Add footer template file caching

[tapaswenipathak]

Added caching for footer html file. Writing one PR for memcache implementation.

Fixes - #6126.

[stsewd]

I think this will cache that fragment for all users and projects, every response is different for each project/version

https://docs.djangoproject.com/en/2.2/topics/cache/#template-fragment-caching

[tapaswenipathak]

Yeah, I require input from your end. I suggest:

• Add template file caching for unchanging header Add footer template file caching #6148
• File based cache for the file https://github.com/readthedocs/readthedocs.org/pull/6149/files
• memcache instead of local cache
• redis + Django cache for keys (https://docs.djangoproject.com/en/2.2/topics/cache/)

?

[davidfischer]

We use redis for caching in production.

[tapaswenipathak]

@davidfischer hi: oh ok, does everything else works w/ you? or you have more ideas?

[tapaswenipathak]

@davidfischer: have any thoughts?

[davidfischer]

@stsewd's comment still stands, I believe. This would cache the footer for one project across all projects.

[tapaswenipathak]

@stsewd, @davidfischer: sure, I require inputs/thoughts for: #6148 (comment).

[humitos]

Hi @tapaswenipathak! Thanks for the contribution here.

I'm not sure what's the problem we are trying to solve. Is the footer rendering causing us any problem? In that case, supposing we want to implement this at template level, we need to be very careful with the variables used as keywords to avoid showing a footer of one project in another one.

This PR probably needs more discussion around the problem and the solution proposed before merging it.

[humitos]

This will cache the footer and use the same footer for all the projects. That's not correct. We need to add more keywords where.

Also, adding cache here, even if we use the proper variables/keywords, could cause confusions on users when a new version is activated, a translation is added, etc. So, we may want to invalidate the cache in those cases as well.

[tapaswenipathak]

@humitos hi: You can read the ticket, the footer view should be cached properly. Why are we going back and forth in discussing what the pr does and wasting time

would cache the footer for one project across all projects

can I please get few notes for #6148 (comment)?

[humitos]

Hi @tapaswenipathak! This PR can't be merged as it is because it will return the same footer for all the projects on Read the Docs as I explained at #6148 (comment).

Also, we did not settle on a proper solution and there should be more discussion around it before continue with an implementation. Unfortunately, the original issue is under "Needed: design decision" and it's not "Approved".

I'm closing this PR for now and we can come back later once we have a better idea of how to cache the footer.