done

Netch/3rd/DnsClient.NET/Internal/StringBuilderObjectPool.cs

@@ -0,0 +1,77 @@
+#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member
+
+using System.Text;
+using System.Threading;
+
+namespace DnsClient.Internal
+{
+    public class StringBuilderObjectPool
+    {
+        private readonly StringBuilder[] _items;
+        private readonly int _initialCapacity;
+        private readonly int _maxPooledCapacity;
+        private StringBuilder _fastAccess;
+
+        public static StringBuilderObjectPool Default { get; } = new StringBuilderObjectPool();
+
+        public StringBuilderObjectPool(int pooledItems = 16, int initialCapacity = 200, int maxPooledCapacity = 1024 * 2)
+        {
+            _items = new StringBuilder[pooledItems];
+            _initialCapacity = initialCapacity;
+            _maxPooledCapacity = maxPooledCapacity;
+            _fastAccess = Create();
+        }
+
+        public StringBuilder Get()
+        {
+            //return Create();
+            var found = _fastAccess;
+
+            if (found == null || Interlocked.CompareExchange(ref _fastAccess, null, found) != found)
+            {
+                for (var i = 0; i < _items.Length; i++)
+                {
+                    found = _items[i];
+
+                    if (found != null && Interlocked.CompareExchange(ref _items[i], null, found) == found)
+                    {
+                        return found;
+                    }
+                }
+            }
+
+            return found ?? Create();
+        }
+
+        public void Return(StringBuilder value)
+        {
+            //return;
+            if (value == null || value.Capacity > _maxPooledCapacity)
+            {
+                return;
+            }
+
+            value.Clear();
+
+            if (_fastAccess == null && Interlocked.CompareExchange(ref _fastAccess, value, null) == null)
+            {
+                return;
+            }
+
+            for (var i = 0; i < _items.Length; i++)
+            {
+                if (Interlocked.CompareExchange(ref _items[i], value, null) == null)
+                {
+                    return;
+                }
+            }
+        }
+
+        private StringBuilder Create()
+        {
+            return new StringBuilder(_initialCapacity);
+        }
+    }
+}
+
+#pragma warning restore CS1591 // Missing XML comment for publicly visible type or member