Current File : //www/varak.net/wiki.varak.net/includes/objectcache/MultiWriteBagOStuff.php
<?php
/**
* Wrapper for object caching in different caches.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup Cache
*/
/**
* A cache class that replicates all writes to multiple child caches. Reads
* are implemented by reading from the caches in the order they are given in
* the configuration until a cache gives a positive result.
*
* @ingroup Cache
*/
class MultiWriteBagOStuff extends BagOStuff {
/** @var BagOStuff[] */
protected $caches;
/** @var bool Use async secondary writes */
protected $asyncWrites = false;
/**
* $params include:
* - caches: This should have a numbered array of cache parameter
* structures, in the style required by $wgObjectCaches. See
* the documentation of $wgObjectCaches for more detail.
* BagOStuff objects can also be used as values.
* The first cache is the primary one, being the first to
* be read in the fallback chain. Writes happen to all stores
* in the order they are defined. However, lock()/unlock() calls
* only use the primary store.
* - replication: Either 'sync' or 'async'. This controls whether writes to
* secondary stores are deferred when possible. Async writes
* require the HHVM register_postsend_function() function.
* Async writes can increase the chance of some race conditions
* or cause keys to expire seconds later than expected. It is
* safe to use for modules when cached values: are immutable,
* invalidation uses logical TTLs, invalidation uses etag/timestamp
* validation against the DB, or merge() is used to handle races.
*
* @param array $params
* @throws InvalidArgumentException
*/
public function __construct( $params ) {
parent::__construct( $params );
if ( empty( $params['caches'] ) || !is_array( $params['caches'] ) ) {
throw new InvalidArgumentException( __METHOD__ . ': "caches" parameter must be an array of caches' );
}
$this->caches = array();
foreach ( $params['caches'] as $cacheInfo ) {
$this->caches[] = ( $cacheInfo instanceof BagOStuff )
? $cacheInfo
: ObjectCache::newFromParams( $cacheInfo );
}
$this->asyncWrites = isset( $params['replication'] ) && $params['replication'] === 'async';
}
/**
* @param bool $debug
*/
public function setDebug( $debug ) {
$this->doWrite( 'setDebug', $debug );
}
public function get( $key, &$casToken = null, $flags = 0 ) {
foreach ( $this->caches as $cache ) {
$value = $cache->get( $key, $casToken, $flags );
if ( $value !== false ) {
return $value;
}
}
return false;
}
/**
* @param string $key
* @param mixed $value
* @param int $exptime
* @return bool
*/
public function set( $key, $value, $exptime = 0 ) {
return $this->doWrite( 'set', $key, $value, $exptime );
}
/**
* @param string $key
* @return bool
*/
public function delete( $key ) {
return $this->doWrite( 'delete', $key );
}
/**
* @param string $key
* @param mixed $value
* @param int $exptime
* @return bool
*/
public function add( $key, $value, $exptime = 0 ) {
return $this->doWrite( 'add', $key, $value, $exptime );
}
/**
* @param string $key
* @param int $value
* @return bool|null
*/
public function incr( $key, $value = 1 ) {
return $this->doWrite( 'incr', $key, $value );
}
/**
* @param string $key
* @param int $value
* @return bool
*/
public function decr( $key, $value = 1 ) {
return $this->doWrite( 'decr', $key, $value );
}
/**
* @param string $key
* @param int $timeout
* @param int $expiry
* @param string $rclass
* @return bool
*/
public function lock( $key, $timeout = 6, $expiry = 6, $rclass = '' ) {
// Lock only the first cache, to avoid deadlocks
return $this->caches[0]->lock( $key, $timeout, $expiry, $rclass );
}
/**
* @param string $key
* @return bool
*/
public function unlock( $key ) {
return $this->caches[0]->unlock( $key );
}
/**
* @param string $key
* @param callable $callback Callback method to be executed
* @param int $exptime Either an interval in seconds or a unix timestamp for expiry
* @param int $attempts The amount of times to attempt a merge in case of failure
* @return bool Success
*/
public function merge( $key, $callback, $exptime = 0, $attempts = 10 ) {
return $this->doWrite( 'merge', $key, $callback, $exptime );
}
public function getLastError() {
return $this->caches[0]->getLastError();
}
public function clearLastError() {
$this->caches[0]->clearLastError();
}
/**
* @param string $method
* @return bool
*/
protected function doWrite( $method /*, ... */ ) {
$ret = true;
$args = func_get_args();
array_shift( $args );
foreach ( $this->caches as $i => $cache ) {
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;
}
} else {
// Secondary write in async mode: do not block this HTTP request
$logger = $this->logger;
DeferredUpdates::addCallableUpdate(
function () use ( $cache, $method, $args, $logger ) {
if ( !call_user_func_array( array( $cache, $method ), $args ) ) {
$logger->warning( "Async $method op failed" );
}
}
);
}
}
return $ret;
}
/**
* Delete objects expiring before a certain date.
*
* Succeed if any of the child caches succeed.
* @param string $date
* @param bool|callable $progressCallback
* @return bool
*/
public function deleteObjectsExpiringBefore( $date, $progressCallback = false ) {
$ret = false;
foreach ( $this->caches as $cache ) {
if ( $cache->deleteObjectsExpiringBefore( $date, $progressCallback ) ) {
$ret = true;
}
}
return $ret;
}
}
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