Simplify service-side interceptor code

3 files changed, 96 insertions, 41 deletions

diff --git a/src/csharp/Grpc.Core/Interceptors/ServerServiceDefinitionExtensions.cs b/src/csharp/Grpc.Core/Interceptors/ServerServiceDefinitionExtensions.cs
new file mode 100644
index 0000000000..21a0782037
--- /dev/null
+++ b/src/csharp/Grpc.Core/Interceptors/ServerServiceDefinitionExtensions.cs
@@ -0,0 +1,82 @@
+#region Copyright notice and license
+
+// Copyright 2018 gRPC authors.
+//
+// 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
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// 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;
+using System.Linq;
+using Grpc.Core.Utils;
+
+namespace Grpc.Core.Interceptors
+{
+    /// <summary>
+    /// Extends the ServerServiceDefinition class to add methods used to register interceptors on the server side.
+    /// This is an EXPERIMENTAL API.
+    /// </summary>
+    public static class ServerServiceDefinitionExtensions
+    {
+        /// <summary>
+        /// Returns a <see cref="Grpc.Core.ServerServiceDefinition" /> instance that
+        /// intercepts incoming calls to the underlying service handler through the given interceptor.
+        /// This is an EXPERIMENTAL API.
+        /// </summary>
+        /// <param name="serverServiceDefinition">The <see cref="Grpc.Core.ServerServiceDefinition" /> instance to register interceptors on.</param>
+        /// <param name="interceptor">The interceptor to intercept the incoming invocations with.</param>
+        /// <remarks>
+        /// Multiple interceptors can be added on top of each other by calling
+        /// "serverServiceDefinition.Intercept(a, b, c)".  The order of invocation will be "a", "b", and then "c".
+        /// Interceptors can be later added to an existing intercepted service definition, effectively
+        /// building a chain like "serverServiceDefinition.Intercept(c).Intercept(b).Intercept(a)".  Note that
+        /// in this case, the last interceptor added will be the first to take control.
+        /// </remarks>
+        public static ServerServiceDefinition Intercept(this ServerServiceDefinition serverServiceDefinition, Interceptor interceptor)
+        {
+            GrpcPreconditions.CheckNotNull(serverServiceDefinition, "serverServiceDefinition");
+            GrpcPreconditions.CheckNotNull(interceptor, "interceptor");
+            return new ServerServiceDefinition(serverServiceDefinition.CallHandlers.ToDictionary(x => x.Key, x => x.Value.Intercept(interceptor)));
+        }
+
+        /// <summary>
+        /// Returns a <see cref="Grpc.Core.ServerServiceDefinition" /> instance that
+        /// intercepts incoming calls to the underlying service handler through the given interceptors.
+        /// This is an EXPERIMENTAL API.
+        /// </summary>
+        /// <param name="serverServiceDefinition">The <see cref="Grpc.Core.ServerServiceDefinition" /> instance to register interceptors on.</param>
+        /// <param name="interceptors">
+        /// An array of interceptors to intercept the incoming invocations with.
+        /// Control is passed to the interceptors in the order specified.
+        /// </param>
+        /// <remarks>
+        /// Multiple interceptors can be added on top of each other by calling
+        /// "serverServiceDefinition.Intercept(a, b, c)".  The order of invocation will be "a", "b", and then "c".
+        /// Interceptors can be later added to an existing intercepted service definition, effectively
+        /// building a chain like "serverServiceDefinition.Intercept(c).Intercept(b).Intercept(a)".  Note that
+        /// in this case, the last interceptor added will be the first to take control.
+        /// </remarks>
+        public static ServerServiceDefinition Intercept(this ServerServiceDefinition serverServiceDefinition, params Interceptor[] interceptors)
+        {
+            GrpcPreconditions.CheckNotNull(serverServiceDefinition, "serverServiceDefinition");
+            GrpcPreconditions.CheckNotNull(interceptors, "interceptors");
+
+            foreach (var interceptor in interceptors.Reverse())
+            {
+                serverServiceDefinition = Intercept(serverServiceDefinition, interceptor);
+            }
+
+            return serverServiceDefinition;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs b/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
index f9bf40f237..add72ad68d 100644
--- a/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
+++ b/src/csharp/Grpc.Core/Internal/ServerCallHandler.cs
@@ -31,14 +31,10 @@ namespace Grpc.Core.Internal
     internal interface IServerCallHandler
     {
         Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq);
-    }
-
-    internal interface IInterceptableCallHandler
-    {
         IServerCallHandler Intercept(Interceptor interceptor);
     }
 
-    internal class UnaryServerCallHandler<TRequest, TResponse> : IServerCallHandler, IInterceptableCallHandler
+    internal class UnaryServerCallHandler<TRequest, TResponse> : IServerCallHandler
         where TRequest : class
         where TResponse : class
     {
@@ -96,13 +92,13 @@ namespace Grpc.Core.Internal
             await finishedTask.ConfigureAwait(false);
         }
 
-        IServerCallHandler IInterceptableCallHandler.Intercept(Interceptor interceptor)
+        public IServerCallHandler Intercept(Interceptor interceptor)
         {
             return new UnaryServerCallHandler<TRequest, TResponse>(method, (request, context) => interceptor.UnaryServerHandler(request, context, handler));
         }
     }
 
