Optimize conversations update on Frontend

[ShGKme]

☑️ Resolves

• Maybe fix 🔥 Sever performance/CPU issue with at least firefox due to Talk page rendering #9630
• Decrease re-rendering time for LeftSidebar on re-fetching conversations every 30 seconds when:
  • External signaling is using
  • This is not full re-fetching every 5 minutes

🖼️ Screenshots

No visual changes

🚧 Tasks

• Add new action addConversationIfChange to add new conversation only if it was moidified according to lastActivity and modifiedSince
• Add new action postAddConversation for common post-action of adding a conversation
• Use new addConversationIfChange in fetchConversations action
• Fix old tests
• Add new test for this case

🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included or not required
• 📘 API documentation in docs/ has been updated or is not required
• 📗 User documentation in https://github.com/nextcloud/documentation/tree/master/user_manual/talk has been updated or is not required
• 🔖 Capability is added or not needed

Alternative and additional solutions

• In comparison, compare lastActivity and old lastActivity, not modifiedSince
• In addition, cache conversations list with KeepAlive to make returning from search fast
  • See: WIP: Fix/9630/cache conversations list rendering #9833
• Instead, decrease number of any state changes by full property comparison
  • Works with any signaling
  • Also works on 5-minute full re-fresh
  • Not domain-specific, a bit more code, but universal solution
  • See: Experiments to increase left sidebar performance #9811
• Instead/In addition use virtual scrolling
  • Increase LeftSidebar performance in general in any case, including memory usage, interactive reaction and etc.
  • Tricky in scrolling part, e2e testing and perhaps more risky
  • See: Experiments to increase left sidebar performance #9811

[ShGKme]

/backport to stable27

[nickvergessen]

🤞🏼

[Antreesy]

Looks good from the code perspective (but still lagging for me because of internal signalling)

[Antreesy]

Suggested change

	}
	} else {
	// Smart update
	}

Don't we want to apply smartUpdate here to cover rest cases (full re-fetch at least)?

[ShGKme]

If we use the smartUpdate approach in else, then we do not need if branch, as smartUpdate covers all possible updates anyway

[ShGKme]

but still lagging for me because of internal signalling

To test on internal you can add:

this.roomListModifiedBefore = ~~(Date.now() / 1000)

after this if

spreed/src/components/LeftSidebar/LeftSidebar.vue

Lines 493 to 499 in d1adff8

	if (loadState('spreed', 'signaling_mode') !== 'internal') {
	if (response?.headers && response.headers['x-nextcloud-talk-modified-before']) {
	this.roomListModifiedBefore = response.headers['x-nextcloud-talk-modified-before']
	}
	}
	this.initialisedConversations = true