refactor caching code into emms-cache.el

* caching support is now provided via two function vars in emms.el,
  emms-cache-get-function and emms-cache-set-function
* (emms-standard) or above will enable caching support
* you'll need to remove .emms-cache or s/emms-info-cache/emms-cache-db/

darcs-hash:20060607125345-4e3e3-7d9ad8d243a395f2f2a5eea004e58ac9e239855b.gz

1 files changed, 12 insertions, 76 deletions

diff --git a/emms-info.el b/emms-info.el
index c4533bd..0edeb85 100644
--- a/emms-info.el
+++ b/emms-info.el
@@ -67,33 +67,6 @@ Each is called with a track as argument."
 (defvar emms-info-asynchronous-tracks 0
   "Number of tracks we're waiting for to be done.")
 
-;; cache support (break into a separate file and make
-;; emms-info-really-initialize-track into a variable controlling which
-;; function to use)?
-
-;; The cache is invalidated when track names are changed. It also does
-;; not differenciate between file or uri tracks, and relies on the
-;; uniqueness of the name.
-
-;; usage - in your .emacs
-
-;; (add-hook 'after-init-hook 'emms-info-cache-restore)
-;; (add-hook 'kill-emacs-hook 'emms-info-cache-save)
-
-;; this is works much better with a later-do-interval of something
-;; like 0.001
-
-(define-hash-table-test 'string-hash 'string= 'sxhash)
-(defvar emms-info-cache (make-hash-table :test 'string-hash)
-  "A mapping of paths to file info.
-This is used to cache file info over emacs sessions.")
-
-(defvar emms-info-cache-file "~/.emms-cache"
-  "A file used to store cached file info information over sessions")
-
-(defvar emms-info-cache-dirty nil
-  "True if the cache has been updated since init.")
-
 (defun emms-info-initialize-track (track)
   "Initialize TRACK with emms-info information.
 This is a suitable value for `emms-track-initialize-functions'."
@@ -107,34 +80,18 @@ This is a suitable value for `emms-track-initialize-functions'."
 Return t when the track got changed."
   (let ((file-mtime (when emms-info-auto-update
                       (emms-info-track-file-mtime track)))
-        (name (emms-track-get track 'name))
-        cached-track
-        updated)
-
-    (when (setq cached-track (gethash name emms-info-cache))
-      ;; We need to modify TRACK. This way we lose information already
-      ;; present in TRACK, which is not necessarily what we want, but
-      ;; it's efficient.
-      (setcar track (car cached-track))
-      (setcdr track (cdr cached-track)))
-
-    ;; if uncached, or cached and the time has changed
-    (when (or (not cached-track)
-              (and cached-track
-               emms-info-auto-update
-               (let ((info-mtime (emms-track-get track 'info-mtime)))
-                 (or (not (consp info-mtime))
-                     (emms-time-less-p info-mtime file-mtime)))))
-      (setq updated t)
-      (run-hook-with-args 'emms-info-functions track))
-
-    (emms-track-set track 'info-mtime file-mtime)
-    (emms-track-updated track)
-
-    (when (or (not cached-track)
-            updated)
-        (puthash name track emms-info-cache)
-        (setq emms-info-cache-dirty t))
+        (info-mtime (emms-track-get track 'info-mtime))
+        (name (emms-track-get track 'name)))
+
+    ;; if the file's been modified or is new
+    (when (or (not info-mtime)
+              (emms-time-less-p
+               info-mtime file-mtime))
+      (run-hook-with-args 'emms-info-functions track)
+      ;; not set by info functions
+      (emms-track-set track 'info-mtime file-mtime)
+      (funcall emms-cache-set-function name track)
+      (emms-track-updated track))
 
     (when emms-info-asynchronously
       (setq emms-info-asynchronous-tracks (1- emms-info-asynchronous-tracks))
@@ -142,27 +99,6 @@ Return t when the track got changed."
         (message "EMMS: All track information loaded.")))
     t))
 
-(defun emms-info-cache-save ()
-  "Save the info cache to a file."
-  (when emms-info-cache-dirty
-    (message "Saving emms info cache...")
-    (set-buffer (get-buffer-create " emms-info-cache "))
-    (erase-buffer)
-    (maphash (lambda (k v)
-               (insert (format
-                        "(puthash %S '%S emms-info-cache)\n" k v)))
-             emms-info-cache)
-    (set-buffer-file-coding-system 'mule-utf-8)
-    (write-region (point-min) (point-max) emms-info-cache-file)
-    (kill-buffer (current-buffer))
-    (message "Saving emms info cache...done")
-    (setq emms-info-cache-dirty nil)))
-
-(defun emms-info-cache-restore ()
-  "Restore the info cache from a file."
-  (load emms-info-cache-file t nil t)
-  (setq emms-info-cache-dirty nil))
-
 (defun emms-info-track-file-mtime (track)
   "Return the mtime of the file of TRACK, if any.
 Return zero otherwise."