SleepWaiter

const SleepWaiter = struct {
    sleeper: Sleeper = undefined,
    cancelable: Cancelable,
    timer: c.dispatch.source_t,
    started: bool = false,

    fn start(context: ?*anyopaque) callconv(.c) void {
        const waiter: *SleepWaiter = @ptrCast(@alignCast(context));
        waiter.cancelable.enter(waiter.sleeper.fiber) catch |err| switch (err) {
            error.CancelRequested => waiter.timer.cancel(),
        };
        waiter.timer.as_object().activate();
    }

    fn timedOut(context: ?*anyopaque) callconv(.c) void {
        const waiter: *SleepWaiter = @ptrCast(@alignCast(context));
        waiter.cancelable.leave(waiter.sleeper.fiber) catch |err| switch (err) {
            error.CancelRequested => return,
        };
        waiter.timer.cancel();
    }

    fn canceled(context: ?*anyopaque) callconv(.c) void {
        const cancelable: *Cancelable = @ptrCast(@alignCast(context));
        const waiter: *SleepWaiter = @fieldParentPtr("cancelable", cancelable);
        cancelable.requested(waiter.sleeper.fiber);
        waiter.timer.cancel();
    }

    fn wake(context: ?*anyopaque) callconv(.c) void {
        const waiter: *SleepWaiter = @ptrCast(@alignCast(context));
        var sleeper = waiter.sleeper;
        waiter.* = undefined;
        Sleeper.wake(&sleeper);
    }
}