'EnqueueJob' => __DIR__ . '/includes/jobqueue/jobs/EnqueueJob.php',
'EraseArchivedFile' => __DIR__ . '/maintenance/eraseArchivedFile.php',
'ErrorPageError' => __DIR__ . '/includes/exception/ErrorPageError.php',
- 'EventRelayer' => __DIR__ . '/includes/eventrelayer/EventRelayer.php',
- 'EventRelayerMCRD' => __DIR__ . '/includes/eventrelayer/EventRelayerMCRD.php',
- 'EventRelayerNull' => __DIR__ . '/includes/eventrelayer/EventRelayer.php',
+ 'EventRelayer' => __DIR__ . '/includes/libs/eventrelayer/EventRelayer.php',
+ 'EventRelayerMCRD' => __DIR__ . '/includes/libs/eventrelayer/EventRelayerMCRD.php',
+ 'EventRelayerNull' => __DIR__ . '/includes/libs/eventrelayer/EventRelayer.php',
'Exif' => __DIR__ . '/includes/media/Exif.php',
'ExifBitmapHandler' => __DIR__ . '/includes/media/ExifBitmap.php',
'ExplodeIterator' => __DIR__ . '/includes/libs/ExplodeIterator.php',
'ViewAction' => __DIR__ . '/includes/actions/ViewAction.php',
'VirtualRESTService' => __DIR__ . '/includes/libs/virtualrest/VirtualRESTService.php',
'VirtualRESTServiceClient' => __DIR__ . '/includes/libs/virtualrest/VirtualRESTServiceClient.php',
- 'WANObjectCache' => __DIR__ . '/includes/objectcache/WANObjectCache.php',
+ 'WANObjectCache' => __DIR__ . '/includes/libs/objectcache/WANObjectCache.php',
'WaitForSlave' => __DIR__ . '/maintenance/waitForSlave.php',
'WantedCategoriesPage' => __DIR__ . '/includes/specials/SpecialWantedcategories.php',
'WantedFilesPage' => __DIR__ . '/includes/specials/SpecialWantedfiles.php',
+++ /dev/null
-<?php
-/**
- * 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
- * @author Aaron Schulz
- */
-
-/**
- * Base class for reliable event relays
- */
-abstract class EventRelayer {
- /**
- * @param array $params
- */
- public function __construct( array $params ) {}
-
- /**
- * @param string $channel
- * @param array $event Event data map
- * @return bool Success
- */
- final public function notify( $channel, $event ) {
- return $this->doNotify( $channel, array( $event ) );
- }
-
- /**
- * @param string $channel
- * @param array $events List of event data maps
- * @return bool Success
- */
- final public function notifyMulti( $channel, $events ) {
- return $this->doNotify( $channel, $events );
- }
-
- /**
- * @param string $channel
- * @param array $events List of event data maps
- * @return bool Success
- */
- abstract protected function doNotify( $channel, array $events );
-}
-
-/**
- * No-op class for publishing messages into a PubSub system
- */
-class EventRelayerNull extends EventRelayer {
- public function doNotify( $channel, array $events ) {
- return true;
- }
-}
+++ /dev/null
-<?php
-/**
- * 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
- * @author Aaron Schulz
- */
-
-/**
- * Relayed that uses the mcrelaypushd server
- */
-class EventRelayerMCRD extends EventRelayer {
- /** @var MultiHttpClient */
- protected $http;
- /** @var string */
- protected $baseUrl;
-
- /**
- * Additional params include 'mcrdConfig', which is a map of:
- * - url : The base URL of the service (without paths)
- * @param array $params
- */
- public function __construct( array $params ) {
- parent::__construct( $params );
-
- $this->baseUrl = $params['mcrdConfig']['url'];
-
- $httpConfig = isset( $params['httpConfig'] ) ? $params['httpConfig'] : array();
- if ( !isset( $httpConfig['connTimeout'] ) ) {
- $httpConfig['connTimeout'] = 1;
- }
- if ( !isset( $httpConfig['reqTimeout'] ) ) {
- $httpConfig['reqTimeout'] = .25;
- }
-
- $this->http = new MultiHttpClient( $httpConfig );
- }
-
- protected function doNotify( $channel, array $events ) {
- if ( !count( $events ) ) {
- return true;
- }
-
- $response = $this->http->run( array(
- 'url' => "{$this->baseUrl}/relayer/api/v1.0/" . rawurlencode( $channel ),
- 'method' => 'POST',
- 'body' => json_encode( array( 'events' => $events ) ),
- 'headers' => array( 'content-type' => 'application/json' )
- ) );
-
- return $response['code'] == 201;
- }
-}
--- /dev/null
+<?php
+/**
+ * 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
+ * @author Aaron Schulz
+ */
+
+/**
+ * Base class for reliable event relays
+ */
+abstract class EventRelayer {
+ /**
+ * @param array $params
+ */
+ public function __construct( array $params ) {}
+
+ /**
+ * @param string $channel
+ * @param array $event Event data map
+ * @return bool Success
+ */
+ final public function notify( $channel, $event ) {
+ return $this->doNotify( $channel, array( $event ) );
+ }
+
+ /**
+ * @param string $channel
+ * @param array $events List of event data maps
+ * @return bool Success
+ */
+ final public function notifyMulti( $channel, $events ) {
+ return $this->doNotify( $channel, $events );
+ }
+
+ /**
+ * @param string $channel
+ * @param array $events List of event data maps
+ * @return bool Success
+ */
+ abstract protected function doNotify( $channel, array $events );
+}
+
+/**
+ * No-op class for publishing messages into a PubSub system
+ */
+class EventRelayerNull extends EventRelayer {
+ public function doNotify( $channel, array $events ) {
+ return true;
+ }
+}
--- /dev/null
+<?php
+/**
+ * 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
+ * @author Aaron Schulz
+ */
+
+/**
+ * Relayed that uses the mcrelaypushd server
+ */
+class EventRelayerMCRD extends EventRelayer {
+ /** @var MultiHttpClient */
+ protected $http;
+ /** @var string */
+ protected $baseUrl;
+
+ /**
+ * Additional params include 'mcrdConfig', which is a map of:
+ * - url : The base URL of the service (without paths)
+ * @param array $params
+ */
+ public function __construct( array $params ) {
+ parent::__construct( $params );
+
+ $this->baseUrl = $params['mcrdConfig']['url'];
+
+ $httpConfig = isset( $params['httpConfig'] ) ? $params['httpConfig'] : array();
+ if ( !isset( $httpConfig['connTimeout'] ) ) {
+ $httpConfig['connTimeout'] = 1;
+ }
+ if ( !isset( $httpConfig['reqTimeout'] ) ) {
+ $httpConfig['reqTimeout'] = .25;
+ }
+
+ $this->http = new MultiHttpClient( $httpConfig );
+ }
+
+ protected function doNotify( $channel, array $events ) {
+ if ( !count( $events ) ) {
+ return true;
+ }
+
+ $response = $this->http->run( array(
+ 'url' => "{$this->baseUrl}/relayer/api/v1.0/" . rawurlencode( $channel ),
+ 'method' => 'POST',
+ 'body' => json_encode( array( 'events' => $events ) ),
+ 'headers' => array( 'content-type' => 'application/json' )
+ ) );
+
+ return $response['code'] == 201;
+ }
+}
--- /dev/null
+<?php
+/**
+ * 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
+ * @author Aaron Schulz
+ */
+
+/**
+ * Multi-datacenter aware caching interface
+ *
+ * All operations go to the local cache, except the delete()
+ * and touchCheckKey(), which broadcast to all clusters.
