Add QElapsedTimer::nsecsElapsed() const

Allow sub-millisecond resolution on systems where it is possible. On UNIX,
with monotonic clock support we get full nanosecond resolution, microsecond
otherwise. On Windows we convert the performance counters to nanoseconds if
availble, otherwise we only have millisecond resolution. On Mac, the mach time
is converted to nanoseconds. On Symbian, we have microsecond resolution.

Reviewed-by: joao

1 files changed, 6 insertions, 1 deletions

diff --git a/tests/auto/qelapsedtimer/tst_qelapsedtimer.cpp b/tests/auto/qelapsedtimer/tst_qelapsedtimer.cpp
index 87df57daeb..bc61f52196 100644
--- a/tests/auto/qelapsedtimer/tst_qelapsedtimer.cpp
+++ b/tests/auto/qelapsedtimer/tst_qelapsedtimer.cpp
@@ -122,11 +122,13 @@ void tst_QElapsedTimer::basics()
 
     quint64 value1 = t1.msecsSinceReference();
     qDebug() << value1 << t1;
+    qint64 nsecs = t1.nsecsElapsed();
     qint64 elapsed = t1.restart();
     QVERIFY(elapsed < minResolution);
+    QVERIFY(nsecs / 1000000 < minResolution);
 
     quint64 value2 = t1.msecsSinceReference();
-    qDebug() << value2 << t1 << elapsed;
+    qDebug() << value2 << t1 << elapsed << nsecs;
     // in theory, elapsed == value2 - value1
 
     // However, since QElapsedTimer keeps internally the full resolution,
@@ -150,7 +152,10 @@ void tst_QElapsedTimer::elapsed()
     // don't check: t1.secsTo(t2)
 //    QVERIFY(t1 - t2 < 0);
 
+    QVERIFY(t1.nsecsElapsed() > 0);
     QVERIFY(t1.elapsed() > 0);
+    // the number of elapsed nanoseconds and milliseconds should match
+    QVERIFY(t1.nsecsElapsed() - t1.elapsed() * 1000000 < 1000000);
     QVERIFY(t1.hasExpired(minResolution));
     QVERIFY(!t1.hasExpired(8*minResolution));
     QVERIFY(!t2.hasExpired(minResolution));