Cache results from Imagick::queryFormats

[joemcgill]

Trac ticket: https://core.trac.wordpress.org/ticket/61532

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Props joemcgill, westonruter, flixos90, adamsilverstein.

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[adamsilverstein]

Great idea, love it! Curious how you came to the realization that the mime type check call was slow/expensive? Did you see it in a trace somewhere?

[westonruter]

Since technically any type could be stored in the cache value:

Suggested change

	if ( ! $supports ) {
	if ( ! is_array( $supports ) ) {

[westonruter]

Hardening, although this function doesn't currently have a strict type hint return value:

Suggested change

	if ( isset( $supports[ $imagick_extension ] ) ) {
	if ( isset( $supports[ $imagick_extension ] ) && is_bool( $supports[ $imagick_extension ] ) ) {

[westonruter]

Alternatively:

Suggested change

	return $supports[ $imagick_extension ];
	return (bool) $supports[ $imagick_extension ];

[felixarntz]

@joemcgill This is a good idea IMO, though at first glance I think this cache would apply at a very low level.

I think a more comprehensive solution would be to cache part of what _wp_image_editor_choose() does, for example:

• After the wp_image_editors filter, hash the array of classes and $args and use that in the cache key.
• This cache would then avoid the entire foreach loop, including any other potentially expensive check methods from other image editor class implementations.
• The values of the filter probably barely ever changes, but by using a hash we can ensure no stale value would be served.

WDYT?

[felixarntz]

We shouldn't use the object cache without a group. Not sure what would be most fitting for this use-case, but I think we should try to find one.

[adamsilverstein]

I think a more comprehensive solution would be to cache part of what _wp_image_editor_choose() does, for example:

Interesting idea to add caching up at this level, although this PR's changes could still be useful for supports_mime_type since that could be called from elsewhere including plugins.

My one concern would be ensuring the cache has some expiration so we can catch new capabilities when users upgrade their systems. This brings me back to wondering how significant this improvement is - does profiling indicate this function is problematic?

[felixarntz]

My one concern would be ensuring the cache has some expiration so we can catch new capabilities when users upgrade their systems. This brings me back to wondering how significant this improvement is - does profiling indicate this function is problematic?

This is a good point, would be good to clarify how bad the performance of the uncached function makes it. And related to expiration, I wonder: @joemcgill Are you thinking this should be persistently cached, or would it already benefit to be cached non-persistently (e.g. because the function is called many times during a single page load)?