Commit a6c9c5f767217ba3591e51047736f0fa6a975a57 | zig

author	Quetzal Bradley <qbradley@qbradley.com> 2019-11-28 02:19:08+00:00
committer	Andrew Kelley <andrew@ziglang.org> 2019-11-27 23:09:24-05:00
log	a6c9c5f767217ba3591e51047736f0fa6a975a57
tree	f2bd2ffa851078b492c3ec4cd762e1957753b755
parent	ca61a5f0b74fb420a21cdbb9e58f9d38ebe9dc0f

implement correct buffer wrapping logic in std.event.Channel

1 files changed, 30 insertions(+), 3 deletions(-)

lib
- std
  - event
    channel.zig

lib/std/event/channel.zig+30-3

...	...	@@ -54,6 +54,10 @@ pub fn Channel(comptime T: type) type {
54	54	/// For a zero length buffer, use `[0]T{}`.
55	55	/// TODO https://github.com/ziglang/zig/issues/2765
56	56	pub fn init(self: *SelfChannel, buffer: []T) void {
	57	// The ring buffer implementation only works with power of 2 buffer sizes
	58	// because of relying on subtracting across zero. For example (0 -% 1) % 10 == 5
	59	assert(buffer.len == 0 or @popCount(usize, buffer.len) == 1);
	60
57	61	self.* = SelfChannel{
58	62	.buffer_len = 0,
59	63	.buffer_nodes = buffer,
...	...	@@ -184,11 +188,11 @@ pub fn Channel(comptime T: type) type {
184	188	const get_node = &self.getters.get().?.data;
185	189	switch (get_node.data) {
186	190	GetNode.Data.Normal => \|info\| {
187		info.ptr.* = self.buffer_nodes[self.buffer_index -% self.buffer_len];
	191	info.ptr.* = self.buffer_nodes[(self.buffer_index -% self.buffer_len) % self.buffer_nodes.len];
188	192	},
189	193	GetNode.Data.OrNull => \|info\| {
190	194	_ = self.or_null_queue.remove(info.or_null);
191		info.ptr.* = self.buffer_nodes[self.buffer_index -% self.buffer_len];
	195	info.ptr.* = self.buffer_nodes[(self.buffer_index -% self.buffer_len) % self.buffer_nodes.len];
192	196	},
193	197	}
194	198	global_event_loop.onNextTick(get_node.tick_node);
...	...	@@ -222,7 +226,7 @@ pub fn Channel(comptime T: type) type {
222	226	while (self.buffer_len != self.buffer_nodes.len and put_count != 0) {
223	227	const put_node = &self.putters.get().?.data;
224	228
225		self.buffer_nodes[self.buffer_index] = put_node.data;
	229	self.buffer_nodes[self.buffer_index % self.buffer_nodes.len] = put_node.data;
226	230	global_event_loop.onNextTick(put_node.tick_node);
227	231	self.buffer_index +%= 1;
228	232	self.buffer_len += 1;
...	...	@@ -283,6 +287,29 @@ test "std.event.Channel" {
283	287	await putter;
284	288	}
285	289
	290	test "std.event.Channel wraparound" {
	291
	292	// TODO provide a way to run tests in evented I/O mode
	293	if (!std.io.is_async) return error.SkipZigTest;
	294
	295	const channel_size = 2;
	296
	297	var buf : [channel_size]i32 = undefined;
	298	var channel: Channel(i32) = undefined;
	299	channel.init(&buf);
	300	defer channel.deinit();
	301
	302	// add items to channel and pull them out until
	303	// the buffer wraps around, make sure it doesn't crash.
	304	var result : i32 = undefined;
	305	channel.put(5);
	306	testing.expectEqual(@as(i32, 5), channel.get());
	307	channel.put(6);
	308	testing.expectEqual(@as(i32, 6), channel.get());
	309	channel.put(7);
	310	testing.expectEqual(@as(i32, 7), channel.get());
	311	}
	312
286	313	async fn testChannelGetter(channel: *Channel(i32)) void {
287	314	const value1 = channel.get();
288	315	testing.expect(value1 == 1234);