Question

我有异步回调，它被传递给Timer（来自System.Threading）构造函数：

private async Task HandleTimerCallback(object state)
{
    if (timer == null) return;

    if (asynTaskCallback != null)
    {
        await HandleAsyncTaskTimerCallback(state);
    }
    else
    {
        HandleSyncTimerCallback(state);
    }
}

和计时器：

timer = new Timer(async o => await HandleTimerCallback(o), state, CommonConstants.InfiniteTimespan,
            CommonConstants.InfiniteTimespan);

有没有办法在lambda中省略o param？非同步的原因我可以将handler作为代理传递

 timer = new Timer(HandleTimerCallback, state, CommonConstants.InfiniteTimespan,
            CommonConstants.InfiniteTimespan);

Answer 1

有没有办法在lambda中省略那个o param？

当然，只需将您的事件处理程序方法定义为async void：

private async void HandleTimerCallback(object state)

Answer 2

您可以使用David Fowler here建议的包装方法：

public class Pinger
{
    private readonly Timer _timer;
    private readonly HttpClient _client;
    
    public Pinger(HttpClient client)
    {
        _client = client;
        _timer = new Timer(Heartbeat, null, 1000, 1000);
    }

    public void Heartbeat(object state)
    {
        // Discard the result
        _ = DoAsyncPing();
    }

    private async Task DoAsyncPing()
    {
        await _client.GetAsync("http://mybackend/api/ping");
    }
}

Answer 3

我使用了上面建议的 Vlad 之类的包装器，然后使用了 Task.Wait 以便异步过程完成：

private void ProcessWork(object state)
{
    Task.WaitAll(ProcessScheduledWorkAsync());
}

protected async Task ProcessWorkAsync()
{
    
}

将异步回调传递给Timer构造函数

3 个答案: