Journal3 relies heavily on file-based caching to ensure that opencart sites that have the theme installed perform reasonably well. It also provides the ability to flush the Journal3 cache from the Journal admin section. This works well when your site is deployed to a single server instance, but does not work well at all when you have a highly available deployment with multiple web servers running behind a load balancer, each with their own file system.

This extension fixes this problem by introducing an innovative solution which means that as soon as the journal3 cache is flushed, all web server instances in the cluster are notified of this and force an invalidation of the cache.

To enusre that the cache is always up to date, the cache is flushed every hour.

If the plugin in installed properly you should see the following log statements appear in your log file:

When you clear the journal 3 cache:

2022-04-30 19:23:22 - 1626d8caa4beeb ControllerJournal3Journal3::clear_cache(): Updating Cluster-aware Journal3 cache key [journal3.cache.timestamp.key=626d8caaea4fb1651346602.9597]

When you try to access the front-end of your site or the admin section:

2022-04-30 19:23:38 - 1626d8cbac335b ControllerJournal3Startup::index(): START - Invalidating Journal3 cache - Cluster-aware Journal3 Cache Guard [journal3.cache.timestamp.key] not found
2022-04-30 19:23:38 - 1626d8cbac335b ControllerJournal3Startup::index(): END - Cache invalidated - Cluster-aware Journal3 Cache Guard [journal3.cache.timestamp.key] created with value [626d8caaea4fb1651346602.9597]


You can now be confident that if you flush your journal3 cache, your website will render any changes consistently every time.

Note: this extension is a vqmod extension. 1) Unzip and upload the "vqmod" folder specific to the version of opencart you use to the root of your OpenCart install. No files are overwritten and it's required to have vqmod installed.