includes/objectcache/MultiWriteBagOStuff.php

   1 <?php
   2 /**
   3  * Wrapper for object caching in different caches.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Cache
  22  */
  23
  24 /**
  25  * A cache class that replicates all writes to multiple child caches. Reads
  26  * are implemented by reading from the caches in the order they are given in
  27  * the configuration until a cache gives a positive result.
  28  *
  29  * @ingroup Cache
  30  */
  31 class MultiWriteBagOStuff extends BagOStuff {
  32         /** @var BagOStuff[] */
  33         protected $caches;
  34         /** @var bool Use async secondary writes */
  35         protected $asyncWrites = false;
  36
  37         /**
  38          * $params include:
  39          *   - caches:      This should have a numbered array of cache parameter
  40          *                  structures, in the style required by $wgObjectCaches. See
  41          *                  the documentation of $wgObjectCaches for more detail.
  42          *                  BagOStuff objects can also be used as values.
  43          *                  The first cache is the primary one, being the first to
  44          *                  be read in the fallback chain. Writes happen to all stores
  45          *                  in the order they are defined. However, lock()/unlock() calls
  46          *                  only use the primary store.
  47          *   - replication: Either 'sync' or 'async'. This controls whether writes to
  48          *                  secondary stores are deferred when possible. Async writes
  49          *                  require the HHVM register_postsend_function() function.
  50          *                  Async writes can increase the chance of some race conditions
  51          *                  or cause keys to expire seconds later than expected. It is
  52          *                  safe to use for modules when cached values: are immutable,
  53          *                  invalidation uses logical TTLs, invalidation uses etag/timestamp
  54          *                  validation against the DB, or merge() is used to handle races.
  55          *
  56          * @param array $params
  57          * @throws InvalidArgumentException
  58          */
  59         public function __construct( $params ) {
  60                 parent::__construct( $params );
  61
  62                 if ( empty( $params['caches'] ) || !is_array( $params['caches'] ) ) {
  63                         throw new InvalidArgumentException(
  64                                 __METHOD__ . ': "caches" parameter must be an array of caches'
  65                         );
  66                 }
  67
  68                 $this->caches = array();
  69                 foreach ( $params['caches'] as $cacheInfo ) {
  70                         $this->caches[] = ( $cacheInfo instanceof BagOStuff )
  71                                 ? $cacheInfo
  72                                 : ObjectCache::newFromParams( $cacheInfo );
  73                 }
  74
  75                 $this->asyncWrites = isset( $params['replication'] ) && $params['replication'] === 'async';
  76         }
  77
  78         /**
  79          * @param bool $debug
  80          */
  81         public function setDebug( $debug ) {
  82                 $this->doWrite( 'setDebug', $debug );
  83         }
  84
  85         public function get( $key, &$casToken = null, $flags = 0 ) {
  86                 foreach ( $this->caches as $cache ) {
  87                         $value = $cache->get( $key, $casToken, $flags );
  88                         if ( $value !== false ) {
  89                                 return $value;
  90                         }
  91                 }
  92                 return false;
  93         }
  94
  95         /**
  96          * @param string $key
  97          * @param mixed $value
  98          * @param int $exptime
  99          * @return bool
 100          */
 101         public function set( $key, $value, $exptime = 0 ) {
 102                 return $this->doWrite( 'set', $key, $value, $exptime );
 103         }
 104
 105         /**
 106          * @param string $key
 107          * @return bool
 108          */
 109         public function delete( $key ) {
 110                 return $this->doWrite( 'delete', $key );
 111         }
 112
 113         /**
 114          * @param string $key
 115          * @param mixed $value
 116          * @param int $exptime
 117          * @return bool
 118          */
 119         public function add( $key, $value, $exptime = 0 ) {
 120                 return $this->doWrite( 'add', $key, $value, $exptime );
 121         }
 122
 123         /**
 124          * @param string $key
 125          * @param int $value
 126          * @return bool|null
 127          */
 128         public function incr( $key, $value = 1 ) {
 129                 return $this->doWrite( 'incr', $key, $value );
 130         }
 131
 132         /**
 133          * @param string $key
 134          * @param int $value
 135          * @return bool
 136          */
 137         public function decr( $key, $value = 1 ) {
 138                 return $this->doWrite( 'decr', $key, $value );
 139         }
 140
 141         /**
 142          * @param string $key
 143          * @param int $timeout
 144          * @param int $expiry
 145          * @param string $rclass
 146          * @return bool
 147          */
 148         public function lock( $key, $timeout = 6, $expiry = 6, $rclass = '' ) {
 149                 // Lock only the first cache, to avoid deadlocks
 150                 return $this->caches[0]->lock( $key, $timeout, $expiry, $rclass );
 151         }
 152
 153         /**
 154          * @param string $key
 155          * @return bool
 156          */
 157         public function unlock( $key ) {
 158                 return $this->caches[0]->unlock( $key );
 159         }
 160
 161         /**
 162          * @param string $key
 163          * @param callable $callback Callback method to be executed
 164          * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
 165          * @param int $attempts The amount of times to attempt a merge in case of failure
 166          * @return bool Success
 167          */
 168         public function merge( $key, $callback, $exptime = 0, $attempts = 10 ) {
 169                 return $this->doWrite( 'merge', $key, $callback, $exptime );
 170         }
 171
 172         public function getLastError() {
 173                 return $this->caches[0]->getLastError();
 174         }
 175
 176         public function clearLastError() {
 177                 $this->caches[0]->clearLastError();
 178         }
 179
 180         /**
 181          * @param string $method
 182          * @return bool
 183          */
 184         protected function doWrite( $method /*, ... */ ) {
 185                 $ret = true;
 186                 $args = func_get_args();
 187                 array_shift( $args );
 188
 189                 foreach ( $this->caches as $i => $cache ) {
 190                         if ( $i == 0 || !$this->asyncWrites ) {
 191                                 // First store or in sync mode: write now and get result
 192                                 if ( !call_user_func_array( array( $cache, $method ), $args ) ) {
 193                                         $ret = false;
 194                                 }
 195                         } else {
 196                                 // Secondary write in async mode: do not block this HTTP request
 197                                 $logger = $this->logger;
 198                                 DeferredUpdates::addCallableUpdate(
 199                                         function () use ( $cache, $method, $args, $logger ) {
 200                                                 if ( !call_user_func_array( array( $cache, $method ), $args ) ) {
 201                                                         $logger->warning( "Async $method op failed" );
 202                                                 }
 203                                         }
 204                                 );
 205                         }
 206                 }
 207
 208                 return $ret;
 209         }
 210
 211         /**
 212          * Delete objects expiring before a certain date.
 213          *
 214          * Succeed if any of the child caches succeed.
 215          * @param string $date
 216          * @param bool|callable $progressCallback
 217          * @return bool
 218          */
 219         public function deleteObjectsExpiringBefore( $date, $progressCallback = false ) {
 220                 $ret = false;
 221                 foreach ( $this->caches as $cache ) {
 222                         if ( $cache->deleteObjectsExpiringBefore( $date, $progressCallback ) ) {
 223                                 $ret = true;
 224                         }
 225                 }
 226
 227                 return $ret;
 228         }
 229 }