Page Caching

[cwilkey]

All,

I'm writing a script to do page caching. I've got the following code - which works, but I was wondering if anyone hand any input to make it run more efficiently.

<?php
error_reporting(E_ALL);

// The ./ location puts the file in the root of your
define('CACHEDIR', './');

// URL of page you wish to cache
$request =  'http://www.google.com';

$cache_filename = 'cached.php';
$cache_fullpath = CACHEDIR.$cache_filename;

// Number of seconds until the cache gets stale
$cache_timeout = 0;

// Check the cache
$response = request_cache($request, $cache_fullpath, $cache_timeout);

if ($response === false) {
	die('Request failed');
}

// Output the XML
echo htmlspecialchars($response, ENT_QUOTES);

// This is the main caching routine.
function request_cache($url, $dest_file) {
		$data = file_get_contents($url);
		if ($data === false) return false;
		$tmpf = tempnam('/tmp','YWS');
		$fp = fopen($tmpf,"w");
		fwrite($fp, $data);
		fclose($fp);
		rename($tmpf, $dest_file);
	return($data);
}

?>

[NightShift58]

I would have expanded the cache function to automatically (1) deliver the cached page if not stale or (2) deliver a fresh version if the cache is stale or (3) a fresh version if no cached copy is present.

I think your current version will also cause you grief retrieving he correct cached copy when requested. You need to devise a working system for naming the cached files.

[cwilkey]

Any suggestions?

[SlappyTheFish]

I've just finished a caching class which will cache the output of any function and covers the points made by NightShift. It's not online yet, but if you can hold on a few days then I'll send you the link and you'd be welcome to use it.

[cwilkey]

That would be much appreciated. Thank you!

[bokeh]

I would have expanded the cache function

Something like this?

<?php

class Cache
{
    /******************************************************
    
    CLASSNAME: 
    Cache
    
    AUTHOR:
    bokeh
    
    THREAD:
    http://webdeveloper.com/forum/showthread.php?t=138529
    
    PURPOSE: 
    To handle server-side and client-side caching of local
    pages. It also GZips all output to save on bandwidth.
    
    PERMISSIONS:
    Be certain this script has sufficient permission 
    to read from and write to the cache directory. 
    
    EXAMPLE USE (your script):
    
    <?php

    # right at the start of your script
    require_once('class.cache.php');
    
    # now call the cache class,
    # first argument: cache location, 
    # second argument: cache file duration in seconds.
    $cache = new cache('./cache/', 3600);  
    
    ?>
    
    Your script content here!
    
    <?php
    
    # right at the end of your script
    $cache->output();
    
    ?>
    
    ******************************************************/
    
    var $buffer;
    
    function Cache($location, $expires)
    {
        ob_start();
        if(empty($_POST))
        {
            if((file_exists($this->filename = $location . md5($_SERVER['REQUEST_URI']))) 
            and (filemtime($this->filename) > (time() - $expires)))
            {
                $this->buffer = file_get_contents($this->filename);
                $this->output(false);
            }
        }
    }
    
    function CachePage()
    {
        if(empty($_POST))
        {
            $fp = fopen($this->filename, 'w');
            fwrite($fp, $this->buffer, strlen($this->buffer));
            fclose($fp);
        }
    }
    
    function output($cache = true)
    {
        $this->buffer or $this->buffer = ob_get_clean();
        if($cache) $this->CachePage();
        header('Etag: "'.($hash = md5($this->buffer)).'"');
        if(isset($_SERVER['HTTP_IF_NONE_MATCH']))
        {
            if($hash == trim(stripslashes($_SERVER['HTTP_IF_NONE_MATCH']), '"'))
            {
                die(header("HTTP/1.1 304 Not Modified"));
            }
        }
        die(ob_gzhandler($this->buffer, 1));
    }
}

?>

[NightShift58]

Perhaps not as professional, but yes, in that direction...

[bokeh]

Perhaps not as professional, but yes, in that direction...

What do you mean?

[NightShift58]

Responding to your question: Something like this?

Yes, something like this - I wouldn't have done as professionally, but it would've have been in that general direction...

[bokeh]

Ok, the class above was for caching internal files and I didn't read the question properly. Now I have read it here is a function to cache external URIs locally.

<?php

function CacheUriLocally($URI, $CachePath, $expires)
{
    /*******************************************************
    
    FUNCTION NAME:
    CacheUriLocally
    
    AUTHOR:
    bokeh
    
    THREAD:
    http://webdeveloper.com/forum/showthread.php?t=138529
    
    PURPOSE:
    To cache a local copy of any URI.
    
    DESCRIPTION:
    string CacheUriLocally( string URI, string CachePath, int expires  )
    
    INPUTS:
    $URI is the full URI of the remote resource including 
    the scheme. $CachePath is an absolute or relative path 
    to the cache folder and must include a trailing slash. 
    $expires is the max age in seconds before the cached 
    data is considered stale.
    
    RETURN VALUE:
    Returns the URI output in a string
    
    NOTES:
    1) If you're opening a URI with special characters, such 
    as spaces, you need to encode the URI with urlencode().
    
    2) Be certain this script has sufficient permission to 
    read from and write to the cache directory.
    
    *********************************************************/
    
    if((file_exists($filename = $CachePath . md5($URI))) 
    and (filemtime($filename) > (time() - $expires)))
    {
        return file_get_contents($filename);
    }
    $fp = fopen($filename, 'w');
    fwrite($fp, $rtn = file_get_contents($URI));
    fclose($fp);
    return $rtn;
}

echo CacheUriLocally('http://www.google.com/', 'cache/', 3600);

?>

[cwilkey]

Thank you all. This is perfect.