+ * This class is intended for caching data from primary stores.
+ * If the get() method does not return a value, then the caller
+ * should query the new value and backfill the cache using set().
+ * When the source data changes, the delete() method should be called.
+ * Since delete() is expensive, it should be avoided. One can do so if:
+ * - a) The object cached is immutable; or
+ * - b) Validity is checked against the source after get(); or
+ * - c) Using a modest TTL is reasonably correct and performant
+ * Consider using getWithSetCallback() instead of the get()/set() cycle.
+ *
+ * Instances of this class must be configured to point to a valid
+ * PubSub endpoint, and there must be listeners on the cache servers
+ * that subscribe to the endpoint and update the caches.
+ *
+ * Broadcasted operations like delete() and touchCheckKey() are done
+ * synchronously in the local cluster, but are relayed asynchronously.
+ * This means that callers in other datacenters will see older values
+ * for a however many milliseconds the datacenters are apart. As with
+ * any cache, this should not be relied on for cases where reads are
+ * used to determine writes to source (e.g. non-cache) data stores.
+ *
+ * All values are wrapped in metadata arrays. Keys use a "WANCache:" prefix
+ * to avoid collisions with keys that are not wrapped as metadata arrays. The
+ * prefixes are as follows:
+ * - a) "WANCache:v" : used for regular value keys
+ * - b) "WANCache:s" : used for temporarily storing values of tombstoned keys
+ * - c) "WANCache:t" : used for storing timestamp "check" keys
+ *
+ * @ingroup Cache
+ * @since 1.26
+ */
+class WANObjectCache {
+ /** @var BagOStuff The local cluster cache */
+ protected $cache;
+ /** @var string Cache pool name */
+ protected $pool;
+ /** @var EventRelayer */
+ protected $relayer;
+
+ /** @var int */
+ protected $lastRelayError = self::ERR_NONE;
+
+ /** Seconds to tombstone keys on delete() */
+ const HOLDOFF_TTL = 10;
+ /** Seconds to keep dependency purge keys around */
+ const CHECK_KEY_TTL = 31536000; // 1 year
+ /** Seconds to keep lock keys around */
+ const LOCK_TTL = 5;
+
+ /** Cache format version number */
+ const VERSION = 1;
+
+ /** Fields of value holder arrays */
+ const FLD_VERSION = 0;
+ const FLD_VALUE = 1;
+ const FLD_TTL = 2;
+ const FLD_TIME = 3;
+
+ /** Possible values for getLastError() */
+ const ERR_NONE = 0; // no error
+ const ERR_NO_RESPONSE = 1; // no response
+ const ERR_UNREACHABLE = 2; // can't connect
+ const ERR_UNEXPECTED = 3; // response gave some error
+ const ERR_RELAY = 4; // relay broadcast failed
+
+ const VALUE_KEY_PREFIX = 'WANCache:v:';
+ const STASH_KEY_PREFIX = 'WANCache:s:';
+ const TIME_KEY_PREFIX = 'WANCache:t:';
+
+ const PURGE_VAL_PREFIX = 'PURGED:';
+
+ /**
+ * @param array $params
+ * - cache : BagOStuff object
+ * - pool : pool name
+ * - relayer : EventRelayer object
+ */
+ public function __construct( array $params ) {
+ $this->cache = $params['cache'];
+ $this->pool = $params['pool'];
+ $this->relayer = $params['relayer'];
+ }
+
+ /**
+ * Fetch the value of a key from cache
+ *
+ * If passed in, $curTTL is set to the remaining TTL (current time left):
+ * - a) INF; if the key exists and has no TTL
+ * - b) float (>=0); if the key exists and has a TTL
+ * - c) float (<0); if the key is tombstoned or expired by $checkKeys
+ * - d) null; if the key does not exist and is not tombstoned
+ *
+ * If a key is tombstoned, $curTTL will reflect the time since delete().
+ *
+ * The timestamp of $key will be checked against the last-purge timestamp
+ * of each of $checkKeys. Those $checkKeys not in cache will have the last-purge
+ * initialized to the current timestamp. If any of $checkKeys have a timestamp
+ * greater than that of $key, then $curTTL will reflect how long ago $key
+ * became invalid. Callers can use $curTTL to know when the value is stale.
+ * The $checkKeys parameter allow mass invalidations by updating a single key:
+ * - a) Each "check" key represents "last purged" of some source data
+ * - b) Callers pass in relevant "check" keys as $checkKeys in get()
+ * - c) When the source data that "check" keys represent changes,
+ * the touchCheckKey() method is called on them
+ *
+ * For keys that are hot/expensive, consider using getWithSetCallback() instead.
