AWSAppender.Core.Services.InstanceMetaDataReader.GetMetaData C# (CSharp) Метод

        public string GetMetaData(string key, out bool outError)
        {
            if (!_metaDataKeys.ContainsKey(key))
                throw new InvalidOperationException(string.Format("Meta data key {0} is not supported or does not exist.", key));

            outError = false;
            var error = false;

            try
            {
                if (_pendingTasks.ContainsKey(key))
                {
                    Debug.WriteLine("Waiting for pending {0}", key);
                    return
                        _pendingTasks[key].ContinueWith(x =>
                                                            {
                                                                Debug.WriteLine("Pending {0} completed", key);

                                                                if (_cachedValues.ContainsKey(key))
                                                                    return _cachedValues[key];

                                                                return null;
                                                            })
                                                            .Result;
                }

                if (!_attempts.ContainsKey(key))
                    _attempts[key] = 0;

                if (!_cachedValues.ContainsKey(key))
                {
                    var uri = serviceUrl + _metaDataKeys[key];
                    Debug.WriteLine("Requesting {0}", uri);

                    var tokenSource = new CancellationTokenSource();
                    var ct = tokenSource.Token;

                    Stream responseStream = null;

                    var task1 =
                    _pendingTasks[key] =
                        Task.Factory.StartNew(() =>
                                                  {
                                                      if (++_attempts[key] > 10)
                                                          _cachedValues[key] = key + "_MaxAttemptsExceeded";

                                                      var task =
                                                          Task.Factory.StartNew(() =>
                                                                                    {
                                                                                        try
                                                                                        {
                                                                                            responseStream =
                                                                                                WebRequest.Create(uri)
                                                                                                    .GetResponse()
                                                                                                    .GetResponseStream();
                                                                                        }
                                                                                        catch (Exception)
                                                                                        {
                                                                                            error = true;
                                                                                        }
                                                                                    }, ct);

                                                      if (!task.Wait(2000))
                                                          tokenSource.Cancel();

                                                      if (responseStream != null)
                                                      {
                                                          var s = new StreamReader(responseStream, true).ReadToEnd();
                                                          if (!string.IsNullOrEmpty(s))
                                                          {
                                                              _cachedValues[key] = s;
                                                              _attempts[key] = 0;
                                                          }
                                                          else
                                                              error = true;
                                                      }
                                                      else
                                                          error = true;
                                                  });

                    var result = task1
                            .ContinueWith(x =>
                                          {
                                              try
                                              {
                                                  _pendingTasks.Remove(key);
                                              }
                                              catch (Exception) { }

                                              if (error || !_cachedValues.ContainsKey(key))
                                              {
                                                  error = true;
                                                  return "error_" + key;
                                              }
                                              Debug.WriteLine(string.Format("Got {0}: {1}", key, _cachedValues[key]));

                                              return _cachedValues[key];
                                          })
                            .Result;

                    outError = error;
                    return result;
                }

                Debug.WriteLine(string.Format("Returning cached {0}: {1}", key, _cachedValues[key]));

                return _cachedValues[key];
            }
            catch (WebException)
            {
                return null;
            }
        }