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cpython/Python/pytime.c

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#include "Python.h"
#ifdef MS_WINDOWS
#include <windows.h>
#endif
#if defined(__APPLE__)
#include <mach/mach_time.h> /* mach_absolute_time(), mach_timebase_info() */
#endif
#define _PyTime_check_mul_overflow(a, b) \
(assert(b > 0), \
(_PyTime_t)(a) < _PyTime_MIN / (_PyTime_t)(b) \
|| _PyTime_MAX / (_PyTime_t)(b) < (_PyTime_t)(a))
/* To millisecond (10^-3) */
#define SEC_TO_MS 1000
/* To microseconds (10^-6) */
#define MS_TO_US 1000
#define SEC_TO_US (SEC_TO_MS * MS_TO_US)
/* To nanoseconds (10^-9) */
#define US_TO_NS 1000
#define MS_TO_NS (MS_TO_US * US_TO_NS)
#define SEC_TO_NS (SEC_TO_MS * MS_TO_NS)
/* Conversion from nanoseconds */
#define NS_TO_MS (1000 * 1000)
#define NS_TO_US (1000)
static void
error_time_t_overflow(void)
{
PyErr_SetString(PyExc_OverflowError,
"timestamp out of range for platform time_t");
}
time_t
_PyLong_AsTime_t(PyObject *obj)
{
#if defined(HAVE_LONG_LONG) && SIZEOF_TIME_T == SIZEOF_LONG_LONG
PY_LONG_LONG val;
val = PyLong_AsLongLong(obj);
#else
long val;
assert(sizeof(time_t) <= sizeof(long));
val = PyLong_AsLong(obj);
#endif
if (val == -1 && PyErr_Occurred()) {
if (PyErr_ExceptionMatches(PyExc_OverflowError))
error_time_t_overflow();
return -1;
}
return (time_t)val;
}
PyObject *
_PyLong_FromTime_t(time_t t)
{
#if defined(HAVE_LONG_LONG) && SIZEOF_TIME_T == SIZEOF_LONG_LONG
return PyLong_FromLongLong((PY_LONG_LONG)t);
#else
assert(sizeof(time_t) <= sizeof(long));
return PyLong_FromLong((long)t);
#endif
}
/* Round to nearest with ties going to nearest even integer
(_PyTime_ROUND_HALF_EVEN) */
static double
_PyTime_RoundHalfEven(double x)
{
double rounded = round(x);
if (fabs(x-rounded) == 0.5)
/* halfway case: round to even */
rounded = 2.0*round(x/2.0);
return rounded;
}
static double
_PyTime_Round(double x, _PyTime_round_t round)
{
/* volatile avoids optimization changing how numbers are rounded */
volatile double d;
d = x;
if (round == _PyTime_ROUND_HALF_EVEN)
d = _PyTime_RoundHalfEven(d);
else if (round == _PyTime_ROUND_CEILING)
d = ceil(d);
else
d = floor(d);
return d;
}
static int
_PyTime_DoubleToDenominator(double d, time_t *sec, long *numerator,
double denominator, _PyTime_round_t round)
{
double intpart, err;
/* volatile avoids optimization changing how numbers are rounded */
volatile double floatpart;
floatpart = modf(d, &intpart);
floatpart *= denominator;
floatpart = _PyTime_Round(floatpart, round);
if (floatpart >= denominator) {
floatpart -= denominator;
intpart += 1.0;
}
else if (floatpart < 0) {
floatpart += denominator;
intpart -= 1.0;
}
assert(0.0 <= floatpart && floatpart < denominator);
*sec = (time_t)intpart;
*numerator = (long)floatpart;
err = intpart - (double)*sec;
if (err <= -1.0 || err >= 1.0) {
error_time_t_overflow();
return -1;
}
return 0;
}
static int
_PyTime_ObjectToDenominator(PyObject *obj, time_t *sec, long *numerator,
double denominator, _PyTime_round_t round)
