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hrtime.h
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hrtime.h
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#ifndef RB_HRTIME_H
#define RB_HRTIME_H
#include "ruby/ruby.h"
#include <time.h>
#if defined(HAVE_SYS_TIME_H)
# include <sys/time.h>
#endif
/*
* Hi-res monotonic clock. It is currently nsec resolution, which has over
* 500 years of range (with an unsigned 64-bit integer). Developers
* targeting small systems may try 32-bit and low-resolution (milliseconds).
*
* TBD: Is nsec even necessary? usec resolution seems enough for userspace
* and it'll be suitable for use with devices lasting over 500,000 years
* (maybe some devices designed for long-term space travel)
*
* Current API:
*
* * rb_hrtime_now - current clock value (monotonic if available)
* * rb_hrtime_mul - multiply with overflow check
* * rb_hrtime_add - add with overflow check
* * rb_timeval2hrtime - convert from timeval
* * rb_timespec2hrtime - convert from timespec
* * rb_msec2hrtime - convert from millisecond
* * rb_sec2hrtime - convert from time_t (seconds)
* * rb_hrtime2timeval - convert to timeval
* * rb_hrtime2timespec - convert to timespec
*
* Note: no conversion to milliseconds is provided here because different
* functions have different limits (e.g. epoll_wait vs w32_wait_events).
* So we provide RB_HRTIME_PER_MSEC and similar macros for implementing
* this for each use case.
*/
#define RB_HRTIME_PER_USEC ((rb_hrtime_t)1000)
#define RB_HRTIME_PER_MSEC (RB_HRTIME_PER_USEC * (rb_hrtime_t)1000)
#define RB_HRTIME_PER_SEC (RB_HRTIME_PER_MSEC * (rb_hrtime_t)1000)
#define RB_HRTIME_MAX UINT64_MAX
/*
* Lets try to support time travelers. Lets assume anybody with a time machine
* also has access to a modern gcc or clang with 128-bit int support
*/
#ifdef MY_RUBY_BUILD_MAY_TIME_TRAVEL
typedef int128_t rb_hrtime_t;
#else
typedef uint64_t rb_hrtime_t;
#endif
/* thread.c */
/* returns the value of the monotonic clock (if available) */
rb_hrtime_t rb_hrtime_now(void);
/*
* multiply @a and @b with overflow check and return the
* (clamped to RB_HRTIME_MAX) result.
*/
static inline rb_hrtime_t
rb_hrtime_mul(rb_hrtime_t a, rb_hrtime_t b)
{
rb_hrtime_t c;
#ifdef HAVE_BUILTIN___BUILTIN_MUL_OVERFLOW
if (__builtin_mul_overflow(a, b, &c))
return RB_HRTIME_MAX;
#else
if (b != 0 && a > RB_HRTIME_MAX / b) /* overflow */
return RB_HRTIME_MAX;
c = a * b;
#endif
return c;
}
/*
* add @a and @b with overflow check and return the
* (clamped to RB_HRTIME_MAX) result.
*/
static inline rb_hrtime_t
rb_hrtime_add(rb_hrtime_t a, rb_hrtime_t b)
{
rb_hrtime_t c;
#ifdef HAVE_BUILTIN___BUILTIN_ADD_OVERFLOW
if (__builtin_add_overflow(a, b, &c))
return RB_HRTIME_MAX;
#else
c = a + b;
if (c < a) /* overflow */
return RB_HRTIME_MAX;
#endif
return c;
}
/*
* convert a timeval struct to rb_hrtime_t, clamping at RB_HRTIME_MAX
*/
static inline rb_hrtime_t
rb_timeval2hrtime(const struct timeval *tv)
{
rb_hrtime_t s = rb_hrtime_mul((rb_hrtime_t)tv->tv_sec, RB_HRTIME_PER_SEC);
rb_hrtime_t u = rb_hrtime_mul((rb_hrtime_t)tv->tv_usec, RB_HRTIME_PER_USEC);
return rb_hrtime_add(s, u);
}
/*
* convert a timespec struct to rb_hrtime_t, clamping at RB_HRTIME_MAX
*/
static inline rb_hrtime_t
rb_timespec2hrtime(const struct timespec *ts)
{
rb_hrtime_t s = rb_hrtime_mul((rb_hrtime_t)ts->tv_sec, RB_HRTIME_PER_SEC);
return rb_hrtime_add(s, (rb_hrtime_t)ts->tv_nsec);
}
/*
* convert a millisecond value to rb_hrtime_t, clamping at RB_HRTIME_MAX
*/
static inline rb_hrtime_t
rb_msec2hrtime(unsigned long msec)
{
return rb_hrtime_mul((rb_hrtime_t)msec, RB_HRTIME_PER_MSEC);
}
/*
* convert a time_t value to rb_hrtime_t, clamping at RB_HRTIME_MAX
* Negative values will be clamped at 0.
*/
static inline rb_hrtime_t
rb_sec2hrtime(time_t sec)
{
if (sec <= 0) return 0;
return rb_hrtime_mul((rb_hrtime_t)sec, RB_HRTIME_PER_SEC);
}
/*
* convert a rb_hrtime_t value to a timespec, suitable for calling
* functions like ppoll(2) or kevent(2)
*/
static inline struct timespec *
rb_hrtime2timespec(struct timespec *ts, const rb_hrtime_t *hrt)
{
if (hrt) {
ts->tv_sec = (time_t)(*hrt / RB_HRTIME_PER_SEC);
ts->tv_nsec = (int32_t)(*hrt % RB_HRTIME_PER_SEC);
return ts;
}
return 0;
}
/*
* convert a rb_hrtime_t value to a timeval, suitable for calling
* functions like select(2)
*/
static inline struct timeval *
rb_hrtime2timeval(struct timeval *tv, const rb_hrtime_t *hrt)
{
if (hrt) {
tv->tv_sec = (time_t)(*hrt / RB_HRTIME_PER_SEC);
tv->tv_usec = (int32_t)((*hrt % RB_HRTIME_PER_SEC)/RB_HRTIME_PER_USEC);
return tv;
}
return 0;
}
#endif /* RB_HRTIME_H */