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[doc] QElapsedTimer: mention more clearly which functions cause undefined behavior

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Change-Id: Ic7ab0d81689e2cc78f39f5f32beaea74ca10ce38
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Marc Mutz 2016-04-03 13:02:47 +02:00
parent 7b4c02d527
commit 045e417eff
1 changed files with 14 additions and 8 deletions
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22
src/corelib/tools/qelapsedtimer_generic.cpp
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@ -79,7 +79,8 @@ void QElapsedTimer::start() Q_DECL_NOTHROW
and then starting the timer again with start(), but it does so in one and then starting the timer again with start(), but it does so in one
single operation, avoiding the need to obtain the clock value twice. single operation, avoiding the need to obtain the clock value twice.
Restarting the timer makes it valid again. Calling this function on a QElapsedTimer that is invalid
results in undefined behavior.
The following example illustrates how to use this function to calibrate a The following example illustrates how to use this function to calibrate a
parameter to a slow operation (for example, an iteration count) so that parameter to a slow operation (for example, an iteration count) so that
@ -87,7 +88,7 @@ void QElapsedTimer::start() Q_DECL_NOTHROW
\snippet qelapsedtimer/main.cpp 3 \snippet qelapsedtimer/main.cpp 3
\sa start(), invalidate(), elapsed() \sa start(), invalidate(), elapsed(), isValid()
*/ */
qint64 QElapsedTimer::restart() Q_DECL_NOTHROW qint64 QElapsedTimer::restart() Q_DECL_NOTHROW
{ {
@ -100,8 +101,10 @@ qint64 QElapsedTimer::restart() Q_DECL_NOTHROW
/*! \since 4.8 /*! \since 4.8
Returns the number of nanoseconds since this QElapsedTimer was last Returns the number of nanoseconds since this QElapsedTimer was last
started. Calling this function in a QElapsedTimer that was invalidated started.
will result in undefined results.
Calling this function on a QElapsedTimer that is invalid
results in undefined behavior.
On platforms that do not provide nanosecond resolution, the value returned On platforms that do not provide nanosecond resolution, the value returned
will be the best estimate available. will be the best estimate available.
@ -115,10 +118,12 @@ qint64 QElapsedTimer::nsecsElapsed() const Q_DECL_NOTHROW
/*! /*!
Returns the number of milliseconds since this QElapsedTimer was last Returns the number of milliseconds since this QElapsedTimer was last
started. Calling this function in a QElapsedTimer that was invalidated started.
will result in undefined results.
\sa start(), restart(), hasExpired(), invalidate() Calling this function on a QElapsedTimer that is invalid
results in undefined behavior.
\sa start(), restart(), hasExpired(), isValid(), invalidate()
*/ */
qint64 QElapsedTimer::elapsed() const Q_DECL_NOTHROW qint64 QElapsedTimer::elapsed() const Q_DECL_NOTHROW
{ {
@ -166,7 +171,8 @@ qint64 QElapsedTimer::msecsTo(const QElapsedTimer &other) const Q_DECL_NOTHROW
\a other was started before this object, the returned value will be \a other was started before this object, the returned value will be
negative. If it was started later, the returned value will be positive. negative. If it was started later, the returned value will be positive.
The return value is undefined if this object or \a other were invalidated. Calling this function on or with a QElapsedTimer that is invalid
results in undefined behavior.
\sa msecsTo(), elapsed() \sa msecsTo(), elapsed()
*/ */