gh-110850: Add PyTime_t C API

Add PyTime_t API:

* PyTime_t type.
* PyTime_MIN and PyTime_MAX constants.
* PyTime_AsSecondsDouble(), PyTime_GetMonotonicClock(),
  PyTime_GetPerfCounter() and PyTime_GetSystemClock() functions.

Doc/c-api/time.rst

@@ -0,0 +1,132 @@
+.. highlight:: c
+
+PyTime API
+==========
+
+.. versionadded:: 3.13
+
+PyTime API
+----------
+
+The PyTime_t API is written to use timestamp and timeout values stored in
+various formats and to read clocks.
+
+The :c:type:`PyTime_t` type is an integer to support directly common arithmetic
+operations such as ``t1 + t2``.
+
+The PyTime_t API supports a resolution of ``1`` nanosecond. The
+:c:type:`PyTime_t` type is signed to support negative timestamps. The supported
+range is around [-292.3 years; +292.3 years]. Using the Unix epoch (January
+1st, 1970), the supported date range is around [1677-09-21; 2262-04-11].
+
+Time formats:
+
+* Seconds.
+* Seconds as a floating pointer number (C :c:type:`double`).
+* Milliseconds (10\ :sup:`-3` seconds).
+* Microseconds (10\ :sup:`-6` seconds).
+* 100 nanoseconds (10\ :sup:`-7` seconds), used on Windows.
+* Nanoseconds (10\ :sup:`-9` seconds).
+* :c:expr:`timeval` structure, 1 microsecond (10\ :sup:`-6` seconds).
+* :c:expr:`timespec` structure, 1 nanosecond (10\ :sup:`-9` seconds).
+
+Integer overflows are detected and raise :exc:`OverflowError`. Conversion to a
+resolution larger than 1 nanosecond is rounded correctly with the requested
+rounding mode. Available rounding modes:
+
+* Round towards minus infinity (-inf). For example, used to read a clock.
+* Round towards infinity (+inf). For example, used for timeout to wait "at
+  least" N seconds.
+* Round to nearest with ties going to nearest even integer. For example, used
+  to round from a Python float.
+* Round away from zero. For example, used for timeout.
+
+Some functions clamp the result in the range [PyTime_MIN; PyTime_MAX]. The
+caller doesn't have to handle errors and so doesn't need to hold the GIL to
+handle exceptions. For example, ``_PyTime_Add(t1, t2)`` computes ``t1+t2`` and
+clamps the result on overflow.
+
+Clocks:
+
+* System clock
+* Monotonic clock
+* Performance counter
+
+Internally, operations like ``(t * k / q)`` with integers are implemented in a
+way to reduce the risk of integer overflow. Such operation is used to convert a
+clock value expressed in ticks with a frequency to PyTime_t, like
+``QueryPerformanceCounter()`` with ``QueryPerformanceFrequency()`` on Windows.
+
+
+Types
+-----
+
+.. c:type:: PyTime_t
+
+   Timestamp type with subsecond precision: 64-bit signed integer.
+
+   This type can be used to store a duration. Indirectly, it can be used to
+   store a date relative to a reference date, such as the UNIX epoch.
+
+
+Constants
+---------
+
+.. c:var:: PyTime_t PyTime_MIN
+
+   Minimum value of the :c:type:`PyTime_t` type.
+   :c:macro`PyTime_MIN` nanoseconds is around -292.3 years.
+
+.. c:var:: PyTime_t PyTime_MAX
+
+   Maximum value of the :c:type:`PyTime_t` type.
+   :c:macro`PyTime_MAX` nanoseconds is around +292.3 years.
+
+
+Functions
+---------
+
+.. c:function:: double PyTime_AsSecondsDouble(PyTime_t t)
+
+   Convert a timestamp to a number of seconds as a C :c:type:`double`.
+
+   The function cannot fail.
+
+
+.. c:function:: PyTime_t PyTime_GetMonotonicClock(void)
+
+   Get the time of a monotonic clock, i.e. a clock that cannot go backwards.
+   The clock is not affected by system clock updates. The reference point of
+   the returned value is undefined, so that only the difference between the
+   results of consecutive calls is valid.
+
+   If reading the clock fails, silently ignore the error and return 0.
+
+   On integer overflow, silently ignore the overflow and clamp the clock to
+   the [PyTime_MIN; PyTime_MAX] range.
+
+   See also the :func:`time.monotonic` function.
+
+.. c:function:: PyTime_t PyTime_GetPerfCounter(void)
+
+   Get the performance counter: clock with the highest available resolution to
+   measure a short duration.
+
+   If reading the clock fails, silently ignore the error and return 0.
+
+   On integer overflow, silently ignore the overflow and clamp the time to the
+   [PyTime_MIN; PyTime_MAX] range.
+
+   See also the :func:`time.perf_counter` function.
+
+
+.. c:function:: PyTime_t PyTime_GetSystemClock(void)
+
+   Get the current time from the system clock.
+
+   If reading the clock fails, silently ignore the error and return ``0``.
+
+   On integer overflow, silently ignore the overflow and clamp the clock to
+   the [PyTime_MIN; PyTime_MAX] range.
+
+   See also the :func:`time.time` function.

