authorgravatar for charles.saternos@gmail.comnc <charles.saternos@gmail.com> 2022-11-26 13:41:12-05:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2023-01-09 14:57:56-07:00
log033dcf78116cc6d99f209cb349eb9daf12101729
tree3ae5b8dad44303406560ce93582abc216e512336
parent39c3889df100ff69a605c3bf0b9148cf093162d7

std.atomic.Queue: fix unget implementation and add doc

1 files changed, 18 insertions(+), 2 deletions(-)

lib/std/atomic/queue.zig+18-2
...@@ -64,6 +64,8 @@ pub fn Queue(comptime T: type) type {...@@ -64,6 +64,8 @@ pub fn Queue(comptime T: type) type {
64 return head;64 return head;
65 }65 }
6666
67 /// Prepends `node` to the front of the queue.
68 /// The lifetime of `node` must be longer than the lifetime of the queue.
67 pub fn unget(self: *Self, node: *Node) void {69 pub fn unget(self: *Self, node: *Node) void {
68 node.prev = null;70 node.prev = null;
6971
...@@ -72,8 +74,8 @@ pub fn Queue(comptime T: type) type {...@@ -72,8 +74,8 @@ pub fn Queue(comptime T: type) type {
7274
73 const opt_head = self.head;75 const opt_head = self.head;
74 self.head = node;76 self.head = node;
75 if (opt_head) |head| {77 if (opt_head) |old_head| {
76 head.next = node;78 node.next = old_head;
77 } else {79 } else {
78 assert(self.tail == null);80 assert(self.tail == null);
79 self.tail = node;81 self.tail = node;
...@@ -330,11 +332,25 @@ test "std.atomic.Queue single-threaded" {...@@ -330,11 +332,25 @@ test "std.atomic.Queue single-threaded" {
330 node_3.next = null;332 node_3.next = null;
331 try expect(!queue.isEmpty());333 try expect(!queue.isEmpty());
332334
335 queue.unget(&node_3);
336 try expect(queue.get().?.data == 3);
337 try expect(!queue.isEmpty());
338
333 try expect(queue.get().?.data == 4);339 try expect(queue.get().?.data == 4);
334 try expect(queue.isEmpty());340 try expect(queue.isEmpty());
335341
336 try expect(queue.get() == null);342 try expect(queue.get() == null);
337 try expect(queue.isEmpty());343 try expect(queue.isEmpty());
344
345 // unget an empty queue
346 queue.unget(&node_4);
347 try expect(queue.tail == &node_4);
348 try expect(queue.head == &node_4);
349
350 try expect(queue.get().?.data == 4);
351
352 try expect(queue.get() == null);
353 try expect(queue.isEmpty());
338}354}
339355
340test "std.atomic.Queue dump" {356test "std.atomic.Queue dump" {