+ *
+ * @param string $key Cache key
+ * @param mixed $curTTL Approximate TTL left on the key if present [returned]
+ * @param array $checkKeys List of "check" keys
+ * @return mixed Value of cache key or false on failure
+ */
+ final public function get( $key, &$curTTL = null, array $checkKeys = array() ) {
+ $curTTLs = array();
+ $values = $this->getMulti( array( $key ), $curTTLs, $checkKeys );
+ $curTTL = isset( $curTTLs[$key] ) ? $curTTLs[$key] : null;
+
+ return isset( $values[$key] ) ? $values[$key] : false;
+ }
+
+ /**
+ * Fetch the value of several keys from cache
+ *
+ * @see WANObjectCache::get()
+ *
+ * @param array $keys List of cache keys
+ * @param array $curTTLs Map of (key => approximate TTL left) for existing keys [returned]
+ * @param array $checkKeys List of "check" keys
+ * @return array Map of (key => value) for keys that exist
+ */
+ final public function getMulti(
+ array $keys, &$curTTLs = array(), array $checkKeys = array()
+ ) {
+ $result = array();
+ $curTTLs = array();
+
+ $vPrefixLen = strlen( self::VALUE_KEY_PREFIX );
+ $valueKeys = self::prefixCacheKeys( $keys, self::VALUE_KEY_PREFIX );
+ $checkKeys = self::prefixCacheKeys( $checkKeys, self::TIME_KEY_PREFIX );
+
+ // Fetch all of the raw values
+ $wrappedValues = $this->cache->getMulti( array_merge( $valueKeys, $checkKeys ) );
+ $now = microtime( true );
+
+ // Get/initialize the timestamp of all the "check" keys
+ $checkKeyTimes = array();
+ foreach ( $checkKeys as $checkKey ) {
+ $timestamp = isset( $wrappedValues[$checkKey] )
+ ? self::parsePurgeValue( $wrappedValues[$checkKey] )
+ : false;
+ if ( !is_float( $timestamp ) ) {
+ // Key is not set or invalid; regenerate
+ $this->cache->add( $checkKey,
+ self::PURGE_VAL_PREFIX . $now, self::CHECK_KEY_TTL );
+ $timestamp = $now;
+ }
+
+ $checkKeyTimes[] = $timestamp;
+ }
+
+ // Get the main cache value for each key and validate them
+ foreach ( $valueKeys as $vKey ) {
+ if ( !isset( $wrappedValues[$vKey] ) ) {
+ continue; // not found
+ }
+
+ $key = substr( $vKey, $vPrefixLen ); // unprefix
+
+ list( $value, $curTTL ) = $this->unwrap( $wrappedValues[$vKey], $now );
+ if ( $value !== false ) {
+ $result[$key] = $value;
+ foreach ( $checkKeyTimes as $checkKeyTime ) {
+ // Force dependant keys to be invalid for a while after purging
+ // to reduce race conditions involving stale data getting cached
+ $safeTimestamp = $checkKeyTime + self::HOLDOFF_TTL;
+ if ( $safeTimestamp >= $wrappedValues[$vKey][self::FLD_TIME] ) {
+ $curTTL = min( $curTTL, $checkKeyTime - $now );
+ }
+ }
+ }
+
+ $curTTLs[$key] = $curTTL;
+ }
+
+ return $result;
+ }
+
+ /**
+ * Set the value of a key from cache
+ *
+ * Simply calling this method when source data changes is not valid because
+ * the changes do not replicate to the other WAN sites. In that case, delete()
+ * should be used instead. This method is intended for use on cache misses.
+ *
+ * @param string $key Cache key
+ * @param mixed $value
+ * @param integer $ttl Seconds to live [0=forever]
+ * @return bool Success
+ */
+ final public function set( $key, $value, $ttl = 0 ) {
+ $key = self::VALUE_KEY_PREFIX . $key;
+ $wrapped = $this->wrap( $value, $ttl );
+
+ $func = function ( $cache, $key, $cWrapped ) use ( $wrapped ) {
+ return ( is_string( $cWrapped ) )
+ ? false // key is tombstoned; do nothing
+ : $wrapped;
+ };
+
+ return $this->cache->merge( $key, $func, $ttl, 1 );
+ }
+
+ /**
+ * Purge a key from all clusters
+ *
+ * This instantiates a hold-off period where the key cannot be
+ * written to avoid race conditions where dependent keys get updated
+ * with a stale value (e.g. from a DB slave).
+ *
+ * This should only be called when the underlying data (being cached)
+ * changes in a significant way. If called twice on the same key, then
+ * the last TTL takes precedence.
+ *
+ * @param string $key Cache key
+ * @param integer $ttl How long to block writes to the key [seconds]
+ * @return bool True if the item was purged or not found, false on failure
+ */
+ final public function delete( $key, $ttl = self::HOLDOFF_TTL ) {
+ $key = self::VALUE_KEY_PREFIX . $key;
+ // Update the local cluster immediately
+ $ok = $this->cache->set( $key, self::PURGE_VAL_PREFIX . microtime( true ), $ttl );
+ // Publish the purge to all clusters
+ return $this->relayPurge( $key, $ttl ) && $ok;
+ }
+
+ /**
+ * Fetch the value of a timestamp "check" key
+ *
+ * @param string $key
+ * @return float|bool TS_UNIX timestamp of the key; false if not present
+ */
+ final public function getCheckKeyTime( $key ) {
+ return self::parsePurgeValue( $this->cache->get( self::TIME_KEY_PREFIX . $key ) );
+ }
+
+ /**
+ * Purge a "check" key from all clusters, invalidating keys that use it
+ *
+ * This should only be called when the underlying data (being cached)
+ * changes in a significant way, and it is impractical to call delete()
+ * on all keys that should be changed. When get() is called on those
+ * keys, the relevant "check" keys must be supplied for this to work.
+ *
+ * The "check" key essentially represents a last-modified field.
+ * It is set in the future a few seconds when this is called, to
+ * avoid race conditions where dependent keys get updated with a
+ * stale value (e.g. from a DB slave).
+ *
+ * @see WANObjectCache::get()
+ *
+ * @param string $key Cache key
+ * @return bool True if the item was purged or not found, false on failure
+ */
+ final public function touchCheckKey( $key ) {
+ $key = self::TIME_KEY_PREFIX . $key;
+ // Update the local cluster immediately
+ $ok = $this->cache->set( $key,
+ self::PURGE_VAL_PREFIX . microtime( true ), self::CHECK_KEY_TTL );
+ // Publish the purge to all clusters
+ return $this->relayPurge( $key, self::CHECK_KEY_TTL ) && $ok;
+ }
+
+ /**
+ * Method to fetch/regenerate cache keys
+ *
+ * On cache miss, the key will be set to the callback result.
+ * The callback function returns the new value given the current
+ * value (false if not present). If false is returned, then nothing
+ * will be saved to cache.
+ *
+ * Most callers should ignore the current value, but it can be used
+ * to maintain "most recent X" values that come from time or sequence
+ * based source data, provided that the "as of" id/time is tracked.
+ *
+ * Usage of $checkKeys is the same as with get().
+ *
+ * The simplest way to avoid stampedes for hot keys is to use
+ * the 'lockTSE' option in $opts. If cache purges are needed, also:
+ * a) Pass $key into $checkKeys
+ * b) Use touchCheckKey( $key ) instead of delete( $key )
+ * Following this pattern lets the old cache be used until a
+ * single thread updates it as needed. Also consider tweaking
+ * the 'lowTTL' parameter.
