Unclear caching documentation: pool namespaces

[luispabon]

The current docs for caching seem to concentrate on the cache component in isolation, with very few hints of how it actually integrates when running on the wider framework.

In fact, I had to pick up the required framework config (see below) off a random blog post on the internet.

Specifically, it looks as if cache pools are given a namespace for cache keys by default. This is fine, but there's no information at all on where this namespace string is actually coming from, whether it's random or deterministic, and how (if at all possible) to configure it.

As a developer, I'm usure of what will happen when I deploy my app as I do not have information to know whether several deployed instances of my app will be using the same namespace.

parameters:
    redis_dsn: "redis://%env(REDIS_HOST)%"

framework:
    [...]
    cache:
        app: cache.adapter.redis
        default_redis_provider: '%redis_dsn%'

[nicolas-grekas]

The namespace is a hash of the service id of the pool, the kernel name, the environment (dev/prod/test/etc.), and a seed you can customize that defaults to the kernel.root_dir. See https://github.com/symfony/recipes/blob/master/symfony/framework-bundle/3.3/config/packages/framework.yaml#L20 for details about the seed.

This means the namespace is stable over time, and varies by (pool x application x environment).

Here is where the logic is: https://github.com/symfony/symfony/blob/master/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/CachePoolPass.php

Would you mind sending a PR to document this?

[luispabon]

I do not mind at all 👍

[luispabon]

It looks like the namespace can actually be supplied as a service tag, thus completely bypassing all the namespace generation, as per here:

https://github.com/symfony/symfony/blob/eb112a5288cbee6d0125c08cf87bbcb2fa16285d/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/CachePoolPass.php#L61

Am I understanding this correctly?

[ahmed-bhs]

@nicolas-grekas @weaverryan how to change cache pool namespace?

@nicolas-grekas : We can disable namespace version but nothing about namespace ?

Here some memcached keys generated :

zJFP3HKYUY%3AEMZ-PROD-blog_article_fr_desktop_755
zJFP3HKYUY%3AEMZ-PROD-blog_category_tag_fr_desktop_22_1
zJFP3HKYUY%3AEMZ-PROD-blog_tag_fr_desktop_2

Is it possible to remove the namespace "zJFP3HKYUY%3A" ?

Thank you.

[nicolas-grekas]

It's not possible when configuring pool via configuration.
It's possible if you define them "manually" as plain old services.