Proposal: track object cache type in update checks

[swissspidy]

Related: #56751, #48116

I think it would be helpful to send the wp_using_ext_object_cache() value as part of the update requests.
We already send the list of installed PHP extensions, so it's possible to know whether e.g. redis or memcached are installed, but not if they are actually used.

Ideally we would also know the exact type of object cache that is being used (e.g. if it's actually redis or memcached or something else). That would be also very useful for the wp cache type command, ​as suggested here.
This could be done via WP_Object_Cache::get_type() and a wp_cache_type() function for example.

[spacedmonkey]

There is already a project underway for this. See ​https://github.com/rhubarbgroup/wp-object-cache-info-spec

Basically the idea behind this, is adding a new function called wp_cache_info function into the caching api. This would have information like object cache type. I would like to focus on that first.

[swissspidy]

Cool. Looks like that covers quite a lot of stuff. While that proposal is being fleshed out, just adding wp_using_ext_object_cache() would already be a great start. That shouldn't be blocked. The second part could very well be its own ticket afterward.

[westonruter]

It would be great to also include information about whether page caching is enabled, such as we ​detect in Site Health.