+ *
+ * Example usage:
+ * <code>
+ * $key = wfMemcKey( 'cat-recent-actions', $catId );
+ * // Function that derives the new key value given the old value
+ * $callback = function( $cValue ) { ... };
+ * // Get the key value from cache or from source on cache miss;
+ * // try to only let one cluster thread manage doing cache updates
+ * $opts = array( 'lockTSE' => 5, 'lowTTL' => 10 );
+ * $value = $cache->getWithSetCallback( $key, $callback, 60, array(), $opts );
+ * </code>
+ *
+ * Example usage:
+ * <code>
+ * $key = wfMemcKey( 'cat-state', $catId );
+ * // The "check" keys that represent things the value depends on;
+ * // Calling touchCheckKey() on them invalidates "cat-state"
+ * $checkKeys = array(
+ * wfMemcKey( 'water-bowls', $houseId ),
+ * wfMemcKey( 'food-bowls', $houseId ),
+ * wfMemcKey( 'people-present', $houseId )
+ * );
+ * // Function that derives the new key value
+ * $callback = function() { ... };
+ * // Get the key value from cache or from source on cache miss;
+ * // try to only let one cluster thread manage doing cache updates
+ * $opts = array( 'lockTSE' => 5, 'lowTTL' => 10 );
+ * $value = $cache->getWithSetCallback( $key, $callback, 60, $checkKeys, $opts );
+ * </code>
+ *
+ * @see WANObjectCache::get()
+ *
+ * @param string $key Cache key
+ * @param callable $callback Value generation function
+ * @param integer $ttl Seconds to live when the key is updated [0=forever]
+ * @param array $checkKeys List of "check" keys
+ * @param array $opts Options map:
+ * - lowTTL : consider pre-emptive updates when the current TTL (sec)
+ * of the key is less than this. It becomes more likely
+ * over time, becoming a certainty once the key is expired.
+ * - lockTSE : if the key is tombstoned or expired less (by $checkKeys)
+ * than this many seconds ago, then try to have a single
+ * thread handle cache regeneration at any given time.
+ * Other threads will try to use stale values if possible.
+ * - tempTTL : when 'lockTSE' is set, this determines the TTL of the temp
+ * key used to cache values while a key is tombstoned.
+ * This avoids excessive regeneration of hot keys on delete() but
+ * may result in stale values.
+ * @return mixed Value to use for the key
+ */
+ final public function getWithSetCallback(
+ $key, $callback, $ttl, array $checkKeys = array(), array $opts = array()
+ ) {
+ $lowTTL = isset( $opts['lowTTL'] ) ? $opts['lowTTL'] : min( 10, $ttl );
+ $lockTSE = isset( $opts['lockTSE'] ) ? $opts['lockTSE'] : -1;
+ $tempTTL = isset( $opts['tempTTL'] ) ? $opts['tempTTL'] : 5;
+
+ // Get the current key value
+ $curTTL = null;
+ $cValue = $this->get( $key, $curTTL, $checkKeys ); // current value
+ $value = $cValue; // return value
+
+ // Determine if a regeneration is desired
+ if ( $value !== false && $curTTL > 0 && !$this->worthRefresh( $curTTL, $lowTTL ) ) {
+ return $value;
+ }
+
+ if ( !is_callable( $callback ) ) {
+ throw new InvalidArgumentException( "Invalid cache miss callback provided." );
+ }
+
+ // Assume a key is hot if requested soon after invalidation
+ $isHot = ( $curTTL !== null && $curTTL <= 0 && abs( $curTTL ) <= $lockTSE );
+ $isTombstone = ( $curTTL !== null && $value === false );
+
+ $locked = false;
+ if ( $isHot || $isTombstone ) {
+ // Acquire a cluster-local non-blocking lock
+ if ( $this->cache->lock( $key, 0, self::LOCK_TTL ) ) {
+ // Lock acquired; this thread should update the key
+ $locked = true;
+ } elseif ( $value !== false ) {
+ // If it cannot be acquired; then the stale value can be used
+ return $value;
+ } else {
+ // Either another thread has the lock or the lock failed.
+ // Use the stash value, which is likely from the prior thread.
+ $value = $this->cache->get( self::STASH_KEY_PREFIX . $key );
+ // Regenerate on timeout or if the other thread failed
+ if ( $value !== false ) {
+ return $value;
+ }
+ }
+ }
+
+ // Generate the new value from the callback...
+ $value = call_user_func( $callback, $cValue );
+ // When delete() is called, writes are write-holed by the tombstone,
+ // so use a special stash key to pass the new value around threads.
+ if ( $value !== false && ( $isHot || $isTombstone ) ) {
+ $this->cache->set( self::STASH_KEY_PREFIX . $key, $value, $tempTTL );
+ }
+
+ if ( $locked ) {
+ $this->cache->unlock( $key );
+ }
+
+ if ( $value !== false ) {
+ // Update the cache; this will fail if the key is tombstoned
+ $this->set( $key, $value, $ttl );
+ }
+
+ return $value;
+ }
+
+ /**
+ * Get the "last error" registered; clearLastError() should be called manually
+ * @return int ERR_* constant for the "last error" registry
+ */
+ final public function getLastError() {
+ if ( $this->lastRelayError ) {
+ // If the cache and the relayer failed, focus on the later.
+ // An update not making it to the relayer means it won't show up
+ // in other DCs (nor will consistent re-hashing see up-to-date values).
+ // On the other hand, if just the cache update failed, then it should
+ // eventually be applied by the relayer.
