fix(meetings): improve handling of websocket reconnections for 5k webinars by marcin-bazyl · Pull Request #4864 · webex/webex-js-sdk

marcin-bazyl · 2026-04-15T11:09:52Z

COMPLETES #SPARK-790957

This pull request addresses

When we regain Mercury connection, Meetings.syncMeetings() is called which does a GET /loci. For meetings that use hash trees we need to additionally do a sync on each dataset.

by making the following changes

added code to Meetings.syncMeetings() to sync hash tree data sets
fixed Meetings.syncMeetings() so that it doesn't remove a meeting if we were moved between breakouts while being offline (it's a fix for a bug I found while working on this feature)
since we already get a locus (but only a partial one) as output of GET /loci that's done by Meetings.syncMeetings(), so I also made sure that we use that partial locus to update our hash tree based LocusInfo (this will be quicker than the syncs that get kicked off), but since the format of that API response is not like a hash tree message but like a normal API, then I had to add code for handling cases of creating new HashTreeParser or resuming a stopped one like we had for messages but now also for API responses
the new method syncAllDatasets() is still needed, because GET /loci doesn't return a full locus, so we still need to try sync all datasets and syncAllDatasets() does a sync of all data sets sequentially, so I've introduced a queue for syncs and made sure that all existing code for syncs also uses that queue, so now any sync is always queued in that queue.

One consequence of using a sync queue now for everything is that previously initializeFromMessage() or initializeFromGetLociResponse() would result in a single callback to LocusInfo.updateFromHashTree() with all the updates in one go after all datasets were synced, now as we're using the queue, as each sync from the queue is processed, the callback LocusInfo.updateFromHashTree() is called with the updates. I think it's fine, I haven't seen any bad effects from this while testing and I think LocusInfo always has to manage to handle partial updates and we make sure that main data set is synced first, followed by self (see sortByInitPriority()), so it should be fine.

Change Type

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to change)
Documentation update
Tooling change
Internal code refactor

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unit tests

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marcin-bazyl · 2026-04-15T11:12:01Z

-   * @param {string} debugText - text to include in logs
-   * @returns {Promise}
-   */
-  private sendInitializationSyncRequestToLocus(


this method is not needed anymore as we're using enqueueSyncForDataset() istead and have the special logic for initialization syncs in performSync() - based on the isInitialization flag in the queued entry

aws-amplify-us-east-2 · 2026-04-15T11:20:28Z

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chatgpt-codex-connector · 2026-04-15T15:25:10Z

+        replacedAt: replaces?.replacedAt,
+      });
+
+      parser.initializeFromGetLociResponse(locus);


Await parser initialization from API response

handleHashTreeParserSwitchForAPIResponse() calls parser.initializeFromGetLociResponse(locus) without awaiting or handling rejection. That initializer propagates failures from getAllVisibleDataSetsFromLocus(), so transient Locus errors during reconnect can raise an unhandled promise rejection and leave a newly created parser active but not actually initialized, which breaks the intended post-reconnect dataset recovery path.

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this is fine, there is nothing more we want to do if initializeFromGetLociResponse() fails and if things fail, there will be warnings already logged by code closer to the failures

chatgpt-codex-connector · 2026-04-15T15:25:10Z

+      locusUrl,
+      entry,
+      replaces,
+      () => entry.parser.resumeFromApiResponse(locus)


Handle async resume failures for stopped parsers

The API-response resume path passes () => entry.parser.resumeFromApiResponse(locus) into resumeStoppedParser(), but that callback’s returned promise is not awaited or caught. If resumeFromApiResponse() fails (for example, fetching visible datasets fails), the rejection is unhandled and the parser is treated as reactivated without completing re-initialization, which can leave hash-tree updates stuck after breakout switches.

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that's ok, there is not much more we can do if it fails. Even if re-initialization fails at some point, at least the parser will no longer be in "stopped" state, so further messages can be processed

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chatgpt-codex-connector · 2026-04-16T08:02:22Z

+      const parser = this.createHashTreeParser({
+        locusUrl,
+        initialLocus: {locus: null, dataSets: []},
+        metadata: null,
+        replacedAt: replaces?.replacedAt,


Skip parser switch when API locus lacks visibleDataSets URL

When handleHashTreeParserSwitchForAPIResponse() creates a parser unconditionally for an unknown locusUrl, it can replace a working parser with one that cannot initialize from the same response. createHashTreeParser() immediately stops the current active parser, and initializeFromGetLociResponse() later bails out if locus.links.resources.visibleDataSets.url is missing. In reconnect/sync flows where GET /loci returns a partial locus without that link, this leaves the meeting with no initialized hash-tree parser and hash-tree updates stop until another successful switch occurs.

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this comment is invalid - if it's creating a new parser for unknown locusUrl, then it cannot be replacing anything

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chatgpt-codex-connector · 2026-04-17T08:40:50Z

+    this.state = 'active';
+    this.dataSets = {};
+


Keep parser stopped until API resume initialization succeeds

resumeFromApiResponse() flips state to active and clears dataSets before initializeFromGetLociResponse() completes, so any initialization failure (including missing visibleDataSets URL or request errors) leaves an active parser with no hash trees. In that state, later hash-tree messages cannot recover the parser because metadata updates are only applied through existing dataset hash trees, so updates get ignored and the meeting can stay desynced after reconnect. Fresh evidence from this change: this method now clears state up front, and parseMessage()/metadata handling requires existing hashTree entries to bootstrap updates.

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marcin-bazyl added 8 commits April 10, 2026 17:26

fix: initial implementation of sync queue

26f49bc

fix: handling empty /hashtree responses

4d8771c

fix: better handling of sync responses

66966bd

fix: handling parser switching for api responses

f5a2748

fix: syncMeetings always syncs hash trees

35fa9fe

fix: resumeFromApiResponse() added

3c4df65

fix: using global id to match locuses

9618552

fix: small refactor of tryReactivateStoppedParser()

03c9b11

marcin-bazyl commented Apr 15, 2026

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fix: cleanup

30ca445

rsarika changed the title ~~fix(meetings): improve handling of websocket reconnections for 5k webinars~~ fix(calling-sdk): improve handling of websocket reconnections for 5k webinars Apr 15, 2026

rsarika changed the title ~~fix(calling-sdk): improve handling of websocket reconnections for 5k webinars~~ fix(meetings): improve handling of websocket reconnections for 5k webinars Apr 15, 2026

marcin-bazyl marked this pull request as ready for review April 15, 2026 15:18

marcin-bazyl requested review from a team as code owners April 15, 2026 15:18

marcin-bazyl added the validated If the pull request is validated for automation. label Apr 15, 2026

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Merge branch 'next' into spark-790957

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mickelr approved these changes Apr 16, 2026

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marcin-bazyl added 2 commits April 17, 2026 09:26

test: new unit tests

49637ad

Merge remote-tracking branch 'upstream/next' into spark-790957

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fix(meetings): improve handling of websocket reconnections for 5k webinars#4864

fix(meetings): improve handling of websocket reconnections for 5k webinars#4864
marcin-bazyl wants to merge 12 commits intowebex:nextfrom
marcin-bazyl:spark-790957

marcin-bazyl commented Apr 15, 2026 •

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marcin-bazyl commented Apr 15, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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COMPLETES #SPARK-790957

This pull request addresses

by making the following changes

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The following scenarios were tested

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marcin-bazyl commented Apr 15, 2026 •

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