cpython/Include/pytime.h

#ifndef Py_LIMITED_API
#ifndef Py_PYTIME_H
#define Py_PYTIME_H

#include "pyconfig.h" /* include for defines */
#include "object.h"

/**************************************************************************
Symbols and macros to supply platform-independent interfaces to time related
functions and constants
**************************************************************************/
#ifdef __cplusplus
extern "C" {
#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;
#define _PyTime_MIN PY_LLONG_MIN
#define _PyTime_MAX PY_LLONG_MAX

typedef enum {
    /* Round towards minus infinity (-inf).
       For example, used to read a clock. */
    _PyTime_ROUND_FLOOR=0,
    /* Round towards infinity (+inf).
       For example, used for timeout to wait "at least" N seconds. */
    _PyTime_ROUND_CEILING=1,
    /* Round to nearest with ties going to nearest even integer.
       For example, used to round from a Python float. */
    _PyTime_ROUND_HALF_EVEN=2,
    /* Round away from zero 
       For example, used for timeout. _PyTime_ROUND_CEILING rounds
       -1e-9 to 0 milliseconds which causes bpo-31786 issue.
       _PyTime_ROUND_UP rounds -1e-9 to -1 millisecond which keeps
       the timeout sign as expected. select.poll(timeout) must block
       for negative values." */
    _PyTime_ROUND_UP=3,
    /* _PyTime_ROUND_TIMEOUT (an alias for _PyTime_ROUND_UP) should be 
       used for timeouts. */
    _PyTime_ROUND_TIMEOUT = _PyTime_ROUND_UP
} _PyTime_round_t;


/* Convert a time_t to a PyLong. */
PyAPI_FUNC(PyObject *) _PyLong_FromTime_t(
    time_t sec);

/* Convert a PyLong to a time_t. */
PyAPI_FUNC(time_t) _PyLong_AsTime_t(
    PyObject *obj);

/* Convert a number of seconds, int or float, to time_t. */
PyAPI_FUNC(int) _PyTime_ObjectToTime_t(
    PyObject *obj,
    time_t *sec,
    _PyTime_round_t);

/* Convert a number of seconds, int or float, to a timeval structure.
   usec is in the range [0; 999999] and rounded towards zero.
   For example, -1.2 is converted to (-2, 800000). */
PyAPI_FUNC(int) _PyTime_ObjectToTimeval(
    PyObject *obj,
    time_t *sec,
    long *usec,
    _PyTime_round_t);

/* Convert a number of seconds, int or float, to a timespec structure.
   nsec is in the range [0; 999999999] and rounded towards zero.
   For example, -1.2 is converted to (-2, 800000000). */
PyAPI_FUNC(int) _PyTime_ObjectToTimespec(
    PyObject *obj,
    time_t *sec,
    long *nsec,
    _PyTime_round_t);


/* Create a timestamp from a number of seconds. */
PyAPI_FUNC(_PyTime_t) _PyTime_FromSeconds(int seconds);

/* Macro to create a timestamp from a number of seconds, no integer overflow.
   Only use the macro for small values, prefer _PyTime_FromSeconds(). */
#define _PYTIME_FROMSECONDS(seconds) \
            ((_PyTime_t)(seconds) * (1000 * 1000 * 1000))

/* Create a timestamp from a number of nanoseconds. */
PyAPI_FUNC(_PyTime_t) _PyTime_FromNanoseconds(long long ns);

/* Convert a number of seconds (Python float or int) to a timetamp.
   Raise an exception and return -1 on error, return 0 on success. */
PyAPI_FUNC(int) _PyTime_FromSecondsObject(_PyTime_t *t,
    PyObject *obj,
    _PyTime_round_t round);

/* Convert a number of milliseconds (Python float or int, 10^-3) to a timetamp.
   Raise an exception and return -1 on error, return 0 on success. */
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. */
PyAPI_FUNC(double) _PyTime_AsSecondsDouble(_PyTime_t t);