Doc/c-api/utilities.rst

@@ -20,4 +20,5 @@ and parsing function arguments and constructing Python values from C values.
    hash.rst
    reflection.rst
    codec.rst
+   time.rst
    perfmaps.rst

Doc/whatsnew/3.13.rst

@@ -1181,6 +1181,16 @@ New Features
   :exc:`KeyError` if the key missing.
   (Contributed by Stefan Behnel and Victor Stinner in :gh:`111262`.)
 
+* Add PyTime_t C API:
+
+  * :c:type:`PyTime_t` type.
+  * :c:var:`PyTime_MIN` and :c:var:`PyTime_MAX` constants.
+  * :c:func:`PyTime_AsSecondsDouble`, :c:func:`PyTime_GetMonotonicClock`,
+    :c:func:`PyTime_GetPerfCounter` and :c:func:`PyTime_GetSystemClock`
+    functions.
+
+  (Contributed by Victor Stinner in :gh:`110850`.)
+
 
 Porting to Python 3.13
 ----------------------

Include/Python.h

@@ -97,6 +97,7 @@
 #include "weakrefobject.h"
 #include "structseq.h"
 #include "cpython/picklebufobject.h"
+#include "cpython/pytime.h"
 #include "codecs.h"
 #include "pyerrors.h"
 #include "pythread.h"

Include/cpython/pytime.h

@@ -0,0 +1,23 @@
+// PyTime_t C API: see Doc/c-api/time.rst for the documentation.
+
+#ifndef Py_LIMITED_API
+#ifndef Py_PYTIME_H
+#define Py_PYTIME_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef int64_t PyTime_t;
+#define PyTime_MIN INT64_MIN
+#define PyTime_MAX INT64_MAX
+
+PyAPI_FUNC(double) PyTime_AsSecondsDouble(PyTime_t t);
+PyAPI_FUNC(PyTime_t) PyTime_GetMonotonicClock(void);
+PyAPI_FUNC(PyTime_t) PyTime_GetPerfCounter(void);
+PyAPI_FUNC(PyTime_t) PyTime_GetSystemClock(void);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* Py_PYTIME_H */
+#endif /* Py_LIMITED_API */

