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Revert "Simplify checks for CLOCK_MONOTONIC"

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This reverts commit 7f66b04bfd.
This commit is contained in:
Matthias Clasen
2011-10-19 17:46:11 -04:00
parent f14eef8402
commit ac386f54ba
2 changed files with 63 additions and 32 deletions
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15
configure.ac
View File

@@ -2512,6 +2512,21 @@ AC_CHECK_FUNCS(clock_gettime, [], [
])
AC_SUBST(GLIB_RT_LIBS)
AC_CACHE_CHECK(for monotonic clocks,
glib_cv_monotonic_clock,AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
#include <time.h>
#include <unistd.h>
int main() {
#if !(defined(_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK >= 0 && defined(CLOCK_MONOTONIC))
#error No monotonic clock
#endif
return 0;
}
]])],glib_cv_monotonic_clock=yes,glib_cv_monotonic_clock=no))
if test "$glib_cv_monotonic_clock" = "yes"; then
AC_DEFINE(HAVE_MONOTONIC_CLOCK,1,[Have a monotonic clock])
fi
dnl ************************
dnl *** g_atomic_* tests ***

80
glib/gmain.c
View File

@@ -2041,50 +2041,66 @@ g_get_monotonic_time (void)
{
#ifdef HAVE_CLOCK_GETTIME
/* librt clock_gettime() is our first choice */
struct timespec ts;
#ifdef CLOCK_MONOTONIC
clock_gettime (CLOCK_MONOTONIC, &ts);
{
#ifdef HAVE_MONOTONIC_CLOCK
static volatile gsize clockid = 0;
#else
clock_gettime (CLOCK_REALTIME, &ts);
static clockid_t clockid = CLOCK_REALTIME;
#endif
struct timespec ts;
#ifdef HAVE_MONOTONIC_CLOCK
if (g_once_init_enter (&clockid))
{
clockid_t best_clockid;
if (sysconf (_SC_MONOTONIC_CLOCK) >= 0)
best_clockid = CLOCK_MONOTONIC;
else
best_clockid = CLOCK_REALTIME;
g_once_init_leave (&clockid, (gsize)best_clockid);
}
#endif
/* In theory monotonic time can have any epoch.
*
* glib presently assumes the following:
*
* 1) The epoch comes some time after the birth of Jesus of Nazareth, but
* not more than 10000 years later.
*
* 2) The current time also falls sometime within this range.
*
* These two reasonable assumptions leave us with a maximum deviation from
* the epoch of 10000 years, or 315569520000000000 seconds.
*
* If we restrict ourselves to this range then the number of microseconds
* will always fit well inside the constraints of a int64 (by a factor of
* about 29).
*
* If you actually hit the following assertion, probably you should file a
* bug against your operating system for being excessively silly.
**/
g_assert (G_GINT64_CONSTANT (-315569520000000000) < ts.tv_sec &&
ts.tv_sec < G_GINT64_CONSTANT (315569520000000000));
clock_gettime (clockid, &ts);
return (((gint64) ts.tv_sec) * 1000000) + (ts.tv_nsec / 1000);
#else /* !HAVE_CLOCK_GETTIME */
/* In theory monotonic time can have any epoch.
*
* glib presently assumes the following:
*
* 1) The epoch comes some time after the birth of Jesus of Nazareth, but
* not more than 10000 years later.
*
* 2) The current time also falls sometime within this range.
*
* These two reasonable assumptions leave us with a maximum deviation from
* the epoch of 10000 years, or 315569520000000000 seconds.
*
* If we restrict ourselves to this range then the number of microseconds
* will always fit well inside the constraints of a int64 (by a factor of
* about 29).
*
* If you actually hit the following assertion, probably you should file a
* bug against your operating system for being excessively silly.
**/
g_assert (G_GINT64_CONSTANT (-315569520000000000) < ts.tv_sec &&
ts.tv_sec < G_GINT64_CONSTANT (315569520000000000));
return (((gint64) ts.tv_sec) * 1000000) + (ts.tv_nsec / 1000);
}
#else
/* It may look like we are discarding accuracy on Windows (since its
* current time is expressed in 100s of nanoseconds) but according to
* many sources, the time is only updated 64 times per second, so
* microsecond accuracy is more than enough.
*/
GTimeVal tv;
{
GTimeVal tv;
g_get_current_time (&tv);
g_get_current_time (&tv);
return (((gint64) tv.tv_sec) * 1000000) + tv.tv_usec;
return (((gint64) tv.tv_sec) * 1000000) + tv.tv_usec;
}
#endif
}