Clarify the ClientEvent that is sent to client.subscribe

[chacha912]

What this PR does / why we need it?

Clarify the ClientEvent that is sent to client.subscribe

• Remove runWatchLoop when activating the client
• Add sending of connected and disconnected events

PeersChanged Event

• Elaborate on the value of the PeersChanged event

• as-is

  • PeersChanged event provides the entire list of peers in its value, so it is necessary to find which peers have been changed.
  • For instance, in the Quill example, findDefectors function is used to remove the cursor of the unwatched peer. https://github.com/yorkie-team/yorkie-js-sdk/pull/369/files

// js-sdk
type PeersChangedValue<P> = Record<string, Record<string, P>>;

• to-be

// js-sdk
type PeersChangedValue<P> = {
  type: 'initialization' | 'watched' | 'unwatched' | 'presence-changed';
  peers: Record<DocumentKey, Array<{ clientID: ActorID; presence: P }>>;
};

// example
client.subscribe((event) => {
  switch (event.type) {
    case 'status-changed': {
      // event.value: activated, deactivated
      break;
    }
    case 'stream-connection-status-changed': {
      // event.value: connected, disconnected
      break;
    }
    case 'document-synced': {
      // event.value: synced, sync-failed
      break;
    }
    case 'document-changed': {
      // event.value: docKey[]
      break;
    }
    case 'peers-changed': {
      const { type, peers } = event.value;
      // type: initialization, watched, unwatched, presence-changed

      switch (event.value.type) {
        case 'initialization': {
          displayCursor(peers[doc.getKey()]); 
          break;
        }
        case 'unwatched': {
          // we can get which peer has unwatched.
          removeCursor(peers[doc.getKey()]);
          break;
        }
        case 'watched':
        case 'presence-changed': {
          // we can partially update for changed peers.
          updateCursor(peers[doc.getKey()]);
          break;
        }
      }

      // if you need entire peers
      displayPeers(client.getPeersByDocKey(doc.getKey()));
      break;
    }
  }
});

ClientEvent flow in test code

• Add test for ClientEvent flow in client.subscribe

Any background context you want to provide?

What are the relevant tickets?

Fixes #

Checklist

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

[chacha912]

The test fails in CI and I've analyzed the cause. To resolve this issue, I think the order of events must be guaranteed. Please let me know if you have any good ideas.

The reason for the test failure is as follows:

In the event flow diagram above, you can see that when clientA attaches the second document(doc2) in events 6-7, the stream connection is disconnected and reconnected.
At this point, clientB, who is subscribed to doc1, receives unwatched and watched events from clientA, but the order of these events is not guaranteed.
Therefore, if the events come in the order of watched, unwatched (in the case where the order of events 5-6 in clientB is reversed), clientB's peerPresenceMap information will only have {doc1: {peerPresenceMap: {clientB: {presence}}} left.

Then, when clientA detaches doc1, clientB receives an event that A has become unwatched.
To send the event to the user that clientA has become unwatched, the peer information is looked up in the peerPresenceMap. However, an error occurs because clientA does not exist in the peerPresenceMap.

[codecov]

Codecov Report

Merging #464 (1838159) into main (7ddcf92) will increase coverage by 0.22%.
The diff coverage is 95.88%.

@@            Coverage Diff             @@
##             main     #464      +/-   ##
==========================================
+ Coverage   89.28%   89.50%   +0.22%     
==========================================
  Files          67       67              
  Lines        5254     5375     +121     
  Branches      524      528       +4     
==========================================
+ Hits         4691     4811     +120     
  Misses        381      381              
- Partials      182      183       +1     

Impacted Files	Coverage Δ
src/document/document.ts	79.00% <ø> (ø)
test/helper/helper.ts	70.83% <85.18%> (+14.31%)	⬆️
src/core/client.ts	77.52% <94.23%> (+1.66%)	⬆️
test/integration/client_test.ts	100.00% <100.00%> (ø)

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[hackerwins]

Thanks for your contribution. The structure and types of PeersChanged have been cleaned up more in this PR. 👍

I left a few comments.

[hackerwins]

Thanks for your reply. Left additional questions.

[hackerwins]

LGTM. 👍