Include/internal/pycore_time.h

@@ -1,45 +1,4 @@
-// The _PyTime_t API is written to use timestamp and timeout values stored in
-// various formats and to read clocks.
-//
-// The _PyTime_t type is an integer to support directly common arithmetic
-// operations like t1 + t2.
-//
-// The _PyTime_t API supports a resolution of 1 nanosecond. The _PyTime_t type
-// is signed to support negative timestamps. The supported range is around
-// [-292.3 years; +292.3 years]. Using the Unix epoch (January 1st, 1970), the
-// supported date range is around [1677-09-21; 2262-04-11].
-//
-// Formats:
-//
-// * seconds
-// * seconds as a floating pointer number (C double)
-// * milliseconds (10^-3 seconds)
-// * microseconds (10^-6 seconds)
-// * 100 nanoseconds (10^-7 seconds)
-// * nanoseconds (10^-9 seconds)
-// * timeval structure, 1 microsecond resolution (10^-6 seconds)
-// * timespec structure, 1 nanosecond resolution (10^-9 seconds)
-//
-// Integer overflows are detected and raise OverflowError. Conversion to a
-// resolution worse than 1 nanosecond is rounded correctly with the requested
-// rounding mode. There are 4 rounding modes: floor (towards -inf), ceiling
-// (towards +inf), half even and up (away from zero).
-//
-// Some functions clamp the result in the range [_PyTime_MIN; _PyTime_MAX], so
-// the caller doesn't have to handle errors and doesn't need to hold the GIL.
-// For example, _PyTime_Add(t1, t2) computes t1+t2 and clamp the result on
-// overflow.
-//
-// Clocks:
-//
-// * System clock
-// * Monotonic clock
-// * Performance counter
-//
-// Operations like (t * k / q) with integers are implemented in a way to reduce
-// the risk of integer overflow. Such operation is used to convert a clock
-// value expressed in ticks with a frequency to _PyTime_t, like
-// QueryPerformanceCounter() with QueryPerformanceFrequency().
+// Internal PyTime_t C API: see Doc/c-api/time.rst for the documentation.
 
 #ifndef Py_INTERNAL_TIME_H
 #define Py_INTERNAL_TIME_H
@@ -66,14 +25,7 @@ struct _time_runtime_state {
 struct timeval;
 #endif
 
-// _PyTime_t: Python timestamp with subsecond precision. It can be used to
-// store a duration, and so indirectly a date (related to another date, like
-// UNIX epoch).
-typedef int64_t _PyTime_t;
-// _PyTime_MIN nanoseconds is around -292.3 years
-#define _PyTime_MIN INT64_MIN
-// _PyTime_MAX nanoseconds is around +292.3 years
-#define _PyTime_MAX INT64_MAX
+typedef PyTime_t _PyTime_t;
 #define _SIZEOF_PYTIME_T 8
 
 typedef enum {
@@ -157,7 +109,7 @@ PyAPI_FUNC(_PyTime_t) _PyTime_FromSecondsDouble(double seconds, _PyTime_round_t
 PyAPI_FUNC(_PyTime_t) _PyTime_FromNanoseconds(_PyTime_t ns);
 
 // Create a timestamp from a number of microseconds.
-// Clamp to [_PyTime_MIN; _PyTime_MAX] on overflow.
+// Clamp to [PyTime_MIN; PyTime_MAX] on overflow.
 extern _PyTime_t _PyTime_FromMicrosecondsClamp(_PyTime_t us);
 
 // Create a timestamp from nanoseconds (Python int).
@@ -179,10 +131,6 @@ PyAPI_FUNC(int) _PyTime_FromMillisecondsObject(_PyTime_t *t,
     PyObject *obj,
     _PyTime_round_t round);
 
-// Convert a timestamp to a number of seconds as a C double.
-// Export for '_socket' shared extension.
-PyAPI_FUNC(double) _PyTime_AsSecondsDouble(_PyTime_t t);
-
 // Convert timestamp to a number of milliseconds (10^-3 seconds).
 // Export for '_ssl' shared extension.
 PyAPI_FUNC(_PyTime_t) _PyTime_AsMilliseconds(_PyTime_t t,
@@ -260,11 +208,11 @@ PyAPI_FUNC(void) _PyTime_AsTimespec_clamp(_PyTime_t t, struct timespec *ts);
 #endif
 
