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<?php
/**
* Simple on-disk variable caching class. Implements file caching logic.
*/
class MyCache {
private function __construct() {}
private function __clone() {}
/**
* Sets given cache line to given value
*
* @param id string cache line name. It should follow file naming conventions.
* @param value object - any serializable variable
*
* @return its second argument
*/
static function set($id, $value) {
file_put_contents(BASEPATH.'/caches/MyCache/'.$id, serialize($value));
return $value;
}
/**
* fetches cached value from disk
*
* @param id string - cache line identifier to fetch. It should follow file naming conventions.
* @param valid int - if exists and non zero, method throws ExceptionCacheLineExpired if cache line
* is older than given time in seconds
*
* @return restored variable contents
*/
static function get($id, $valid=0, $callback=null, $passexception=true) {
$isValid = self::valid($id, $valid);
if ($valid != 0 && !$isValid && $callback===null) {
throw new CacheLineExpiredException();
}
if ($isValid) {
return unserialize(file_get_contents(BASEPATH.'/caches/MyCache/'.$id));
}
elseif ($callback===null) {
if (file_exists(BASEPATH.'/caches/MyCache/'.$id)) {
throw new CacheLineExpiredException();
}
else {
throw new CacheLineNotFoundException($id);
}
}
else {
try {
$value = call_user_func($callback);
self::set($id,$value);
return $value;
}
catch (Exception $e) {
if ($passexception) {
throw $e;
}
return self::get($id);
}
}
}
/**
* Removes given cache line from disk
*
* @param id string cache line name
*
* @return void
*/
static function delete($id) {
if (file_exists(BASEPATH.'/caches/MyCache/'.$id)) {
unlink(BASEPATH.'/caches/MyCache/'.$id);
}
}
/**
* validates if cache line is not older than given time in seconds
*
* @param id string cache line name.
* @param cacheLifeTime int cache line age limit (default 300 seconds)
*
* @return true if cache is stil valid, false otherwise
*/
static function valid($id, $cacheLifeTime=null) {
$cacheLifeTime = (int)$cacheLifeTime; //seconds
if ($cacheLifeTime==null) {
return is_readable(BASEPATH.'/caches/MyCache/'.$id);
}
if (!is_readable(BASEPATH.'/caches/MyCache/'.$id)) {
return false;
}
return (time()-filemtime(BASEPATH.'/caches/MyCache/'.$id)) <= $cacheLifeTime;
}
/**
* checks if cache line exists without validating its age
*
* @param id sting cache line name
*
* @return boolean true if cache line is found
*/
static function exist($id) {
return is_readable(BASEPATH .'/caches/MyCache/'.$id);
}
}
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