add C# call flags API

src/csharp/Grpc.Core.Tests/CallOptionsTest.cs

@@ -67,6 +67,9 @@ namespace Grpc.Core.Tests
             var credentials = new FakeCallCredentials();
             Assert.AreSame(credentials, options.WithCredentials(credentials).Credentials);
 
+            var flags = CallFlags.WaitForReady | CallFlags.CacheableRequest;
+            Assert.AreEqual(flags, options.WithFlags(flags).Flags);
+
             // Check that the original instance is unchanged.
             Assert.IsNull(options.Headers);
             Assert.IsNull(options.Deadline);
@@ -74,6 +77,7 @@ namespace Grpc.Core.Tests
             Assert.IsNull(options.WriteOptions);
             Assert.IsNull(options.PropagationToken);
             Assert.IsNull(options.Credentials);
+            Assert.AreEqual(default(CallFlags), options.Flags);
         }
 
         [Test]

src/csharp/Grpc.Core/CallFlags.cs

+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * 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.
+//
+// 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.
+
+#endregion
+
+using System;
+
+namespace Grpc.Core
+{
+    /// <summary>
+    /// Flags for various call behaviors (client-side only).
+    /// </summary>
+    [Flags]
+    public enum CallFlags
+    {
+        /// <summary>
+        /// The call is idempotent (retrying the call doesn't change the outcome of the operation).
+        /// </summary>
+        IdempotentRequest = 0x10,
+
+        /// <summary>
+        /// If channel is in <c>ChannelState.TransientFailure</c>, attempt waiting for the channel to recover
+        /// instead of failing the call immediately.
+        /// </summary>
+        WaitForReady = 0x20,
+
+        /// <summary>
+        /// The call is cacheable. gRPC is free to use GET verb */
+        /// </summary>
+        CacheableRequest = 0x40
+    }
+}

src/csharp/Grpc.Core/CallOptions.cs

@@ -50,6 +50,7 @@ namespace Grpc.Core
         WriteOptions writeOptions;
         ContextPropagationToken propagationToken;
         CallCredentials credentials;
+        CallFlags flags;
 
         /// <summary>
         /// Creates a new instance of <c>CallOptions</c> struct.
@@ -60,8 +61,10 @@ namespace Grpc.Core
         /// <param name="writeOptions">Write options that will be used for this call.</param>
         /// <param name="propagationToken">Context propagation token obtained from <see cref="ServerCallContext"/>.</param>
         /// <param name="credentials">Credentials to use for this call.</param>
+        /// <param name="flags">Flags to use for this call.</param>
         public CallOptions(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken),
-                           WriteOptions writeOptions = null, ContextPropagationToken propagationToken = null, CallCredentials credentials = null)
+                           WriteOptions writeOptions = null, ContextPropagationToken propagationToken = null, CallCredentials credentials = null,
+                           CallFlags flags = default(CallFlags))
         {
             this.headers = headers;
             this.deadline = deadline;
@@ -69,6 +72,7 @@ namespace Grpc.Core
             this.writeOptions = writeOptions;
             this.propagationToken = propagationToken;
             this.credentials = credentials;
+            this.flags = flags;
         }
 
         /// <summary>
@@ -125,6 +129,14 @@ namespace Grpc.Core
             get { return this.credentials; }
         }
 
+        /// <summary>
+        /// Flags to use for this call.
+        /// </summary>
+        public CallFlags Flags
+        {
+            get { return this.flags; }
+        }
+
         /// <summary>
         /// Returns new instance of <see cref="CallOptions"/> with
         /// <c>Headers</c> set to the value provided. Values of all other fields are preserved.
@@ -197,6 +209,18 @@ namespace Grpc.Core
             return newOptions;
         }
 
+        /// <summary>
+        /// Returns new instance of <see cref="CallOptions"/> with
+        /// <c>Flags</c> set to the value provided. Values of all other fields are preserved.
+        /// </summary>
+        /// <param name="flags">The call flags.</param>
+        public CallOptions WithFlags(CallFlags flags)
+        {
+            var newOptions = this;
+            newOptions.flags = flags;
+            return newOptions;
+        }
+
         /// <summary>
         /// Returns a new instance of <see cref="CallOptions"/> with 
         /// all previously unset values set to their defaults and deadline and cancellation

src/csharp/Grpc.Core/Grpc.Core.csproj

@@ -48,6 +48,7 @@
     <Compile Include="AsyncServerStreamingCall.cs" />
     <Compile Include="AsyncAuthInterceptor.cs" />
     <Compile Include="CallCredentials.cs" />
+    <Compile Include="CallFlags.cs" />
     <Compile Include="IClientStreamWriter.cs" />
     <Compile Include="Internal\NativeMethods.cs" />
     <Compile Include="Internal\PlatformApis.cs" />
@@ -153,4 +154,4 @@
       <Link>roots.pem</Link>
     </EmbeddedResource>
   </ItemGroup>
-</Project>
+</Project>
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