Class: Cache
- Package: saf.Cache
- Author: John Luxford <lux@simian.ca>
- Copyright: Copyright (C) 2001-2003, Simian Systems Inc.
- License: http://www.sitellite.org/index/license Simian Open Software License
- Version: 1.2, 2003-06-28, $Id: Cache.php,v 1.6 2008/05/22 21:16:28 cbrunet Exp $
- Access: public
Cache provides a simple and lightweight system for caching dynamic web
pages. Offers ordinary filesystem caching, as well as caching to Berkeley
Databases (BDB) (good for persistent objects), and optionally to a proxy server.
In the proxy server situation, Cache does not actually store the data, instead,
Cache simply passes an HTTP Expires header, setting a time for the proxy server
to cache for us. Can optionally use the saf.File.Store package to improve the
performance of filesystem-based caching on large volume stores.
New in 1.2:
- Added a shutdown() method.
New in 1.4:
- New logic in is_cacheable() allows subsequent rules to override previous ones.
New in 1.6:
- Added memcache support (requires PHP's memcache extension). Just set the dir
to "memcache:servername:portnum". The memcached keys are the URI and the values
are uncompressed HTML.
Usage Example
<?php
loader_import ("saf.Cache");
$cache = new Cache ("cache");
$uri = $_SERVER["REQUEST_URI"];
// set cache to expire every 15 minutes
if ($cache->expired ($uri, 900)) {
// re-cache the page
ob_start ();
// go about creating the page
// now we need to send the data to the cache file
// as well as to the visitor
$data = ob_get_contents ();
ob_end_clean ();
$cache->file ($uri, $data);
echo $data;
} else {
// show the cached version
echo $cache->show ($uri);
}
?>
Properties
$dir
- Access: public
Contains the path to the directory used to store the cached pages.
$set
- Access: public
Stores whether the URI was determined cacheable.
$error
- Access: public
Contains the error message if an error occurs.
$duration = 3600
- Access: public
The length of time to store cached objects before expiring them.
Methods
Cache ($dir = '', $duration = 3600)
- Access: public
Constructor method. Defines the directory Cache will use to store pages.
If the string 'mod:proxy' is given instead, Cache will know not to cache the data
locally, but rather to simply pass an HTTP Expires header for the proxy server to
do the work. If $dir is a string beginning with 'bdb:', Cache will store the data
in a Berkeley Database identified by the rest of the value of $dir. If the $dir
string begins with 'store:', Cache will use the saf.File.Store package to store
cached documents, which is recommended over the default file handling for caches
with a larger number of documents. See that package for more details.
setIgnoreChars ($ignore = 0)
- Access: public
Sets the number of characters to ignore when using the 'store:' data
store. This allows for better distribution of files across folders by
ignoring a specified number of characters at the beginning of the file name.
Note that the serialize() method will be called before the characters are
evaluated, so any non-valid characters will be stripped out and should not
be counted in this number.
serialize ($file = '')
- Access: public
- Return: string
Takes the string provided (which is usually the global $REQUEST_URI,
and returns a version of it without illegal characters so it can be used as a
file name to store a cached page.
file ($file = '', $data = '')
- Access: public
- Return: boolean
Takes a string (to serialize into a file name) and page data to be
cached, and creates a cached file that can be recalled later. Also serves as
the caching call in BDB and proxy server caching situations. Note: For BDB
data stores, you will want to call $cache_obj->bdb->close (); after you have
finished caching, so that BDB doesn't lock the database on you for the next
user.
expired ($file = '', $duration = 0)
- Access: public
- Return: boolean
Takes a string (to serialize into a file name) and a duration (the number
of seconds to keep the cached file for), and returns whether or not the file has
expired. True means it has.
expire ($file)
- Access: public
Cause a single cached file to expire so it can be regenerated on the next
request for it.
show ($file = '')
- Access: public
- Return: string
Takes a string (to serialize into a file name), and returns its contents
in a string (for the purpose of passing on to the visitor).
is_cacheable ($uri, $list)
- Access: public
- Return: boolean
Checks a URI against a list of cacheable pages, and returns a true/false
as to whether or not that URI is cacheable. Pages in the cacheable list may
include a wildcard (*) character to imply any number of characters.
shutdown ()
- Access: public
Performs any possible shutdown logic, depending on the cache
storage method.
clear ()
- Access: public
Flush the entire cache at once so that all files will be regenerated
on their next request.