perf: reduce number of avatar requests

[hamza221]

No description provided.

[ChristophWurst]

Quick review

[hamza221]

I broke RecipientBubble 😨, converting to draft

[hamza221]

The avatar controller and frontend service are still needed for Recipient bubble (Thread.vue) , because the message object contains only from's avatar ( to, cc, bcc ) still need to be fetched , and assuming that we need them and pre-fetching is counterproductive because we can't assume that all threads are gonna be opened

[ChristophWurst]

How will this handle worst case scenarios? Imagine you load 20 messages and each of them is sent by someone else, and there is no contacts picture so gravatar favicon sources are tapped. These make external HTTP requests that could take several seconds, e.g. when the favicon request times out because the domain does not correspond to a HTTP server.

Will this slow down the loading of messages?

If so, we have to fine-tune the approach. Let me know, I have some ideas.

[hamza221]

So I did a little benchmarking and here are the results

Main

1. /api/messages?mailboxId=1&limit=20 => 501.22 ms
2. First batch of requests /api/avatars/url/{email}=> 9583 ms
   total = 10084 ms
3. external avatars (3 email addresses ) api/avatars/image/{email} => 5158 ms

This branch

• /api/messages?mailboxId=1&limit=20 (combines 1 and 2 from above) => 1.4 minutes / 2.4 minutes / 2.3 minutes
• fetching additional messages => 16.94 seconds

Doesn't look like a good approach
Ps: tests done with caching disabling and no additional throttling / timeouts

[ChristophWurst]

Okay, that is what I was afraid of.

Then we do it like follows: check the cache for an avatar URL. If it exists, attach it to the recipient. Also attach a false if there is one, it indicates that there is no avatar for the user.
Leave the rest of the fetching in tact.

This means that the initial loading with empty cache is still done in many requests, but those help us offload the slow fetching into async operations that don't block the main app functionality. For page reloads, mailbox switches, messages of senders seen previously etc we will preload the avatar URLs and save some requests.

[hamza221]

I'm not sure how to return a 3rd state "elegantly" ( Avatar => avatar exists , null => avatar doesn't exist, ? => we want to fetch it from the frontend)

https://github.com/nextcloud/mail/pull/10486/files#diff-a7e5eb4728a4ad105af312d21ceb1bd6dd7a70068ba67d4b1881099dcae1076bR99