I have a random image generator for my site. The problem is, it takes a really long time.. I was wondering if anybody could help to speed it up in any ways. The site is http://viralaftermath.com/, and this is the script:
header('Content-type: image/jpeg;');
$images = glob("images/" . '*.{jpg,jpeg,png,gif}', GLOB_BRACE);
echo file_get_contents($images[array_rand($images)]);
This is a pretty resource-intensive way to do this, as you are passing the image data through PHP and not specifying any caching headers, so the image has to be reloaded every single time you open the page.
A much better approach would be to have glob() list the files within the HTML page that you're using to embed the image. Then randomize that list, and emit an <img> tag pointing to the actual file name that you determined randomly.
When you are linking to a static image instead of the PHP script, you also likely benefit from the web server's caching defaults for static resources. (You could use PHP to send caching headers as well, but in this scenario it really makes the most sense to randomly point to static images.)
$images = glob("images/" . '*.{jpg,jpeg,png,gif}', GLOB_BRACE);
# Randomize order
shuffle ($images);
# Create URL
$url = "images/".basename($images[0]);
echo "<img src='$url'>";
Profile your code and find the bottlenecks. I can only make guesses.
echo file_get_contents($file);
This will first read the complete file into memory and then send it to the output buffer. It would be way nicer if the file goes directly into output buffer. readfile() is your friend. It would be even better to avoid buffering completely. ob_end_flush() will help you there.
A next candidate is the image directory. If searching for one image takes a significant time, you have to optimize that. This can be achieved by an index (e.g. with a database).