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class method
Process.clock_getres
Process.clock_getres(clock_id, unit = :float_second) → number
process.c
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static VALUE
rb_clock_getres(int argc, VALUE *argv, VALUE _)
{
int ret;
struct timetick tt;
timetick_int_t numerators[2];
timetick_int_t denominators[2];
int num_numerators = 0;
int num_denominators = 0;
#ifdef HAVE_CLOCK_GETRES
clockid_t c;
#endif
VALUE unit = (rb_check_arity(argc, 1, 2) == 2) ? argv[1] : Qnil;
VALUE clk_id = argv[0];
if (SYMBOL_P(clk_id)) {
#ifdef CLOCK_REALTIME
if (clk_id == RUBY_CLOCK_REALTIME) {
c = CLOCK_REALTIME;
goto getres;
}
#endif
#ifdef CLOCK_MONOTONIC
if (clk_id == RUBY_CLOCK_MONOTONIC) {
c = CLOCK_MONOTONIC;
goto getres;
}
#endif
#ifdef CLOCK_PROCESS_CPUTIME_ID
if (clk_id == RUBY_CLOCK_PROCESS_CPUTIME_ID) {
c = CLOCK_PROCESS_CPUTIME_ID;
goto getres;
}
#endif
#ifdef CLOCK_THREAD_CPUTIME_ID
if (clk_id == RUBY_CLOCK_THREAD_CPUTIME_ID) {
c = CLOCK_THREAD_CPUTIME_ID;
goto getres;
}
#endif
#ifdef RUBY_GETTIMEOFDAY_BASED_CLOCK_REALTIME
if (clk_id == RUBY_GETTIMEOFDAY_BASED_CLOCK_REALTIME) {
tt.giga_count = 0;
tt.count = 1000;
denominators[num_denominators++] = 1000000000;
goto success;
}
#endif
#ifdef RUBY_TIME_BASED_CLOCK_REALTIME
if (clk_id == RUBY_TIME_BASED_CLOCK_REALTIME) {
tt.giga_count = 1;
tt.count = 0;
denominators[num_denominators++] = 1000000000;
goto success;
}
#endif
#ifdef RUBY_TIMES_BASED_CLOCK_MONOTONIC
if (clk_id == RUBY_TIMES_BASED_CLOCK_MONOTONIC) {
tt.count = 1;
tt.giga_count = 0;
denominators[num_denominators++] = get_clk_tck();
goto success;
}
#endif
#ifdef RUBY_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID
if (clk_id == RUBY_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID) {
tt.giga_count = 0;
tt.count = 1000;
denominators[num_denominators++] = 1000000000;
goto success;
}
#endif
#ifdef RUBY_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID
if (clk_id == RUBY_TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID) {
tt.count = 1;
tt.giga_count = 0;
denominators[num_denominators++] = get_clk_tck();
goto success;
}
#endif
#ifdef RUBY_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID
if (clk_id == RUBY_CLOCK_BASED_CLOCK_PROCESS_CPUTIME_ID) {
tt.count = 1;
tt.giga_count = 0;
denominators[num_denominators++] = CLOCKS_PER_SEC;
goto success;
}
#endif
#ifdef RUBY_MACH_ABSOLUTE_TIME_BASED_CLOCK_MONOTONIC
if (clk_id == RUBY_MACH_ABSOLUTE_TIME_BASED_CLOCK_MONOTONIC) {
const mach_timebase_info_data_t *info = get_mach_timebase_info();
tt.count = 1;
tt.giga_count = 0;
numerators[num_numerators++] = info->numer;
denominators[num_denominators++] = info->denom;
denominators[num_denominators++] = 1000000000;
goto success;
}
#endif
}
else if (NUMERIC_CLOCKID) {
#if defined(HAVE_CLOCK_GETRES)
struct timespec ts;
c = NUM2CLOCKID(clk_id);
getres:
ret = clock_getres(c, &ts);
if (ret == -1)
clock_failed("getres", errno, clk_id);
tt.count = (int32_t)ts.tv_nsec;
tt.giga_count = ts.tv_sec;
denominators[num_denominators++] = 1000000000;
goto success;
#endif
}
else {
rb_unexpected_type(clk_id, T_SYMBOL);
}
clock_failed("getres", EINVAL, clk_id);
success:
if (unit == ID2SYM(id_hertz)) {
return timetick2dblnum_reciprocal(&tt, numerators, num_numerators, denominators, num_denominators);
}
else {
return make_clock_result(&tt, numerators, num_numerators, denominators, num_denominators, unit);
}
}
Returns a clock resolution as determined by POSIX function clock_getres():
Example
Process.clock_getres(:CLOCK_REALTIME) # => 1.0e-09
See Process.clock_gettime for the values of clock_id and unit.
Examples:
Example
Process.clock_getres(:CLOCK_PROCESS_CPUTIME_ID, :float_microsecond) # => 0.001 Process.clock_getres(:CLOCK_PROCESS_CPUTIME_ID, :float_millisecond) # => 1.0e-06 Process.clock_getres(:CLOCK_PROCESS_CPUTIME_ID, :float_second) # => 1.0e-09 Process.clock_getres(:CLOCK_PROCESS_CPUTIME_ID, :microsecond) # => 0 Process.clock_getres(:CLOCK_PROCESS_CPUTIME_ID, :millisecond) # => 0 Process.clock_getres(:CLOCK_PROCESS_CPUTIME_ID, :nanosecond) # => 1 Process.clock_getres(:CLOCK_PROCESS_CPUTIME_ID, :second) # => 0
In addition to the values for unit supported in Process.clock_gettime, this method supports :hertz, the integer number of clock ticks per second (which is the reciprocal of :float_second):
Example
Process.clock_getres(:TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID, :hertz) # => 100.0 Process.clock_getres(:TIMES_BASED_CLOCK_PROCESS_CPUTIME_ID, :float_second) # => 0.01
Accuracy: Note that the returned resolution may be inaccurate on some platforms due to underlying bugs. Inaccurate resolutions have been reported for various clocks including :CLOCK_MONOTONIC and :CLOCK_MONOTONIC_RAW on Linux, macOS, BSD or AIX platforms, when using ARM processors, or when using virtualization.