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;;; gh-cache.el --- caching for gh.el
;; Copyright (C) 2011 Yann Hodique
;; Author: Yann Hodique <>
;; Keywords:
;; This file 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 2, or (at your option)
;; any later version.
;; This file is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to
;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Commentary:
;;; Code:
(require 'cl))
(require 'eieio)
(require 'pcache)
(defconst gh-cache-outdated-expiration-delay (* 60 60 24))
(defconst gh-cache-internal-version-constant 4)
(defconst gh-cache-version-constant
(format "%s/gh-%s" pcache-version-constant gh-cache-internal-version-constant))
(defclass gh-cache (pcache-repository)
((version-constant :allocation :class)
(entries :initarg :entries :initform (make-hash-table :test 'equal))
(safe-methods :allocation :class :initform ("HEAD" "GET" "OPTIONS" "TRACE"))
(invalidation-chain :allocation :class :initform nil)
(entry-cls :initarg :entry-cls :initform gh-cache-entry)))
(oset-default 'gh-cache version-constant gh-cache-version-constant)
(defclass gh-cache-entry (pcache-entry)
((etag :initarg :etag :initform nil)
(outdated :initarg :outdated :initform nil)
;; (ttl :initarg :ttl :initform 0)
(defmethod pcache-invalidate :after ((cache gh-cache) key)
(let ((resource (car key)))
(pcache-map cache #'(lambda (k v)
(when (equal (car k) resource)
(pcache-invalidate cache k))))
(dolist (next (oref cache invalidation-chain))
(let ((nextresource
(replace-regexp-in-string (car next) (cdr next) resource)))
(when (not (equal nextresource resource))
(pcache-map cache #'(lambda (k v)
(when (equal (car k) nextresource)
(pcache-invalidate cache k)))))))))
(defmethod pcache-get ((cache gh-cache) key &optional default)
(let* ((table (oref cache :entries))
(entry (gethash key table)))
(if (not entry)
(unless (pcache-entry-valid-p entry)
(oset entry :outdated t))
(oref entry :value))))
(defmethod pcache-has ((cache pcache-repository) key)
(let* ((default (make-symbol ":nil"))
(table (oref cache :entries))
(entry (gethash key table default)))
(not (eq entry default))))
(defmethod pcache-purge-invalid ((cache gh-cache))
(let ((table (oref cache :entries)))
(maphash #'(lambda (k e)
(unless (gh-cache-expired-p e)
(remhash k table)))
(pcache-save cache)))
(defmethod gh-cache-outdated-p ((cache gh-cache) key)
(let* ((table (oref cache :entries))
(entry (gethash key table)))
(and entry
(oref entry :outdated))))
(defmethod gh-cache-expired-p ((cache gh-cache) key)
(let* ((table (oref cache :entries))
(entry (gethash key table)))
(and (gh-cache-outdated-p cache key)
(let ((time (float-time (current-time))))
(< time (+ gh-cache-outdated-expiration-delay
(oref entry :timestamp))))))))
(defmethod gh-cache-revive ((cache gh-cache) key)
(let* ((table (oref cache :entries))
(entry (gethash key table)))
(and entry
(oset entry :outdated nil)
(oset entry :timestamp (float-time (current-time)))
(defmethod gh-cache-etag ((cache gh-cache) key)
(let* ((table (oref cache :entries))
(entry (gethash key table)))
(and entry
(oref entry :etag))))
(defmethod gh-cache-set-etag ((cache gh-cache) key etag)
(let* ((table (oref cache :entries))
(entry (gethash key table)))
(and entry
(oset entry :etag etag))))
(provide 'gh-cache)
;;; gh-cache.el ends here
;; Local Variables:
;; indent-tabs-mode: nil
;; End: