[Feature] Optimized TagAware Symfony Cache File & Redis Adapters

[andrerom]

Reduces lookups to cache backend by half 🎉

This is done by changing tag design to not have to do seperate lookup for tag info on reads to figure out if they have expired. Instead it's modeled to handle lookup of tag info when needed on invalidation by storing tag info separately (Filesystem: symlinks, Redis: a Set with no expiry).

Further info on design in doc and phpdoc.

This is meant to be contributed to Symfony, but as we are on Symfony 3, need this asap, and as it will probably take some iterations to get it right there. We add it here first, then contribute to Symfony 4, and then adapt code here to become a backport.

Dev testing done:

• Light manual testing with
  • Filesystem
  • Redis with Predis, but not with phpredis from my side
• Unit / integration testing? Is there some TagAware test suites in symfony we can copy in here and run across the misc setups?

Dependency:

• ezsystems/ezpublish-kernel@548f7d6 (merged to 7.3.x-dev and up)

Side, but for the overall story; eZ specific cache/performance followups:

• Continue on new Bulk API loading improvements, as in take advantage in admin, page builder, .. to reduce number of lookups/roundtrips. +Document how end users should do the same
• Open kernel PR for in-memory SPI caching for v2.5
• Further profiling to identify remaining bottlenecks planned for March by engineering

[kmadejski]

Besides mentioned below, I'm getting the following PHP's fatal error while trying to clear the cache:

PHP Fatal error:  Uncaught Error: Call to undefined method Symfony\Component\Cache\Adapter\TraceableTagAwareAdapter::__destruct() in /Users/kamil/ez/var/cache/dev/ContainerKgikhg8/TagAwareAdapter_5b4740c.php:95
Stack trace:
#0 [internal function]: TagAwareAdapter_5b4740c->__destruct()
#1 {main}
  thrown in /Users/kamil/www/ez/var/cache/dev/ContainerKgikhg8/TagAwareAdapter_5b4740c.php on line 95

but the cache clearing finishes successfully and the application works fine. Not everything. Investigating.

[kmadejski]

Apparently, the index value may not exists if you are about to use this Adapter without clearing the cache before.

Suggested change

	$item->value = $value['value'];
	$item->value = $value['value'] ?? null;

[andrerom]

If you have not cleared cache it will not be an array and you will be missing info on tags.

So maybe we need to throw exception if value is missing saying you need to clear cache after enabling the adapter ;)

[andrerom]

PHP Fatal error: Uncaught Error: Call to undefined method Symfony\Component\Cache\Adapter\TraceableTagAwareAdapter::__destruct()

This one should have been fixed in: ezsystems/ezpublish-kernel@548f7d6

[andrerom]

@kmadejski PR updated now after PR with these adapters was opened on Symfony.

Some of things ended up being possible to simplify, including ended up getting some performance issues for RedisCluster on fetch logic merged to 3.4, which further helped simplify things here by getting rid of some of the overloading needs.

[andrerom]

@kmadejski suggestions for second person for review?

[kmadejski]

Honestly, all good candidates which come into my mind are already on the list. Maybe @vidarl or @dspe could take a look as well?

[andrerom]

@kmadejski Besides missing links in php doc for source, could you review?

REVIEW NOTE: I ended up back-porting a few more classes/traits from Symfony 4 to fix RedisCluster things, but intention is to try to propose fixes to Redis Cluster on 3.4 to back-port some smaller fixes there so RedisTrait and RedisClusterProxy can be removed from this repo.