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;;; emms-cache.el --- persistence for emms-track
;; Copyright (C) 2006, 2007, 2008 Free Software Foundation, Inc.
;; Author: Damien Elmes <emacs@repose.cx>
;; Keywords: emms, mp3, mpeg, multimedia
;; This file is part of EMMS.
;; EMMS 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 3, or (at your option)
;; any later version.
;; EMMS 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 EMMS; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
;;; Commentary:
;; The cache is a mapping of a full path name to information, and so
;; it is invalidated when you rename or move files about. It also does
;; not differentiate between file or uri tracks.
;; Because cache lookups are much faster than disk access, this works
;; much better with a later-do-interval of something like 0.001. Also
;; consider using synchronous mode, as it's quite fast now.
;; This code is activated by (emms-standard) and above.
;; To activate it by hand, use:
;; (emms-cache 1)
;;; Code:
(require 'emms)
(require 'emms-info)
(when (fboundp 'define-hash-table-test)
(define-hash-table-test 'string-hash 'string= 'sxhash))
(defvar emms-cache-db (make-hash-table
:test (if (fboundp 'define-hash-table-test)
'string-hash
'equal))
"A mapping of paths to file info.
This is used to cache over emacs sessions.")
(defvar emms-cache-dirty nil
"True if the cache has been updated since init.")
(defcustom emms-cache-file (concat (file-name-as-directory emms-directory) "cache")
"A file used to store cached file information over sessions."
:group 'emms
:type 'file)
(defcustom emms-cache-file-coding-system 'utf-8
"Coding system used for saving `emms-cache-file'."
:group 'emms
:type 'coding-system)
(defun emms-cache (arg)
"Turn on Emms caching if ARG is positive, off otherwise."
(interactive "p")
(if (and arg (> arg 0))
(progn
(add-hook 'after-init-hook 'emms-cache-restore)
(add-hook 'kill-emacs-hook 'emms-cache-save)
(setq emms-cache-get-function 'emms-cache-get)
(setq emms-cache-set-function 'emms-cache-set)
(setq emms-cache-modified-function 'emms-cache-dirty))
(remove-hook 'after-init-hook 'emms-cache-restore)
(remove-hook 'kill-emacs-hook 'emms-cache-save)
(setq emms-cache-get-function nil)
(setq emms-cache-set-function nil)
(setq emms-cache-modified-function nil)))
;;;###autoload
(defun emms-cache-enable ()
"Enable caching of Emms track data."
(interactive)
(emms-cache 1)
(message "Emms cache enabled"))
;;;###autoload
(defun emms-cache-disable ()
"Disable caching of Emms track data."
(interactive)
(emms-cache -1)
(message "Emms cache disabled"))
;;;###autoload
(defun emms-cache-toggle ()
"Toggle caching of Emms track data."
(interactive)
(if emms-cache-get-function
(emms-cache-disable)
(emms-cache-enable)))
(defsubst emms-cache-dirty (&rest ignored)
"Mark the cache as dirty."
(setq emms-cache-dirty t))
(defun emms-cache-get (type path)
"Return a cache element for PATH, or nil."
(gethash path emms-cache-db))
;; Note we ignore TYPE, as it's stored in TRACK
(defun emms-cache-set (type path track)
"Set PATH to TRACK in the cache."
(puthash path track emms-cache-db)
(emms-cache-dirty))
(defun emms-cache-del (path)
"Remove a track from the cache, with key PATH."
(remhash path emms-cache-db)
(emms-cache-dirty))
(defun emms-cache-save ()
"Save the track cache to a file."
(interactive)
(when emms-cache-dirty
(message "Saving emms track cache...")
(set-buffer (get-buffer-create " emms-cache "))
(erase-buffer)
(insert
(concat ";;; .emms-cache -*- mode: emacs-lisp; coding: "
(symbol-name emms-cache-file-coding-system)
"; -*-\n"))
(maphash (lambda (k v)
(insert (format
"(puthash %S '%S emms-cache-db)\n" k v)))
emms-cache-db)
(when (fboundp 'set-buffer-file-coding-system)
(set-buffer-file-coding-system emms-cache-file-coding-system))
(write-region (point-min) (point-max) emms-cache-file)
(kill-buffer (current-buffer))
(message "Saving emms track cache...done")
(setq emms-cache-dirty nil)))
(defun emms-cache-restore ()
"Restore the track cache from a file."
(interactive)
(load emms-cache-file t nil t)
(setq emms-cache-dirty nil))
(defun emms-cache-sync ()
"Sync the cache with the data on disc.
Remove non-existent files, and update data for files which have
been modified."
(interactive)
(message "Syncing emms track cache...")
(let (removed)
(maphash (lambda (path track)
(when (eq (emms-track-get track 'type) 'file)
;; if no longer here, remove
(if (not (file-exists-p path))
(progn
(remhash path emms-cache-db)
(setq removed t))
(let ((file-mtime (emms-info-track-file-mtime track))
(info-mtime (emms-track-get track 'info-mtime)))
(when (or (not info-mtime)
(emms-time-less-p
info-mtime file-mtime))
(run-hook-with-args 'emms-info-functions track))))))
emms-cache-db)
(when removed
(setq emms-cache-dirty t)))
(message "Syncing emms track cache...done"))
(provide 'emms-cache)
;;; emms-cache.el ends here
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