More context for clean_post_cache()

[mdawaffe]

I'd like more context to be available when the clean_post_cache hook is run.

Scenario: I have a plugin caches the post_IDs of most post queries that go through WP_Query. Invalidating that cache is done via the clean_post_cache hook, but requires a bunch of fragile hacks to prevent cache invalidation for things like comment inserts, which update the post's comment_count (which could, in theory, affect a WP_Query, but that's another story).

Option 1: Add extra actions to provide context. This is the simpler option. Patch 1 does this for the above scenario.

Option 2: Add an optional context parameter to clean_post_cache(). This is more general, but I can't think of anyplace else WordPress uses as similar approach. Patch two.

[mdawaffe]

Option 1

[mdawaffe]

Option 2

[mdawaffe]

Option 2 also provides a way to detect if clean_post_cache() is being run recursively, another case that the scenario I mentioned above has to hack around.

[scribu]

We have a $context arg for escaping functions like sanitize_term(), but it's just a string.

[westi]

Option 2 looks good.

We should add context to all call to clean_post_cache so that a caching plugin can always know what is going on.

[johnjamesjacoby]

Note: this would be great for bbPress and anywhere custom post-types are being used creatively. If you invalidate tens of thousands of child-post caches, you're going to have a bad time.

[nacin]

I like this in theory. What would all of the contexts look like, for the various uses of clean_post_cache()?

[jkudish]

related: #11399

[ryan]

Related: #22176

[wonderboymusic]

This may no longer be a thing since nacin fixed clean_post_cache() in 3.5, but I refreshed the patch against trunk - let's make a decision on it in 3.7

[nacin]

It might still be helpful to include a context for some uses of clean_post_cache(), but it no longer needs to be an array as it is no longer called in recursive fashion.

It seems like the only context you may wish to know is comment_count. Other kinds of cache clears (post and attachment CRUD, set_post_type(), publishing a post) should really not be messed with. Even post reassignments in wp_delete_user() should probably be cleared, though those have the potential to be expensive so that might be the only other situation where context is desired.

[desrosj]

Re-adding a milestone to this one.

You've been focusing a lot on the Cache API lately, @spacedmonkey. Is this something you'd be interested in exploring?

[spacedmonkey]

This is heavily related to #22176. So I will take ownership of this.