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( __METHOD__ . ': "caches" parameter must be an array of caches' );
  64                 }
  65
  66                 $this->caches = array();
  67                 foreach ( $params['caches'] as $cacheInfo ) {
  68                         $this->caches[] = ( $cacheInfo instanceof BagOStuff )
  69                                 ? $cacheInfo
  70                                 : ObjectCache::newFromParams( $cacheInfo );
  71                 }
  72
  73                 $this->asyncWrites = isset( $params['replication'] ) && $params['replication'] === 'async';
  74         }
  75
  76         /**
  77          * @param bool $debug
  78          */
  79         public function setDebug( $debug ) {
  80                 $this->doWrite( 'setDebug', $debug );
  81         }
  82
  83         public function get( $key, &$casToken = null, $flags = 0 ) {
  84                 foreach ( $this->caches as $cache ) {
  85                         $value = $cache->get( $key, $casToken, $flags );
  86                         if ( $value !== false ) {
  87                                 return $value;
  88                         }
  89                 }
  90                 return false;
  91         }
  92
  93         /**
  94          * @param string $key
  95          * @param mixed $value
  96          * @param int $exptime
  97          * @return bool
  98          */
  99         public function set( $key, $value, $exptime = 0 ) {
 100                 return $this->doWrite( 'set', $key, $value, $exptime );
 101         }
 102
 103         /**
 104          * @param string $key
 105          * @return bool
 106          */
 107         public function delete( $key ) {
 108                 return $this->doWrite( 'delete', $key );
 109         }
 110
 111         /**
 112          * @param string $key
 113          * @param mixed $value
 114          * @param int $exptime
 115          * @return bool
 116          */
 117         public function add( $key, $value, $exptime = 0 ) {
 118                 return $this->doWrite( 'add', $key, $value, $exptime );
 119         }
 120
 121         /**
 122          * @param string $key
 123          * @param int $value
 124          * @return bool|null
 125          */
 126         public function incr( $key, $value = 1 ) {
 127                 return $this->doWrite( 'incr', $key, $value );
 128         }
 129
 130         /**
 131          * @param string $key
 132          * @param int $value
 133          * @return bool
 134          */
 135         public function decr( $key, $value = 1 ) {
 136                 return $this->doWrite( 'decr', $key, $value );
 137         }
 138
 139         /**
 140          * @param string $key
 141          * @param int $timeout
 142          * @param int $expiry
 143          * @param string $rclass
 144          * @return bool
 145          */
 146         public function lock( $key, $timeout = 6, $expiry = 6, $rclass = '' ) {
 147                 // Lock only the first cache, to avoid deadlocks
 148                 return $this->caches[0]->lock( $key, $timeout, $expiry, $rclass );
 149         }
 150
 151         /**
 152          * @param string $key
 153          * @return bool
 154          */
 155         public function unlock( $key ) {
 156                 return $this->caches[0]->unlock( $key );
 157         }
 158
 159         /**
 160          * @param string $key
 161          * @param callable $callback Callback method to be executed
 162          * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
 163          * @param int $attempts The amount of times to attempt a merge in case of failure
 164          * @return bool Success
 165          */
 166         public function merge( $key, $callback, $exptime = 0, $attempts = 10 ) {
 167                 return $this->doWrite( 'merge', $key, $callback, $exptime );
 168         }
 169
 170         public function getLastError() {
 171                 return $this->caches[0]->getLastError();
 172         }
 173
 174         public function clearLastError() {
 175                 $this->caches[0]->clearLastError();
 176         }
 177
 178         /**
 179          * @param string $method
 180          * @return bool
 181          */
 182         protected function doWrite( $method /*, ... */ ) {
 183                 $ret = true;
 184                 $args = func_get_args();
 185                 array_shift( $args );
 186
 187                 foreach ( $this->caches as $i => $cache ) {
 188                         if ( $i == 0 || !$this->asyncWrites ) {
 189                                 // First store or in sync mode: write now and get result
 190                                 if ( !call_user_func_array( array( $cache, $method ), $args ) ) {
 191                                         $ret = false;
 192                                 }
 193                         } else {
 194                                 // Secondary write in async mode: do not block this HTTP request
 195                                 $logger = $this->logger;
 196                                 DeferredUpdates::addCallableUpdate(
 197                                         function () use ( $cache, $method, $args, $logger ) {
 198                                                 if ( !call_user_func_array( array( $cache, $method ), $args ) ) {
 199                                                         $logger->warning( "Async $method op failed" );
 200                                                 }
 201                                         }
 202                                 );
 203                         }
 204                 }
 205
 206                 return $ret;
 207         }
 208
 209         /**
 210          * Delete objects expiring before a certain date.
 211          *
 212          * Succeed if any of the child caches succeed.
 213          * @param string $date
 214          * @param bool|callable $progressCallback
 215          * @return bool
 216          */
 217         public function deleteObjectsExpiringBefore( $date, $progressCallback = false ) {
 218                 $ret = false;
 219                 foreach ( $this->caches as $cache ) {
 220                         if ( $cache->deleteObjectsExpiringBefore( $date, $progressCallback ) ) {
 221                                 $ret = true;
 222                         }
 223                 }
 224
 225                 return $ret;
 226         }
 227 }