class MultiWriteBagOStuff extends BagOStuff {
/** @var BagOStuff[] */
protected $caches;
+ /** @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
/**
- * Constructor. Parameters are:
- *
- * - 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.
+ * $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 ( !isset( $params['caches'] ) ) {
- throw new InvalidArgumentException( __METHOD__ . ': the caches parameter is required' );
+
+ 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[] = ObjectCache::newFromParams( $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 );
+ $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;
}
/**
* @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 );
}
/**
* @return bool
*/
public function delete( $key ) {
- return $this->doWrite( 'delete', $key );
+ return $this->doWrite( self::ALL, 'delete', $key );
}
/**
* @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 );
}
/**
* @return bool|null
*/
public function incr( $key, $value = 1 ) {
- return $this->doWrite( 'incr', $key, $value );
+ return $this->doWrite( self::ALL, 'incr', $key, $value );
}
/**
* @return bool
*/
public function decr( $key, $value = 1 ) {
- return $this->doWrite( 'decr', $key, $value );
+ return $this->doWrite( self::ALL, 'decr', $key, $value );
}
/**
*/
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 );
}
/**
* @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 );
}
/**
* @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 $cache ) {
- if ( !call_user_func_array( array( $cache, $method ), $args ) ) {
- $ret = false;
+ 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 ) ) {
+ $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;
}
$ret = true;
}
}
+
return $ret;
}
}
dépôts / lhc / web / wiklou.git / blobdiff