6e9b4f0e9c
Per wikitech-l consensus: https://lists.wikimedia.org/pipermail/wikitech-l/2016-February/084821.html Notes: * Disabled CallTimePassByReference due to false positives (T127163) Change-Id: I2c8ce713ce6600a0bb7bf67537c87044c7a45c4b
131 lines
3.2 KiB
PHP
131 lines
3.2 KiB
PHP
<?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 a simple LRU key/value map with a maximum number of entries
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*
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* Use ProcessCacheLRU if hierarchical purging is needed or objects can become stale
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*
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* @see ProcessCacheLRU
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* @ingroup Cache
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* @since 1.23
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*/
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class MapCacheLRU {
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/** @var array */
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protected $cache = []; // (key => value)
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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 Exception When $maxCacheKeys is not an int or not above zero.
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*/
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public function __construct( $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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}
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/**
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* Set a key/value pair.
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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 mixed $value
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* @return void
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*/
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public function set( $key, $value ) {
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if ( array_key_exists( $key, $this->cache ) ) {
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$this->ping( $key );
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} 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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}
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$this->cache[$key] = $value;
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}
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/**
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* Check if a key exists
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*
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* @param string $key
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* @return bool
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*/
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public function has( $key ) {
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return array_key_exists( $key, $this->cache );
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}
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/**
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* Get the value for a key.
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* This returns null if the key 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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* @return mixed
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*/
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public function get( $key ) {
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if ( !array_key_exists( $key, $this->cache ) ) {
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return null;
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}
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$this->ping( $key );
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return $this->cache[$key];
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}
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/**
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* @return array
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* @since 1.25
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*/
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public function getAllKeys() {
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return array_keys( $this->cache );
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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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} else {
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foreach ( (array)$keys as $key ) {
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unset( $this->cache[$key] );
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}
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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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