Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/BufferAllocator.cs

@@ -0,0 +1,425 @@
+//------------------------------------------------------------------------------
+// <copyright file="BufferAllocator.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+/*
+ * Buffer Allocators with recycling
+ * 
+ * Copyright (c) 1999 Microsoft Corporation
+ */
+namespace System.Web {
+
+    using System.Collections;
+    using System.Collections.Generic;
+    using System.IO;
+    using System.Globalization;
+
+    using System.Web.Util;
+
+    //////////////////////////////////////////////////////////////////////////////
+    // Generic buffer recycling
+
+    internal interface IBufferAllocator {
+        object GetBuffer();
+        void ReuseBuffer(object buffer);
+        void ReleaseAllBuffers();
+        int BufferSize { get; }
+    }
+
+    internal interface IBufferAllocator<T> : IBufferAllocator {
+        new T[] GetBuffer();
+        T[] GetBuffer(int minSize);
+        void ReuseBuffer(T[] buffer);
+    }
+
+    internal interface IAllocatorProvider {
+        IBufferAllocator<char>  CharBufferAllocator { get; }
+        IBufferAllocator<int>   IntBufferAllocator { get; }
+        IBufferAllocator<IntPtr> IntPtrBufferAllocator { get; }
+
+        void TrimMemory();
+    }
+
+    /*
+     * Base class for allocator doing buffer recycling
+     */
+    internal abstract class BufferAllocator : IBufferAllocator {
+        private int _maxFree;
+        private int _numFree;
+        private Stack _buffers;
+
+        private static int s_ProcsFudgeFactor;
+
+        static BufferAllocator() {
+            s_ProcsFudgeFactor = SystemInfo.GetNumProcessCPUs();
+            if (s_ProcsFudgeFactor < 1) 
+                s_ProcsFudgeFactor = 1;
+
+            if (s_ProcsFudgeFactor > 4)
+                s_ProcsFudgeFactor = 4;
+        }
+
+
+        internal BufferAllocator(int maxFree) {
+            _buffers = new Stack();
+            _numFree = 0;
+            _maxFree = maxFree * s_ProcsFudgeFactor;
+        }
+
+        public void ReleaseAllBuffers() {
+            if (_numFree > 0) {
+                lock (this) {
+                    _buffers.Clear();
+                    _numFree = 0;
+                }
+            }
+        }
+
+        public object GetBuffer() {
+            Object buffer = null;
+
+            if (_numFree > 0) {
+                lock(this) {
+                    if (_numFree > 0) {
+                        buffer = _buffers.Pop();
+                        _numFree--;
+                    }
+                }
+            }
+
+            if (buffer == null)
+                buffer = AllocBuffer();
+
+            return buffer;
+        }
+
+        public void ReuseBuffer(object buffer) {
+            if (_numFree < _maxFree) {
+                lock(this) {
+                    if (_numFree < _maxFree) {
+                        _buffers.Push(buffer);
+                        _numFree++;
+                    }
+                }
+            }
+        }
+
+        /*
+         * To be implemented by a derived class
+         */
+        abstract protected Object AllocBuffer();
+        abstract public int BufferSize { get; }
+    }
+
+    /*
+     * Concrete allocator class for ubyte[] buffer recycling
+     */
+    internal class UbyteBufferAllocator : BufferAllocator {
+        private int _bufferSize;
+
+        internal UbyteBufferAllocator(int bufferSize, int maxFree) : base(maxFree) {
+            _bufferSize = bufferSize;
+        }
+
+        protected override Object AllocBuffer() {
+            return new byte[_bufferSize];
+        }
+
+        public override int BufferSize { 
+            get {
+                return _bufferSize;
+            } 
+        }
+    }
+
+    /*
+     * Concrete allocator class for char[] buffer recycling
+     */
+    internal class CharBufferAllocator : BufferAllocator {
+        private int _bufferSize;
+
+        internal CharBufferAllocator(int bufferSize, int maxFree)
+
+        : base(maxFree) {
+            _bufferSize = bufferSize;
+        }
+
+        protected override Object AllocBuffer() {
+            return new char[_bufferSize];
+        }
+
+        public override int BufferSize {
+            get {
+                return _bufferSize;
+            }
+        }
+    }
+
+    /*
+     * Concrete allocator class for int[] buffer recycling
+     */
+    internal class IntegerArrayAllocator : BufferAllocator {
+        private int _arraySize;
+
+        internal IntegerArrayAllocator(int arraySize, int maxFree)
+
+        : base(maxFree) {
+            _arraySize = arraySize;
+        }
+
+        protected override Object AllocBuffer() {
+            return new int[_arraySize];
+        }
+
+        public override int BufferSize {
+            get {
+                return _arraySize;
+            }
+        }
+    }
+
+    /*
+     * Concrete allocator class for IntPtr[] buffer recycling
+     */
+    internal class IntPtrArrayAllocator : BufferAllocator {
+        private int _arraySize;
+
+        internal IntPtrArrayAllocator(int arraySize, int maxFree)
+
+        : base(maxFree) {
+            _arraySize = arraySize;
+        }
+
+        protected override Object AllocBuffer() {
+            return new IntPtr[_arraySize];
+        }
+
+        public override int BufferSize {
+            get {
+                return _arraySize;
+            }
+        }
+    }
+
+
+
+    /*
+     * Simple Buffer Allocator - Reusable buffers pool
+     * Thread UNSAFE! Lock free. Caller must guarantee non-concurent access.
