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Refine nstime_update().

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Add missing #include <time.h>.  The critical time facilities appear to
have been transitively included via unistd.h and sys/time.h, but in
principle this omission was capable of having caused
clock_gettime(CLOCK_MONOTONIC, ...) to have been overlooked in favor of
gettimeofday(), which in turn could cause spurious non-monotonic time
updates.

Refactor nstime_get() out of nstime_update() and add configure tests for
all variants.

Add CLOCK_MONOTONIC_RAW support (Linux-specific) and
mach_absolute_time() support (OS X-specific).

Do not fall back to clock_gettime(CLOCK_REALTIME, ...).  This was a
fragile Linux-specific workaround, which we're unlikely to use at all
now that clock_gettime(CLOCK_MONOTONIC_RAW, ...) is supported, and if we
have no choice besides non-monotonic clocks, gettimeofday() is only
incrementally worse.
This commit is contained in:
Jason Evans 2016-10-07 08:47:16 -07:00
parent b6c0867142
commit e0164bc63c
5 changed files with 109 additions and 38 deletions
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76
src/nstime.c
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@ -97,6 +97,54 @@ nstime_divide(const nstime_t *time, const nstime_t *divisor)
return (time->ns / divisor->ns);
}
#ifdef _WIN32
static void
nstime_get(nstime_t *time)
{
FILETIME ft;
uint64_t ticks_100ns;
GetSystemTimeAsFileTime(&ft);
ticks_100ns = (((uint64_t)ft.dwHighDateTime) << 32) | ft.dwLowDateTime;
nstime_init(time, ticks_100ns * 100);
}
#elif JEMALLOC_HAVE_CLOCK_MONOTONIC_RAW
static void
nstime_get(nstime_t *time)
{
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
nstime_init2(time, ts.tv_sec, ts.tv_nsec);
}
#elif JEMALLOC_HAVE_CLOCK_MONOTONIC
static void
nstime_get(nstime_t *time)
{
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
nstime_init2(time, ts.tv_sec, ts.tv_nsec);
}
#elif JEMALLOC_HAVE_MACH_ABSOLUTE_TIME
static void
nstime_get(nstime_t *time)
{
nstime_init(time, mach_absolute_time());
}
#else
static void
nstime_get(nstime_t *time)
{
struct timeval tv;
gettimeofday(&tv, NULL);
nstime_init2(time, tv.tv_sec, tv.tv_usec * 1000);
}
#endif
#ifdef JEMALLOC_JET
#undef nstime_update
#define nstime_update JEMALLOC_N(n_nstime_update)
@ -107,33 +155,7 @@ nstime_update(nstime_t *time)
nstime_t old_time;
nstime_copy(&old_time, time);
#ifdef _WIN32
{
FILETIME ft;
uint64_t ticks;
GetSystemTimeAsFileTime(&ft);
ticks = (((uint64_t)ft.dwHighDateTime) << 32) |
ft.dwLowDateTime;
time->ns = ticks * 100;
}
#elif JEMALLOC_CLOCK_GETTIME
{
struct timespec ts;
if (sysconf(_SC_MONOTONIC_CLOCK) > 0)
clock_gettime(CLOCK_MONOTONIC, &ts);
else
clock_gettime(CLOCK_REALTIME, &ts);
time->ns = ts.tv_sec * BILLION + ts.tv_nsec;
}
#else
{
struct timeval tv;
gettimeofday(&tv, NULL);
time->ns = tv.tv_sec * BILLION + tv.tv_usec * 1000;
}
#endif
nstime_get(time);
/* Handle non-monotonic clocks. */
if (unlikely(nstime_compare(&old_time, time) > 0)) {