Tunnel requested abort exception to semaphore wait caller #2601
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@scylladb/seastar-maint please review and consider merging |
xemul
reviewed
Jan 9, 2025
tests/unit/semaphore_test.cc
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| }); | ||
| as.request_abort_ex(std::runtime_error("expected")); | ||
| sem.signal(); | ||
| BOOST_CHECK_THROW(fut1.get(), std::runtime_error); |
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How confident are we, that this thrown-and-caught runtime_exception is the one from above as.request_abort_ex(), but not some "generic" runtime error that accidentally crept in along the way?
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I have no reason to suspect that, but I can change this to a unique exception type to increase the confidence.
So that users can distinguish between timer expiration to other abort sources. Signed-off-by: Benny Halevy <[email protected]>
Signed-off-by: Benny Halevy <[email protected]>
For passing an exception_ptr from the abort_source to the callback, allow the OnAbort class to have a call operator accepting an optional exception_ptr. Signed-off-by: Benny Halevy <[email protected]>
Signed-off-by: Benny Halevy <[email protected]>
If waiting with timeout or abort_source, check (under [[unlikely]]) if the timeout is already expired, or abort requested, before appending an entry to the wait_list, which is rather expensive. We do this so that we can easily distinguish between timeout error to aborted errors, as in `make_back_abortable` there isn't a good way to distingush the two if abort is already requested by the type-erased abort_source. Signed-off-by: Benny Halevy <[email protected]>
Move into tests/unit/expected_exception.hh Signed-off-by: Benny Halevy <[email protected]>
Accept an optional exception_ptr in the expiry_handler and pass it on to the entry promise, so that the original abort exception can be passed to the user. This way we can distinguish between, e.g. timed_out_error and abort_requested_error. Signed-off-by: Benny Halevy <[email protected]>
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In v2 (f8c36db):
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Today, when calling
wait(abort_source&)the caller always getssemaphore_abortederror when abort is requested.However, with
abort_on_expiry, the actual reason could be timeout expiry, which should be distinguishable from the abort error.This series modifies
abort_on_expiryfirst to request abort with atimed_out_errorexception, and theninternal::abortable_fifoandsemaphoreare changed to tunnel that exception to the caller.Respective unit tests were added to test those cases.
The motivation for this change is scylladb/scylladb#22017
which will use scylladb utils::composite_abort_source to compose an
abort_on_expiryabort_source, used for point request timeout and a global abort_source used on shutdown.