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<?php |
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/** |
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* Per-process memory cache for storing items. |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License along |
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* with this program; if not, write to the Free Software Foundation, Inc., |
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
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* http://www.gnu.org/copyleft/gpl.html |
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* |
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* @file |
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* @ingroup Cache |
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*/ |
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use Wikimedia\Assert\Assert; |
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/** |
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* Handles per process caching of items |
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* @ingroup Cache |
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*/ |
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class ProcessCacheLRU { |
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/** @var Array */ |
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protected $cache = []; // (key => prop => value) |
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/** @var Array */ |
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protected $cacheTimes = []; // (key => prop => UNIX timestamp) |
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protected $maxCacheKeys; // integer; max entries |
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/** |
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* @param int $maxKeys Maximum number of entries allowed (min 1). |
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* @throws UnexpectedValueException When $maxCacheKeys is not an int or =< 0. |
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*/ |
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public function __construct( $maxKeys ) { |
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$this->resize( $maxKeys ); |
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} |
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/** |
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* Set a property field for a cache entry. |
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* This will prune the cache if it gets too large based on LRU. |
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* If the item is already set, it will be pushed to the top of the cache. |
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* |
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* @param string $key |
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* @param string $prop |
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* @param mixed $value |
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* @return void |
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*/ |
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public function set( $key, $prop, $value ) { |
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if ( isset( $this->cache[$key] ) ) { |
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$this->ping( $key ); |
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View Code Duplication |
} elseif ( count( $this->cache ) >= $this->maxCacheKeys ) { |
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reset( $this->cache ); |
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$evictKey = key( $this->cache ); |
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unset( $this->cache[$evictKey] ); |
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unset( $this->cacheTimes[$evictKey] ); |
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} |
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$this->cache[$key][$prop] = $value; |
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$this->cacheTimes[$key][$prop] = microtime( true ); |
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} |
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/** |
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* Check if a property field exists for a cache entry. |
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* |
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* @param string $key |
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* @param string $prop |
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* @param float $maxAge Ignore items older than this many seconds (since 1.21) |
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* @return bool |
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*/ |
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public function has( $key, $prop, $maxAge = 0.0 ) { |
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if ( isset( $this->cache[$key][$prop] ) ) { |
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return ( $maxAge <= 0 || |
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( microtime( true ) - $this->cacheTimes[$key][$prop] ) <= $maxAge |
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); |
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} |
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return false; |
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} |
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/** |
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* Get a property field for a cache entry. |
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* This returns null if the property is not set. |
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* If the item is already set, it will be pushed to the top of the cache. |
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* |
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* @param string $key |
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* @param string $prop |
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* @return mixed |
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*/ |
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public function get( $key, $prop ) { |
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if ( !isset( $this->cache[$key][$prop] ) ) { |
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return null; |
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} |
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$this->ping( $key ); |
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return $this->cache[$key][$prop]; |
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} |
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/** |
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* Clear one or several cache entries, or all cache entries. |
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* |
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* @param string|array $keys |
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* @return void |
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*/ |
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public function clear( $keys = null ) { |
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if ( $keys === null ) { |
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$this->cache = []; |
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$this->cacheTimes = []; |
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} else { |
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foreach ( (array)$keys as $key ) { |
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unset( $this->cache[$key] ); |
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unset( $this->cacheTimes[$key] ); |
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} |
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} |
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} |
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/** |
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* Resize the maximum number of cache entries, removing older entries as needed |
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* |
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* @param int $maxKeys |
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* @return void |
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* @throws UnexpectedValueException |
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*/ |
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public function resize( $maxKeys ) { |
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Assert::parameterType( 'integer', $maxKeys, '$maxKeys' ); |
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Assert::parameter( $maxKeys > 0, '$maxKeys', 'must be above zero' ); |
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$this->maxCacheKeys = $maxKeys; |
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while ( count( $this->cache ) > $this->maxCacheKeys ) { |
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reset( $this->cache ); |
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$evictKey = key( $this->cache ); |
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unset( $this->cache[$evictKey] ); |
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unset( $this->cacheTimes[$evictKey] ); |
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} |
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} |
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/** |
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* Push an entry to the top of the cache |
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* |
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* @param string $key |
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*/ |
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protected function ping( $key ) { |
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$item = $this->cache[$key]; |
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unset( $this->cache[$key] ); |
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$this->cache[$key] = $item; |
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} |
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/** |
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* Get cache size |
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* @return int |
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*/ |
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public function getSize() { |
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return $this->maxCacheKeys; |
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} |
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} |
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wikimedia /
mediawiki
