grpc/src/csharp/Grpc.Core/Calls.cs

#region Copyright notice and license

// Copyright 2015, Google Inc.
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// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#endregion

using System;
using System.Threading;
using System.Threading.Tasks;
using Grpc.Core.Internal;

namespace Grpc.Core
{
    /// <summary>
    /// Helper methods for generated client stubs to make RPC calls.
    /// </summary>
    public static class Calls
    {
        public static TResponse BlockingUnaryCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
            where TRequest : class
            where TResponse : class
        {
            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
            // TODO(jtattermusch): this gives a race that cancellation can be requested before the call even starts.
            RegisterCancellationCallback(asyncCall, token);
            return asyncCall.UnaryCall(call.Channel, call.Name, req, call.Headers);
        }

        public static async Task<TResponse> AsyncUnaryCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
            where TRequest : class
            where TResponse : class
        {
            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
            var asyncResult = asyncCall.UnaryCallAsync(req, call.Headers);
            RegisterCancellationCallback(asyncCall, token);
            return await asyncResult;
        }

        public static AsyncServerStreamingCall<TResponse> AsyncServerStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, TRequest req, CancellationToken token)
            where TRequest : class
            where TResponse : class
        {
            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
            asyncCall.StartServerStreamingCall(req, call.Headers);
            RegisterCancellationCallback(asyncCall, token);
            var responseStream = new ClientResponseStream<TRequest, TResponse>(asyncCall);
            return new AsyncServerStreamingCall<TResponse>(responseStream, asyncCall.Cancel);
        }

        public static AsyncClientStreamingCall<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, CancellationToken token)
            where TRequest : class
            where TResponse : class
        {
            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
            var resultTask = asyncCall.ClientStreamingCallAsync(call.Headers);
            RegisterCancellationCallback(asyncCall, token);
            var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
            return new AsyncClientStreamingCall<TRequest, TResponse>(requestStream, resultTask, asyncCall.Cancel);
        }

        public static AsyncDuplexStreamingCall<TRequest, TResponse> AsyncDuplexStreamingCall<TRequest, TResponse>(Call<TRequest, TResponse> call, CancellationToken token)
            where TRequest : class
            where TResponse : class
        {
            var asyncCall = new AsyncCall<TRequest, TResponse>(call.RequestMarshaller.Serializer, call.ResponseMarshaller.Deserializer);
            asyncCall.Initialize(call.Channel, GetCompletionQueue(), call.Name);
            asyncCall.StartDuplexStreamingCall(call.Headers);
            RegisterCancellationCallback(asyncCall, token);
            var requestStream = new ClientRequestStream<TRequest, TResponse>(asyncCall);
            var responseStream = new ClientResponseStream<TRequest, TResponse>(asyncCall);
            return new AsyncDuplexStreamingCall<TRequest, TResponse>(requestStream, responseStream, asyncCall.Cancel);
        }

        private static void RegisterCancellationCallback<TRequest, TResponse>(AsyncCall<TRequest, TResponse> asyncCall, CancellationToken token)
        {
            if (token.CanBeCanceled)
            {
                token.Register(() => asyncCall.Cancel());
            }
        }

        /// <summary>
        /// Gets shared completion queue used for async calls.
        /// </summary>
        private static CompletionQueueSafeHandle GetCompletionQueue()
        {
            return GrpcEnvironment.ThreadPool.CompletionQueue;
        }
    }
}