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tst_QSet: make qhash() test deterministic

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Change-Id: I857e66f21030da2210122c8c95c95f05a73da50a
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
This commit is contained in:
Marc Mutz 2015-01-23 17:32:00 +01:00
parent 6a1d9134b8
commit f272c40697
1 changed files with 18 additions and 1 deletions
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19
tests/auto/corelib/tools/qset/tst_qset.cpp
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@ -973,18 +973,35 @@ QT_BEGIN_NAMESPACE
extern Q_CORE_EXPORT QBasicAtomicInt qt_qhash_seed; // from qhash.cpp
QT_END_NAMESPACE
class QtQHashSeedSaver {
int oldSeed, newSeed;
public:
explicit QtQHashSeedSaver(int seed)
: oldSeed(qt_qhash_seed.fetchAndStoreRelaxed(seed)),
newSeed(seed)
{}
~QtQHashSeedSaver()
{
// only restore when no-one else changed the seed in the meantime:
qt_qhash_seed.testAndSetRelaxed(newSeed, oldSeed);
}
};
void tst_QSet::qhash()
{
//
// check that sets containing the same elements hash to the same value
//
{
// create some deterministic initial state:
const QtQHashSeedSaver seed1(0);
QSet<int> s1;
s1.reserve(4);
s1 << 400 << 300 << 200 << 100;
// also change the seed:
qt_qhash_seed = qt_qhash_seed + 0x9e3779b9;
const QtQHashSeedSaver seed2(0x10101010);
QSet<int> s2;
s2.reserve(100); // provoke different bucket counts