{
assert(denominator <= (double)LONG_MAX);
if (PyFloat_Check(obj)) {
double d = PyFloat_AsDouble(obj);
return _PyTime_DoubleToDenominator(d, sec, numerator,
denominator, round);
}
else {
*sec = _PyLong_AsTime_t(obj);
*numerator = 0;
if (*sec == (time_t)-1 && PyErr_Occurred())
return -1;
return 0;
}
}
int
_PyTime_ObjectToTime_t(PyObject *obj, time_t *sec, _PyTime_round_t round)
{
if (PyFloat_Check(obj)) {
double intpart, err;
/* volatile avoids optimization changing how numbers are rounded */
volatile double d;
d = PyFloat_AsDouble(obj);
d = _PyTime_Round(d, round);
(void)modf(d, &intpart);
*sec = (time_t)intpart;
err = intpart - (double)*sec;
if (err <= -1.0 || err >= 1.0) {
error_time_t_overflow();
return -1;
}
return 0;
}
else {
*sec = _PyLong_AsTime_t(obj);
if (*sec == (time_t)-1 && PyErr_Occurred())
return -1;
return 0;
}
}
int
_PyTime_ObjectToTimespec(PyObject *obj, time_t *sec, long *nsec,
_PyTime_round_t round)
{
int res;
res = _PyTime_ObjectToDenominator(obj, sec, nsec, 1e9, round);
assert(0 <= *nsec && *nsec < SEC_TO_NS);
return res;
}
int
_PyTime_ObjectToTimeval(PyObject *obj, time_t *sec, long *usec,
_PyTime_round_t round)
{
int res;
res = _PyTime_ObjectToDenominator(obj, sec, usec, 1e6, round);
assert(0 <= *usec && *usec < SEC_TO_US);
return res;
}
static void
_PyTime_overflow(void)
{
PyErr_SetString(PyExc_OverflowError,
"timestamp too large to convert to C _PyTime_t");
}
_PyTime_t
_PyTime_FromSeconds(int seconds)
{
_PyTime_t t;
t = (_PyTime_t)seconds;
/* ensure that integer overflow cannot happen, int type should have 32
bits, whereas _PyTime_t type has at least 64 bits (SEC_TO_MS takes 30
bits). */
assert((t >= 0 && t <= _PyTime_MAX / SEC_TO_NS)
|| (t < 0 && t >= _PyTime_MIN / SEC_TO_NS));
t *= SEC_TO_NS;
return t;
}
_PyTime_t
_PyTime_FromNanoseconds(PY_LONG_LONG ns)
{
_PyTime_t t;
assert(sizeof(PY_LONG_LONG) <= sizeof(_PyTime_t));
t = Py_SAFE_DOWNCAST(ns, PY_LONG_LONG, _PyTime_t);
return t;
}
#ifdef HAVE_CLOCK_GETTIME
static int
_PyTime_FromTimespec(_PyTime_t *tp, struct timespec *ts, int raise)
{
_PyTime_t t;
int res = 0;
assert(sizeof(ts->tv_sec) <= sizeof(_PyTime_t));
t = (_PyTime_t)ts->tv_sec;
if (_PyTime_check_mul_overflow(t, SEC_TO_NS)) {
if (raise)
_PyTime_overflow();
res = -1;
}
t = t * SEC_TO_NS;
t += ts->tv_nsec;
*tp = t;
return res;
}
#elif !defined(MS_WINDOWS)
static int
_PyTime_FromTimeval(_PyTime_t *tp, struct timeval *tv, int raise)
{
_PyTime_t t;
int res = 0;
assert(sizeof(tv->tv_sec) <= sizeof(_PyTime_t));
t = (_PyTime_t)tv->tv_sec;
if (_PyTime_check_mul_overflow(t, SEC_TO_NS)) {
if (raise)
_PyTime_overflow();
res = -1;
}
t = t * SEC_TO_NS;
t += (_PyTime_t)tv->tv_usec * US_TO_NS;
*tp = t;
return res;
}
#endif
static int
_PyTime_FromFloatObject(_PyTime_t *t, double value, _PyTime_round_t round,
long unit_to_ns)
{
double err;
/* volatile avoids optimization changing how numbers are rounded */
volatile double d;
/* convert to a number of nanoseconds */
d = value;
d *= (double)unit_to_ns;
d = _PyTime_Round(d, round);