+ return $this->lastRelayError;
+ }
+
+ $code = $this->cache->getLastError();
+ switch ( $code ) {
+ case BagOStuff::ERR_NONE:
+ return self::ERR_NONE;
+ case BagOStuff::ERR_NO_RESPONSE:
+ return self::ERR_NO_RESPONSE;
+ case BagOStuff::ERR_UNREACHABLE:
+ return self::ERR_UNREACHABLE;
+ default:
+ return self::ERR_UNEXPECTED;
+ }
+ }
+
+ /**
+ * Clear the "last error" registry
+ */
+ final public function clearLastError() {
+ $this->cache->clearLastError();
+ $this->lastRelayError = self::ERR_NONE;
+ }
+
+ /**
+ * Do the actual async bus purge of a key
+ *
+ * This must set the key to "PURGED:<UNIX timestamp>"
+ *
+ * @param string $key Cache key
+ * @param integer $ttl How long to keep the tombstone [seconds]
+ * @return bool Success
+ */
+ protected function relayPurge( $key, $ttl ) {
+ $event = $this->cache->modifySimpleRelayEvent( array(
+ 'cmd' => 'set',
+ 'key' => $key,
+ 'val' => 'PURGED:$UNIXTIME$',
+ 'ttl' => max( $ttl, 1 ),
+ 'sbt' => true, // substitute $UNIXTIME$ with actual microtime
+ ) );
+
+ $ok = $this->relayer->notify( "{$this->pool}:purge", $event );
+ if ( !$ok ) {
+ $this->lastRelayError = self::ERR_RELAY;
+ }
+
+ return $ok;
+ }
+
+ /**
+ * Check if a key should be regenerated (using random probability)
+ *
+ * This returns false if $curTTL >= $lowTTL. Otherwise, the chance
+ * of returning true increases steadily from 0% to 100% as the $curTTL
+ * moves from $lowTTL to 0 seconds. This handles widely varying
+ * levels of cache access traffic.
+ *
+ * @param float|INF $curTTL Approximate TTL left on the key if present
+ * @param float $lowTTL Consider a refresh when $curTTL is less than this
+ * @return bool
+ */
+ protected function worthRefresh( $curTTL, $lowTTL ) {
+ if ( $curTTL >= $lowTTL ) {
+ return false;
+ } elseif ( $curTTL <= 0 ) {
+ return true;
+ }
+
+ $chance = ( 1 - $curTTL / $lowTTL );
+
+ return mt_rand( 1, 1e9 ) <= 1e9 * $chance;
+ }
+
+ /**
+ * Do not use this method outside WANObjectCache
+ *
+ * @param mixed $value
+ * @param integer $ttl [0=forever]
+ * @return string
+ */
+ protected function wrap( $value, $ttl ) {
+ return array(
+ self::FLD_VERSION => self::VERSION,
+ self::FLD_VALUE => $value,
+ self::FLD_TTL => $ttl,
+ self::FLD_TIME => microtime( true )
+ );
+ }
+
+ /**
+ * Do not use this method outside WANObjectCache
+ *
+ * @param array|string|bool $wrapped
+ * @param float $now Unix Current timestamp (preferrable pre-query)
+ * @return array (mixed; false if absent/invalid, current time left)
+ */
+ protected function unwrap( $wrapped, $now ) {
+ // Check if the value is a tombstone
+ $purgeTimestamp = self::parsePurgeValue( $wrapped );
+ if ( is_float( $purgeTimestamp ) ) {
+ // Purged values should always have a negative current $ttl
+ $curTTL = min( -0.000001, $purgeTimestamp - $now );
+ return array( false, $curTTL );
+ }
+
+ if ( !is_array( $wrapped ) // not found
+ || !isset( $wrapped[self::FLD_VERSION] ) // wrong format
+ || $wrapped[self::FLD_VERSION] !== self::VERSION // wrong version
+ ) {
+ return array( false, null );
+ }
+
+ if ( $wrapped[self::FLD_TTL] > 0 ) {
+ // Get the approximate time left on the key
+ $age = $now - $wrapped[self::FLD_TIME];
+ $curTTL = max( $wrapped[self::FLD_TTL] - $age, 0.0 );
+ } else {
+ // Key had no TTL, so the time left is unbounded
+ $curTTL = INF;
+ }
+
+ return array( $wrapped[self::FLD_VALUE], $curTTL );
+ }
+
+ /**
+ * @param array $keys
+ * @param string $prefix
+ * @return string
+ */
+ protected static function prefixCacheKeys( array $keys, $prefix ) {
+ $res = array();
+ foreach ( $keys as $key ) {
+ $res[] = $prefix . $key;
+ }
+
+ return $res;
+ }
+
+ /**
+ * @param string $value String like "PURGED:<timestamp>"
+ * @return float|bool UNIX timestamp or false on failure
+ */
+ protected static function parsePurgeValue( $value ) {
+ $m = array();
+ if ( is_string( $value ) &&
+ preg_match( '/^' . self::PURGE_VAL_PREFIX . '([^:]+)$/', $value, $m )
+ ) {
+ return (float)$m[1];
+ } else {
+ return false;
+ }
+ }
+}
+++ /dev/null
-<?php
-/**
- * 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
- * @author Aaron Schulz
- */
-
-/**
- * Multi-datacenter aware caching interface
- *
- * All operations go to the local cache, except the delete()
- * and touchCheckKey(), which broadcast to all clusters.
- * This class is intended for caching data from primary stores.
- * If the get() method does not return a value, then the caller
- * should query the new value and backfill the cache using set().
- * When the source data changes, the delete() method should be called.
- * Since delete() is expensive, it should be avoided. One can do so if:
- * - a) The object cached is immutable; or
- * - b) Validity is checked against the source after get(); or
- * - c) Using a modest TTL is reasonably correct and performant
- * Consider using getWithSetCallback() instead of the get()/set() cycle.
- *
- * Instances of this class must be configured to point to a valid
- * PubSub endpoint, and there must be listeners on the cache servers
- * that subscribe to the endpoint and update the caches.
- *
- * Broadcasted operations like delete() and touchCheckKey() are done
- * synchronously in the local cluster, but are relayed asynchronously.
- * This means that callers in other datacenters will see older values
- * for a however many milliseconds the datacenters are apart. As with
- * any cache, this should not be relied on for cases where reads are
- * used to determine writes to source (e.g. non-cache) data stores.
