Instant caching with PHP
5th May 2003
I’ve been getting more database timeout errors today, probably due to increased traffic from links to recent entries. A permanent solution would be to switch to generating static HTML (this site is currently dynamically generated for every request), but I don’t have time for a full re-write at the moment. Luckily, PHP offers an extremely simple solution to dynamic caching in the form of output buffering. The front page of the site (which generates by far the most traffic) is now served from a cached copy if it has been cached within the last 5 minutes. Best of all, I didn’t have to edit any of my core application logic—I just dropped in some extra code at the top and bottom of the index.php
file. Here’s how it works:
<?php
$cachefile = 'cache/index-cached.html';
$cachetime = 5 * 60;
// Serve from the cache if it is younger than $cachetime
if (file_exists($cachefile) && time() - $cachetime < filemtime($cachefile)) {
include($cachefile);
echo "<!-- Cached copy, generated ".date('H:i', filemtime($cachefile))." -->\n";
exit;
}
ob_start(); // Start the output buffer
/* The code to dynamically generate the page goes here */
// Cache the output to a file
$fp = fopen($cachefile, 'w');
fwrite($fp, ob_get_contents());
fclose($fp);
ob_end_flush(); // Send the output to the browser
?>
I’ve added a few extra bits of logic to check that the page being cached isn’t itself a database error page, but the above is the bulk of the code. Best of all, due to the nature of output buffering it should work on practically any PHP application.
More recent articles
- llm cmd undo last git commit - a new plugin for LLM - 26th March 2024
- Building and testing C extensions for SQLite with ChatGPT Code Interpreter - 23rd March 2024
- Claude and ChatGPT for ad-hoc sidequests - 22nd March 2024
- Weeknotes: the aftermath of NICAR - 16th March 2024
- The GPT-4 barrier has finally been broken - 8th March 2024
- Prompt injection and jailbreaking are not the same thing - 5th March 2024
- Interesting ideas in Observable Framework - 3rd March 2024
- Weeknotes: Getting ready for NICAR - 27th February 2024
- The killer app of Gemini Pro 1.5 is video - 21st February 2024
- Weeknotes: a Datasette release, an LLM release and a bunch of new plugins - 9th February 2024