*t = (_PyTime_t)d;
err = d - (double)*t;
if (fabs(err) >= 1.0) {
_PyTime_overflow();
return -1;
}
return 0;
}
static int
_PyTime_FromObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round,
long unit_to_ns)
{
if (PyFloat_Check(obj)) {
double d;
d = PyFloat_AsDouble(obj);
return _PyTime_FromFloatObject(t, d, round, unit_to_ns);
}
else {
#ifdef HAVE_LONG_LONG
PY_LONG_LONG sec;
assert(sizeof(PY_LONG_LONG) <= sizeof(_PyTime_t));
sec = PyLong_AsLongLong(obj);
#else
long sec;
assert(sizeof(PY_LONG_LONG) <= sizeof(_PyTime_t));
sec = PyLong_AsLong(obj);
#endif
if (sec == -1 && PyErr_Occurred()) {
if (PyErr_ExceptionMatches(PyExc_OverflowError))
_PyTime_overflow();
return -1;
}
if (_PyTime_check_mul_overflow(sec, unit_to_ns)) {
_PyTime_overflow();
return -1;
}
*t = sec * unit_to_ns;
return 0;
}
}
int
_PyTime_FromSecondsObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round)
{
return _PyTime_FromObject(t, obj, round, SEC_TO_NS);
}
int
_PyTime_FromMillisecondsObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round)
{
return _PyTime_FromObject(t, obj, round, MS_TO_NS);
}
double
_PyTime_AsSecondsDouble(_PyTime_t t)
{
/* volatile avoids optimization changing how numbers are rounded */
volatile double d;
if (t % SEC_TO_NS == 0) {
_PyTime_t secs;
/* Divide using integers to avoid rounding issues on the integer part.
1e-9 cannot be stored exactly in IEEE 64-bit. */
secs = t / SEC_TO_NS;
d = (double)secs;
}
else {
d = (double)t;
d /= 1e9;
}
return d;
}
PyObject *
_PyTime_AsNanosecondsObject(_PyTime_t t)
{
#ifdef HAVE_LONG_LONG
assert(sizeof(PY_LONG_LONG) >= sizeof(_PyTime_t));
return PyLong_FromLongLong((PY_LONG_LONG)t);
#else
assert(sizeof(long) >= sizeof(_PyTime_t));
return PyLong_FromLong((long)t);
#endif
}
static _PyTime_t
_PyTime_Divide(const _PyTime_t t, const _PyTime_t k,
const _PyTime_round_t round)
{
assert(k > 1);
if (round == _PyTime_ROUND_HALF_EVEN) {
_PyTime_t x, r, abs_r;
x = t / k;
r = t % k;
abs_r = Py_ABS(r);
if (abs_r > k / 2 || (abs_r == k / 2 && (Py_ABS(x) & 1))) {
if (t >= 0)
x++;
else
x--;
}
return x;
}
else if (round == _PyTime_ROUND_CEILING) {
if (t >= 0)
return (t + k - 1) / k;
else
return t / k;
}
else {
if (t >= 0)
return t / k;
else
return (t - (k - 1)) / k;
}
}
_PyTime_t
_PyTime_AsMilliseconds(_PyTime_t t, _PyTime_round_t round)
{
return _PyTime_Divide(t, NS_TO_MS, round);
}
_PyTime_t
_PyTime_AsMicroseconds(_PyTime_t t, _PyTime_round_t round)
{
return _PyTime_Divide(t, NS_TO_US, round);
}
static int
_PyTime_AsTimeval_impl(_PyTime_t t, struct timeval *tv, _PyTime_round_t round,
int raise)
{
_PyTime_t secs, ns;
int res = 0;
int usec;
secs = t / SEC_TO_NS;
ns = t % SEC_TO_NS;
#ifdef MS_WINDOWS
tv->tv_sec = (long)secs;
#else
tv->tv_sec = secs;
#endif
if ((_PyTime_t)tv->tv_sec != secs)
res = -1;
usec = (int)_PyTime_Divide(ns, US_TO_NS, round);
if (usec < 0) {
usec += SEC_TO_US;
tv->tv_sec -= 1;
}
else if (usec >= SEC_TO_US) {
usec -= SEC_TO_US;
tv->tv_sec += 1;
}
assert(0 <= usec && usec < SEC_TO_US);
tv->tv_usec = usec;
