shithub: mc

ref: 7c2f25e309226a9506ea4b37e94e560017e83994
dir: /lib/thread/futex+osx.myr/

use std
use sys

use "common"

pkg thread =
	const ftxwait : (uaddr : uint64#, val : uint64, timeout : sys.timespec# -> int)
	const ftxwake : (uaddr : uint64# -> int)
;;

/*
 * The ulock_ functions are undocumented but the relevant source can be found at
 * https://github.com/apple/darwin-xnu/blob/0a798f6738bc1db01281fc08ae024145e84df927/bsd/kern/sys_ulock.c
 */
const ftxwait = {uaddr, val, timeout
	if timeout == Zptr
		-> sys.ulock_wait(sys.Ulockcompareandwait, uaddr, val, 0)
	;;

	var ts
	var err = sys.clock_gettime(`sys.Clockmonotonic, &ts)
	std.assert(err == 0, "error: clock_gettime returned {}\n", err)

	var usec = 0
	if timeout.sec > ts.sec
		var sec = (timeout.sec - ts.sec) * 1000
		std.assert(sec <= 0xffffffff, "error: maximum futex timeout exceeded\n")
		usec = (sec : uint32)
	;;
	if timeout.nsec > ts.nsec
		var nsec = (timeout.nsec - ts.nsec) / 1000
		std.assert(usec + nsec > usec, "error: maximum futex timeout exceeded\n")
		usec += nsec
	;;

	if usec == 0
		-> (std.Etimedout : int)
	;;
	-> sys.ulock_wait(sys.Ulockcompareandwait, uaddr, val, 0)
}

const ftxwake = {uaddr
	-> sys.ulock_wake(sys.Ulockcompareandwait, uaddr, 0)
}