basic pooling of requestcallcontext

src/csharp/Grpc.Core/Internal/CompletionRegistry.cs

@@ -37,14 +37,16 @@ namespace Grpc.Core.Internal
 
         readonly GrpcEnvironment environment;
         readonly Func<BatchContextSafeHandle> batchContextFactory;
+        readonly Func<RequestCallContextSafeHandle> requestCallContextFactory;
         readonly Dictionary<IntPtr, IOpCompletionCallback> dict = new Dictionary<IntPtr, IOpCompletionCallback>(new IntPtrComparer());
         SpinLock spinLock = new SpinLock(Debugger.IsAttached);
         IntPtr lastRegisteredKey;  // only for testing
 
-        public CompletionRegistry(GrpcEnvironment environment, Func<BatchContextSafeHandle> batchContextFactory)
+        public CompletionRegistry(GrpcEnvironment environment, Func<BatchContextSafeHandle> batchContextFactory, Func<RequestCallContextSafeHandle> requestCallContextFactory)
         {
             this.environment = GrpcPreconditions.CheckNotNull(environment);
             this.batchContextFactory = GrpcPreconditions.CheckNotNull(batchContextFactory);
+            this.requestCallContextFactory = GrpcPreconditions.CheckNotNull(requestCallContextFactory);
         }
 
         public void Register(IntPtr key, IOpCompletionCallback callback)
@@ -73,10 +75,12 @@ namespace Grpc.Core.Internal
             return ctx;
         }
 
-        public void RegisterRequestCallCompletion(RequestCallContextSafeHandle ctx, RequestCallCompletionDelegate callback)
+        public RequestCallContextSafeHandle RegisterRequestCallCompletion(RequestCallCompletionDelegate callback)
         {
+            var ctx = requestCallContextFactory();
             ctx.CompletionCallback = callback;
             Register(ctx.Handle, ctx);
+            return ctx;
         }
 
         public IOpCompletionCallback Extract(IntPtr key)

src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs

@@ -219,7 +219,7 @@ namespace Grpc.Core.Internal
             var list = new List<CompletionQueueSafeHandle>();
             for (int i = 0; i < completionQueueCount; i++)
             {
-                var completionRegistry = new CompletionRegistry(environment, () => environment.BatchContextPool.Lease());
+                var completionRegistry = new CompletionRegistry(environment, () => environment.BatchContextPool.Lease(), () => RequestCallContextSafeHandle.Create());
                 list.Add(CompletionQueueSafeHandle.CreateAsync(completionRegistry));
             }
             return list.AsReadOnly();

src/csharp/Grpc.Core/Internal/ServerSafeHandle.cs

@@ -75,8 +75,7 @@ namespace Grpc.Core.Internal
         {
             using (completionQueue.NewScope())
             {
-                var ctx = RequestCallContextSafeHandle.Create();
+                var ctx = completionQueue.CompletionRegistry.RegisterRequestCallCompletion(callback);
-                completionQueue.CompletionRegistry.RegisterRequestCallCompletion(ctx, callback);
                 Native.grpcsharp_server_request_call(this, completionQueue, ctx).CheckOk();
             }
         }

src/csharp/Grpc.Core/Server.cs

@@ -300,6 +300,7 @@ namespace Grpc.Core
         {
             if (!shutdownRequested)
             {
+                // TODO(jtattermusch): avoid unnecessary delegate allocation
                 handle.RequestCall((success, ctx) => HandleNewServerRpc(success, ctx, cq), cq);
             }
         }

src/csharp/Grpc.Microbenchmarks/CompletionRegistryBenchmark.cs

@@ -43,7 +43,7 @@ namespace Grpc.Microbenchmarks
         public void Run(int threadCount, int iterations, bool useSharedRegistry)
         {
             Console.WriteLine(string.Format("CompletionRegistryBenchmark: threads={0}, iterations={1}, useSharedRegistry={2}", threadCount, iterations, useSharedRegistry));
-            CompletionRegistry sharedRegistry = useSharedRegistry ? new CompletionRegistry(environment, () => BatchContextSafeHandle.Create()) : null;
+            CompletionRegistry sharedRegistry = useSharedRegistry ? new CompletionRegistry(environment, () => BatchContextSafeHandle.Create(), () => RequestCallContextSafeHandle.Create()) : null;
             var threadedBenchmark = new ThreadedBenchmark(threadCount, () => ThreadBody(iterations, sharedRegistry));
             threadedBenchmark.Run();
             // TODO: parametrize by number of pending completions
@@ -51,7 +51,7 @@ namespace Grpc.Microbenchmarks
 
         private void ThreadBody(int iterations, CompletionRegistry optionalSharedRegistry)
         {
-            var completionRegistry = optionalSharedRegistry ?? new CompletionRegistry(environment, () => BatchContextSafeHandle.Create());
+            var completionRegistry = optionalSharedRegistry ?? new CompletionRegistry(environment, () => BatchContextSafeHandle.Create(), () => RequestCallContextSafeHandle.Create());
             var ctx = BatchContextSafeHandle.Create();
   
             var stopwatch = Stopwatch.StartNew();

src/csharp/Grpc.Microbenchmarks/SendMessageBenchmark.cs

@@ -52,7 +52,7 @@ namespace Grpc.Microbenchmarks
 
         private void ThreadBody(int iterations, int payloadSize)
         {
-            var completionRegistry = new CompletionRegistry(environment, () => environment.BatchContextPool.Lease());
+            var completionRegistry = new CompletionRegistry(environment, () => environment.BatchContextPool.Lease(), () => RequestCallContextSafeHandle.Create());
             var cq = CompletionQueueSafeHandle.CreateAsync(completionRegistry);
             var call = CreateFakeCall(cq);