WP Super Cache 1.5.0

WP Super Cache is a fast full-page caching plugin for WordPress. Download it from your dashboard or get it here.

Version 1.5.0 has been in development for some time. It has a ton of bug fixes and new features.

REST API

The headline new feature is REST API access to the settings. This will allow developers to create their own interface to the settings of the plugin. Unfortunately it isn’t yet documented but you can see the code in the rest directory. Start with load.php where you’ll find the code that registers all the endpoints. Users who access the API must be logged in as admin users. If you want to test the API, see the end of this post.

Settings Page

We have also simplified the settings page to make it easier to choose which caching method is used.

Instead of maybe confusing the user with technical words like PHP, mod_rewrite and WP-Cache we have split them up into “Simple” and “Expert” delivery methods, and done away with mentioning WP-Cache completely. Simple delivery uses PHP, expert uses mod_rewrite and well, WP-Cache got the boot because it’s always active anyway.

WP-Cache caching is always active, but it can be disabled in different ways.

  • Disable caching for known users.
  • Don’t cache pages with GET parameters
  • Disable caching of feeds

Headers

We expanded the number of headers cached by the plugin. The list of headers was borrowed from Comet Cache. However, anonymous users will still only see the bare minimum like content-length or content-type. If you need to use security headers like “X-Frame-Options” or “Content-Security-Policy” you should enable caching of HTTP headers. This unfortunately disables super caching so only WP-Caching is used but it’s still very fast (and faster in this release than before which I will get to below). You can also use the “wpsc_known_headers” filter to modify the list of recognised headers.

WP-Cache Reorganisation

WP-Cache cache files are split into two files – one holds the page content, the other (meta file) holds information about the page such as cookies, headers and url. In the past these files were stored in two directories which could become a problem if there were many thousands of those files. Even with only a few hundred files, maintenance could be an issue as deleting related files (like page archives, or copies of the front page) needed every meta file to be inspected.
Now the files are stored in the supercache directory structure that mirrors your permalink structure. Deleting related files is is simpler and serving files will be faster as the operating system won’t need to open a directory of thousands of files.
If you currently rely on WP-Cache files, the plugin will still look for them where they are, but new WP-Cache files will be created in cache/supercache/example.com/ (where example.com is your hostname).

Sitemaps

We added support for caching sitemaps, but your sitemap plugin will need to cooperate to get it to work. The sitemap plugin needs to identify the sitemap request as a feed. Jetpack 5.1 now supports this since #7397. You can disable the caching by excluding feeds from caching.

Debugging Improved

The debug log is now protected by a username/password. For convenience, the username and password are the same but they are a long md5 string:

Deleting the log file clears it and resets it ready for more logging. Before, toggling debugging would create a new debug log and the old one would be kept around, but not linked, until deleted by garbage collection, and of course they were text files anyone could access.

This release includes lots of other small bug fixes and changes. Take a look at the number of closed PRs for an exhaustive list of those changes!

Testing the REST API

There are a number of ways to send POST requests to a web server but one I like is using curl in a shell script. You’ll need two bits of information from the website:

  1. The “wordpress_logged_in” cookie from your browser.
  2. The wp_rest nonce which you can get by adding `echo wp_create_nonce( ‘wp_rest’ );` somewhere on your site where you’re logged in. It’s good for 24 hours.

My test script looks something like this:
export NONCE='1234567890'
export COOKIE='wordpress_logged_in_xxxxxxxxxxxxxxxxxxxx=1234567890'
curl -v -X "GET" -H "Content-Type: application/json" -H "X-WP-Nonce: $NONCE" -H "Cache-Control: no-cache" -H "Cookie: wordpress_test_cookie=WP+Cookie+check; $COOKIE" \
-d '{}' "https://example.com/wp-json/wp-super-cache/v1/settings/"

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