1 files changed, 50 insertions, 26 deletions

diff --git a/src/csharp/Grpc.Core/Channel.cs b/src/csharp/Grpc.Core/Channel.cs
index 4f29c35b32..1803920662 100644
--- a/src/csharp/Grpc.Core/Channel.cs
+++ b/src/csharp/Grpc.Core/Channel.cs
@@ -1,32 +1,17 @@
 #region Copyright notice and license
-// Copyright 2015, Google Inc.
-// All rights reserved.
+// Copyright 2015 gRPC authors.
 //
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
 //
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
+//     http://www.apache.org/licenses/LICENSE-2.0
 //
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
 #endregion
 
 using System;
@@ -59,6 +44,8 @@ namespace Grpc.Core
         readonly ChannelSafeHandle handle;
         readonly Dictionary<string, ChannelOption> options;
 
+        readonly Task connectivityWatcherTask;
+
         bool shutdownRequested;
 
         /// <summary>
@@ -99,6 +86,9 @@ namespace Grpc.Core
                     this.handle = ChannelSafeHandle.CreateInsecure(target, nativeChannelArgs);
                 }
             }
+            // TODO(jtattermusch): Workaround for https://github.com/GoogleCloudPlatform/google-cloud-dotnet/issues/822.
+            // Remove once retries are supported in C core
+            this.connectivityWatcherTask = RunConnectivityWatcherAsync();
             GrpcEnvironment.RegisterChannel(this);
         }
 
@@ -244,7 +234,7 @@ namespace Grpc.Core
 
             handle.Dispose();
 
-            await GrpcEnvironment.ReleaseAsync().ConfigureAwait(false);
+            await Task.WhenAll(GrpcEnvironment.ReleaseAsync(), connectivityWatcherTask).ConfigureAwait(false);
         }
 
         internal ChannelSafeHandle Handle
@@ -299,6 +289,40 @@ namespace Grpc.Core
             }
         }
 
+        /// <summary>
+        /// Constantly Watches channel connectivity status to work around https://github.com/GoogleCloudPlatform/google-cloud-dotnet/issues/822
+        /// </summary>
+        private async Task RunConnectivityWatcherAsync()
+        {
+            try
+            {
+                var lastState = State;
+                while (lastState != ChannelState.Shutdown)
+                {
+                    lock (myLock)
+                    {
+                        if (shutdownRequested)
+                        {
+                            break;
+                        }
+                    }
+
+                    try
+                    {
+                        await WaitForStateChangedAsync(lastState, DateTime.UtcNow.AddSeconds(1)).ConfigureAwait(false);
+                    }
+                    catch (TaskCanceledException)
+                    {
+                        // ignore timeout
+                    }
+                    lastState = State;
+                }
+            }
+            catch (ObjectDisposedException) {
+                // during shutdown, channel is going to be disposed.
+            }
+        }
+
         private static void EnsureUserAgentChannelOption(Dictionary<string, ChannelOption> options)
         {
             var key = ChannelOptions.PrimaryUserAgentString;