Rss-Bridge/lib/Cache.php
logmanoriginal 556a417dd6 core: Add support for custom cache types via config.ini.php
This commit adds support for a new parameter which specifies the type
of cache to use for caching. It is specified in config.ini.php:

 [cache]

 type = "..."

Currently only one type of cache is supported (see /caches). All uses
of 'FileCache' were replaced by this configuration option.

Note: Caching currently depends on files and folders (due to FileCache).
Experience may vary depending on the selected cache type. For now always
check if FileCache is working before testing alternative types.

References #1000
2019-02-06 18:52:44 +01:00

213 lines
5.8 KiB
PHP

<?php
/**
* This file is part of RSS-Bridge, a PHP project capable of generating RSS and
* Atom feeds for websites that don't have one.
*
* For the full license information, please view the UNLICENSE file distributed
* with this source code.
*
* @package Core
* @license http://unlicense.org/ UNLICENSE
* @link https://github.com/rss-bridge/rss-bridge
*/
/**
* Factory class responsible for creating cache objects from a given working
* directory.
*
* This class is capable of:
* - Locating cache classes in the specified working directory (see {@see Cache::$workingDir})
* - Creating new cache instances based on the cache's name (see {@see Cache::create()})
*
* The following example illustrates the intended use for this class.
*
* ```PHP
* require_once __DIR__ . '/rssbridge.php';
*
* // Step 1: Set the working directory
* Cache::setWorkingDir(__DIR__ . '/../caches/');
*
* // Step 2: Create a new instance of a cache object (based on the name)
* $cache = Cache::create('FileCache');
* ```
*/
class Cache {
/**
* Holds a path to the working directory.
*
* Do not access this property directly!
* Use {@see Cache::setWorkingDir()} and {@see Cache::getWorkingDir()} instead.
*
* @var string|null
*/
protected static $workingDir = null;
/**
* Throws an exception when trying to create a new instance of this class.
* Use {@see Cache::create()} to create a new cache object from the working
* directory.
*
* @throws \LogicException if called.
*/
public function __construct(){
throw new \LogicException('Use ' . __CLASS__ . '::create($name) to create cache objects!');
}
/**
* Creates a new cache object from the working directory.
*
* @throws \InvalidArgumentException if the requested cache name is invalid.
* @throws \Exception if the requested cache file doesn't exist in the
* working directory.
* @param string $name Name of the cache object.
* @return object|bool The cache object or false if the class is not instantiable.
*/
public static function create($name){
$name = self::sanitizeCacheName($name) . 'Cache';
if(!self::isCacheName($name)) {
throw new \InvalidArgumentException('Cache name invalid!');
}
$filePath = self::getWorkingDir() . $name . '.php';
if(!file_exists($filePath)) {
throw new \Exception('Cache file ' . $filePath . ' does not exist!');
}
require_once $filePath;
if((new \ReflectionClass($name))->isInstantiable()) {
return new $name();
}
return false;
}
/**
* Sets the working directory.
*
* @param string $dir Path to a directory containing cache classes
* @throws \InvalidArgumentException if $dir is not a string.
* @throws \Exception if the working directory doesn't exist.
* @throws \InvalidArgumentException if $dir is not a directory.
* @return void
*/
public static function setWorkingDir($dir){
self::$workingDir = null;
if(!is_string($dir)) {
throw new \InvalidArgumentException('Working directory is not a valid string!');
}
if(!file_exists($dir)) {
throw new \Exception('Working directory does not exist!');
}
if(!is_dir($dir)) {
throw new \InvalidArgumentException('Working directory is not a directory!');
}
self::$workingDir = realpath($dir) . '/';
}
/**
* Returns the working directory.
* The working directory must be set with {@see Cache::setWorkingDir()}!
*
* @throws \LogicException if the working directory is not set.
* @return string The current working directory.
*/
public static function getWorkingDir(){
if(is_null(self::$workingDir)) {
throw new \LogicException('Working directory is not set!');
}
return self::$workingDir;
}
/**
* Returns true if the provided name is a valid cache name.
*
* A valid cache name starts with a capital letter ([A-Z]), followed by
* zero or more alphanumeric characters or hyphen ([A-Za-z0-9-]).
*
* @param string $name The cache name.
* @return bool true if the name is a valid cache name, false otherwise.
*/
public static function isCacheName($name){
return is_string($name) && preg_match('/^[A-Z][a-zA-Z0-9-]*$/', $name) === 1;
}
/**
* Returns a list of cache names from the working directory.
*
* The list is cached internally to allow for successive calls.
*
* @return array List of cache names
*/
public static function getCacheNames(){
static $cacheNames = array(); // Initialized on first call
if(empty($cacheNames)) {
$files = scandir(self::getWorkingDir());
if($files !== false) {
foreach($files as $file) {
if(preg_match('/^([^.]+)Cache\.php$/U', $file, $out)) {
$cacheNames[] = $out[1];
}
}
}
}
return $cacheNames;
}
/**
* Returns the sanitized cache name.
*
* The cache name can be specified in various ways:
* * The PHP file name (i.e. `FileCache.php`)
* * The PHP file name without file extension (i.e. `FileCache`)
* * The cache name (i.e. `file`)
*
* Casing is ignored (i.e. `FILE` and `fIlE` are the same).
*
* A cache file matching the given cache name must exist in the working
* directory!
*
* @param string $name The cache name
* @return string|null The sanitized cache name if the provided name is
* valid, null otherwise.
*/
protected static function sanitizeCacheName($name) {
if(is_string($name)) {
// Trim trailing '.php' if exists
if(preg_match('/(.+)(?:\.php)/', $name, $matches)) {
$name = $matches[1];
}
// Trim trailing 'Cache' if exists
if(preg_match('/(.+)(?:Cache)/i', $name, $matches)) {
$name = $matches[1];
}
// The name is valid if a corresponding file is found on disk
if(in_array(strtolower($name), array_map('strtolower', self::getCacheNames()))) {
$index = array_search(strtolower($name), array_map('strtolower', self::getCacheNames()));
return self::getCacheNames()[$index];
}
Debug::log('Invalid cache name specified: "' . $name . '"!');
}
return null; // Bad parameter
}
}