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@abidibo abidibo/cache.php
Last active Dec 15, 2015

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A class to manage the caching of html outputs and data structures
<?php
/**
* @file cache.php
* @brief Contains the \ref cache, outputCache and dataCache classes.
*
* @author abidibo abidibo@gmail.com
* @version 0.99
* @date 2011-2012
* @copyright Otto srl [MIT License](http://www.opensource.org/licenses/mit-license.php)
*/
/**
* @defgroup cache Outputs and data caching
* Library to store outputs (text, html, xml) and data structures writing to file
*/
/**
* @ingroup cache
* @brief cache super class
*
* Provides methods to handle file operations.
*
* @author abidibo abidibo@gmail.com
* @version 0.99
* @date 2011-2012
* @copyright Otto srl [MIT License](http://www.opensource.org/licenses/mit-license.php)
*/
class cache {
/**
* @brief directory separator
*/
protected $_ds;
/**
* @brief absolute path to the cache folder storing all the cache files
*/
protected $_fld;
/**
* @brief cache files prefix
*/
protected $_prefix;
/**
* @brief cache content group
*/
protected $_grp;
/**
* @brief cache content identifier
*/
protected $id;
/**
* @brief caching time
*/
protected $_tc;
/**
* @brief status
*/
protected $_enabled;
/**
* @brief Construct a cache instance
*
* @return cache instance
*/
function __construct() {
$this->_ds = DS;
$this->_fld = ABS_CACHE;
$this->_prefix = 'cache_';
$this->_enabled = true;
}
/**
* @brief Writes data to file
*
* @param string $data
* @return void
*/
protected function write($data) {
$filename = $this->getFilename();
if($fp = @fopen($filename, "xb")) {
if(flock($fp, LOCK_EX)) fwrite($fp, $data);
fclose($fp);
touch($filename, time());
}
}
/**
* @brief Reads data from file
*
* @return data in string format
*/
protected function read() {
return file_get_contents($this->getFilename());
}
/**
* @brief Gets the cached filename
*
* @return the filename
*/
protected function getFilename() {
return $this->_fld . $this->_ds . $this->_prefix . $this->_grp ."_". md5($this->_id);
}
/**
* @brief Cheks if data are cached and not expired
*
* @return true if data are cached and the cache time is not expired, false otherwise
*/
protected function isCached() {
$filename = $this->getFilename();
if($this->_enabled && file_exists($filename) && time() < (filemtime($filename) + $this->_tc)) return true;
else @unlink($filename);
return false;
}
}
/**
* @ingroup cache
* @brief Cache implemetation to store html/text/xml outputs
*
* ### Usage
*
* ~~~~~~~~~~~~~~~~~~~{.php}
* $buffer = "previous text-";
* $cache = new outputCache($buffer);
* if($cache->start("group_name", "id", 3600)) {
*
* $cache_buffer = "some content-";
*
* $cache->stop($cache_buffer);
*
* }
* $buffer .= "next text";
* ~~~~~~~~~~~~~~~~~~~
*
* the result is:
* ~~~~~~~~~~~~~~~~~~~{.php}
* $buffer = "previous text-somec content-next text";
* ~~~~~~~~~~~~~~~~~~~
*
* if the content is cached the if statement is skipped and the content is
* concatenated to $buffer,
* if content is not cached the if statemet runs, the content is prepared
* and then saved in cache and added to $buffer (through stop method)
*
* @author abidibo abidibo@gmail.com
* @version 0.99
* @date 2011-2012
* @copyright Otto srl [MIT License](http://www.opensource.org/licenses/mit-license.php)
*/
class outputCache extends cache {
/**
* @brief reference to the output to which add the cached data
*/
protected $_buffer;
/**
* @brief Constructs a outputCache instance
*
* @param mixed &$buffer reference to the $_buffer variable
* @param mixed $enable status
* @return outputCache instance
*/
function __construct(&$buffer, $enable = true) {
parent::__construct();
$this->_buffer = &$buffer;
$this->_enabled = $enable;
}
/**
* @brief Starts the caching process
*
* If data are cached and not expired adds data to the $_buffer member and returns false, else returns true.
*
* @param string $grp the output data group
* @param mixed $id the output data identifier
* @param mixed $tc the caching time
* @return false if data are already cached and not expired, true otherwise
*/
public function start($grp, $id, $tc) {
$this->_grp = $grp;
$this->_id = $id;
$this->_tc = $tc;
if($this->isCached()) {
$this->_buffer .= $this->read();
return false;
}
return true;
}
/**
* @brief Stops the caching process
*
* Writes data to file and adds it to the $_buffer member.
*
* @param string $data the output data
* @return void
*/
public function stop($data) {
if($this->_enabled) $this->write($data);
$this->_buffer .= $data;
}
}
/**
* @ingroup cache
* @brief Cache implementation to store data structures
*
* ### Usage
*
* ~~~~~~~~~~~~~~~~~~~{.php}
* $cache = new dataCache();
* if(!$data = $cache->get('group_name', 'id', 3600)) {
*
* $data = someCalculations();
* $cache->save($data);
*
*}
* ~~~~~~~~~~~~~~~~~~~
*
* if data is stored it's returned by get method and if statement is not processed, otherwise data
* is calculated and saved in cache
*
* @author abidibo abidibo@gmail.com
* @version 0.99
* @date 2011-2012
* @copyright Otto srl [MIT License](http://www.opensource.org/licenses/mit-license.php)
*/
class dataCache extends cache {
/**
* @brief Constructs a dataCache instance
*
* @param mixed $enable status
* @return dataCache instance
*/
function __construct($enable = true) {
parent::__construct();
$this->_enabled = $enable;
}
/**
* @brief Tries to retrieve cached data
*
* If data are cached and not expired returns them, else returns false.
*
* @param string $grp the output data group
* @param mixed $id the output data identifier
* @param mixed $tc the caching time
* @return data if are already cached and not expired, false otherwise
*/
public function get($grp, $id, $tc) {
$this->_grp = $grp;
$this->_id = $id;
$this->_tc = $tc;
if($this->isCached()) return unserialize($this->read());
return false;
}
/**
* @brief Saves data in cache
*
* @param string $data the data to put in cache
* @return void
*/
public function save($data) {
if($this->_enabled) $this->write(serialize($data));
}
}
?>
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