if (res && raise)
error_time_t_overflow();
return res;
}
int
_PyTime_AsTimeval(_PyTime_t t, struct timeval *tv, _PyTime_round_t round)
{
return _PyTime_AsTimeval_impl(t, tv, round, 1);
}
int
_PyTime_AsTimeval_noraise(_PyTime_t t, struct timeval *tv, _PyTime_round_t round)
{
return _PyTime_AsTimeval_impl(t, tv, round, 0);
}
#if defined(HAVE_CLOCK_GETTIME) || defined(HAVE_KQUEUE)
int
_PyTime_AsTimespec(_PyTime_t t, struct timespec *ts)
{
_PyTime_t secs, nsec;
secs = t / SEC_TO_NS;
nsec = t % SEC_TO_NS;
if (nsec < 0) {
nsec += SEC_TO_NS;
secs -= 1;
}
ts->tv_sec = (time_t)secs;
assert(0 <= nsec && nsec < SEC_TO_NS);
ts->tv_nsec = nsec;
if ((_PyTime_t)ts->tv_sec != secs) {
error_time_t_overflow();
return -1;
}
return 0;
}
#endif
static int
pygettimeofday_new(_PyTime_t *tp, _Py_clock_info_t *info, int raise)
{
#ifdef MS_WINDOWS
FILETIME system_time;
ULARGE_INTEGER large;
assert(info == NULL || raise);
GetSystemTimeAsFileTime(&system_time);
large.u.LowPart = system_time.dwLowDateTime;
large.u.HighPart = system_time.dwHighDateTime;
/* 11,644,473,600,000,000,000: number of nanoseconds between
the 1st january 1601 and the 1st january 1970 (369 years + 89 leap
days). */
*tp = large.QuadPart * 100 - 11644473600000000000;
if (info) {
DWORD timeAdjustment, timeIncrement;
BOOL isTimeAdjustmentDisabled, ok;
info->implementation = "GetSystemTimeAsFileTime()";
info->monotonic = 0;
ok = GetSystemTimeAdjustment(&timeAdjustment, &timeIncrement,
&isTimeAdjustmentDisabled);
if (!ok) {
PyErr_SetFromWindowsErr(0);
return -1;
}
info->resolution = timeIncrement * 1e-7;
info->adjustable = 1;
}
#else /* MS_WINDOWS */
int err;
#ifdef HAVE_CLOCK_GETTIME
struct timespec ts;
#else
struct timeval tv;
#endif
assert(info == NULL || raise);
#ifdef HAVE_CLOCK_GETTIME
err = clock_gettime(CLOCK_REALTIME, &ts);
if (err) {
if (raise)
PyErr_SetFromErrno(PyExc_OSError);
return -1;
}
if (_PyTime_FromTimespec(tp, &ts, raise) < 0)
return -1;
if (info) {
struct timespec res;
info->implementation = "clock_gettime(CLOCK_REALTIME)";
info->monotonic = 0;
info->adjustable = 1;
if (clock_getres(CLOCK_REALTIME, &res) == 0)
info->resolution = res.tv_sec + res.tv_nsec * 1e-9;
else
info->resolution = 1e-9;
}
#else /* HAVE_CLOCK_GETTIME */
/* test gettimeofday() */
#ifdef GETTIMEOFDAY_NO_TZ
err = gettimeofday(&tv);
#else
err = gettimeofday(&tv, (struct timezone *)NULL);
#endif
if (err) {
if (raise)
PyErr_SetFromErrno(PyExc_OSError);
return -1;
}
if (_PyTime_FromTimeval(tp, &tv, raise) < 0)
return -1;
if (info) {
info->implementation = "gettimeofday()";
info->resolution = 1e-6;
info->monotonic = 0;
info->adjustable = 1;
}
#endif /* !HAVE_CLOCK_GETTIME */
#endif /* !MS_WINDOWS */
return 0;
}
_PyTime_t
_PyTime_GetSystemClock(void)
{
_PyTime_t t;
if (pygettimeofday_new(&t, NULL, 0) < 0) {
/* should not happen, _PyTime_Init() checked the clock at startup */
assert(0);
/* use a fixed value instead of a random value from the stack */
t = 0;
}
return t;
}
int
_PyTime_GetSystemClockWithInfo(_PyTime_t *t, _Py_clock_info_t *info)
