Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.ServiceModel/System/ServiceModel/Channels/ConnectionBufferPool.cs

@@ -0,0 +1,72 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+namespace System.ServiceModel.Channels
+{
+    using System.Runtime;
+
+    class ConnectionBufferPool : QueuedObjectPool<byte[]>
+    {
+        const int SingleBatchSize = 128 * 1024;
+        const int MaxBatchCount = 16;
+        const int MaxFreeCountFactor = 4;
+        int bufferSize;
+
+        public ConnectionBufferPool(int bufferSize)
+        {
+            int batchCount = ComputeBatchCount(bufferSize);
+            this.Initialize(bufferSize, batchCount, batchCount * MaxFreeCountFactor);
+        }
+
+        public ConnectionBufferPool(int bufferSize, int maxFreeCount)
+        {
+            this.Initialize(bufferSize, ComputeBatchCount(bufferSize), maxFreeCount);
+        }
+
+        void Initialize(int bufferSize, int batchCount, int maxFreeCount)
+        {
+            Fx.Assert(bufferSize >= 0, "bufferSize must be non-negative");
+            Fx.Assert(batchCount > 0, "batchCount must be positive");
+            Fx.Assert(maxFreeCount >= 0, "maxFreeCount must be non-negative");
+
+            this.bufferSize = bufferSize;
+            if (maxFreeCount < batchCount)
+            {
+                maxFreeCount = batchCount;
+            }
+            base.Initialize(batchCount, maxFreeCount);
+        }
+
+        public int BufferSize
+        {
+            get
+            {
+                return this.bufferSize;
+            }
+        }
+
+        protected override byte[] Create()
+        {
+            return DiagnosticUtility.Utility.AllocateByteArray(this.bufferSize);
+        }
+
+        static int ComputeBatchCount(int bufferSize)
+        {
+            int batchCount;
+            if (bufferSize != 0)
+            {
+                batchCount = (SingleBatchSize + bufferSize - 1) / bufferSize;
+                if (batchCount > MaxBatchCount)
+                {
+                    batchCount = MaxBatchCount;
+                }
+            }
+            else
+            {
+                // It's OK to have zero bufferSize
+                batchCount = MaxBatchCount;
+            }
+            return batchCount;
+        }
+    }
+}