shithub: mc

ref: 10afb24e03c3aed48ae92ccf876f092e7337ab01
dir: /lib/thread/future.myr/

use std

use "mutex"

pkg thread =
	type future(@a) = struct
		mtx	: mutex
		set	: bool
		val	: @a
	;;

	generic mkfut	: (-> future(@a))
	generic futset	: (fut : future(@a)#, val : @a -> bool)
	generic futget	: (fut : future(@a)# -> @a)
	generic futtryget	: (fut : future(@a)# -> std.option(@a))
	generic futclear	: (fut : future(@a)# -> void)
;;

const Unset = 0
const Waiting = 1
const Set = 2

generic mkfut = {
	var fut

	fut = [.mtx = mkmtx() ]
	mtxlock(&fut.mtx)
	-> fut
}

generic futset = {fut, val
	if fut.set
		-> false
	;;
	/* compiler doesn't reorder shit */
	fut.val = val
	fut.set = true
	mtxunlock(&fut.mtx)
	-> true
}

generic futtryget = {fut
	var val

	if !fut.set
		-> `std.None
	;;
	mtxlock(&fut.mtx)
	val = fut.val
	mtxunlock(&fut.mtx)
	-> `std.Some val
}

generic futget = {fut
	var val

	mtxlock(&fut.mtx)
	val = fut.val
	mtxunlock(&fut.mtx)
	-> val
}