APCu - Remove not needed serialize / unserialize

[mongeron]

Question	Answer
Bug fix?	no
New feature?	no
BC breaks?	no
Deprecations?	no
Tests pass?	composer test -> Command "test" is not defined -> couldn't run
Fixed tickets	-
License	MIT
Doc PR	reference to the documentation PR, if any

Description

As https://www.php.net/manual/en/function.apcu-store.php tells, apcu_store() accepts mixed as variable type. APCu module performs serialization / unserialization internally. The serializer to use is configured as APCu module runtime configuration: https://www.php.net/manual/en/apcu.configuration.php#ini.apcu.serializer

One alternative serializer is https://www.php.net/manual/en/intro.igbinary.php, which uses more efficient encoding for serialization than the standard PHP text serialization.

If the cache adapter serializes apc_store() values, there is no benefit in using igbinary serializer, because the input is always text.

As a summary: There is no need to serialize / unserialize input / output from cache. It adds the overhead of second serialize and deserialize calls, and cripples optimisations from improved serialzers.

Personally I have used APCu functionality without serialization for years in production environment without any issues.

This change shouldn't need any additional tests. I assume the store / fetch correctness is tested in existing tests.

TODO

• Add tests
• Add documentation
• Updated Changelog.md