Need local caching for this image script

[Marcel_de_Haas]

Hi All,

I have searched this forum for a solution, but I cannot find exactly what I need and my PHP is too rusty to complete this task by myself. I have the following script which gets an image, resizes it and outputs the resampled image. It ran like a charm, but the source web server is experiencing heavy loads and regularly returns a HTTP error 500. So I want the script to cache the image on the server where the script runs (Which is fully under my control).
The image on the source server is update once every week (or less frequently if I don't provide new input). So what I would like is the following:

• Use cached data when the cache is less than 24 hours old
• Update cached image if the cached image is older than 24 hours
• Allow argument to the script to force update the image (?update=force)
• When the server returns an Error 500 or server or image isn't found use the cached data even when update is forced.

Here is the script I have in place now:

<?php

// File and new size
$filename = 'http://www.itsnotaboutthenumbers.com/europe_findsmap_export.php?id=1094028';
$percent = 0.35;

// Content type
header('Content-type: image/png');

// Get new sizes
list($width, $height) = getimagesize($filename);
$newwidth = $width * $percent;
$newheight = $height * $percent;

// Load
$thumb = imagecreatetruecolor($newwidth, $newheight);
$source = imagecreatefromjpeg($filename);

// Resize without visible artifacts
imagecopyresampled($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);

// Output
imagepng($thumb);

?>

[bpat1434]

When the server returns an Error 500 or server or image isn't found use the cached data even when update is forced.

THat's not entirely possible to fix. The 500 error code is returned by Apache or IIS. Totally not touchable by PHP. If you were using OO code and throwing errors, that would be catchable; however, server errors aren't available to PHP. PHP sits behind the server, not in front of it.

As for using a cached version, you could add this check:

if(filemtime('/path/to/image/file') < strtotime('NOW - 24 hours'))
{
    // Recreate image (update cache)
}
else
{
    // Use cached image
}

If you wanted to have a "force" option, then adding on to that if statement...

if($_GET['update'] == 'force' || filemtime('/path/to/file') < strtotime('Now - 24 hours'))
{
    // Update cache
}
else
{
    // Use cached image
}

Hope that helps.