Package COM.INFORMATIMAGO.COMMON-LISP.CESARUM.CACHE

This package implements a generic disk-based cache.

Example:

    (defparameter *web-cache* (make-instance 'cache :directory-path "CACHE:WEB;"
                                                    :value-file-type "HTML"
                                                    :producer (function get-url)))

    (cache-get *web-cache* "http://www.informatimago.com/")
     --> "&lt;!DOCTYPE html PUBLIC …" ; :FETCHED

    (cache-get *web-cache* "http://www.informatimago.com/")
     --> "&lt;!DOCTYPE html PUBLIC …" ; :IN-CORE

License:

    AGPL3

    Copyright Pascal J. Bourguignon 2005 - 2015

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program 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 Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.
    If not, see <http://www.gnu.org/licenses/>

cache

class

A generic disk-based cache.

Class precedence list: CACHE STANDARD-OBJECT T

Class init args: DIRECTORY-PATH VALUE-FILE-TYPE PRODUCER

(cache-directory-path cache)

generic-function

Path to the directory where the cache data is stored.

(cache-expiration cache key)

generic-function

RETURN: NIL or the universal-time of expiration of the CACHE.

(cache-expire cache key &key keep-file)

generic-function

DO:         Expire the entry KEY from the CACHE.
KEEP-FILE:  When true, the file is not deleted from the cache.

(cache-expire-all cache &key keep-files)

generic-function

DO:         Expire all the entries from the CACHE.
KEEP-FILE:  When true, the files are not deleted from the cache.

(cache-get cache key)

generic-function

RETURN:  the value stored in the CACHE for the KEY;
         :FETCHED --> the value was obtained by the CACHE-PRODUCER.
         :IN-CORE --> the value was in memory
         :ON-DISK --> the value was on disk (in the disk cache).

(cache-index-file-path cache)

generic-function

RETURN: The path to the cache index file.

(cache-producer cache)

generic-function

RETURN: The cache producer of the cache.

(cache-value-file-type cache)

generic-function

RETURN: The type used for value files in the cache directory.

entry

structure

A cache index entry, mapping a key with the date the resource
was fetched and the file-name of the files where the resource and
the parsed html are stored, and references to these data when they
are loaded in core.

(entry-expire-date entry)

function

RETURN: The universal-time when the entry expires.

(entry-fetch-date entry)

function

RETURN: The universal-time when the entry was stored.

(entry-file-name entry)

function

RETURN: The name of the file where the value is stored.

(entry-key entry)

function

RETURN: The key of the entry.

(entry-value entry)

function

PRE:    (entry-value-p entry)
RETURN: The value of the entry.

(entry-value-p entry)

function

RETURN: Whether the value of the entry is loaded.

(make-cache directory producer &key value-file-type)

function

DO:     Make a new cache instance.
NOTE:   Send synchronize

(synchronize-cache cache)

generic-function

DO:     Ensure the cache index in core and on disk are synchronized.