BatchWaiter

const BatchWaiter = struct {
    sleeper: Sleeper,
    queue: c.dispatch.queue_t,
    timer: ?c.dispatch.source_t = null,

    const already_signaled: c.dispatch.source_t = @ptrFromInt(1);

    fn signal(context: ?*anyopaque) callconv(.c) void {
        const waiter: *BatchWaiter = @ptrCast(@alignCast(context));
        if (waiter.timer) |timer| {
            if (timer != already_signaled) timer.cancel();
        } else {
            waiter.timer = already_signaled;
            waiter.queue.async(waiter, &@"suspend");
        }
    }

    fn @"suspend"(context: ?*anyopaque) callconv(.c) void {
        const waiter: *BatchWaiter = @ptrCast(@alignCast(context));
        if (waiter.timer) |timer| if (timer != already_signaled) timer.as_object().release();
        waiter.queue.as_object().@"suspend"();
        waiter.wake();
    }

    fn wake(waiter: *BatchWaiter) void {
        var sleeper = waiter.sleeper;
        waiter.* = undefined;
        Sleeper.wake(&sleeper);
    }
}