- *
- * All values are wrapped in metadata arrays. Keys use a "WANCache:" prefix
- * to avoid collisions with keys that are not wrapped as metadata arrays. The
- * prefixes are as follows:
- * - a) "WANCache:v" : used for regular value keys
- * - b) "WANCache:s" : used for temporarily storing values of tombstoned keys
- * - c) "WANCache:t" : used for storing timestamp "check" keys
- *
- * @ingroup Cache
- * @since 1.26
- */
-class WANObjectCache {
- /** @var BagOStuff The local cluster cache */
- protected $cache;
- /** @var string Cache pool name */
- protected $pool;
- /** @var EventRelayer */
- protected $relayer;
-
- /** @var int */
- protected $lastRelayError = self::ERR_NONE;
-
- /** Seconds to tombstone keys on delete() */
- const HOLDOFF_TTL = 10;
- /** Seconds to keep dependency purge keys around */
- const CHECK_KEY_TTL = 31536000; // 1 year
- /** Seconds to keep lock keys around */
- const LOCK_TTL = 5;
-
- /** Cache format version number */
- const VERSION = 1;
-
- /** Fields of value holder arrays */
- const FLD_VERSION = 0;
- const FLD_VALUE = 1;
- const FLD_TTL = 2;
- const FLD_TIME = 3;
-
- /** Possible values for getLastError() */
- const ERR_NONE = 0; // no error
- const ERR_NO_RESPONSE = 1; // no response
- const ERR_UNREACHABLE = 2; // can't connect
- const ERR_UNEXPECTED = 3; // response gave some error
- const ERR_RELAY = 4; // relay broadcast failed
-
- const VALUE_KEY_PREFIX = 'WANCache:v:';
- const STASH_KEY_PREFIX = 'WANCache:s:';
- const TIME_KEY_PREFIX = 'WANCache:t:';
-
- const PURGE_VAL_PREFIX = 'PURGED:';
-
- /**
- * @param array $params
- * - cache : BagOStuff object
- * - pool : pool name
- * - relayer : EventRelayer object
- */
- public function __construct( array $params ) {
- $this->cache = $params['cache'];
- $this->pool = $params['pool'];
- $this->relayer = $params['relayer'];
- }
-
- /**
- * Fetch the value of a key from cache
- *
- * If passed in, $curTTL is set to the remaining TTL (current time left):
- * - a) INF; if the key exists and has no TTL
- * - b) float (>=0); if the key exists and has a TTL
- * - c) float (<0); if the key is tombstoned or expired by $checkKeys
- * - d) null; if the key does not exist and is not tombstoned
- *
- * If a key is tombstoned, $curTTL will reflect the time since delete().
- *
- * The timestamp of $key will be checked against the last-purge timestamp
- * of each of $checkKeys. Those $checkKeys not in cache will have the last-purge
- * initialized to the current timestamp. If any of $checkKeys have a timestamp
- * greater than that of $key, then $curTTL will reflect how long ago $key
- * became invalid. Callers can use $curTTL to know when the value is stale.
- * The $checkKeys parameter allow mass invalidations by updating a single key:
- * - a) Each "check" key represents "last purged" of some source data
- * - b) Callers pass in relevant "check" keys as $checkKeys in get()
- * - c) When the source data that "check" keys represent changes,
- * the touchCheckKey() method is called on them
- *
- * For keys that are hot/expensive, consider using getWithSetCallback() instead.
- *
- * @param string $key Cache key
- * @param mixed $curTTL Approximate TTL left on the key if present [returned]
- * @param array $checkKeys List of "check" keys
- * @return mixed Value of cache key or false on failure
- */
- final public function get( $key, &$curTTL = null, array $checkKeys = array() ) {
- $curTTLs = array();
- $values = $this->getMulti( array( $key ), $curTTLs, $checkKeys );
- $curTTL = isset( $curTTLs[$key] ) ? $curTTLs[$key] : null;
-
- return isset( $values[$key] ) ? $values[$key] : false;
- }
-
- /**
- * Fetch the value of several keys from cache
- *
- * @see WANObjectCache::get()
- *
- * @param array $keys List of cache keys
- * @param array $curTTLs Map of (key => approximate TTL left) for existing keys [returned]
- * @param array $checkKeys List of "check" keys
- * @return array Map of (key => value) for keys that exist
- */
- final public function getMulti(
- array $keys, &$curTTLs = array(), array $checkKeys = array()
- ) {
- $result = array();
- $curTTLs = array();
-
- $vPrefixLen = strlen( self::VALUE_KEY_PREFIX );
- $valueKeys = self::prefixCacheKeys( $keys, self::VALUE_KEY_PREFIX );
- $checkKeys = self::prefixCacheKeys( $checkKeys, self::TIME_KEY_PREFIX );
-
- // Fetch all of the raw values
- $wrappedValues = $this->cache->getMulti( array_merge( $valueKeys, $checkKeys ) );
- $now = microtime( true );
-
- // Get/initialize the timestamp of all the "check" keys
- $checkKeyTimes = array();
- foreach ( $checkKeys as $checkKey ) {
- $timestamp = isset( $wrappedValues[$checkKey] )
- ? self::parsePurgeValue( $wrappedValues[$checkKey] )
- : false;
- if ( !is_float( $timestamp ) ) {
- // Key is not set or invalid; regenerate
- $this->cache->add( $checkKey,
- self::PURGE_VAL_PREFIX . $now, self::CHECK_KEY_TTL );
- $timestamp = $now;
- }
-
- $checkKeyTimes[] = $timestamp;
- }
-
- // Get the main cache value for each key and validate them
- foreach ( $valueKeys as $vKey ) {
- if ( !isset( $wrappedValues[$vKey] ) ) {
- continue; // not found
- }
-
- $key = substr( $vKey, $vPrefixLen ); // unprefix
-
- list( $value, $curTTL ) = $this->unwrap( $wrappedValues[$vKey], $now );
- if ( $value !== false ) {
- $result[$key] = $value;
- foreach ( $checkKeyTimes as $checkKeyTime ) {
- // Force dependant keys to be invalid for a while after purging
- // to reduce race conditions involving stale data getting cached
- $safeTimestamp = $checkKeyTime + self::HOLDOFF_TTL;
- if ( $safeTimestamp >= $wrappedValues[$vKey][self::FLD_TIME] ) {
- $curTTL = min( $curTTL, $checkKeyTime - $now );
- }
- }
- }
-
- $curTTLs[$key] = $curTTL;
- }
-
- return $result;
- }
-
- /**
- * Set the value of a key from cache
- *
- * Simply calling this method when source data changes is not valid because
- * the changes do not replicate to the other WAN sites. In that case, delete()
- * should be used instead. This method is intended for use on cache misses.
- *
- * @param string $key Cache key
- * @param mixed $value
- * @param integer $ttl Seconds to live [0=forever]
- * @return bool Success
- */
- final public function set( $key, $value, $ttl = 0 ) {
- $key = self::VALUE_KEY_PREFIX . $key;
- $wrapped = $this->wrap( $value, $ttl );
-
- $func = function ( $cache, $key, $cWrapped ) use ( $wrapped ) {
- return ( is_string( $cWrapped ) )
- ? false // key is tombstoned; do nothing
- : $wrapped;
- };
-
- return $this->cache->merge( $key, $func, $ttl, 1 );
- }
-
- /**
- * Purge a key from all clusters
- *
- * This instantiates a hold-off period where the key cannot be
- * written to avoid race conditions where dependent keys get updated
- * with a stale value (e.g. from a DB slave).
