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gh-63207: Use GetSystemTimePreciseAsFileTime() in time.time() (#116822)

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Victor Stinner 2024-03-18 17:13:01 +01:00 • committed by GitHub
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3 changed files with 33 additions and 17 deletions
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6
Doc/whatsnew/3.13.rst
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@ -570,6 +570,12 @@ time
instead of the ``GetTickCount64()`` clock which has a resolution of 15.6 ms. instead of the ``GetTickCount64()`` clock which has a resolution of 15.6 ms.
(Contributed by Victor Stinner in :gh:`88494`.) (Contributed by Victor Stinner in :gh:`88494`.)
* On Windows, :func:`time.time()` now uses the
``GetSystemTimePreciseAsFileTime()`` clock to have a resolution better
than 1 us, instead of the ``GetSystemTimeAsFileTime()`` clock which has a
resolution of 15.6 ms.
(Contributed by Victor Stinner in :gh:`63207`.)
tkinter tkinter
------- -------

4
Misc/NEWS.d/next/Library/2024-03-14-17-21-25.gh-issue-63207.LV16SL.rst Normal file
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@ -0,0 +1,4 @@
On Windows, :func:`time.time()` now uses the
``GetSystemTimePreciseAsFileTime()`` clock to have a resolution better than 1
us, instead of the ``GetSystemTimeAsFileTime()`` clock which has a resolution
of 15.6 ms. Patch by Victor Stinner.

40
Python/pytime.c
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@ -55,6 +55,14 @@
#endif #endif
#ifdef MS_WINDOWS
static _PyTimeFraction py_qpc_base = {0, 0};
// Forward declaration
static int py_win_perf_counter_frequency(_PyTimeFraction *base, int raise_exc);
#endif
static PyTime_t static PyTime_t
_PyTime_GCD(PyTime_t x, PyTime_t y) _PyTime_GCD(PyTime_t x, PyTime_t y)
{ {
@ -895,7 +903,7 @@ py_get_system_clock(PyTime_t *tp, _Py_clock_info_t *info, int raise_exc)
FILETIME system_time; FILETIME system_time;
ULARGE_INTEGER large; ULARGE_INTEGER large;
GetSystemTimeAsFileTime(&system_time); GetSystemTimePreciseAsFileTime(&system_time);
large.u.LowPart = system_time.dwLowDateTime; large.u.LowPart = system_time.dwLowDateTime;
large.u.HighPart = system_time.dwHighDateTime; large.u.HighPart = system_time.dwHighDateTime;
/* 11,644,473,600,000,000,000: number of nanoseconds between /* 11,644,473,600,000,000,000: number of nanoseconds between
@ -904,18 +912,17 @@ py_get_system_clock(PyTime_t *tp, _Py_clock_info_t *info, int raise_exc)
PyTime_t ns = large.QuadPart * 100 - 11644473600000000000; PyTime_t ns = large.QuadPart * 100 - 11644473600000000000;
*tp = ns; *tp = ns;
if (info) { if (info) {
DWORD timeAdjustment, timeIncrement; // GetSystemTimePreciseAsFileTime() is implemented using
BOOL isTimeAdjustmentDisabled, ok; // QueryPerformanceCounter() internally.
if (py_qpc_base.denom == 0) {
info->implementation = "GetSystemTimeAsFileTime()"; if (py_win_perf_counter_frequency(&py_qpc_base, raise_exc) < 0) {
info->monotonic = 0; return -1;
ok = GetSystemTimeAdjustment(&timeAdjustment, &timeIncrement, }
&isTimeAdjustmentDisabled);
if (!ok) {
PyErr_SetFromWindowsErr(0);
return -1;
} }
info->resolution = timeIncrement * 1e-7;
info->implementation = "GetSystemTimePreciseAsFileTime()";
info->monotonic = 0;
info->resolution = _PyTimeFraction_Resolution(&py_qpc_base);
info->adjustable = 1; info->adjustable = 1;
} }
@ -1063,16 +1070,15 @@ py_get_win_perf_counter(PyTime_t *tp, _Py_clock_info_t *info, int raise_exc)
{ {
assert(info == NULL || raise_exc); assert(info == NULL || raise_exc);
static _PyTimeFraction base = {0, 0}; if (py_qpc_base.denom == 0) {
if (base.denom == 0) { if (py_win_perf_counter_frequency(&py_qpc_base, raise_exc) < 0) {
if (py_win_perf_counter_frequency(&base, raise_exc) < 0) {
return -1; return -1;
} }
} }
if (info) { if (info) {
info->implementation = "QueryPerformanceCounter()"; info->implementation = "QueryPerformanceCounter()";
info->resolution = _PyTimeFraction_Resolution(&base); info->resolution = _PyTimeFraction_Resolution(&py_qpc_base);
info->monotonic = 1; info->monotonic = 1;
info->adjustable = 0; info->adjustable = 0;
} }
@ -1088,7 +1094,7 @@ py_get_win_perf_counter(PyTime_t *tp, _Py_clock_info_t *info, int raise_exc)
"LONGLONG is larger than PyTime_t"); "LONGLONG is larger than PyTime_t");
ticks = (PyTime_t)ticksll; ticks = (PyTime_t)ticksll;
*tp = _PyTimeFraction_Mul(ticks, &base); *tp = _PyTimeFraction_Mul(ticks, &py_qpc_base);
return 0; return 0;
} }
#endif // MS_WINDOWS #endif // MS_WINDOWS