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Diffstat (limited to 'www/wiki/includes/libs/ProcessCacheLRU.php')
-rw-r--r-- | www/wiki/includes/libs/ProcessCacheLRU.php | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/www/wiki/includes/libs/ProcessCacheLRU.php b/www/wiki/includes/libs/ProcessCacheLRU.php new file mode 100644 index 00000000..b374259f --- /dev/null +++ b/www/wiki/includes/libs/ProcessCacheLRU.php @@ -0,0 +1,163 @@ +<?php +/** + * Per-process memory cache for storing items. + * + * 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 + */ +use Wikimedia\Assert\Assert; + +/** + * Class for process caching individual properties of expiring items + * + * When the key for an entire item is deleted, all properties for it are deleted + * + * @ingroup Cache + */ +class ProcessCacheLRU { + /** @var array */ + protected $cache = []; // (key => prop => value) + + /** @var array */ + protected $cacheTimes = []; // (key => prop => UNIX timestamp) + + protected $maxCacheKeys; // integer; max entries + + /** + * @param int $maxKeys Maximum number of entries allowed (min 1). + * @throws UnexpectedValueException When $maxCacheKeys is not an int or =< 0. + */ + public function __construct( $maxKeys ) { + $this->resize( $maxKeys ); + } + + /** + * Set a property field for a cache entry. + * This will prune the cache if it gets too large based on LRU. + * If the item is already set, it will be pushed to the top of the cache. + * + * @param string $key + * @param string $prop + * @param mixed $value + * @return void + */ + public function set( $key, $prop, $value ) { + if ( isset( $this->cache[$key] ) ) { + $this->ping( $key ); + } elseif ( count( $this->cache ) >= $this->maxCacheKeys ) { + reset( $this->cache ); + $evictKey = key( $this->cache ); + unset( $this->cache[$evictKey] ); + unset( $this->cacheTimes[$evictKey] ); + } + $this->cache[$key][$prop] = $value; + $this->cacheTimes[$key][$prop] = microtime( true ); + } + + /** + * Check if a property field exists for a cache entry. + * + * @param string $key + * @param string $prop + * @param float $maxAge Ignore items older than this many seconds (since 1.21) + * @return bool + */ + public function has( $key, $prop, $maxAge = 0.0 ) { + if ( isset( $this->cache[$key][$prop] ) ) { + return ( $maxAge <= 0 || + ( microtime( true ) - $this->cacheTimes[$key][$prop] ) <= $maxAge + ); + } + + return false; + } + + /** + * Get a property field for a cache entry. + * This returns null if the property is not set. + * If the item is already set, it will be pushed to the top of the cache. + * + * @param string $key + * @param string $prop + * @return mixed + */ + public function get( $key, $prop ) { + if ( !isset( $this->cache[$key][$prop] ) ) { + return null; + } + $this->ping( $key ); + return $this->cache[$key][$prop]; + } + + /** + * Clear one or several cache entries, or all cache entries. + * + * @param string|array $keys + * @return void + */ + public function clear( $keys = null ) { + if ( $keys === null ) { + $this->cache = []; + $this->cacheTimes = []; + } else { + foreach ( (array)$keys as $key ) { + unset( $this->cache[$key] ); + unset( $this->cacheTimes[$key] ); + } + } + } + + /** + * Resize the maximum number of cache entries, removing older entries as needed + * + * @param int $maxKeys + * @return void + * @throws UnexpectedValueException + */ + public function resize( $maxKeys ) { + Assert::parameterType( 'integer', $maxKeys, '$maxKeys' ); + Assert::parameter( $maxKeys > 0, '$maxKeys', 'must be above zero' ); + + $this->maxCacheKeys = $maxKeys; + while ( count( $this->cache ) > $this->maxCacheKeys ) { + reset( $this->cache ); + $evictKey = key( $this->cache ); + unset( $this->cache[$evictKey] ); + unset( $this->cacheTimes[$evictKey] ); + } + } + + /** + * Push an entry to the top of the cache + * + * @param string $key + */ + protected function ping( $key ) { + $item = $this->cache[$key]; + unset( $this->cache[$key] ); + $this->cache[$key] = $item; + } + + /** + * Get cache size + * @return int + */ + public function getSize() { + return $this->maxCacheKeys; + } +} |