MediaWiki 1.30.2

[autoinstallsdev/mediawiki.git] / includes / libs / ProcessCacheLRU.php

diff --git a/includes/libs/ProcessCacheLRU.php b/includes/libs/ProcessCacheLRU.php
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+<?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;
+
+/**
+ * Handles per process caching of items
+ * @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;
+       }
+}