diff options
Diffstat (limited to 'src/corelib/global/qglobal.cpp')
| -rw-r--r-- | src/corelib/global/qglobal.cpp | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp index 742f4ec..5a7b559 100644 --- a/src/corelib/global/qglobal.cpp +++ b/src/corelib/global/qglobal.cpp @@ -46,6 +46,7 @@ #include "qthreadstorage.h" #include "qdir.h" #include "qstringlist.h" +#include "qdatetime.h" #ifndef QT_NO_QOBJECT #include <private/qthread_p.h> @@ -2523,6 +2524,33 @@ void qsrand(uint seed) #endif } +/*! \internal + \relates <QtGlobal> + \since 4.6 + + Seed the PRNG, but only if it has not already been seeded. + + The default seed is a combination of current time, a stack address and a + serial counter (since thread stack addresses are re-used). +*/ +void qsrand() +{ +#if defined(Q_OS_UNIX) && !defined(QT_NO_THREAD) && !defined(Q_OS_SYMBIAN) + SeedStorageType *pseed = randTLS()->localData(); + if (pseed) { + // already seeded + return; + } + randTLS()->setLocalData(pseed = new SeedStorageType); + static QBasicAtomicInt serial = Q_BASIC_ATOMIC_INITIALIZER(0); + *pseed = QDateTime::currentDateTime().toTime_t() + + quintptr(&pseed) + + serial.fetchAndAddRelaxed(1); +#else + // On Windows, we assume that rand() already does the right thing +#endif +} + /*! \relates <QtGlobal> \since 4.2 @@ -2645,7 +2673,7 @@ int qrand() \relates <QtGlobal> Marks the string literal \a sourceText for dynamic translation in - the given \a context, i.e the stored \a sourceText will not be + the given \a context; i.e, the stored \a sourceText will not be altered. The \a context is typically a class and also needs to be specified as string literal. |