{
return pygettimeofday_new(t, info, 1);
}
static int
pymonotonic(_PyTime_t *tp, _Py_clock_info_t *info, int raise)
{
#if defined(MS_WINDOWS)
ULONGLONG ticks;
_PyTime_t t;
assert(info == NULL || raise);
ticks = GetTickCount64();
assert(sizeof(ticks) <= sizeof(_PyTime_t));
t = (_PyTime_t)ticks;
if (_PyTime_check_mul_overflow(t, MS_TO_NS)) {
if (raise) {
_PyTime_overflow();
return -1;
}
/* Hello, time traveler! */
assert(0);
}
*tp = t * MS_TO_NS;
if (info) {
DWORD timeAdjustment, timeIncrement;
BOOL isTimeAdjustmentDisabled, ok;
info->implementation = "GetTickCount64()";
info->monotonic = 1;
ok = GetSystemTimeAdjustment(&timeAdjustment, &timeIncrement,
&isTimeAdjustmentDisabled);
if (!ok) {
PyErr_SetFromWindowsErr(0);
return -1;
}
info->resolution = timeIncrement * 1e-7;
info->adjustable = 0;
}
#elif defined(__APPLE__)
static mach_timebase_info_data_t timebase;
uint64_t time;
if (timebase.denom == 0) {
/* According to the Technical Q&A QA1398, mach_timebase_info() cannot
fail: https://developer.apple.com/library/mac/#qa/qa1398/ */
(void)mach_timebase_info(&timebase);
}
time = mach_absolute_time();
/* apply timebase factor */
time *= timebase.numer;
time /= timebase.denom;
*tp = time;
if (info) {
info->implementation = "mach_absolute_time()";
info->resolution = (double)timebase.numer / timebase.denom * 1e-9;
info->monotonic = 1;
info->adjustable = 0;
}
#else
struct timespec ts;
#ifdef CLOCK_HIGHRES
const clockid_t clk_id = CLOCK_HIGHRES;
const char *implementation = "clock_gettime(CLOCK_HIGHRES)";
#else
const clockid_t clk_id = CLOCK_MONOTONIC;
const char *implementation = "clock_gettime(CLOCK_MONOTONIC)";
#endif
assert(info == NULL || raise);
if (clock_gettime(clk_id, &ts) != 0) {
if (raise) {
PyErr_SetFromErrno(PyExc_OSError);
return -1;
}
return -1;
}
if (info) {
struct timespec res;
info->monotonic = 1;
info->implementation = implementation;
info->adjustable = 0;
if (clock_getres(clk_id, &res) != 0) {
PyErr_SetFromErrno(PyExc_OSError);
return -1;
}
info->resolution = res.tv_sec + res.tv_nsec * 1e-9;
}
if (_PyTime_FromTimespec(tp, &ts, raise) < 0)
return -1;
#endif
return 0;
}
_PyTime_t
_PyTime_GetMonotonicClock(void)
{
_PyTime_t t;
if (pymonotonic(&t, NULL, 0) < 0) {
/* should not happen, _PyTime_Init() checked that monotonic clock at
startup */
assert(0);
/* use a fixed value instead of a random value from the stack */
t = 0;
}
return t;
}
int
_PyTime_GetMonotonicClockWithInfo(_PyTime_t *tp, _Py_clock_info_t *info)
{
return pymonotonic(tp, info, 1);
}
int
_PyTime_Init(void)
{
_PyTime_t t;
/* ensure that the system clock works */
if (_PyTime_GetSystemClockWithInfo(&t, NULL) < 0)
return -1;
/* ensure that the operating system provides a monotonic clock */
if (_PyTime_GetMonotonicClockWithInfo(&t, NULL) < 0)
return -1;
/* check that _PyTime_FromSeconds() cannot overflow */
assert(INT_MAX <= _PyTime_MAX / SEC_TO_NS);
assert(INT_MIN >= _PyTime_MIN / SEC_TO_NS);
return 0;
}
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