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QtConcurrent: use QDeadlineTimer to get the clock tick 

Instead of duplicating what QElapsedTimer & QDeadlineTimer already do.
Well, technically speaking, we aren't getting ticks, but nanoseconds
now, but the times are only used in comparisons with each other, to
measure the control overhead, so the unit in which they are measured
doesn't matter.

This also makes all OSes use the same type of timers. There's no
exception for per-thread timing.

Change-Id: I115db302eb114bed8cd1fffd14557b228284f2c0
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Thiago Macieira 2016-06-06 06:30:41 -05:00
parent ec770a8530
commit b630a4513c
2 changed files with 2 additions and 77 deletions
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4
src/concurrent/concurrent.pro
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@ -37,8 +37,4 @@ HEADERS += \
# private headers
HEADERS += \
qtConfig(clock-gettime) {
linux-*|hpux-*|solaris-*: LIBS_PRIVATE *= -lrt
}
load(qt_module)

75
src/concurrent/qtconcurrentiteratekernel.cpp
View File

@ -39,20 +39,7 @@
#include "qtconcurrentiteratekernel.h"
#if defined(Q_OS_MAC)
#include <mach/mach.h>
#include <mach/mach_time.h>
#include <unistd.h>
#elif defined(Q_OS_UNIX)
#if defined(Q_OS_HURD)
#include <sys/time.h>
#endif
#include <time.h>
#include <unistd.h>
#elif defined(Q_OS_WIN)
#include <qt_windows.h>
#endif
#include <qdeadlinetimer.h>
#include "private/qfunctions_p.h"
@ -65,69 +52,11 @@ enum {
MedianSize = 7
};
#if defined(Q_OS_MAC)
static qint64 getticks()
{
return mach_absolute_time();
return QDeadlineTimer::current(Qt::PreciseTimer).deadlineNSecs();
}
#elif defined(Q_OS_UNIX)
static qint64 getticks()
{
#if (defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0)) || defined(Q_OS_OPENBSD)
clockid_t clockId;
#ifndef _POSIX_THREAD_CPUTIME
clockId = CLOCK_REALTIME;
#elif (_POSIX_THREAD_CPUTIME-0 <= 0)
// if we don't have CLOCK_THREAD_CPUTIME_ID, we have to just use elapsed realtime instead
clockId = CLOCK_REALTIME;
# if (_POSIX_THREAD_CPUTIME-0 == 0)
// detect availablility of CLOCK_THREAD_CPUTIME_ID
static QBasicAtomicInt sUseThreadCpuTime = Q_BASIC_ATOMIC_INITIALIZER(-2);
int useThreadCpuTime = sUseThreadCpuTime.load();
if (useThreadCpuTime == -2) {
// sysconf() will return either -1L or _POSIX_VERSION
// (don't care about sysconf's exact return value)
useThreadCpuTime = sysconf(_SC_THREAD_CPUTIME) == -1L ? -1 : 0 ;
sUseThreadCpuTime.store(useThreadCpuTime); // might happen multiple times, but doesn't matter
}
if (useThreadCpuTime != -1)
clockId = CLOCK_THREAD_CPUTIME_ID;
# endif
#else
clockId = CLOCK_THREAD_CPUTIME_ID;
#endif
struct timespec ts;
if (clock_gettime(clockId, &ts) == -1)
return 0;
return (ts.tv_sec * 1000000000) + ts.tv_nsec;
#else
// no clock_gettime(), fall back to wall time
struct timeval tv;
gettimeofday(&tv, 0);
return (tv.tv_sec * 1000000) + tv.tv_usec;
#endif
}
#elif defined(Q_OS_WIN)
static qint64 getticks()
{
LARGE_INTEGER x;
if (!QueryPerformanceCounter(&x))
return 0;
return x.QuadPart;
}
#endif
static double elapsed(qint64 after, qint64 before)
{
return double(after - before);