- *
- * This should only be called when the underlying data (being cached)
- * changes in a significant way. If called twice on the same key, then
- * the last TTL takes precedence.
- *
- * @param string $key Cache key
- * @param integer $ttl How long to block writes to the key [seconds]
- * @return bool True if the item was purged or not found, false on failure
- */
- final public function delete( $key, $ttl = self::HOLDOFF_TTL ) {
- $key = self::VALUE_KEY_PREFIX . $key;
- // Update the local cluster immediately
- $ok = $this->cache->set( $key, self::PURGE_VAL_PREFIX . microtime( true ), $ttl );
- // Publish the purge to all clusters
- return $this->relayPurge( $key, $ttl ) && $ok;
- }
-
- /**
- * Fetch the value of a timestamp "check" key
- *
- * @param string $key
- * @return float|bool TS_UNIX timestamp of the key; false if not present
- */
- final public function getCheckKeyTime( $key ) {
- return self::parsePurgeValue( $this->cache->get( self::TIME_KEY_PREFIX . $key ) );
- }
-
- /**
- * Purge a "check" key from all clusters, invalidating keys that use it
- *
- * This should only be called when the underlying data (being cached)
- * changes in a significant way, and it is impractical to call delete()
- * on all keys that should be changed. When get() is called on those
- * keys, the relevant "check" keys must be supplied for this to work.
- *
- * The "check" key essentially represents a last-modified field.
- * It is set in the future a few seconds when this is called, to
- * avoid race conditions where dependent keys get updated with a
- * stale value (e.g. from a DB slave).
- *
- * @see WANObjectCache::get()
- *
- * @param string $key Cache key
- * @return bool True if the item was purged or not found, false on failure
- */
- final public function touchCheckKey( $key ) {
- $key = self::TIME_KEY_PREFIX . $key;
- // Update the local cluster immediately
- $ok = $this->cache->set( $key,
- self::PURGE_VAL_PREFIX . microtime( true ), self::CHECK_KEY_TTL );
- // Publish the purge to all clusters
- return $this->relayPurge( $key, self::CHECK_KEY_TTL ) && $ok;
- }
-
- /**
- * Method to fetch/regenerate cache keys
- *
- * On cache miss, the key will be set to the callback result.
- * The callback function returns the new value given the current
- * value (false if not present). If false is returned, then nothing
- * will be saved to cache.
- *
- * Most callers should ignore the current value, but it can be used
- * to maintain "most recent X" values that come from time or sequence
- * based source data, provided that the "as of" id/time is tracked.
- *
- * Usage of $checkKeys is the same as with get().
- *
- * The simplest way to avoid stampedes for hot keys is to use
- * the 'lockTSE' option in $opts. If cache purges are needed, also:
- * a) Pass $key into $checkKeys
- * b) Use touchCheckKey( $key ) instead of delete( $key )
- * Following this pattern lets the old cache be used until a
- * single thread updates it as needed. Also consider tweaking
- * the 'lowTTL' parameter.
- *
- * Example usage:
- * <code>
- * $key = wfMemcKey( 'cat-recent-actions', $catId );
- * // Function that derives the new key value given the old value
- * $callback = function( $cValue ) { ... };
- * // Get the key value from cache or from source on cache miss;
- * // try to only let one cluster thread manage doing cache updates
- * $opts = array( 'lockTSE' => 5, 'lowTTL' => 10 );
- * $value = $cache->getWithSetCallback( $key, $callback, 60, array(), $opts );
- * </code>
- *
- * Example usage:
- * <code>
- * $key = wfMemcKey( 'cat-state', $catId );
- * // The "check" keys that represent things the value depends on;
- * // Calling touchCheckKey() on them invalidates "cat-state"
- * $checkKeys = array(
- * wfMemcKey( 'water-bowls', $houseId ),
- * wfMemcKey( 'food-bowls', $houseId ),
- * wfMemcKey( 'people-present', $houseId )
- * );
- * // Function that derives the new key value
- * $callback = function() { ... };
- * // Get the key value from cache or from source on cache miss;
- * // try to only let one cluster thread manage doing cache updates
- * $opts = array( 'lockTSE' => 5, 'lowTTL' => 10 );
- * $value = $cache->getWithSetCallback( $key, $callback, 60, $checkKeys, $opts );
- * </code>
- *
- * @see WANObjectCache::get()
- *
- * @param string $key Cache key
- * @param callable $callback Value generation function
- * @param integer $ttl Seconds to live when the key is updated [0=forever]
- * @param array $checkKeys List of "check" keys
- * @param array $opts Options map:
- * - lowTTL : consider pre-emptive updates when the current TTL (sec)
- * of the key is less than this. It becomes more likely
- * over time, becoming a certainty once the key is expired.
- * - lockTSE : if the key is tombstoned or expired less (by $checkKeys)
- * than this many seconds ago, then try to have a single
- * thread handle cache regeneration at any given time.
- * Other threads will try to use stale values if possible.
- * - tempTTL : when 'lockTSE' is set, this determines the TTL of the temp
- * key used to cache values while a key is tombstoned.
- * This avoids excessive regeneration of hot keys on delete() but
- * may result in stale values.
- * @return mixed Value to use for the key
- */
- final public function getWithSetCallback(
- $key, $callback, $ttl, array $checkKeys = array(), array $opts = array()
- ) {
- $lowTTL = isset( $opts['lowTTL'] ) ? $opts['lowTTL'] : min( 10, $ttl );
- $lockTSE = isset( $opts['lockTSE'] ) ? $opts['lockTSE'] : -1;
- $tempTTL = isset( $opts['tempTTL'] ) ? $opts['tempTTL'] : 5;
-
- // Get the current key value
- $curTTL = null;
- $cValue = $this->get( $key, $curTTL, $checkKeys ); // current value
- $value = $cValue; // return value
-
- // Determine if a regeneration is desired
- if ( $value !== false && $curTTL > 0 && !$this->worthRefresh( $curTTL, $lowTTL ) ) {
- return $value;
- }
-
- if ( !is_callable( $callback ) ) {
- throw new InvalidArgumentException( "Invalid cache miss callback provided." );
- }
-
- // Assume a key is hot if requested soon after invalidation
- $isHot = ( $curTTL !== null && $curTTL <= 0 && abs( $curTTL ) <= $lockTSE );
- $isTombstone = ( $curTTL !== null && $value === false );
-
- $locked = false;
- if ( $isHot || $isTombstone ) {
- // Acquire a cluster-local non-blocking lock
- if ( $this->cache->lock( $key, 0, self::LOCK_TTL ) ) {
- // Lock acquired; this thread should update the key
- $locked = true;
- } elseif ( $value !== false ) {
- // If it cannot be acquired; then the stale value can be used
- return $value;
- } else {
- // Either another thread has the lock or the lock failed.
