Refactor cancellation of IOCP::OverlappedOperation
#14754
Merged
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When an overlapped operation gets cancelled, we still need to wait for completion of the operation (with status
ERROR_OPERATION_ABORTED
) before it can be freed.Previously we stored a reference to cancelled operations in a linked list and removed them when complete. This allows continuing executing the fiber directly after the cancellation is triggered, but it's also quite a bit of overhead.
Also it makes it impossible to allocate operations on the stack.
Cancellation is triggered when an operation times out.
The change in this patch is that after a timeout the fiber is suspended again, expecting completion via the event loop. Then the operation can be freed.
CANCELLED
state. It's no longer necessary, we only need to distinguish whether a fiber was woken up due to timeout or completion. A follow-up will further simplify the state handling.sleep
andsuspend
@@cancelled
linked list.IOCP::OverlappedOperation
internalizehandle
andwait_for_completion
#14724 (comment)