-    internal class ServerStreamingServerCallHandler<TRequest, TResponse> : IServerCallHandler, IInterceptableCallHandler
+    internal class ServerStreamingServerCallHandler<TRequest, TResponse> : IServerCallHandler
         where TRequest : class
         where TResponse : class
     {
@@ -159,13 +155,13 @@ namespace Grpc.Core.Internal
             await finishedTask.ConfigureAwait(false);
         }
 
-        IServerCallHandler IInterceptableCallHandler.Intercept(Interceptor interceptor)
+        public IServerCallHandler Intercept(Interceptor interceptor)
         {
             return new ServerStreamingServerCallHandler<TRequest, TResponse>(method, (request, responseStream, context) => interceptor.ServerStreamingServerHandler(request, responseStream, context, handler));
         }
     }
 
-    internal class ClientStreamingServerCallHandler<TRequest, TResponse> : IServerCallHandler, IInterceptableCallHandler
+    internal class ClientStreamingServerCallHandler<TRequest, TResponse> : IServerCallHandler
         where TRequest : class
         where TResponse : class
     {
@@ -222,13 +218,13 @@ namespace Grpc.Core.Internal
             await finishedTask.ConfigureAwait(false);
         }
 
-        IServerCallHandler IInterceptableCallHandler.Intercept(Interceptor interceptor)
+        public IServerCallHandler Intercept(Interceptor interceptor)
         {
             return new ClientStreamingServerCallHandler<TRequest, TResponse>(method, (requestStream, context) => interceptor.ClientStreamingServerHandler(requestStream, context, handler));
         }
     }
 
-    internal class DuplexStreamingServerCallHandler<TRequest, TResponse> : IServerCallHandler, IInterceptableCallHandler
+    internal class DuplexStreamingServerCallHandler<TRequest, TResponse> : IServerCallHandler
         where TRequest : class
         where TResponse : class
     {
@@ -282,7 +278,7 @@ namespace Grpc.Core.Internal
             await finishedTask.ConfigureAwait(false);
         }
 
-        IServerCallHandler IInterceptableCallHandler.Intercept(Interceptor interceptor)
+        public IServerCallHandler Intercept(Interceptor interceptor)
         {
             return new DuplexStreamingServerCallHandler<TRequest, TResponse>(method, (requestStream, responseStream, context) => interceptor.DuplexStreamingServerHandler(requestStream, responseStream, context, handler));
         }
@@ -314,6 +310,11 @@ namespace Grpc.Core.Internal
         {
             return callHandlerImpl.HandleCall(newRpc, cq);
         }
+
+        public IServerCallHandler Intercept(Interceptor interceptor)
+        {
+            return this;  // Do not intercept unimplemented services
+        }
     }
 
     internal static class HandlerUtils
diff --git a/src/csharp/Grpc.Core/ServerServiceDefinition.cs b/src/csharp/Grpc.Core/ServerServiceDefinition.cs
index a42f543a5a..07c6aa1796 100644
--- a/src/csharp/Grpc.Core/ServerServiceDefinition.cs
+++ b/src/csharp/Grpc.Core/ServerServiceDefinition.cs
@@ -35,7 +35,7 @@ namespace Grpc.Core
     {
         readonly ReadOnlyDictionary<string, IServerCallHandler> callHandlers;
 
-        private ServerServiceDefinition(Dictionary<string, IServerCallHandler> callHandlers)
+        internal ServerServiceDefinition(Dictionary<string, IServerCallHandler> callHandlers)
         {
             this.callHandlers = new ReadOnlyDictionary<string, IServerCallHandler>(callHandlers);
         }
@@ -49,34 +49,6 @@ namespace Grpc.Core
         }
 
         /// <summary>
-        /// Returns a <see cref="Grpc.Core.ServerServiceDefinition" /> instance that
-        /// intercepts calls to the underlying service handler via the given interceptor.
-        /// This is an EXPERIMENTAL API.
-        /// </summary>
-        /// <param name="interceptor">The interceptor to register on service.</param>
-        /// <remarks>
-        /// Multiple interceptors can be added on top of each other by chaining them
-        /// like "service.Intercept(c).Intercept(b).Intercept(a)".  Note that
-        /// in this case, the last interceptor added will be the first to take control,
-        /// i.e. "a" will run before "b" before "c".
-        /// </remarks>
-        public ServerServiceDefinition Intercept(Interceptor interceptor)
-        {
-            GrpcPreconditions.CheckNotNull(interceptor, "interceptor");
-            return new ServerServiceDefinition(CallHandlers.ToDictionary(
-                x => x.Key, x =>
-                {
-                    var value = x.Value;
-                    var interceptable = value as IInterceptableCallHandler;
-                    if (interceptable == null)
-                    {
-                        return value;
-                    }
-                    return interceptable.Intercept(interceptor);
-                }));
-        }
-
-        /// <summary>
         /// Creates a new builder object for <c>ServerServiceDefinition</c>.
         /// </summary>
         /// <returns>The builder object.</returns>