- // Use the stash value, which is likely from the prior thread.
- $value = $this->cache->get( self::STASH_KEY_PREFIX . $key );
- // Regenerate on timeout or if the other thread failed
- if ( $value !== false ) {
- return $value;
- }
- }
- }
-
- // Generate the new value from the callback...
- $value = call_user_func( $callback, $cValue );
- // When delete() is called, writes are write-holed by the tombstone,
- // so use a special stash key to pass the new value around threads.
- if ( $value !== false && ( $isHot || $isTombstone ) ) {
- $this->cache->set( self::STASH_KEY_PREFIX . $key, $value, $tempTTL );
- }
-
- if ( $locked ) {
- $this->cache->unlock( $key );
- }
-
- if ( $value !== false ) {
- // Update the cache; this will fail if the key is tombstoned
- $this->set( $key, $value, $ttl );
- }
-
- return $value;
- }
-
- /**
- * Get the "last error" registered; clearLastError() should be called manually
- * @return int ERR_* constant for the "last error" registry
- */
- final public function getLastError() {
- if ( $this->lastRelayError ) {
- // If the cache and the relayer failed, focus on the later.
- // An update not making it to the relayer means it won't show up
- // in other DCs (nor will consistent re-hashing see up-to-date values).
- // On the other hand, if just the cache update failed, then it should
- // eventually be applied by the relayer.
- return $this->lastRelayError;
- }
-
- $code = $this->cache->getLastError();
- switch ( $code ) {
- case BagOStuff::ERR_NONE:
- return self::ERR_NONE;
- case BagOStuff::ERR_NO_RESPONSE:
- return self::ERR_NO_RESPONSE;
- case BagOStuff::ERR_UNREACHABLE:
- return self::ERR_UNREACHABLE;
- default:
- return self::ERR_UNEXPECTED;
- }
- }
-
- /**
- * Clear the "last error" registry
- */
- final public function clearLastError() {
- $this->cache->clearLastError();
- $this->lastRelayError = self::ERR_NONE;
- }
-
- /**
- * Do the actual async bus purge of a key
- *
- * This must set the key to "PURGED:<UNIX timestamp>"
- *
- * @param string $key Cache key
- * @param integer $ttl How long to keep the tombstone [seconds]
- * @return bool Success
- */
- protected function relayPurge( $key, $ttl ) {
- $event = $this->cache->modifySimpleRelayEvent( array(
- 'cmd' => 'set',
- 'key' => $key,
- 'val' => 'PURGED:$UNIXTIME$',
- 'ttl' => max( $ttl, 1 ),
- 'sbt' => true, // substitute $UNIXTIME$ with actual microtime
- ) );
-
- $ok = $this->relayer->notify( "{$this->pool}:purge", $event );
- if ( !$ok ) {
- $this->lastRelayError = self::ERR_RELAY;
- }
-
- return $ok;
- }
-
- /**
- * Check if a key should be regenerated (using random probability)
- *
- * This returns false if $curTTL >= $lowTTL. Otherwise, the chance
- * of returning true increases steadily from 0% to 100% as the $curTTL
- * moves from $lowTTL to 0 seconds. This handles widely varying
- * levels of cache access traffic.
- *
- * @param float|INF $curTTL Approximate TTL left on the key if present
- * @param float $lowTTL Consider a refresh when $curTTL is less than this
- * @return bool
- */
- protected function worthRefresh( $curTTL, $lowTTL ) {
- if ( $curTTL >= $lowTTL ) {
- return false;
- } elseif ( $curTTL <= 0 ) {
- return true;
- }
-
- $chance = ( 1 - $curTTL / $lowTTL );
-
- return mt_rand( 1, 1e9 ) <= 1e9 * $chance;
- }
-
- /**
- * Do not use this method outside WANObjectCache
- *
- * @param mixed $value
- * @param integer $ttl [0=forever]
- * @return string
- */
- protected function wrap( $value, $ttl ) {
- return array(
- self::FLD_VERSION => self::VERSION,
- self::FLD_VALUE => $value,
- self::FLD_TTL => $ttl,
- self::FLD_TIME => microtime( true )
- );
- }
-
- /**
- * Do not use this method outside WANObjectCache
- *
- * @param array|string|bool $wrapped
- * @param float $now Unix Current timestamp (preferrable pre-query)
- * @return array (mixed; false if absent/invalid, current time left)
- */
- protected function unwrap( $wrapped, $now ) {
- // Check if the value is a tombstone
- $purgeTimestamp = self::parsePurgeValue( $wrapped );
- if ( is_float( $purgeTimestamp ) ) {
- // Purged values should always have a negative current $ttl
- $curTTL = min( -0.000001, $purgeTimestamp - $now );
- return array( false, $curTTL );
- }
-
- if ( !is_array( $wrapped ) // not found
- || !isset( $wrapped[self::FLD_VERSION] ) // wrong format
- || $wrapped[self::FLD_VERSION] !== self::VERSION // wrong version
- ) {
- return array( false, null );
- }
-
- if ( $wrapped[self::FLD_TTL] > 0 ) {
- // Get the approximate time left on the key
- $age = $now - $wrapped[self::FLD_TIME];
- $curTTL = max( $wrapped[self::FLD_TTL] - $age, 0.0 );
- } else {
- // Key had no TTL, so the time left is unbounded
- $curTTL = INF;
- }
-
- return array( $wrapped[self::FLD_VALUE], $curTTL );
- }
-
- /**
- * @param array $keys
- * @param string $prefix
- * @return string
- */
- protected static function prefixCacheKeys( array $keys, $prefix ) {
- $res = array();
- foreach ( $keys as $key ) {
- $res[] = $prefix . $key;
- }
-
- return $res;
- }
-
- /**
- * @param string $value String like "PURGED:<timestamp>"
- * @return float|bool UNIX timestamp or false on failure
- */
- protected static function parsePurgeValue( $value ) {
- $m = array();
- if ( is_string( $value ) &&
- preg_match( '/^' . self::PURGE_VAL_PREFIX . '([^:]+)$/', $value, $m )
- ) {
- return (float)$m[1];
- } else {
- return false;
- }
- }
-}
dépôts / lhc / web / wiklou.git / commitdiff