Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.ServiceModel/System/ServiceModel/SynchronizedDisposablePool.cs

@@ -0,0 +1,93 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+namespace System.ServiceModel
+{
+    using System.Collections.Generic;
+    using System.Threading;
+
+    class SynchronizedDisposablePool<T> where T : class, IDisposable
+    {
+        List<T> items;
+        int maxCount;
+        bool disposed;
+
+        public SynchronizedDisposablePool(int maxCount)
+        {
+            this.items = new List<T>();
+            this.maxCount = maxCount;
+        }
+
+        object ThisLock
+        {
+            get { return this; }
+        }
+
+        public void Dispose()
+        {
+            T[] items;
+            lock (ThisLock)
+            {
+                if (!disposed)
+                {
+                    disposed = true;
+                    if (this.items.Count > 0)
+                    {
+                        items = new T[this.items.Count];
+                        this.items.CopyTo(items, 0);
+                        this.items.Clear();
+                    }
+                    else
+                    {
+                        items = null;
+                    }
+                }
+                else
+                {
+                    items = null;
+                }
+            }
+            if (items != null)
+            {
+                for (int i = 0; i < items.Length; i++)
+                {
+                    items[i].Dispose();
+                }
+            }
+        }
+
+        public bool Return(T value)
+        {
+            if (!disposed && this.items.Count < this.maxCount)
+            {
+                lock (ThisLock)
+                {
+                    if (!disposed && this.items.Count < this.maxCount)
+                    {
+                        this.items.Add(value);
+                        return true;
+                    }
+                }
+            }
+            return false;
+        }
+
+        public T Take()
+        {
+            if (!disposed && this.items.Count > 0)
+            {
+                lock (ThisLock)
+                {
+                    if (!disposed && this.items.Count > 0)
+                    {
+                        int index = this.items.Count - 1;
+                        T item = this.items[index];
+                        this.items.RemoveAt(index);
+                        return item;
+                    }
+                }
+            }
+            return null;
+        }
+    }
+}