axelhahn / ahcache

php class to store serializable data in the filesystem

cache.class.php

AXELS CONTENT CACHE CLASS

Version 2.11

👤 Author: Axel Hahn
🧾 Source: https://github.com/axelhahn/ahcache/
📜 License: GNU GPL 3.0
📗 Docs: https://www.axel-hahn.de/docs/ahcache/

Description

The cache class AhCache caches all serializable objects in local files. In short: nearly all kind of data you can create in PHP: strings, arrays, ... whatever.

You can use it for any long running process, i.e. database requests, requests to external resources/ APIs, any long running procedure.

Write it ... and instead of repeating the long running process on a frequent requests you can access a cached result. What is quite fast.

Reqirements

PHP7 or 8 (up to PHP 8.2)

Features

• Fast filebased local cache
• cache items are initialized with any application and an id to make it unique and to separate all cache items by an application or task
• invalidate your cache with different methods:
  • by a TTL vlue in seconds
• by a local reference file (you can touch a file to invalidate a cache)
  • touch a single module based file to all cache items of th module
• a cleanup method can delete all outdated cache items of all applications or a selected application
• a cache admin (web ui) visualizes the created cache items

History

2009-07-20  1.0  cache class on www.axel-hahn.de
2011-08-27  1.1  comments added; sCacheFile is private
2012-02-04  2.0  cache serialzable types; more methods, i.e.:
                  - comparison of timestimp with a sourcefile
                  - cleanup unused cachefiles
2012-05-15  2.1  isExpired() returns as bool; new method iExpired() to get
                 expiration in sec
2012-05-15  2.2  - rename to AhCache
                 - _cleanup checks with file_exists
2014-03-31  2.3  - added _setup() that to includes custom settings
                 - limit number of files in cache directory
2019-11-24  2.4  - added getCachedItems() to get a filtered list of cache files
                 - added remove file to make complete cache of a module invalid
                 - rename var in cache.class_config.php to "$this->_sCacheDirDivider"
2019-11-26  2.5  - added getModules() to get a list of existing modules that stored
                   a cached item
2019-11-xx  2.7  - class was moved to folder src
                 - added admin webgui
                 - method getCachedItems - fix filter lifetime_greater
2021-09-28  2.6  added a simple admin UI; the cache class got a few new methods
                 - update: cleanup() now always deletes expired items
                 - update: dump() styles output as table
                 - added: getCurrentModule 
                 - added: deleteModule 
                 - added: loadCachefile
                 - added: removefileDelete
                 - added: setCacheId
                 - added: setModule
2021-10-07  2.7  FIX: remove chdir() in _readCacheItem()
                 ADD reference file to expire a cache item
                 - added: getRefFile
                 - added: setRefFile
                 - update: dump, isExpired, isNewerThanFile, write
                 - update cache admin
2021-10-07  2.8  FIX: remove chdir() in _readCacheItem()
                 ADD reference file to expire a cache item
                 - added: getRefFile
                 - added: setRefFile
                 - update: dump, isExpired, isNewerThanFile, write
                 - update cache admin
2023-03-17  2.9  FIX: harden _getAllCacheData to prevent PHP warnings
2023-06-02  2.10 shorten code: defaults using ??; short array syntax
2023-11-20  2.11 check data subkey before writing

Code examples

In your application for caching and cleanup you need the file cache.class.php only (which is in the folder src). Copy it into your classes folder.

Typical usage:

Example using expiration (ttl value):

$sContent='';  
$iTtl=60*5; // 5 min 
  
require_once("/php/cache.class.php");  
$myCache=new AhCache("my-app","task-id");  
  
if($myCache->isExpired()) {  
	// cache does not exist or is expired
	$sContent=...  
  
	// save cache
	$myCache->write($sContent, $iTtl);  
  
} else {  
	// read cached data
	$sContent=$myCache->read();  
}  
  
// output
echo $sContent;  

Example: compare age of cache with age of a sourcefile (before version v 2.8)

require_once("/php/cache.class.php");  
$sCsvFile="my_source_file.csv"  
  
$myCache=new AhCache("my-app","task-id");  
$sContent=$myCache->read(); // read cached data
  
// comparison of last modified time (mtime)
if (!$myCache->isNewerThanFile($sCsvFile)) {  
  
	// update content 
	$sContent=...  
  
	// ... and save cache
	$myCache->write($sContent);  
};  
  
// output
echo $sContent;

Cleanup cache directory

require_once("/php/cache.class.php");  

// delete all Cachefiles of the module "my-app" older 1 day
$o=new AhCache("my-app");
$o->cleanup(60*60*24*1); 

// or cleanup cachefiles of all modules
$o=new Cache(); $o->cleanup(60*60*24*1);

Cache admin

Optionally you can enable a web ui to browse all modules and its known cache items.