/* Convert timestamp to a number of milliseconds (10^-3 seconds). */
PyAPI_FUNC(_PyTime_t) _PyTime_AsMilliseconds(_PyTime_t t,
    _PyTime_round_t round);

/* Convert timestamp to a number of microseconds (10^-6 seconds). */
PyAPI_FUNC(_PyTime_t) _PyTime_AsMicroseconds(_PyTime_t t,
    _PyTime_round_t round);

/* Convert timestamp to a number of nanoseconds (10^-9 seconds) as a Python int
   object. */
PyAPI_FUNC(PyObject *) _PyTime_AsNanosecondsObject(_PyTime_t t);

/* Convert a timestamp to a timeval structure (microsecond resolution).
   tv_usec is always positive.
   Raise an exception and return -1 if the conversion overflowed,
   return 0 on success. */
PyAPI_FUNC(int) _PyTime_AsTimeval(_PyTime_t t,
    struct timeval *tv,
    _PyTime_round_t round);

/* Similar to _PyTime_AsTimeval(), but don't raise an exception on error. */
PyAPI_FUNC(int) _PyTime_AsTimeval_noraise(_PyTime_t t,
    struct timeval *tv,
    _PyTime_round_t round);

/* Convert a timestamp to a number of seconds (secs) and microseconds (us).
   us is always positive. This function is similar to _PyTime_AsTimeval()
   except that secs is always a time_t type, whereas the timeval structure
   uses a C long for tv_sec on Windows.
   Raise an exception and return -1 if the conversion overflowed,
   return 0 on success. */
PyAPI_FUNC(int) _PyTime_AsTimevalTime_t(
    _PyTime_t t,
    time_t *secs,
    int *us,
    _PyTime_round_t round);

#if defined(HAVE_CLOCK_GETTIME) || defined(HAVE_KQUEUE)
/* Convert a timestamp to a timespec structure (nanosecond resolution).
   tv_nsec is always positive.
   Raise an exception and return -1 on error, return 0 on success. */
PyAPI_FUNC(int) _PyTime_AsTimespec(_PyTime_t t, struct timespec *ts);
#endif

/* Get the current time from the system clock.

   The function cannot fail. _PyTime_Init() ensures that the system clock
   works. */
PyAPI_FUNC(_PyTime_t) _PyTime_GetSystemClock(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.

   The function cannot fail. _PyTime_Init() ensures that a monotonic clock
   is available and works. */
PyAPI_FUNC(_PyTime_t) _PyTime_GetMonotonicClock(void);


/* Structure used by time.get_clock_info() */
typedef struct {
    const char *implementation;
    int monotonic;
    int adjustable;
    double resolution;
} _Py_clock_info_t;

/* Get the current time from the system clock.
 * Fill clock information if info is not NULL.
 * Raise an exception and return -1 on error, return 0 on success.
 */
PyAPI_FUNC(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.

   Fill info (if set) with information of the function used to get the time.

   Return 0 on success, raise an exception and return -1 on error. */
PyAPI_FUNC(int) _PyTime_GetMonotonicClockWithInfo(
    _PyTime_t *t,
    _Py_clock_info_t *info);


/* Initialize time.
   Return 0 on success, raise an exception and return -1 on error. */
PyAPI_FUNC(int) _PyTime_Init(void);

/* Converts a timestamp to the Gregorian time, using the local time zone.
   Return 0 on success, raise an exception and return -1 on error. */
PyAPI_FUNC(int) _PyTime_localtime(time_t t, struct tm *tm);

/* Converts a timestamp to the Gregorian time, assuming UTC.
   Return 0 on success, raise an exception and return -1 on error. */
PyAPI_FUNC(int) _PyTime_gmtime(time_t t, struct tm *tm);

#ifdef __cplusplus
}
#endif

#endif /* Py_PYTIME_H */
#endif /* Py_LIMITED_API */