1 files changed, 22 insertions, 0 deletions
diff --git a/src/WaitGroup.zig b/src/WaitGroup.zig
new file mode 100644
index 0000000000..295dfd39dc
--- /dev/null
+++ b/src/WaitGroup.zig
@@ -0,0 +1,22 @@
+const std = @import("std");
+const WaitGroup = @This();
+
+counter: usize = 0,
+event: ?*std.AutoResetEvent = null,
+
+pub fn start(self: *WaitGroup) void {
+    _ = @atomicRmw(usize, &self.counter, .Add, 1, .SeqCst);
+}
+
+pub fn stop(self: *WaitGroup) void {
+    if (@atomicRmw(usize, &self.counter, .Sub, 1, .SeqCst) == 1)
+        if (@atomicRmw(?*std.AutoResetEvent, &self.event, .Xchg, null, .SeqCst)) |event|
+            event.set();
+}
+
+pub fn wait(self: *WaitGroup) void {
+    var event = std.AutoResetEvent{};
+    @atomicStore(?*std.AutoResetEvent, &self.event, &event, .SeqCst);
+    if (@atomicLoad(usize, &self.counter, .SeqCst) != 0)
+        event.wait();
+}