Simplify service-side interceptor code

1 files changed, 82 insertions, 0 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;
+        }
+    }
+}
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