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File: class.CachedDB.php

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  Classes of marcelo entraigas  >  Simple DB  >  class.CachedDB.php  >  Download  
File: class.CachedDB.php
Role: Class source
Content type: text/plain
Description: class file
Class: Simple DB
Store and retrieve data from a MySQL database
Author: By
Last change: Accessible without user login
Date: 5 years ago
Size: 2,339 bytes
 

Contents

Class file image Download
<?php
class CachedDB extends Database {
   
    var
$is_cached = null;
    var
$cache_id = '';
   
    function
CachedDB($config = 'default'){
       
parent::Database($config);
        global
$cfg_resource;
       
$this->_connection['cache_ttl'] = $cfg_resource[$config]['cache_ttl']? intval($cfg_resource[$config]['cache_ttl']) : 0;
       
$this->_connection['cache_path'] = $cfg_resource[$config]['cache_path']? $cfg_resource[$config]['cache_path'] : '';
       
$this->_connection['cache_prefix'] = $cfg_resource[$config]['cache_prefix']? $cfg_resource[$config]['cache_prefix'] : 'db_';
    }
   
   
/**
     * Check is the Database object is cached and not expired
     *
     * @param string $sql sql query
     * @return boolean true|false
     */
   
function is_cached ($sql){
       
$this->cache_id = $this->_connection['cache_path'] . $this->_connection['cache_prefix'] . md5($sql);
       
//is it cached?
       
if($this->cached) return true;
       
//is it not cached?
       
if($this->_connection['cache_ttl'] <= 0 or !file_exists($this->cache_id)) return false;
       
//is it expired?
       
if(!($mtime = filemtime($this->cache_id))) return false;
        if((
$mtime + $this->_connection['cache_ttl']) < time()) {
           
//erase the cached template
           
@unlink($this->cache_id);
            return
false;
        } else {
           
//cache the result of is_cached() call
           
$this->cached = true;
            return
true;
        }
    }

   
/**
     * Reimplement the query method with caching system
     *
     * @param string $sql sql query
     * @return integer number of affected rows
     */
   
function query($sql, $ttl=''){
        if(
$ttl>0)
           
$this->_connection['cache_ttl'] = $ttl;
       
$return = 0;
        if(
$this->is_cached($sql)){
           
//try to load object from disk
           
$vars = unserialize(file_get_contents($this->cache_id));
            foreach(
$vars as $key=>$val)
                eval(
"$"."this->$key = $"."vars['"."$key'];");
           
$return = $this->affected_rows;
        }else{
           
//execute the query
           
$return = parent::query($sql);
           
//try to save it to disk
           
if($f = @fopen($this->cache_id,"w")){
               
$arr_tmp = array(
                   
'results' => $this->results,
                   
'metadata' => $this->metadata,
                   
'insert_id' => $this->insert_id,
                   
'affected_rows' => $this->affected_rows,
                );
                @
fwrite($f,serialize($arr_tmp));
                @
fclose($f);
            }else{
               
$this->error('Could not save db cache file');
            }
        }
        return
$return;
    }
}
?>