Canceled and/or removed campaigns are not stopped

[kbzowski]

Version:

• listmonk: 2.2.0
• OS: Docker (listmonk/listmonk:latest)

Description of the bug and steps to reproduce:
The canceled and/or deleted campaign is further sent. I don't know if this is related, but I have a very low sending limit set (1 message per minute)

[knadh]

A batch size worth of e-mails may be held in the in-memory queue. Even if a campaign is cancelled, this batch size is drained. With a rate as low as 1/minute, it'll take a long time to drain!

[kbzowski]

@knadh Thank you for the clarification. Correct me if I'm wrong, but isn't it confusing that pausing doesn't pause immediately? I assumed that deleting the campaign should also clear the message queue to send immediately. Especially since there could be a situation where after deleting a campaign, a new one won't start because the previous one is still running (which is no longer visible on the UI side). I noticed these situations when I tested listmonk internally (hence this window).

[knadh]

Yep, it's not ideal behaviour. Instant cancellation has been on the long list of to-dos for a while. Will look into this.

[knadh]

I've come back to this from time to time with no clear visible solutions. Have narrowed down on attaching a Go context.Context per campaign to every campaign message and using that to track cancellations/pausing/resumption. This involves major changes to how campaign messages are handled internally. Will experiment and figure out if this can be rolled out in the next version.

[knadh]

This is now being tested and almost ready to merge: #1636 -- It involved fully refactoring and changing the architecture of concurrent message handling in the core.