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Use QElapsedTimer in tst_qmutex

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This requires fixing the test on Windows: QMutex internally uses
WaitForSingleObjectEx which can wake up early, according to the system
timer resolution:

https://msdn.microsoft.com/en-us/library/windows/desktop/ms687069(v=vs.85).aspx#waitfunctionsandtime-outintervals

QTime must be so slow that it hides the early wakes, but QElapsedTimer is
accurate enough to make the test fail unless we add back some tolerance to
compensate for the early wakeups.

Change-Id: I20b38af9c87a0b0e38a19b9bff1c3c24975c78f5
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Giuseppe D'Angelo 2016-07-16 18:06:48 +02:00
parent 8ea51f8aaa
commit 7814bf126a
2 changed files with 69 additions and 14 deletions
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1
tests/auto/corelib/thread/qmutex/qmutex.pro
View File

@ -2,3 +2,4 @@ CONFIG += testcase
TARGET = tst_qmutex
QT = core testlib
SOURCES = tst_qmutex.cpp
win32:QT += core-private

82
tests/auto/corelib/thread/qmutex/tst_qmutex.cpp
View File

@ -31,15 +31,21 @@
#include <qatomic.h>
#include <qcoreapplication.h>
#include <qdatetime.h>
#include <qelapsedtimer.h>
#include <qmutex.h>
#include <qthread.h>
#include <qwaitcondition.h>
#ifdef Q_OS_WIN
#include <private/qsystemlibrary_p.h>
#include <cmath>
#endif
class tst_QMutex : public QObject
{
Q_OBJECT
private slots:
void initTestCase();
void tryLock();
void lock_unlock_locked_tryLock();
void stressTest();
@ -48,6 +54,8 @@ private slots:
void tryLockNegative_data();
void tryLockNegative();
void moreStress();
private:
void initializeSystemTimersResolution();
};
static const int iterations = 100;
@ -58,6 +66,52 @@ QSemaphore testsTurn;
QSemaphore threadsTurn;
enum { waitTime = 100 };
uint systemTimersResolution = 1;
/*
Depending on the OS, tryWaits may return early than expected because of the
resolution of the underlying timer is too coarse. E.g.: on Windows
WaitForSingleObjectEx does *not* use high resolution multimedia timers, and
it's actually very coarse, about 16msec by default.
Try to find out the timer resolution in here, so that the tryLock tests can
actually take into account early wakes.
*/
void tst_QMutex::initializeSystemTimersResolution()
{
#ifdef Q_OS_WIN
// according to MSDN, Windows can default up to this
systemTimersResolution = 16;
// private API. There's no way on Windows to otherwise know the
// actual resolution of the application's timers (you can only set it)
// cf. https://stackoverflow.com/questions/7685762/windows-7-timing-functions-how-to-use-getsystemtimeadjustment-correctly/11743614#11743614
typedef NTSTATUS (NTAPI *NtQueryTimerResolutionType)(OUT PULONG MinimumResolution,
OUT PULONG MaximumResolution,
OUT PULONG ActualResolution);
const NtQueryTimerResolutionType NtQueryTimerResolutionPtr =
reinterpret_cast<NtQueryTimerResolutionType>(QSystemLibrary::resolve(QStringLiteral("ntdll"), "NtQueryTimerResolution"));
if (!NtQueryTimerResolutionPtr)
return;
ULONG minimumResolution;
ULONG maximumResolution;
ULONG actualResolution;
if (!NtQueryTimerResolutionPtr(&minimumResolution, &maximumResolution, &actualResolution)) {
// the result is in 100ns units => adjust to msec
