c# - FromAsyncPattern 会处理不再使用的资源吗？

Question

FromAsyncPattern 会关闭我的网络响应吗:

var o = Observable.Return(HttpWebRequest.Create("http://foo.com"))
                  .SelectMany(r => Observable.FromAsyncPattern<WebResponse>(
                      r.BeginGetResponse,
                      r.EndGetResponse)())
                  .Select(r => r.ContentLength);
// The response is now disposed

还是我必须手动完成？

var o = Observable.Return(HttpWebRequest.Create("http://foo.com"))
                  .SelectMany(r => Observable.FromAsyncPattern<WebResponse>(
                      r.BeginGetResponse,
                      r.EndGetResponse)())
                  .Select(r => Tuple.Create(r, r.ContentLength))
                  .Do(t => t.Item1.Close())
                  .Select(t => t.Item2);

如果我必须手动完成，有没有比这更好的方法？

Answer 1

Observable.Using 可用于此目的:

var o = Observable.Return(HttpWebRequest.Create("http://www.google.com"))
                  .SelectMany(r => Observable.FromAsyncPattern<WebResponse>(
                      r.BeginGetResponse,
                      r.EndGetResponse)())
                  .SelectMany(r =>
                  {
                      return Observable.Using( () => r, (resp) => Observable.Return(resp.ContentLength));
                  });