Use php's readfile() or redirect to display a image file?

Question

I've a directory outside the webroot with images, css and javascripts.
These files often change.
I could write a script which locates the file, figures out the mime type and outputs it to the browser.
Or
i could locate the file, copy it to a webaccessable directory and redirect to that file using header location. When the file is requested again, there first will be a check if the file is modified, and again a redirect.

What would be a better performance wise? Every request a readfile, or every request a timestamp check and redirect ( so 2 requests instead of one )

Answer 1

First rule of performance: benchmark, don't speculate.

I'll promptly break that first rule and speculate that the readfile will be faster, because it eliminates a network round-trip.

How much performance do you need? The very fastest way to do this would be to setup a separate static-content web server under a subdomain (e.g. http://static.mysite.com/foo.jpg ) on a completely different machine, and then let that web server there handle the often-changing image/css/javascript files.

Answer 2

Another suggestion: if you have control of the filesystem, you could perhaps create a symbolic link in the web-accessable directory to the image file? Either using exec() to invoke the 'ln' command or maybe the PHP symlink() function might work.

Answer 3

How about a symbolic link directly to the file, not the entire directory? You could even make it a 'static' filename, and then let the web server do the modification timestamp check and caching, which would likely be much, much faster.

Benchmarks though, of course :)