Improve caching when fetching capabilities.

[fancycode]

• Honor "max-age" in "Cache-Control" header.
• Use "ETag" to avoid fetching unmodified data.

@nickvergessen I could not find where it is set, but Nextcloud seems to always include an "cache-control: max-age=60" header. I'd rather use the caching headers as set by the server instead of hardcoding a cache time of 1 hour.

[coveralls]

Pull Request Test Coverage Report for Build 10088939132

Details

• 103 of 125 (82.4%) changed or added relevant lines in 1 file are covered.
• 10 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.1%) to 57.308%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
capabilities.go	103	125	82.4%

Files with Coverage Reduction	New Missed Lines	%
capabilities.go	3	82.73%
client.go	7	72.54%

Totals
Change from base Build 10077388196:	0.1%
Covered Lines:	9798
Relevant Lines:	17097

---

💛 - Coveralls

[nickvergessen]

I could not find where it is set, but Nextcloud seems to always include an "cache-control: max-age=60" header.

I think this the fallback via htaccess/nginx config?
Don't see it in PHP code

[fancycode]

I think this the fallback via htaccess/nginx config? Don't see it in PHP code

Thanks, that explains why I could not find it.

Looks like there was a suggestion to set a default cache policy expires 1m in the past that got removed in nextcloud/documentation#5857 (which I have locally set in my nginx).

So I will assume none will be sent by default in recent setups. Should I just honor that and check for the capabilities whenever needed (using If-None-Match and the ETag) or should I forcefully cache the capabilities for some time?

[nickvergessen]

Either way is fine I guess.

[fancycode]

Ok, so I'll honor the Cache-Control header if one is set, otherwise I will use a default cache duration of one minute to avoid overloading a Nextcloud backend if many participants join at the same time.