const double actualResolutionMsec = actualResolution / 10000.0;
systemTimersResolution = static_cast<int>(std::ceil(actualResolutionMsec));
}
#endif // Q_OS_WIN
}
void tst_QMutex::initTestCase()
{
initializeSystemTimersResolution();
}
void tst_QMutex::tryLock()
{
@ -86,22 +140,22 @@ void tst_QMutex::tryLock()
// TEST 3: thread can't acquire lock, timeout = waitTime
threadsTurn.acquire();
QTime timer;
QElapsedTimer timer;
timer.start();
QVERIFY(!normalMutex.tryLock(waitTime));
QVERIFY(timer.elapsed() >= waitTime);
QVERIFY(timer.elapsed() >= waitTime - systemTimersResolution);
testsTurn.release();
// TEST 4: thread can acquire lock, timeout = waitTime
threadsTurn.acquire();
timer.start();
QVERIFY(normalMutex.tryLock(waitTime));
QVERIFY(timer.elapsed() <= waitTime);
QVERIFY(timer.elapsed() <= waitTime + systemTimersResolution);
QVERIFY(lockCount.testAndSetRelaxed(0, 1));
timer.start();
// it's non-recursive, so the following lock needs to fail
QVERIFY(!normalMutex.tryLock(waitTime));
QVERIFY(timer.elapsed() >= waitTime);
QVERIFY(timer.elapsed() >= waitTime - systemTimersResolution);
QVERIFY(lockCount.testAndSetRelaxed(1, 0));
normalMutex.unlock();
testsTurn.release();
@ -115,7 +169,7 @@ void tst_QMutex::tryLock()
threadsTurn.acquire();
timer.start();
QVERIFY(normalMutex.tryLock(0));
QVERIFY(timer.elapsed() < waitTime);
QVERIFY(timer.elapsed() < waitTime + systemTimersResolution);
QVERIFY(lockCount.testAndSetRelaxed(0, 1));
QVERIFY(!normalMutex.tryLock(0));
QVERIFY(lockCount.testAndSetRelaxed(1, 0));
@ -126,7 +180,7 @@ void tst_QMutex::tryLock()
threadsTurn.acquire();
timer.start();
QVERIFY(normalMutex.tryLock(3000));
QVERIFY(timer.elapsed() < 3000);
QVERIFY(timer.elapsed() < 3000 + systemTimersResolution);
normalMutex.unlock();
testsTurn.release();
@ -211,17 +265,17 @@ void tst_QMutex::tryLock()
testsTurn.release();
threadsTurn.acquire();
QTime timer;
QElapsedTimer timer;
timer.start();
QVERIFY(!recursiveMutex.tryLock(waitTime));
QVERIFY(timer.elapsed() >= waitTime);
QVERIFY(timer.elapsed() >= waitTime - systemTimersResolution);
QVERIFY(!recursiveMutex.tryLock(0));
testsTurn.release();
threadsTurn.acquire();
timer.start();
QVERIFY(recursiveMutex.tryLock(waitTime));
QVERIFY(timer.elapsed() <= waitTime);
QVERIFY(timer.elapsed() <= waitTime + systemTimersResolution);
QVERIFY(lockCount.testAndSetRelaxed(0, 1));
QVERIFY(recursiveMutex.tryLock(waitTime));
QVERIFY(lockCount.testAndSetRelaxed(1, 2));
@ -239,7 +293,7 @@ void tst_QMutex::tryLock()
threadsTurn.acquire();
timer.start();
QVERIFY(recursiveMutex.tryLock(0));
QVERIFY(timer.elapsed() < waitTime);
QVERIFY(timer.elapsed() < waitTime + systemTimersResolution);
QVERIFY(lockCount.testAndSetRelaxed(0, 1));
QVERIFY(recursiveMutex.tryLock(0));
QVERIFY(lockCount.testAndSetRelaxed(1, 2));
@ -439,7 +493,7 @@ enum { one_minute = 6 * 1000, //not really one minute, but else it is too long.
class StressTestThread : public QThread
{
QTime t;
QElapsedTimer t;
public:
static QBasicAtomicInt lockCount;
static QBasicAtomicInt sentinel;
@ -491,7 +545,7 @@ public:
void run()
{
QTime t;
QElapsedTimer t;
t.start();
do {
if (mutex.tryLock())
@ -619,7 +673,7 @@ void tst_QMutex::tryLockNegative()
class MoreStressTestThread : public QThread
{
QTime t;
QElapsedTimer t;
public:
static QAtomicInt lockCount;
static QAtomicInt sentinel[threadCount];