Front-load handling of callback responses from the client. #79
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Previously, a notification handler that issues a call back to the client could block delivery of the reply for its own callback: The barrier we use to preserve issue order means another batch cannot be issued to the dispatcher until all previously-issued notifications have completed. To prevent the handler from deadlocking itself in this case, filter out response messages from the client when the input is received, rather than enqueuing them with the handlers. This basically just moves the existing logic earlier in the transaction, but it means replies can be delivered even if the barrier is active. Fixes #78.
radeksimko
approved these changes
Feb 8, 2022
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This fix is now releaseed at v0.35.5. |
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Previously, a notification handler that issues a call back to the client could
block delivery of the reply for its own callback: The barrier we use to
preserve issue order means another batch cannot be issued to the dispatcher
until all previously-issued notifications have completed.
To prevent the handler from deadlocking itself in this case, filter out
response messages from the client when the input is received, rather than
enqueuing them with the handlers. This basically just moves the existing logic
earlier in the transaction, but it means replies can be delivered even if the
barrier is active.
Add regression test for deadlock bug.
Fixes #78.