class MultiWriteBagOStuff extends BagOStuff {
        /** @var bool Use async secondary writes */
        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:
         *   - caches:      This should have a numbered array of cache parameter
@@ -60,7 +65,9 @@ class MultiWriteBagOStuff extends BagOStuff {
                parent::__construct( $params );
 
                if ( empty( $params['caches'] ) || !is_array( $params['caches'] ) ) {
-                       throw new InvalidArgumentException( __METHOD__ . ': "caches" parameter must be an array of caches' );
+                       throw new InvalidArgumentException(
+                               __METHOD__ . ': "caches" parameter must be an array of caches'
+                       );
                }
 
                $this->caches = array();
@@ -77,17 +84,28 @@ class MultiWriteBagOStuff extends BagOStuff {
         * @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;
+               }
+
+               if ( $value !== false
+                       && $misses > 0
+                       && ( $flags & self::READ_VERIFIED ) == self::READ_VERIFIED
+               ) {
+                       $this->doWrite( $misses, 'set', $key, $value, self::UPGRADE_TTL );
                }
-               return false;
+
+               return $value;
        }
 
        /**
@@ -97,7 +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 );
        }
 
        /**
@@ -105,7 +123,7 @@ class MultiWriteBagOStuff extends BagOStuff {
         * @return bool
         */
        public function delete( $key ) {
-               return $this->doWrite( 'delete', $key );
+               return $this->doWrite( self::ALL, 'delete', $key );
        }
 
        /**
@@ -115,7 +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 );
        }
 
        /**
@@ -124,7 +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 );
        }
 
        /**
@@ -133,7 +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 );
        }
 
        /**
@@ -164,7 +182,7 @@ 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() {
@@ -176,15 +194,22 @@ class MultiWriteBagOStuff extends BagOStuff {
        }
 
        /**
+        * 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 >= $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 ) ) {