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Diffstat (limited to 'includes/filerepo/FileCache.php')
| -rw-r--r-- | includes/filerepo/FileCache.php | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/includes/filerepo/FileCache.php b/includes/filerepo/FileCache.php new file mode 100644 index 00000000..7840d1a3 --- /dev/null +++ b/includes/filerepo/FileCache.php @@ -0,0 +1,156 @@ +<?php +/** + * Cache of file objects, wrapping some RepoGroup functions to avoid redundant + * queries. Loosely inspired by the LinkCache / LinkBatch classes for titles. + * + * ISSUE: Merge with RepoGroup? + * + * @ingroup FileRepo + */ +class FileCache { + var $repoGroup; + var $cache = array(), $notFound = array(); + + protected static $instance; + + /** + * Get a FileCache instance. Typically, only one instance of FileCache + * is needed in a MediaWiki invocation. + */ + static function singleton() { + if ( self::$instance ) { + return self::$instance; + } + self::$instance = new FileCache( RepoGroup::singleton() ); + return self::$instance; + } + + /** + * Destroy the singleton instance, so that a new one will be created next + * time singleton() is called. + */ + static function destroySingleton() { + self::$instance = null; + } + + /** + * Set the singleton instance to a given object + */ + static function setSingleton( $instance ) { + self::$instance = $instance; + } + + /** + * Construct a group of file repositories. + * @param RepoGroup $repoGroup + */ + function __construct( $repoGroup ) { + $this->repoGroup = $repoGroup; + } + + + /** + * Add some files to the cache. This is a fairly low-level function, + * which most users should not need to call. Note that any existing + * entries for the same keys will not be replaced. Call clearFiles() + * first if you need that. + * @param array $files array of File objects, indexed by DB key + */ + function addFiles( $files ) { + wfDebug( "FileCache adding ".count( $files )." files\n" ); + $this->cache += $files; + } + + /** + * Remove some files from the cache, so that their existence will be + * rechecked. This is a fairly low-level function, which most users + * should not need to call. + * @param array $remove array indexed by DB keys to remove (the values are ignored) + */ + function clearFiles( $remove ) { + wfDebug( "FileCache clearing data for ".count( $remove )." files\n" ); + $this->cache = array_diff_keys( $this->cache, $remove ); + $this->notFound = array_diff_keys( $this->notFound, $remove ); + } + + /** + * Mark some DB keys as nonexistent. This is a fairly low-level + * function, which most users should not need to call. + * @param array $dbkeys array of DB keys + */ + function markNotFound( $dbkeys ) { + wfDebug( "FileCache marking ".count( $dbkeys )." files as not found\n" ); + $this->notFound += array_fill_keys( $dbkeys, true ); + } + + + /** + * Search the cache for a file. + * @param mixed $title Title object or string + * @return File object or false if it is not found + * @todo Implement searching for old file versions(?) + */ + function findFile( $title ) { + if( !( $title instanceof Title ) ) { + $title = Title::makeTitleSafe( NS_FILE, $title ); + } + if( !$title ) { + return false; // invalid title? + } + + $dbkey = $title->getDBkey(); + if( array_key_exists( $dbkey, $this->cache ) ) { + wfDebug( "FileCache HIT for $dbkey\n" ); + return $this->cache[$dbkey]; + } + if( array_key_exists( $dbkey, $this->notFound ) ) { + wfDebug( "FileCache negative HIT for $dbkey\n" ); + return false; + } + + // Not in cache, fall back to a direct query + $file = $this->repoGroup->findFile( $title ); + if( $file ) { + wfDebug( "FileCache MISS for $dbkey\n" ); + $this->cache[$dbkey] = $file; + } else { + wfDebug( "FileCache negative MISS for $dbkey\n" ); + $this->notFound[$dbkey] = true; + } + return $file; + } + + /** + * Search the cache for multiple files. + * @param array $titles Title objects or strings to search for + * @return array of File objects, indexed by DB key + */ + function findFiles( $titles ) { + $titleObjs = array(); + foreach ( $titles as $title ) { + if ( !( $title instanceof Title ) ) { + $title = Title::makeTitleSafe( NS_FILE, $title ); + } + if ( $title ) { + $titleObjs[$title->getDBkey()] = $title; + } + } + + $result = array_intersect_key( $this->cache, $titleObjs ); + + $unsure = array_diff_key( $titleObjs, $result, $this->notFound ); + if( $unsure ) { + wfDebug( "FileCache MISS for ".count( $unsure )." files out of ".count( $titleObjs )."...\n" ); + // XXX: We assume the array returned by findFiles() is + // indexed by DBkey; this appears to be true, but should + // be explicitly documented. + $found = $this->repoGroup->findFiles( $unsure ); + $result += $found; + $this->addFiles( $found ); + $this->markNotFound( array_keys( array_diff_key( $unsure, $found ) ) ); + } + + wfDebug( "FileCache found ".count( $result )." files out of ".count( $titleObjs )."\n" ); + return $result; + } +} |