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diff --git a/www/wiki/includes/libs/MapCacheLRU.php b/www/wiki/includes/libs/MapCacheLRU.php
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+++ b/www/wiki/includes/libs/MapCacheLRU.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 a simple LRU key/value map with a maximum number of entries
+ *
+ * Use ProcessCacheLRU if hierarchical purging is needed or objects can become stale
+ *
+ * @see ProcessCacheLRU
+ * @ingroup Cache
+ * @since 1.23
+ */
+class MapCacheLRU {
+	/** @var array */
+	protected $cache = []; // (key => value)
+
+	protected $maxCacheKeys; // integer; max entries
+
+	/**
+	 * @param int $maxKeys Maximum number of entries allowed (min 1).
+	 * @throws Exception When $maxCacheKeys is not an int or not above zero.
+	 */
+	public function __construct( $maxKeys ) {
+		Assert::parameterType( 'integer', $maxKeys, '$maxKeys' );
+		Assert::parameter( $maxKeys > 0, '$maxKeys', 'must be above zero' );
+
+		$this->maxCacheKeys = $maxKeys;
+	}
+
+	/**
+	 * @param array $values Key/value map in order of increasingly recent access
+	 * @param int $maxKeys
+	 * @return MapCacheLRU
+	 * @since 1.30
+	 */
+	public static function newFromArray( array $values, $maxKeys ) {
+		$mapCache = new self( $maxKeys );
+		$mapCache->cache = ( count( $values ) > $maxKeys )
+			? array_slice( $values, -$maxKeys, null, true )
+			: $values;
+
+		return $mapCache;
+	}
+
+	/**
+	 * @return array Key/value map in order of increasingly recent access
+	 * @since 1.30
+	 */
+	public function toArray() {
+		return $this->cache;
+	}
+
+	/**
+	 * Set a key/value pair.
+	 * 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.
+	 *
+	 * To reduce evictions due to one-off use of many new keys, $rank can be
+	 * set to have keys start at the top of a bottom fraction of the list. A value
+	 * of 3/8 means values start at the top of the bottom 3/8s of the list and are
+	 * moved to the top of the list when accessed a second time.
+	 *
+	 * @param string $key
+	 * @param mixed $value
+	 * @param float $rank Bottom fraction of the list where keys start off [Default: 1.0]
+	 * @return void
+	 */
+	public function set( $key, $value, $rank = 1.0 ) {
+		if ( $this->has( $key ) ) {
+			$this->ping( $key );
+		} elseif ( count( $this->cache ) >= $this->maxCacheKeys ) {
+			reset( $this->cache );
+			$evictKey = key( $this->cache );
+			unset( $this->cache[$evictKey] );
+		}
+
+		if ( $rank < 1.0 && $rank > 0 ) {
+			$offset = intval( $rank * count( $this->cache ) );
+			$this->cache = array_slice( $this->cache, 0, $offset, true )
+				+ [ $key => $value ]
+				+ array_slice( $this->cache, $offset, null, true );
+		} else {
+			$this->cache[$key] = $value;
+		}
+	}
+
+	/**
+	 * Check if a key exists
+	 *
+	 * @param string $key
+	 * @return bool
+	 */
+	public function has( $key ) {
+		if ( !is_int( $key ) && !is_string( $key ) ) {
+			throw new UnexpectedValueException(
+				__METHOD__ . ' called with invalid key. Must be string or integer.' );
+		}
+		return array_key_exists( $key, $this->cache );
+	}
+
+	/**
+	 * Get the value for a key.
+	 * This returns null if the key is not set.
+	 * If the item is already set, it will be pushed to the top of the cache.
+	 *
+	 * @param string $key
+	 * @return mixed Returns null if the key was not found
+	 */
+	public function get( $key ) {
+		if ( !$this->has( $key ) ) {
+			return null;
+		}
+
+		$this->ping( $key );
+
+		return $this->cache[$key];
+	}
+
+	/**
+	 * @return array
+	 * @since 1.25
+	 */
+	public function getAllKeys() {
+		return array_keys( $this->cache );
+	}
+
+	/**
+	 * Get an item with the given key, producing and setting it if not found.
+	 *
+	 * If the callback returns false, then nothing is stored.
+	 *
+	 * @since 1.28
+	 * @param string $key
+	 * @param callable $callback Callback that will produce the value
+	 * @param float $rank Bottom fraction of the list where keys start off [Default: 1.0]
+	 * @return mixed The cached value if found or the result of $callback otherwise
+	 */
+	public function getWithSetCallback( $key, callable $callback, $rank = 1.0 ) {
+		if ( $this->has( $key ) ) {
+			$value = $this->get( $key );
+		} else {
+			$value = call_user_func( $callback );
+			if ( $value !== false ) {
+				$this->set( $key, $value, $rank );
+			}
+		}
+
+		return $value;
+	}
+
+	/**
+	 * Clear one or several cache entries, or all cache entries
+	 *
+	 * @param string|array $keys
+	 * @return void
+	 */
+	public function clear( $keys = null ) {
+		if ( $keys === null ) {
+			$this->cache = [];
+		} else {
+			foreach ( (array)$keys as $key ) {
+				unset( $this->cache[$key] );
+			}
+		}
+	}
+
+	/**
+	 * 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;
+	}
+}