1 #region Copyright notice and license
2 
3 // Copyright 2018 gRPC authors.
4 //
5 // Licensed under the Apache License, Version 2.0 (the "License");
6 // you may not use this file except in compliance with the License.
7 // You may obtain a copy of the License at
8 //
9 //     http://www.apache.org/licenses/LICENSE-2.0
10 //
11 // Unless required by applicable law or agreed to in writing, software
12 // distributed under the License is distributed on an "AS IS" BASIS,
13 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 // See the License for the specific language governing permissions and
15 // limitations under the License.
16 
17 #endregion
18 
19 using System;
20 using System.Linq;
21 using Grpc.Core.Utils;
22 
23 namespace Grpc.Core.Interceptors
24 {
25     /// <summary>
26     /// Extends the ServerServiceDefinition class to add methods used to register interceptors on the server side.
27     /// </summary>
28     public static class ServerServiceDefinitionExtensions
29     {
30         /// <summary>
31         /// Returns a <see cref="Grpc.Core.ServerServiceDefinition" /> instance that
32         /// intercepts incoming calls to the underlying service handler through the given interceptor.
33         /// </summary>
34         /// <param name="serverServiceDefinition">The <see cref="Grpc.Core.ServerServiceDefinition" /> instance to register interceptors on.</param>
35         /// <param name="interceptor">The interceptor to intercept the incoming invocations with.</param>
36         /// <remarks>
37         /// Multiple interceptors can be added on top of each other by calling
38         /// "serverServiceDefinition.Intercept(a, b, c)".  The order of invocation will be "a", "b", and then "c".
39         /// Interceptors can be later added to an existing intercepted service definition, effectively
40         /// building a chain like "serverServiceDefinition.Intercept(c).Intercept(b).Intercept(a)".  Note that
41         /// in this case, the last interceptor added will be the first to take control.
42         /// </remarks>
Intercept(this ServerServiceDefinition serverServiceDefinition, Interceptor interceptor)43         public static ServerServiceDefinition Intercept(this ServerServiceDefinition serverServiceDefinition, Interceptor interceptor)
44         {
45             GrpcPreconditions.CheckNotNull(serverServiceDefinition, nameof(serverServiceDefinition));
46             GrpcPreconditions.CheckNotNull(interceptor, nameof(interceptor));
47             return new ServerServiceDefinition(serverServiceDefinition.CallHandlers.ToDictionary(x => x.Key, x => x.Value.Intercept(interceptor)));
48         }
49 
50         /// <summary>
51         /// Returns a <see cref="Grpc.Core.ServerServiceDefinition" /> instance that
52         /// intercepts incoming calls to the underlying service handler through the given interceptors.
53         /// </summary>
54         /// <param name="serverServiceDefinition">The <see cref="Grpc.Core.ServerServiceDefinition" /> instance to register interceptors on.</param>
55         /// <param name="interceptors">
56         /// An array of interceptors to intercept the incoming invocations with.
57         /// Control is passed to the interceptors in the order specified.
58         /// </param>
59         /// <remarks>
60         /// Multiple interceptors can be added on top of each other by calling
61         /// "serverServiceDefinition.Intercept(a, b, c)".  The order of invocation will be "a", "b", and then "c".
62         /// Interceptors can be later added to an existing intercepted service definition, effectively
63         /// building a chain like "serverServiceDefinition.Intercept(c).Intercept(b).Intercept(a)".  Note that
64         /// in this case, the last interceptor added will be the first to take control.
65         /// </remarks>
Intercept(this ServerServiceDefinition serverServiceDefinition, params Interceptor[] interceptors)66         public static ServerServiceDefinition Intercept(this ServerServiceDefinition serverServiceDefinition, params Interceptor[] interceptors)
67         {
68             GrpcPreconditions.CheckNotNull(serverServiceDefinition, nameof(serverServiceDefinition));
69             GrpcPreconditions.CheckNotNull(interceptors, nameof(interceptors));
70 
71             foreach (var interceptor in interceptors.Reverse())
72             {
73                 serverServiceDefinition = Intercept(serverServiceDefinition, interceptor);
74             }
75 
76             return serverServiceDefinition;
77         }
78     }
79 }