Appservice incorrectly handling a batch of events with the same transaction ID

[tak-hntlabs]

Background information

• Dendrite version or git SHA: 0ea948c (latest main on 9/14)
• Monolith or Polylith?: Monolith
• SQLite3 or Postgres?: SQLite3
• Running in Docker?: No
• go version: go version go1.19 darwin/amd64
• Client used (if applicable):

Description

• What is the problem:

I am seeing a regression with appservice. I am working on an appservice that uses the matrix-bot-sdk. My appservice was working prior to this PR that was merged: Refactor appservices component

Before the PR was merged, my appservice is able to see all events associated with a new space/ room creation. When a space is created, it was able to see all the related events - room.create, room.join, etc. After pulling the latest main, the appservice is no longer able to see the events when a space is created.

I traced it to this logic in appservice/consumers/roomserver.go. In line 178 of the func sendEvents( ... ):

txnID := events[0].Event.OriginServerTS()

What's happening is that the batch of events associated with space / room creation has the same OriginServerTS(). Dendrite sends the first event to the appservice. The appservice processes the event, and completes the transaction. The sendEvents func is invoked again with the rest of the events. The txnID is exactly the same as before. Consequently, the appservice thinks that this transaction has been processed, and ignores the events.

• Who is affected:
  I am building on matrix-bot-sdk. This regression could affect any projects using that sdk. Didn't try other appservice sdk.

• How is this bug manifesting:
  Configure an appservice (based on matrix-bot-sdk). Create a space or a room. Appservice no longer gets all the associated events with creating the room.

• When did this first appear:
  After this PR was merged: Refactor appservices component

I will create a PR for fixing it. Will gather feedback in the PR.