Fixed thread concurrency issue on http cookie handling.

src/NzbDrone.Common.Test/Http/HttpClientFixture.cs

@@ -226,6 +226,29 @@ namespace NzbDrone.Common.Test.Http
 
             ExceptionVerification.IgnoreErrors();
         }
+
+        [Test]
+        public void should_overwrite_response_cookie()
+        {
+            var requestSet = new HttpRequest("http://eu.httpbin.org/cookies/set?my=cookie");
+            requestSet.AllowAutoRedirect = false;
+            requestSet.StoreResponseCookie = true;
+            requestSet.AddCookie("my", "oldcookie");
+
+            var responseSet = Subject.Get(requestSet);
+
+            var request = new HttpRequest("http://eu.httpbin.org/get");
+
+            var response = Subject.Get<HttpBinResource>(request);
+
+            response.Resource.Headers.Should().ContainKey("Cookie");
+
+            var cookie = response.Resource.Headers["Cookie"].ToString();
+
+            cookie.Should().Contain("my=cookie");
+
+            ExceptionVerification.IgnoreErrors();
+        }
     }
 
     public class HttpBinResource

src/NzbDrone.Common/Http/HttpClient.cs

@@ -73,50 +73,81 @@ namespace NzbDrone.Common.Http
                 AddRequestHeaders(webRequest, request.Headers);
             }
 
-            var cookieContainer = _cookieContainerCache.Get("container", () => new CookieContainer());
+            PrepareRequestCookies(request, webRequest);
+
+            var response = ExecuteRequest(request, webRequest);
+
+            HandleResponseCookies(request, webRequest);
+
+            stopWatch.Stop();
+
+            _logger.Trace("{0} ({1:n0} ms)", response, stopWatch.ElapsedMilliseconds);
+
+            if (request.AllowAutoRedirect && !RuntimeInfoBase.IsProduction &&
+                (response.StatusCode == HttpStatusCode.Moved ||
+                response.StatusCode == HttpStatusCode.MovedPermanently ||
+                response.StatusCode == HttpStatusCode.Found))
+            {
+                _logger.Error("Server requested a redirect to [" + response.Headers["Location"] + "]. Update the request URL to avoid this redirect.");
+            }
+
+            if (!request.SuppressHttpError && response.HasHttpError)
+            {
+                _logger.Warn("HTTP Error - {0}", response);
+                throw new HttpException(request, response);
+            }
+
+            return response;
+        }
+
+        private void PrepareRequestCookies(HttpRequest request, HttpWebRequest webRequest)
+        {
+            lock (_cookieContainerCache)
+            {
+                var persistentCookieContainer = _cookieContainerCache.Get("container", () => new CookieContainer());
 
                 if (request.Cookies.Count != 0)
                 {
                     foreach (var pair in request.Cookies)
                     {
-                    cookieContainer.Add(new Cookie(pair.Key, pair.Value, "/", request.Url.Host)
+                        persistentCookieContainer.Add(new Cookie(pair.Key, pair.Value, "/", request.Url.Host)
                         {
                             Expires = DateTime.UtcNow.AddHours(1)
                         });
                     }
                 }
 
-            if (request.StoreResponseCookie)
+                var requestCookies = persistentCookieContainer.GetCookies(request.Url);
+
+                if (requestCookies.Count == 0 && !request.StoreResponseCookie)
                 {
-                webRequest.CookieContainer = cookieContainer;
+                    return;
                 }
-            else
+
+                if (webRequest.CookieContainer == null)
                 {
                     webRequest.CookieContainer = new CookieContainer();
-                webRequest.CookieContainer.Add(cookieContainer.GetCookies(request.Url));
                 }
 
-            var response = ExecuteRequest(request, webRequest);
-
-            stopWatch.Stop();
-
-            _logger.Trace("{0} ({1:n0} ms)", response, stopWatch.ElapsedMilliseconds);
+                webRequest.CookieContainer.Add(requestCookies);
+            }
+        }
 
-            if (request.AllowAutoRedirect && !RuntimeInfoBase.IsProduction &&
-                (response.StatusCode == HttpStatusCode.Moved ||
-                response.StatusCode == HttpStatusCode.MovedPermanently ||
-                response.StatusCode == HttpStatusCode.Found))
+        private void HandleResponseCookies(HttpRequest request, HttpWebRequest webRequest)
         {
-                _logger.Error("Server requested a redirect to [" + response.Headers["Location"] + "]. Update the request URL to avoid this redirect.");
+            if (!request.StoreResponseCookie)
+            {
+                return;
             }
 
-            if (!request.SuppressHttpError && response.HasHttpError)
+            lock (_cookieContainerCache)
             {
-                _logger.Warn("HTTP Error - {0}", response);
-                throw new HttpException(request, response);
-            }
+                var persistentCookieContainer = _cookieContainerCache.Get("container", () => new CookieContainer());
 
-            return response;
+                var cookies = webRequest.CookieContainer.GetCookies(request.Url);
+
+                persistentCookieContainer.Add(cookies);
+            }
         }
 
         private HttpResponse ExecuteRequest(HttpRequest request, HttpWebRequest webRequest)