Initial checkin of gRPC to third_party/

third_party/grpc/src/csharp/Grpc.Core/Utils/AsyncStreamExtensions.cs

+#region Copyright notice and license
+
+// Copyright 2015, 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.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace Grpc.Core.Utils
+{
+    /// <summary>
+    /// Extension methods that simplify work with gRPC streaming calls.
+    /// </summary>
+    public static class AsyncStreamExtensions
+    {
+        /// <summary>
+        /// Reads the entire stream and executes an async action for each element.
+        /// </summary>
+        public static async Task ForEachAsync<T>(this IAsyncStreamReader<T> streamReader, Func<T, Task> asyncAction)
+            where T : class
+        {
+            while (await streamReader.MoveNext().ConfigureAwait(false))
+            {
+                await asyncAction(streamReader.Current).ConfigureAwait(false);
+            }
+        }
+
+        /// <summary>
+        /// Reads the entire stream and creates a list containing all the elements read.
+        /// </summary>
+        public static async Task<List<T>> ToListAsync<T>(this IAsyncStreamReader<T> streamReader)
+            where T : class
+        {
+            var result = new List<T>();
+            while (await streamReader.MoveNext().ConfigureAwait(false))
+            {
+                result.Add(streamReader.Current);
+            }
+            return result;
+        }
+
+        /// <summary>
+        /// Writes all elements from given enumerable to the stream.
+        /// Completes the stream afterwards unless close = false.
+        /// </summary>
+        public static async Task WriteAllAsync<T>(this IClientStreamWriter<T> streamWriter, IEnumerable<T> elements, bool complete = true)
+            where T : class
+        {
+            foreach (var element in elements)
+            {
+                await streamWriter.WriteAsync(element).ConfigureAwait(false);
+            }
+            if (complete)
+            {
+                await streamWriter.CompleteAsync().ConfigureAwait(false);
+            }
+        }
+
+        /// <summary>
+        /// Writes all elements from given enumerable to the stream.
+        /// </summary>
+        public static async Task WriteAllAsync<T>(this IServerStreamWriter<T> streamWriter, IEnumerable<T> elements)
+            where T : class
+        {
+            foreach (var element in elements)
+            {
+                await streamWriter.WriteAsync(element).ConfigureAwait(false);
+            }
+        }
+    }
+}