Add a new FileCache class to wrap RepoGroup::findFile() and findFiles(), and make...

XXX: The code seems to more or less work, but it obviously needs more testing, regarding both stability and memory usage.  In particular, I have not tested file uploads yet -- there may be consistency issues there.

diff --git a/RELEASE-NOTES b/RELEASE-NOTES
index 866e81f..feca50a 100644 (file)
--- a/RELEASE-NOTES
+++ b/RELEASE-NOTES
@@ -229,6 +229,7 @@ The following extensions are migrated into MediaWiki 1.14:
   your language) instead of Wikipedia.
 * (bug 16635) The "view and edit watchlist" page (Special:Watchlist/edit) now
   includes a table of contents
+* File objects returned by wfFindFile() are now cached by default
 
 === Bug fixes in 1.14 ===
 

diff --git a/includes/AutoLoader.php b/includes/AutoLoader.php
index f6eb5d8..ce1912e 100644 (file)
--- a/includes/AutoLoader.php
+++ b/includes/AutoLoader.php
@@ -365,6 +365,7 @@ $wgAutoloadLocalClasses = array(
        # includes/filerepo
        'ArchivedFile' => 'includes/filerepo/ArchivedFile.php',
        'File' => 'includes/filerepo/File.php',
+       'FileCache' => 'includes/filerepo/FileCache.php',
        'FileRepo' => 'includes/filerepo/FileRepo.php',
        'FileRepoStatus' => 'includes/filerepo/FileRepoStatus.php',
        'ForeignAPIFile' => 'includes/filerepo/ForeignAPIFile.php',

diff --git a/includes/GlobalFunctions.php b/includes/GlobalFunctions.php
index 4430440..d450836 100644 (file)
--- a/includes/GlobalFunctions.php
+++ b/includes/GlobalFunctions.php
@@ -2719,10 +2719,15 @@ function &wfGetLBFactory() {
  *                    current version. An image object will be returned which
  *                    was created at the specified time.
  * @param mixed $flags FileRepo::FIND_ flags
+ * @param boolean $bypass Bypass the file cache even if it could be used
  * @return File, or false if the file does not exist
  */
-function wfFindFile( $title, $time = false, $flags = 0 ) {
-       return RepoGroup::singleton()->findFile( $title, $time, $flags );
+function wfFindFile( $title, $time = false, $flags = 0, $bypass = false ) {
+        if( !$time && !$flags && !$bypass ) {
+               return FileCache::singleton()->findFile( $title );
+       } else {
+               return RepoGroup::singleton()->findFile( $title, $time, $flags );
+       }
 }
 
 /**

diff --git a/includes/filerepo/FileCache.php b/includes/filerepo/FileCache.php
new file mode 100644 (file)
index 0000000..7840d1a
--- /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;
+       }
+}