From 4afde6f85050cc3e9267947999dc55918b1bd36c Mon Sep 17 00:00:00 2001 From: Thiago Macieira Date: Wed, 10 Jul 2013 09:52:39 -0700 Subject: Accept defeat when select(2)ing without a monotonic clock We prefer to use the monotonic clock because it's never affected by time jumps (such as the user changing the date, or the system adjusting for any other reasons, including automatic leap seconds). But if a system doesn't have a monotonic clock, we simply accept the regular, real time clock and hope it doesn't jump. This is better than the current code that never restarts a call. The side-effect is that a 30-second select may become a 3630-second select if someone sets the clock back one hour. Task-number: QTBUG-22301 Change-Id: Ia5a3bb453cd475f45b03637e2549165589fd2524 (cherry-picked from qtbase commit c64d602df3712c0d147b7b689d29f79c700e63bc) Reviewed-by: Oswald Buddenhagen --- src/corelib/kernel/qcore_unix.cpp | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/src/corelib/kernel/qcore_unix.cpp b/src/corelib/kernel/qcore_unix.cpp index cc54798..8b1c2a3 100644 --- a/src/corelib/kernel/qcore_unix.cpp +++ b/src/corelib/kernel/qcore_unix.cpp @@ -63,12 +63,8 @@ QT_BEGIN_NAMESPACE static inline bool time_update(struct timeval *tv, const struct timeval &start, const struct timeval &timeout) { - if (!QElapsedTimer::isMonotonic()) { - // we cannot recalculate the timeout without a monotonic clock as the time may have changed - return false; - } - - // clock source is monotonic, so we can recalculate how much timeout is left + // clock source is (hopefully) monotonic, so we can recalculate how much timeout is left; + // if it isn't monotonic, we'll simply hope that it hasn't jumped, because we have no alternative struct timeval now = qt_gettime(); *tv = timeout + start - now; return tv->tv_sec >= 0; -- cgit v0.12