php 缓存技术(1/4)

class cache{
/*
class name: cache
description: control to cache data,$cache_out_time is a array to save cache date time out.
version: 1.0
author: 老农 cjjer
last modify:2006-2-26
author url: http://www.111cn.net*/
private $cache_dir;
private $expiretime=180;//缓存的时间是 60 秒
function __construct($cache_dirname){
if(!@is_dir($cache_dirname)){
if(!@mkdir($cache_dirname,0777)){
$this->warn('缓存文件不存在而且不能创建,需要手动创建.');
return false;
}
}
$this->cache_dir = $cache_dirname;
}
function __destruct(){
echo 'cache class bye.';
}

function get_url() {
if (!isset($_server['request_uri'])) {
$url = $_server['request_uri'];
}else{
$url = $_server['script_name'];
$url .= (!empty($_server['query_string'])) ? '?' . $_server['query_string'] : '';
}

return $url;
}

function warn($errorstring){
echo "发生错误:

".$errorstring."

function cache_page($pageurl,$pagedata){
if(!$fso=fopen($pageurl,'w')){
$this->warns('无法打开缓存文件.');//trigger_error
return false;
}
if(!flock($fso,lock_ex)){//lock_nb,排它型锁定
$this->warns('无法锁定缓存文件.');//trigger_error
return false;
}
if(!fwrite($fso,$pagedata)){//写入字节流,serialize写入其他格式
$this->warns('无法写入缓存文件.');//trigger_error
return false;
}
flock($fso,lock_un);//释放锁定
fclose($fso);
return true;
}