AuroraMiddleware/qt5base-lts
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

QSemaphore: fix regression when the timeout < 0

Browse Source 
The issue was introduced by eaee1209f0, so
it affected only 5.9.2.

[ChangeLog][QtCore][QSemaphore] Fixed a regression that would make
tryAcquire() not to wait forever if the timeout was a negative
value. Note: new code is advised to only use -1 to indicate "forever",
as some other functions taking timeout periods do not accept other
values.

Task-number: QTBUG-64413
Change-Id: I57a1bd6e0c194530b732fffd14f58fce60d5dfc9
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This commit is contained in:
Thiago Macieira 2017-11-09 15:49:26 -08:00 committed by Jani Heikkinen
parent d583030f2c
commit 4870282117
2 changed files with 68 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/corelib/thread/qsemaphore.cpp
View File

@ -214,13 +214,15 @@ bool QSemaphore::tryAcquire(int n)
bool QSemaphore::tryAcquire(int n, int timeout)
{
Q_ASSERT_X(n >= 0, "QSemaphore::tryAcquire", "parameter 'n' must be non-negative");
if (timeout < 0)
return tryAcquire(n);
// We're documented to accept any negative value as "forever"
// but QDeadlineTimer only accepts -1.
timeout = qMax(timeout, -1);
QDeadlineTimer timer(timeout);
QMutexLocker locker(&d->mutex);
qint64 remainingTime = timer.remainingTime();
while (n > d->avail && remainingTime > 0) {
while (n > d->avail && remainingTime != 0) {
if (!d->cond.wait(locker.mutex(), remainingTime))
return false;
remainingTime = timer.remainingTime();

63
tests/auto/corelib/thread/qsemaphore/tst_qsemaphore.cpp
View File

@ -41,6 +41,8 @@ private slots:
void tryAcquireWithTimeout_data();
void tryAcquireWithTimeout();
void tryAcquireWithTimeoutStarvation();
void tryAcquireWithTimeoutForever_data();
void tryAcquireWithTimeoutForever();
void producerConsumer();
};
@ -155,21 +157,25 @@ void tst_QSemaphore::tryAcquire()
semaphore.release();
QCOMPARE(semaphore.available(), 1);
QVERIFY(!semaphore.tryAcquire(2));
QVERIFY(!semaphore.tryAcquire(2, 0));
QCOMPARE(semaphore.available(), 1);
semaphore.release();
QCOMPARE(semaphore.available(), 2);
QVERIFY(!semaphore.tryAcquire(3));
QVERIFY(!semaphore.tryAcquire(3, 0));
QCOMPARE(semaphore.available(), 2);
semaphore.release(10);
QCOMPARE(semaphore.available(), 12);
QVERIFY(!semaphore.tryAcquire(100));
QVERIFY(!semaphore.tryAcquire(100, 0));
QCOMPARE(semaphore.available(), 12);
semaphore.release(10);
QCOMPARE(semaphore.available(), 22);
QVERIFY(!semaphore.tryAcquire(100));
QVERIFY(!semaphore.tryAcquire(100, 0));
QCOMPARE(semaphore.available(), 22);
QVERIFY(semaphore.tryAcquire());
@ -178,23 +184,38 @@ void tst_QSemaphore::tryAcquire()
QVERIFY(semaphore.tryAcquire());
QCOMPARE(semaphore.available(), 20);
semaphore.release(2);
QVERIFY(semaphore.tryAcquire(1, 0));
QCOMPARE(semaphore.available(), 21);
QVERIFY(semaphore.tryAcquire(1, 0));
QCOMPARE(semaphore.available(), 20);
QVERIFY(semaphore.tryAcquire(10));
QCOMPARE(semaphore.available(), 10);
semaphore.release(10);
QVERIFY(semaphore.tryAcquire(10, 0));
QCOMPARE(semaphore.available(), 10);
QVERIFY(semaphore.tryAcquire(10));
QCOMPARE(semaphore.available(), 0);
// should not be able to acquire more
QVERIFY(!semaphore.tryAcquire());
QVERIFY(!semaphore.tryAcquire(1, 0));
QCOMPARE(semaphore.available(), 0);
QVERIFY(!semaphore.tryAcquire());
QVERIFY(!semaphore.tryAcquire(1, 0));
QCOMPARE(semaphore.available(), 0);
QVERIFY(!semaphore.tryAcquire(10));
QVERIFY(!semaphore.tryAcquire(10, 0));
QCOMPARE(semaphore.available(), 0);
QVERIFY(!semaphore.tryAcquire(10));
QVERIFY(!semaphore.tryAcquire(10, 0));
QCOMPARE(semaphore.available(), 0);
}
@ -344,6 +365,48 @@ void tst_QSemaphore::tryAcquireWithTimeoutStarvation()
QVERIFY(consumer.wait());
}
void tst_QSemaphore::tryAcquireWithTimeoutForever_data()
{
QTest::addColumn<int>("timeout");
QTest::newRow("-1") << -1;
// tryAcquire is documented to take any negative value as "forever"
QTest::newRow("INT_MIN") << INT_MIN;
}
void tst_QSemaphore::tryAcquireWithTimeoutForever()
{
enum { WaitTime = 1000 };
struct Thread : public QThread {
QSemaphore sem;
void run() override
{
QTest::qWait(WaitTime);
sem.release(2);
}
};
QFETCH(int, timeout);
Thread t;
// sanity check it works if we can immediately acquire
t.sem.release(11);
QVERIFY(t.sem.tryAcquire(1, timeout));
QVERIFY(t.sem.tryAcquire(10, timeout));
// verify that we do wait for at least WaitTime if we can't acquire immediately
QElapsedTimer timer;
timer.start();
t.start();
QVERIFY(t.sem.tryAcquire(1, timeout));
QVERIFY(timer.elapsed() >= WaitTime);
QVERIFY(t.wait());
QCOMPARE(t.sem.available(), 1);
}
const char alphabet[] = "ACGTH";
const int AlphabetSize = sizeof(alphabet) - 1;