qelapsedtimer_unix.cpp File Reference

#include "qelapsedtimer.h"
#include <sys/time.h>
#include <time.h>
#include <unistd.h>

Go to the source code of this file.

Macros
#define	is_likely(x)   (x)
#define	load_acquire(x)   ((volatile const int&)(x))
#define	store_release(x, v)   ((volatile int&)(x) = (v))

Functions
static void	do_gettime (qint64 *sec, qint64 *frac)
static qint64	elapsedAndRestart (qint64 sec, qint64 frac, qint64 *nowsec, qint64 *nowfrac)
static qint64	fractionAdjustment ()
bool	operator< (const QElapsedTimer &v1, const QElapsedTimer &v2)
timeval	qt_gettime ()
static void	unixCheckClockType ()

Variables
static int	monotonicClockAvailable = false
static int	monotonicClockChecked = false

Macro Definition Documentation

is_likely

#define is_likely

(

x

)

(x)

Definition at line 72 of file qelapsedtimer_unix.cpp.

Referenced by do_gettime(), and unixCheckClockType().

load_acquire

#define load_acquire

(

x

)

((volatile const int&)(x))

Definition at line 74 of file qelapsedtimer_unix.cpp.

Referenced by unixCheckClockType().

store_release

#define store_release	(		x,
			v
	)		((volatile int&)(x) = (v))

Definition at line 75 of file qelapsedtimer_unix.cpp.

Referenced by unixCheckClockType().

Function Documentation

do_gettime()

static void do_gettime ( qint64 *  sec, qint64 *  frac  )

inlinestatic

Definition at line 121 of file qelapsedtimer_unix.cpp.

Referenced by elapsedAndRestart(), and qt_gettime().

{
#if (_POSIX_MONOTONIC_CLOCK-0 >= 0)
    unixCheckClockType();
    if (is_likely(monotonicClockAvailable)) {
        timespec ts;
        clock_gettime(CLOCK_MONOTONIC, &ts);
        *sec = ts.tv_sec;
        *frac = ts.tv_nsec;
        return;
    }
#endif
    // use gettimeofday
    struct timeval tv;
    ::gettimeofday(&tv, 0);
    *sec = tv.tv_sec;
    *frac = tv.tv_usec;
}

elapsedAndRestart()

static qint64 elapsedAndRestart ( qint64  sec, qint64  frac, qint64 *  nowsec, qint64 *  nowfrac  )

static

Definition at line 155 of file qelapsedtimer_unix.cpp.

{
    do_gettime(nowsec, nowfrac);
    sec = *nowsec - sec;
    frac = *nowfrac - frac;
    return sec * Q_INT64_C(1000) + frac / fractionAdjustment();
}

fractionAdjustment()

static qint64 fractionAdjustment ( )

inlinestatic

Definition at line 93 of file qelapsedtimer_unix.cpp.

Referenced by elapsedAndRestart().

{
    // disabled, but otherwise indicates bad usage of QElapsedTimer
    //Q_ASSERT(monotonicClockChecked);

    if (monotonicClockAvailable) {
        // the monotonic timer is measured in nanoseconds
        // 1 ms = 1000000 ns
        return 1000*1000ull;
    } else {
        // gettimeofday is measured in microseconds
        // 1 ms = 1000 us
        return 1000;
    }
}

operator<()

bool operator<	(	const QElapsedTimer &	v1,
		const QElapsedTimer &	v2
	)

Definition at line 208 of file qelapsedtimer_unix.cpp.

{
    return v1.t1 < v2.t1 || (v1.t1 == v2.t1 && v1.t2 < v2.t2);
}

qt_gettime()

timeval qt_gettime

(

)

Definition at line 141 of file qelapsedtimer_unix.cpp.

Referenced by qt_safe_select(), QTimerInfoList::QTimerInfoList(), QEventDispatcherBlackberry::select(), time_update(), and QTimerInfoList::updateCurrentTime().

{
    qint64 sec, frac;
    do_gettime(&sec, &frac);

    timeval tv;
    tv.tv_sec = sec;
    tv.tv_usec = frac;
    if (monotonicClockAvailable)
        tv.tv_usec /= 1000;

    return tv;
}

unixCheckClockType()

static void unixCheckClockType ( )

static

Definition at line 77 of file qelapsedtimer_unix.cpp.

Referenced by do_gettime(), and fractionAdjustment().

{
#if (_POSIX_MONOTONIC_CLOCK-0 == 0)
    if (is_likely(load_acquire(monotonicClockChecked)))
        return;

# if defined(_SC_MONOTONIC_CLOCK)
    // detect if the system support monotonic timers
    long x = sysconf(_SC_MONOTONIC_CLOCK);
    store_release(monotonicClockAvailable, x >= 200112L);
# endif

    store_release(monotonicClockChecked, true);
#endif
}

Variable Documentation

monotonicClockAvailable

int monotonicClockAvailable = false

static

Definition at line 66 of file qelapsedtimer_unix.cpp.

Referenced by do_gettime(), elapsedAndRestart(), fractionAdjustment(), qt_gettime(), and unixCheckClockType().

monotonicClockChecked

int monotonicClockChecked = false

static

Definition at line 65 of file qelapsedtimer_unix.cpp.

Referenced by unixCheckClockType().