includes/user/ActorCache.php
<?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
*/
namespace MediaWiki\User;
/**
* Simple in-memory cache for UserIdentity objects indexed by user ID,
* actor ID and user name.
*
* We cannot just use MapCacheLRU for this because of eviction semantics:
* we need to be able to remove UserIdentity from the cache even if
* user ID or user name has changed, so we track the most accessed VALUES
* in the cache, not keys, and evict them alongside with all their indexes.
*
* @since 1.37
* @internal for use by ActorStore
* @package MediaWiki\User
*/
class ActorCache {
/** @var string Key by actor ID */
public const KEY_ACTOR_ID = 'actorId';
/** @var string Key by user ID */
public const KEY_USER_ID = 'userId';
/** @var string Key by user name */
public const KEY_USER_NAME = 'name';
private int $maxSize;
/**
* @var array[][] Contains 3 keys, KEY_ACTOR_ID, KEY_USER_ID, and KEY_USER_NAME,
* each of which has a value of an array of arrays with actor ids and UserIdentity objects,
* keyed with the corresponding actor id/user id/user name
*/
private $cache = [ self::KEY_ACTOR_ID => [], self::KEY_USER_NAME => [], self::KEY_USER_ID => [] ];
/**
* @param int $maxSize hold up to this many UserIdentity values
*/
public function __construct( int $maxSize ) {
$this->maxSize = $maxSize;
}
/**
* Get user identity which has $keyType equal to $keyValue
* @param string $keyType one of self::KEY_* constants.
* @param string|int $keyValue
* @return UserIdentity|null
*/
public function getActor( string $keyType, $keyValue ): ?UserIdentity {
return $this->getCachedValue( $keyType, $keyValue )['actor'] ?? null;
}
/**
* Get actor ID of the user which has $keyType equal to $keyValue.
* @param string $keyType one of self::KEY_* constants.
* @param string|int $keyValue
* @return int|null
*/
public function getActorId( string $keyType, $keyValue ): ?int {
return $this->getCachedValue( $keyType, $keyValue )['actorId'] ?? null;
}
/**
* Add $actor with $actorId to the cache.
* @param int $actorId
* @param UserIdentity $actor
*/
public function add( int $actorId, UserIdentity $actor ) {
while ( count( $this->cache[self::KEY_ACTOR_ID] ) >= $this->maxSize ) {
$evictId = array_key_first( $this->cache[self::KEY_ACTOR_ID] );
$this->remove( $this->cache[self::KEY_ACTOR_ID][$evictId]['actor'] );
}
$value = [ 'actorId' => $actorId, 'actor' => $actor ];
$this->cache[self::KEY_ACTOR_ID][$actorId] = $value;
$userId = $actor->getId( $actor->getWikiId() );
if ( $userId ) {
$this->cache[self::KEY_USER_ID][$userId] = $value;
}
$this->cache[self::KEY_USER_NAME][$actor->getName()] = $value;
}
/**
* Remove $actor from cache.
* @param UserIdentity $actor
*/
public function remove( UserIdentity $actor ) {
$oldByName = $this->cache[self::KEY_USER_NAME][$actor->getName()] ?? null;
$oldByUserId = $this->cache[self::KEY_USER_ID][$actor->getId( $actor->getWikiId() )] ?? null;
if ( $oldByName ) {
unset( $this->cache[self::KEY_USER_ID][$oldByName['actor']->getId( $oldByName['actor']->getWikiId() )] );
unset( $this->cache[self::KEY_ACTOR_ID][$oldByName['actorId']] );
}
if ( $oldByUserId ) {
unset( $this->cache[self::KEY_USER_NAME][$oldByUserId['actor']->getName()] );
unset( $this->cache[self::KEY_ACTOR_ID][$oldByUserId['actorId']] );
}
unset( $this->cache[self::KEY_USER_NAME][$actor->getName()] );
unset( $this->cache[self::KEY_USER_ID][$actor->getId( $actor->getWikiId() )] );
}
/**
* Remove everything from the cache.
* @internal
*/
public function clear() {
$this->cache = [ self::KEY_ACTOR_ID => [], self::KEY_USER_NAME => [], self::KEY_USER_ID => [] ];
}
/**
* @param string $keyType one of self::KEY_* constants.
* @param string|int $keyValue
* @return array|null [ 'actor' => UserIdentity, 'actorId' => int ]
*/
private function getCachedValue( string $keyType, $keyValue ): ?array {
if ( isset( $this->cache[$keyType][$keyValue] ) ) {
$cached = $this->cache[$keyType][$keyValue];
$actorId = $cached['actorId'];
// Record the actor with $actorId was recently used.
$item = $this->cache[self::KEY_ACTOR_ID][$actorId];
unset( $this->cache[self::KEY_ACTOR_ID][$actorId] );
$this->cache[self::KEY_ACTOR_ID][$actorId] = $item;
return $cached;
}
return null;
}
}