Merge pull request #18086 from chwarr/servercallcontext-userstate

Add UserState dictionary to C# ServerCallContext

src/csharp/Grpc.Core.Api/ServerCallContext.cs

@@ -17,6 +17,7 @@
 #endregion
 
 using System;
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -27,6 +28,8 @@ namespace Grpc.Core
     /// </summary>
     public abstract class ServerCallContext
     {
+        private Dictionary<object, object> userState;
+
         /// <summary>
         /// Creates a new instance of <c>ServerCallContext</c>.
         /// </summary>
@@ -113,6 +116,12 @@ namespace Grpc.Core
         /// </summary>
         public AuthContext AuthContext => AuthContextCore;
 
+        /// <summary>
+        /// Gets a dictionary that can be used by the various interceptors and handlers of this
+        /// call to store arbitrary state.
+        /// </summary>
+        public IDictionary<object, object> UserState => UserStateCore;
+
         /// <summary>Provides implementation of a non-virtual public member.</summary>
         protected abstract Task WriteResponseHeadersAsyncCore(Metadata responseHeaders);
         /// <summary>Provides implementation of a non-virtual public member.</summary>
@@ -137,5 +146,18 @@ namespace Grpc.Core
         protected abstract WriteOptions WriteOptionsCore { get; set; }
         /// <summary>Provides implementation of a non-virtual public member.</summary>
         protected abstract AuthContext AuthContextCore { get; }
+        /// <summary>Provides implementation of a non-virtual public member.</summary>
+        protected virtual IDictionary<object, object> UserStateCore
+        {
+            get
+            {
+                if (userState == null)
+                {
+                    userState = new Dictionary<object, object>();
+                }
+
+                return userState;
+            }
+        }
     }
 }

src/csharp/Grpc.Core.Tests/Interceptors/ServerInterceptorTest.cs

@@ -77,6 +77,53 @@ namespace Grpc.Core.Interceptors.Tests
             Assert.AreEqual("CB1B2B3A", stringBuilder.ToString());
         }
 
+        [Test]
+        public void UserStateVisibleToAllInterceptors()
+        {
+            object key1 = new object();
+            object value1 = new object();
+            const string key2 = "Interceptor #2";
+            const string value2 = "Important state";
+
+            var interceptor1 = new ServerCallContextInterceptor(ctx => {
+                // state starts off empty
+                Assert.AreEqual(0, ctx.UserState.Count);
+
+                ctx.UserState.Add(key1, value1);
+            });
+
+            var interceptor2 = new ServerCallContextInterceptor(ctx => {
+                // second interceptor can see state set by the first
+                bool found = ctx.UserState.TryGetValue(key1, out object storedValue1);
+                Assert.IsTrue(found);
+                Assert.AreEqual(value1, storedValue1);
+
+                ctx.UserState.Add(key2, value2);
+            });
+
+            var helper = new MockServiceHelper(Host);
+            helper.UnaryHandler = new UnaryServerMethod<string, string>((request, context) => {
+                // call handler can see all the state
+                bool found = context.UserState.TryGetValue(key1, out object storedValue1);
+                Assert.IsTrue(found);
+                Assert.AreEqual(value1, storedValue1);
+
+                found = context.UserState.TryGetValue(key2, out object storedValue2);
+                Assert.IsTrue(found);
+                Assert.AreEqual(value2, storedValue2);
+
+                return Task.FromResult("PASS");
+            });
+            helper.ServiceDefinition = helper.ServiceDefinition
+                .Intercept(interceptor2)
+                .Intercept(interceptor1);
+
+            var server = helper.GetServer();
+            server.Start();
+            var channel = helper.GetChannel();
+            Assert.AreEqual("PASS", Calls.BlockingUnaryCall(helper.CreateUnaryCall(), ""));
+        }
+
         [Test]
         public void CheckNullInterceptorRegistrationFails()
         {