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<?php
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/**
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* File-based Output Cache Library
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*
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* @author Zhou Yuan <yuanzhou19@gmail.com>
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* @link http://www.infopotato.com/
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* @copyright Copyright © 2009-2011 Zhou Yuan
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* @license http://www.opensource.org/licenses/mit-license.php MIT Licence
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* @link based on http://www.jongales.com/blog/2009/02/18/simple-file-based-php-cache-class/
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* @link based on http://www.rooftopsolutions.nl/article/107
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*/
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class Output_Cache_Library {
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/**
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* The cache dir. The dir should end with DIRECTORY_SEPARATOR
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*
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* @var string
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*/
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private $_dir;
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/**
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* Constructor
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*
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* @param array $config['cache_dir']
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*
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*/
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public function __construct(array $config = NULL) {
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if (count($config) > 0) {
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if (isset($config['cache_dir'])) {
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$this->_dir = $config['cache_dir'];
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}
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}
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}
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/**
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* Find the filename for a certain key
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*
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* @param string
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* @return string
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*/
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private function _name($key) {
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return ($this->_dir).sha1($key);
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}
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/**
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* Get the cached file for a certain key
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*
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* @param $key string
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* @return mixed - FALSE|string (cached data)
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*/
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public function get($key) {
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if ( ! is_dir($this->_dir)) {
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return FALSE;
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}
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$cache_path = $this->_name($key);
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if ( ! file_exists($cache_path) || ! is_readable($cache_path)) {
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return FALSE;
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}
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// Open for reading only; use 'b' to force binary mode
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if ( ! $fp = fopen($cache_path, 'rb')) {
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return FALSE;
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}
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// To acquire a shared lock (reader)
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flock($fp, LOCK_SH);
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// file_get_contents() is much faster than fread()
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// $cached_data is an array contains [0] => expire time, [1] => cached content
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$cached_data = unserialize(file_get_contents($cache_path));
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// To release a lock (shared or exclusive)
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flock($fp, LOCK_UN);
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// The lock is released also by fclose() (which is also called automatically when script finished).
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fclose($fp);
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if ($cached_data) {
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// Check if the cached file was expired
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if (time() > $cached_data[0]) {
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$this->clear($key);
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return FALSE;
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}
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return $cached_data[1];
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}
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return FALSE;
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}
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/**
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* Create the cache file for a certain key
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*
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* @param $key string
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* @param $data string the data to be cached
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* @param $ttl integer - time to life (seconds)
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* @return boolean
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*/
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public function set($key, $data, $ttl = 3600) {
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if ( ! is_dir($this->_dir) || ! $this->_is_really_writable($this->_dir)) {
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return FALSE;
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}
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$cache_path = $this->_name($key);
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// Open for writing only; use 'b' to force binary mode
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if ( ! $fp = fopen($cache_path, 'wb')) {
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return FALSE;
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}
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// To acquire an exclusive lock (writer)
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if (flock($fp, LOCK_EX)) {
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// fwrite is faster than file_put_contents()
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fwrite($fp, serialize(array(time() + $ttl, $data)));
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// To release a lock (shared or exclusive)
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flock($fp, LOCK_UN);
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// The lock is released also by fclose() (which is also called automatically when script finished).
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fclose($fp);
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} else {
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return FALSE;
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}
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chmod($cache_path, 0777);
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return TRUE;
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}
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/**
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* Delete the cached file for a certain key
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*
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* @param $key string
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* @return boolean
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*/
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public function clear($key) {
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$cache_path = $this->_name($key);
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if (file_exists($cache_path)) {
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// Deletes cached file
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unlink($cache_path);
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return TRUE;
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}
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return FALSE;
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}
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/**
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* Tests for file writability
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*
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* is_writable() returns TRUE on Windows servers when you really can't write to
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* the file, based on the read-only attribute. is_writable() is also unreliable
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* on Unix servers if safe_mode is on.
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*
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* @return void
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*/
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private function _is_really_writable($file) {
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// If we're on a Unix server with safe_mode off we call is_writable
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if (DIRECTORY_SEPARATOR == '/' && @ini_get("safe_mode") == FALSE) {
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return is_writable($file);
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}
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// For windows servers and safe_mode "on" installations we'll actually
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// write a file then read it. Bah...
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if (is_dir($file)) {
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$file = rtrim($file, '/').'/'.md5(rand(1, 100));
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if (($fp = @fopen($file, 'ab')) === FALSE) {
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return FALSE;
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}
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fclose($fp);
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@chmod($file, 0777);
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@unlink($file);
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return TRUE;
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} elseif (($fp = @fopen($file, 'ab')) === FALSE) {
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return FALSE;
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}
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fclose($fp);
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return TRUE;
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}
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}
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/* End of file: ./system/libraries/output_cache/output_cache_library.php */
Page URI: http://www.infopotato.com/index.php/code/library/output_cache/