mach_wait_until

Sleep the current thread until an absolute mach_absolute_time() deadline.

Prototype

kern_return_t mach_wait_until(/* 2 args */);

Returns: kern_return_t

Version history

XNU tag	macOS	#
xnu-123.5	macOS 10.0 Cheetah	-89
xnu-201	macOS 10.1 Puma	-89
xnu-344	macOS 10.2 Jaguar	-89
xnu-517	macOS 10.3 Panther	-89
xnu-124.1	—	-89
xnu-124.13	—	-89
xnu-124.7	—	-89
xnu-201.14	—	-89
xnu-201.19	—	-89
xnu-201.19.3	—	-89
xnu-201.42.3	—	-89
xnu-201.5	—	-89
xnu-344.12.2	—	-89
xnu-344.2	—	-89
xnu-344.21.73	—	-89
xnu-344.21.74	—	-89
xnu-344.23	—	-89
xnu-344.26	—	-89
xnu-344.32	—	-89
xnu-344.34	—	-89
xnu-344.49	—	-89
xnu-517.11.1	—	-89
xnu-517.12.7	—	-89
xnu-517.3.15	—	-89
xnu-517.3.7	—	-89
xnu-517.7.21	—	-89
xnu-517.7.7	—	-89
xnu-517.9.4	—	-89
xnu-517.9.5	—	-89

Examples

Sleep 5 ms with high precision

#include <mach/mach_time.h>

static mach_timebase_info_data_t tb;
if (tb.denom == 0) mach_timebase_info(&tb);
uint64_t now = mach_absolute_time();
uint64_t ns_to_ticks = (5ULL * 1000000ULL) * tb.denom / tb.numer;
mach_wait_until(now + ns_to_ticks);

Notes

mach_wait_until is the canonical high-resolution sleep on Darwin: it takes a uint64_t deadline in mach ticks (convert ns via mach_timebase_info) and returns when that monotonic time is reached. It is implemented as a thin wrapper around mach_wait_until_trap and is what dispatch_after, CADisplayLink, and most media frameworks ultimately call. Unlike nanosleep it is not interrupted by signals delivered to the process unless the wait is explicitly aborted.

Detection

DTrace mach_trap and sched providers; not surfaced in Endpoint Security.

Related APIs

mach_wait_until_trapmach_absolute_timemach_timebase_infoclock_sleep_trapnanosleep