Let Client.attach wait until stream initialization is finished

[cozitive]

What this PR does / why we need it?

Client.attach can be terminated before getting peer presence map in WatchDocuments stream initialization. It can cause presence missing, which breaks eventual consistency, when updatePresence is called before the initialization.
This PR made Client.attach wait until the initialization is finished. Presence updates will be executed after peer presence map is properly set.

Any background context you want to provide?

If delay() is removed in the code below, test in the last line intermittently fails.

yorkie-js-sdk/test/integration/client_test.ts

Lines 291 to 309 in 717383d

	// Since attach's response doesn't wait for the watch ready,
	// We need to wait here until the threshold.
	await delay(100);
	const unsub1 = c1.subscribe(spy1);
	const unsub2 = c2.subscribe(spy2);
	// Since `updatePresence` handles event publishing synchronously with
	// Memory Coordinator, We need to wait for the event from the peer wihout
	// waiting for the response of `updatePresence` here.
	c1.updatePresence('name', 'c1+');
	await waitFor(ClientEventType.PeersChanged, emitter1);
	assert.equal(c1.getPresence().name, 'c1+');
	await waitFor(ClientEventType.PeersChanged, emitter2);
	c2.updatePresence('name', 'c2+');
	await waitFor(ClientEventType.PeersChanged, emitter2);
	assert.equal(c2.getPresence().name, 'c2+');
	await waitFor(ClientEventType.PeersChanged, emitter1);
	assert.deepEqual(c1.getPeers(d1.getKey()), c2.getPeers(d2.getKey()));

It means the eventual values of c1.getPeers() and c2.getPeers() become different. To be precise, c1's presence in c2.getPeers() is not updated. Although these two clients are attached to the same document, the stream initialization timing issue (mentioned above) breaks eventual consistency.

What are the relevant tickets?

Fixes #428

Checklist

• Added relevant tests or not required
• Didn't break anything

[codecov]

Codecov Report

Merging #440 (8d1720a) into main (d67e898) will decrease coverage by 0.14%.
The diff coverage is 87.17%.

@@            Coverage Diff             @@
##             main     #440      +/-   ##
==========================================
- Coverage   89.51%   89.37%   -0.14%     
==========================================
  Files          69       69              
  Lines        5321     5289      -32     
  Branches      524      524              
==========================================
- Hits         4763     4727      -36     
- Misses        381      385       +4     
  Partials      177      177              

Impacted Files	Coverage Δ
src/core/client.ts	75.86% <79.16%> (-0.59%)	⬇️
test/integration/client_test.ts	100.00% <100.00%> (ø)
test/helper/helper.ts	81.81% <0.00%> (-9.10%)	⬇️

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[hackerwins]

Thanks for your contribution. I have a few questions.

Do we need to add await this.runWatchLoop() on client.detach and client.activate as well?

[cozitive]

I missed runWatchLoop() is also called in client.detach and client.activate. await keyword should also be added on them.

[hackerwins]

@skhugh, @7hong13, @humdrum This PR changed the response time of client.attach. It would be nice to review this PR together.

[hackerwins]

Thanks for your contribution.