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QPromise: Propagate cancellation through failure handlers

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Previously, failure handlers did not propagate cancellation. This would
lead to crashes when a QPromise was cancelled without having generated
any result. Subsequent continuations would be invoked and try to access
the result (which was nonexistent) and then crash.
This patch propagates cancellation through failure handlers to prevent
subsequent continuations from being called in the first place.

Fixes: QTBUG-114606
Change-Id: I23b28a8e70a76e1ba6416be4440360c6dbaef2a3
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
(cherry picked from commit 855c4484693015cb6498f2183d95de1377d49898)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Arno Rehn 2023-06-15 17:12:02 +02:00 committed by Qt Cherry-pick Bot
parent 40b99f7fc6
commit f0765c556d
2 changed files with 35 additions and 0 deletions
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2
src/corelib/thread/qfuture_impl.h
View File

@ -732,6 +732,8 @@ void FailureHandler<Function, ResultType>::run()
} else {
handleException<ArgType>();
}
} else if (parentFuture.d.isChainCanceled()) {
promise.future().cancel();
} else {
QtPrivate::fulfillPromise(promise, parentFuture);
}

33
tests/auto/corelib/thread/qpromise/tst_qpromise.cpp
View File

@ -44,6 +44,7 @@ private slots:
void cancelWhenReassigned();
void cancelWhenDestroyedWithoutStarting();
void cancelWhenDestroyedRunsContinuations();
void cancelWhenDestroyedWithFailureHandler(); // QTBUG-114606
void continuationsRunWhenFinished();
void finishWhenSwapped();
void cancelWhenMoved();
@ -577,6 +578,38 @@ void tst_QPromise::cancelWhenDestroyedRunsContinuations()
testCancelWhenDestroyedRunsContinuations<MoveOnlyType>();
}
template <typename T>
static inline void testCancelWhenDestroyedWithFailureHandler()
{
QFuture<T> future;
bool onFailedCalled = false;
bool thenCalled = false;
{
QPromise<T> promise;
future = promise.future();
future
.onFailed([&] () {
onFailedCalled = true;
if constexpr (!std::is_same_v<void, T>)
return T{};
})
.then([&] (auto&&) {
thenCalled = true;
});
}
QVERIFY(future.isFinished());
QVERIFY(!onFailedCalled);
QVERIFY(!thenCalled);
}
void tst_QPromise::cancelWhenDestroyedWithFailureHandler()
{
testCancelWhenDestroyedWithFailureHandler<void>();
testCancelWhenDestroyedWithFailureHandler<int>();
testCancelWhenDestroyedWithFailureHandler<CopyOnlyType>();
testCancelWhenDestroyedWithFailureHandler<MoveOnlyType>();
}
template <typename T>
static inline void testContinuationsRunWhenFinished()
{