[FIX] IMAP execution management #2090
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Arsnael merged 6 commits intoapache:masterfrom Mar 6, 2024
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- Abort ongoing processing first - Logout asynchronously
Arsnael
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Mar 6, 2024
quantranhong1999
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Mar 6, 2024
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That is my best shot at explaining:
CF linagora#4688 which was mostly fixed incorrectly...
The Netty stack enforce linearisability of operation conducted on the event loop for a single channel, including command decoding.
For command execution, we trigger the processing only reactor. We rely on a linarizer to enforce sequential IMAP execution.
So in theory we do never execute two IMAP commands of a given connection at the same time.
However no mechanism prevents decoding at the same time than command execution - and that is fine - however the channel operations (inactive, idle, parsing failures) MAY interfere with command execution by deciding a logout eventually deselecting the current mailbox and resulting in the NPE.
Lessons learned: always cancel current command execution before deciding to log out!
That, and we were executing blocking code onto the netty event loop which IS BAD.