ae63b9ae10
Callers often tend to end up calling getFileStat(), at least indirectly, or in various successive function on the same path. This created RTTs when the file didn't exist since negatives were not cached. This change does the following: * Cache definitive negatives (404s) in the process cache. Nothing is cached on failure (like network problems). * Ignore process cache entries after a brief time period so long running scripts do not have overly stale entries. Change-Id: I356bd9f48281e3c7e7a273778b2aca59c521a0c7
131 lines
3.6 KiB
PHP
131 lines
3.6 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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/**
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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 = array(); // (key => prop => value)
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/** @var Array */
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protected $cacheTimes = array(); // (key => prop => UNIX timestamp)
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protected $maxCacheKeys; // integer; max entries
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/**
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* @param $maxKeys integer Maximum number of entries allowed (min 1).
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* @throws MWException When $maxCacheKeys is not an int or =< 0.
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*/
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public function __construct( $maxKeys ) {
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if ( !is_int( $maxKeys ) || $maxKeys < 1 ) {
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throw new MWException( __METHOD__ . " must be given an integer and >= 1" );
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}
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$this->maxCacheKeys = $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 $key string
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* @param $prop string
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* @param $value mixed
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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 ); // push to top
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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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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] = time();
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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 $key string
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* @param $prop string
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* @param $maxAge integer 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 ) {
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if ( isset( $this->cache[$key][$prop] ) ) {
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return ( $maxAge <= 0 || ( time() - $this->cacheTimes[$key][$prop] ) <= $maxAge );
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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 $key string
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* @param $prop string
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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][$prop] ) ) {
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$this->ping( $key ); // push to top
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return $this->cache[$key][$prop];
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} else {
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return null;
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}
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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 $keys string|Array
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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 = array();
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$this->cacheTimes = array();
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} else {
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foreach ( (array)$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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* Push an entry to the top of the cache
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*
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* @param $key string
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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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