Latency improved for activity keyer and tree composer

[pranavjoshi001]

Changelog Entry

• Improved latency of ActivityKeyerComposer and ActivityTreeComposer
• Deleted ActivitListenerComposer and useUpsertedActivities hook as it is not needed anymore.

Description

This is to improve latency of composer as we get larger number of activities when streaming is enabled and having multiple iteration in composer makes rendering slow

Visuals

Specific Changes

• use useReducerActivities in ActivityTreeComposer to avoid recompute everything when new activity comes in
• Only compute last activity in ActivityKeyerComposer rather than re-computing and iterating through all activities when new activity comes in

• I have added tests and executed them locally
• I have updated CHANGELOG.md
• I have updated documentation

Review Checklist

This section is for contributors to review your work.

• Accessibility reviewed (tab order, content readability, alt text, color contrast)
• Browser and platform compatibilities reviewed
• CSS styles reviewed (minimal rules, no z-index)
• Documents reviewed (docs, samples, live demo)
• Internationalization reviewed (strings, unit formatting)
• package.json and package-lock.json reviewed
• Security reviewed (no data URIs, check for nonce leak)
• Tests reviewed (coverage, legitimacy)

[pranavjoshi001]

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[compulim]

Sort.

[compulim]

I am curious why this would work.

In the new code, activityToKeyMapRef is always frozen and setting to it should throw (in strict mode) or no-op (in non-strict mode).

[compulim]

The activities array can change at any given position. Says, we have 3 activities [a1, b1, c1].

It could be updated and become [a2, b1, c1] and the lastProcessedIndexRef would missed that change.

Can we use useReduceActivities here?

[pranavjoshi001]

I tried with useReduceActivities but then I was not aware that activities can change at any given position in that case updated activity will come in prevActivities in hook's argument and we need to process it again to fill our ref maps, that would nothing but iteration through all activities like before - is my understanding correct ?

[compulim]

If the activity is removed from the rawActivities, it will still keep in the activityMapRef forever and this will cause memory leak.

[compulim]

Let's separate this PR into 3 parts:

• Remove useUpsertedActivities
• Move ActivityTreeComposer to use useReduceActivities
• Make ActivityKeyerComposer better

[compulim]

One thing to consider across all these changes: the result returning from useActivities() can change at any random position, including:

• Appending an activity at the end of the array
• Replacing an existing activity
• Removing an existing activity
• Inserting an activity at any position

The algorithm need to be more robust against this. Also make sure when activity is being replaced/removed, they will not be lingering in the system.

Please run tests locally.