Commit 84e370d0b2ce2240356ebd0a6007aec8620dfa10 | zig

1 files changed, 28 insertions(+), 16 deletions(-)

lib/std/spinlock.zig+28-16

...	...	@@ -21,23 +21,10 @@ pub const SpinLock = struct {
21	21	return SpinLock{ .lock = 0 };
22	22	}
23	23
24		// Hybrid spinning from
25		// http://www.1024cores.net/home/lock-free-algorithms/tricks/spinning
26	24	pub fn acquire(self: *SpinLock) Held {
27		var backoff: usize = 0;
28		while (@atomicRmw(u8, &self.lock, .Xchg, 1, .Acquire) != 0) : (backoff +%= 1) {
29		if (backoff < 10) {
30		yieldCpu();
31		} else if (backoff < 20) {
32		for (([30]void)(undefined)) \|_\| yieldCpu();
33		} else if (backoff < 24) {
34		yieldThread();
35		} else if (backoff < 26) {
36		time.sleep(1 * time.millisecond);
37		} else {
38		time.sleep(10 * time.millisecond);
39		}
40		}
	25	var backoff = Backoff.init();
	26	while (@atomicRmw(u8, &self.lock, .Xchg, 1, .Acquire) != 0)
	27	backoff.yield();
41	28	return Held{ .spinlock = self };
42	29	}
43	30
...	...	@@ -56,6 +43,31 @@ pub const SpinLock = struct {
56	43	else => time.sleep(1 * time.microsecond),
57	44	}
58	45	}
	46
	47	const Backoff = struct {
	48	iteration: usize,
	49
	50	fn init() @This() {
	51	return @This(){ .iteration = 0 };
	52	}
	53
	54	// Hybrid yielding from
	55	// http://www.1024cores.net/home/lock-free-algorithms/tricks/spinning
	56	fn yield(self: *@This()) void {
	57	defer self.iteration +%= 1;
	58	if (self.iteration < 10) {
	59	yieldCpu();
	60	} else if (self.iteration < 20) {
	61	for (([30]void)(undefined)) \|_\| yieldCpu();
	62	} else if (self.iteration < 24) {
	63	yieldThread();
	64	} else if (self.iteration < 26) {
	65	time.sleep(1 * time.millisecond);
	66	} else {
	67	time.sleep(10 * time.millisecond);
	68	}
	69	}
	70	};
59	71	};
60	72
61	73	test "spinlock" {