Initial checkin of gRPC to third_party/

third_party/grpc/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs

+#region Copyright notice and license
+// Copyright 2015-2016, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// 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
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+using System;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
+using Grpc.Core.Profiling;
+
+using Grpc.Core.Utils;
+
+namespace Grpc.Core.Internal
+{
+    /// <summary>
+    /// grpc_completion_queue from <c>grpc/grpc.h</c>
+    /// </summary>
+    internal class CompletionQueueSafeHandle : SafeHandleZeroIsInvalid
+    {
+        static readonly NativeMethods Native = NativeMethods.Get();
+
+        AtomicCounter shutdownRefcount = new AtomicCounter(1);
+
+        private CompletionQueueSafeHandle()
+        {
+        }
+
+        public static CompletionQueueSafeHandle Create()
+        {
+            return Native.grpcsharp_completion_queue_create();
+
+        }
+
+        public CompletionQueueEvent Next()
+        {
+            return Native.grpcsharp_completion_queue_next(this);
+        }
+
+        public CompletionQueueEvent Pluck(IntPtr tag)
+        {
+            using (Profilers.ForCurrentThread().NewScope("CompletionQueueSafeHandle.Pluck"))
+            {
+                return Native.grpcsharp_completion_queue_pluck(this, tag);
+            }
+        }
+
+        /// <summary>
+        /// Creates a new usage scope for this completion queue. Once successfully created,
+        /// the completion queue won't be shutdown before scope.Dispose() is called.
+        /// </summary>
+        public UsageScope NewScope()
+        {
+            return new UsageScope(this);
+        }
+
+        public void Shutdown()
+        {
+            DecrementShutdownRefcount();
+        }
+
+        protected override bool ReleaseHandle()
+        {
+            Native.grpcsharp_completion_queue_destroy(handle);
+            return true;
+        }
+
+        private void DecrementShutdownRefcount()
+        {
+            if (shutdownRefcount.Decrement() == 0)
+            {
+                Native.grpcsharp_completion_queue_shutdown(this);
+            }
+        }
+
+        private void BeginOp()
+        {
+            bool success = false;
+            shutdownRefcount.IncrementIfNonzero(ref success);
+            GrpcPreconditions.CheckState(success, "Shutdown has already been called");
+        }
+
+        private void EndOp()
+        {
+            DecrementShutdownRefcount();
+        }
+
+        // Allows declaring BeginOp and EndOp of a completion queue with a using statement.
+        // Declared as struct for better performance.
+        public struct UsageScope : IDisposable
+        {
+            readonly CompletionQueueSafeHandle cq;
+
+            public UsageScope(CompletionQueueSafeHandle cq)
+            {
+                this.cq = cq;
+                this.cq.BeginOp();
+            }
+
+            public void Dispose()
+            {
+                cq.EndOp();
+            }
+        }
+    }
+}