 
-// Compute t1 + t2. Clamp to [_PyTime_MIN; _PyTime_MAX] on overflow.
+// Compute t1 + t2. Clamp to [PyTime_MIN; PyTime_MAX] on overflow.
 extern _PyTime_t _PyTime_Add(_PyTime_t t1, _PyTime_t t2);
 
 // Compute ticks * mul / div.
-// Clamp to [_PyTime_MIN; _PyTime_MAX] on overflow.
+// Clamp to [PyTime_MIN; PyTime_MAX] on overflow.
 // The caller must ensure that ((div - 1) * mul) cannot overflow.
 extern _PyTime_t _PyTime_MulDiv(_PyTime_t ticks,
     _PyTime_t mul,
@@ -278,36 +226,13 @@ typedef struct {
     double resolution;
 } _Py_clock_info_t;
 
-// Get the current time from the system clock.
-//
-// If the internal clock fails, silently ignore the error and return 0.
-// On integer overflow, silently ignore the overflow and clamp the clock to
-// [_PyTime_MIN; _PyTime_MAX].
-//
-// Use _PyTime_GetSystemClockWithInfo() to check for failure.
-// Export for '_random' shared extension.
-PyAPI_FUNC(_PyTime_t) _PyTime_GetSystemClock(void);
-
 // Get the current time from the system clock.
 // On success, set *t and *info (if not NULL), and return 0.
 // On error, raise an exception and return -1.
 extern int _PyTime_GetSystemClockWithInfo(
     _PyTime_t *t,
     _Py_clock_info_t *info);
 
-// Get the time of a monotonic clock, i.e. a clock that cannot go backwards.
-// The clock is not affected by system clock updates. The reference point of
-// the returned value is undefined, so that only the difference between the
-// results of consecutive calls is valid.
-//
-// If the internal clock fails, silently ignore the error and return 0.
-// On integer overflow, silently ignore the overflow and clamp the clock to
-// [_PyTime_MIN; _PyTime_MAX].
-//
-// Use _PyTime_GetMonotonicClockWithInfo() to check for failure.
-// Export for '_random' shared extension.
-PyAPI_FUNC(_PyTime_t) _PyTime_GetMonotonicClock(void);
-
 // Get the time of a monotonic clock, i.e. a clock that cannot go backwards.
 // The clock is not affected by system clock updates. The reference point of
 // the returned value is undefined, so that only the difference between the
@@ -332,17 +257,6 @@ PyAPI_FUNC(int) _PyTime_localtime(time_t t, struct tm *tm);
 // Export for '_datetime' shared extension.
 PyAPI_FUNC(int) _PyTime_gmtime(time_t t, struct tm *tm);
 
-// Get the performance counter: clock with the highest available resolution to
-// measure a short duration.
-//
-// If the internal clock fails, silently ignore the error and return 0.
-// On integer overflow, silently ignore the overflow and clamp the clock to
-// [_PyTime_MIN; _PyTime_MAX].
-//
-// Use _PyTime_GetPerfCounterWithInfo() to check for failure.
-// Export for '_lsprof' shared extension.
-PyAPI_FUNC(_PyTime_t) _PyTime_GetPerfCounter(void);
-
 // Get the performance counter: clock with the highest available resolution to
 // measure a short duration.
 //
@@ -355,12 +269,12 @@ extern int _PyTime_GetPerfCounterWithInfo(
 
 
 // Create a deadline.
-// Pseudo code: _PyTime_GetMonotonicClock() + timeout.
+// Pseudo code: PyTime_GetMonotonicClock() + timeout.
 // Export for '_ssl' shared extension.
 PyAPI_FUNC(_PyTime_t) _PyDeadline_Init(_PyTime_t timeout);
 
 // Get remaining time from a deadline.
-// Pseudo code: deadline - _PyTime_GetMonotonicClock().
+// Pseudo code: deadline - PyTime_GetMonotonicClock().
 // Export for '_ssl' shared extension.
 PyAPI_FUNC(_PyTime_t) _PyDeadline_Get(_PyTime_t deadline);