+     * Use as member of already pooled instances (like HttpApplication) that prohibit concurent access to avoid taking locks
+     */
+    internal class SimpleBufferAllocator<T> : IBufferAllocator<T> {
+        private Stack<T[]>   _buffers;
+        private readonly int _bufferSize;
+
+        public SimpleBufferAllocator(int bufferSize) {
+            if (bufferSize <= 0) {
+                throw new ArgumentOutOfRangeException("bufferSize");
+            }
+
+            _buffers = new Stack<T[]>();
+            _bufferSize = bufferSize;
+        }
+
+        public T[] GetBuffer() {
+            return GetBufferImpl();
+        }
+
+        public T[] GetBuffer(int minSize) {
+            if (minSize < 0) {
+                throw new ArgumentOutOfRangeException("minSize");
+            }
+
+            T[] buffer = null;
+
+            if (minSize <= BufferSize) {
+                // Get from the pool
+                buffer = GetBufferImpl();
+            }
+            else {
+                // Allocate a new buffer. It will not be reused later
+                buffer = AllocBuffer(minSize);
+            }
+
+            return buffer;
+        }
+
+        object IBufferAllocator.GetBuffer() {
+            return GetBufferImpl();
+        }
+
+        public void ReuseBuffer(T[] buffer) {
+            ReuseBufferImpl(buffer);
+        }
+
+        void IBufferAllocator.ReuseBuffer(object buffer) {
+            ReuseBufferImpl((T[]) buffer);
+        }
+
+        public void ReleaseAllBuffers() {
+            _buffers.Clear();
+        }
+
+        public int BufferSize {
+            get {
+                return _bufferSize;
+            }
+        }
+
+        private T[] GetBufferImpl() {
+            T[] buffer = null;
+
+            if (_buffers.Count > 0) {
+                // Get an exisitng buffer
+                buffer = _buffers.Pop();
+            }
+            else {
+                // Create a new buffer
+                buffer = AllocBuffer(BufferSize);
+            }
+
+            return buffer;
+        }
+
+        private void ReuseBufferImpl(T[] buffer) {
+            // Accept back only buffers that match the orirignal buffer size
+            if (buffer != null && buffer.Length == BufferSize) {
+                _buffers.Push(buffer);
+            }
+        }
+
+        private static T[] AllocBuffer(int size) {
+            return new T[size];
+        }
+    }
+
+
+    /*
+     * Adapter to convert IBufferAllocator to generic IBufferAllocator<>
+     */
+    class BufferAllocatorWrapper<T> : IBufferAllocator<T> {
+        private IBufferAllocator _allocator;
+
+        public BufferAllocatorWrapper(IBufferAllocator allocator) {
+            Debug.Assert(allocator != null);
+
+            _allocator = allocator;
+        }
+
+        public T[] GetBuffer() {
+            return (T[])_allocator.GetBuffer();
+        }
+
+        public T[] GetBuffer(int minSize) {
+            if (minSize < 0) {
+                throw new ArgumentOutOfRangeException("minSize");
+            }
+
+            T[] buffer = null;
+
+            if (minSize <= BufferSize) {
+                // Get from the allocator
+                buffer = (T[])_allocator.GetBuffer();
+            }
+            else {
+                // Allocate a new buffer. It will not be reused later
+                buffer = new T[minSize];
+            }
+
+            return buffer;
+        }
+
+        public void ReuseBuffer(T[] buffer) {
+            // Accept back only buffers that match the orirignal buffer size
+            if (buffer != null && buffer.Length == BufferSize) {
+                _allocator.ReuseBuffer(buffer);
+            }
+        }
+
+        object IBufferAllocator.GetBuffer() {
+            return _allocator.GetBuffer();
+        }
+
+        void IBufferAllocator.ReuseBuffer(object buffer) {
+            ReuseBuffer((T[])buffer);
+        }
+
+        public void ReleaseAllBuffers() {
+            _allocator.ReleaseAllBuffers();
+        }
+
+        public int BufferSize {
+            get {
+                return _allocator.BufferSize;
+            }
+        }
+    }
+
+
+    /*
+     * Provider for different buffer allocators
+     */
+    internal class AllocatorProvider : IAllocatorProvider {
+        private IBufferAllocator<char>   _charAllocator = null;
+        private IBufferAllocator<int> _intAllocator = null;
+        private IBufferAllocator<IntPtr> _intPtrAllocator = null;
+
+        public IBufferAllocator<char> CharBufferAllocator {
+            get {
+                return _charAllocator;
+            }
+
+            set {
+                if (value == null) {
+                    throw new ArgumentNullException("value");
+                }
+
+                _charAllocator = value;
+            }
+        }
+
+        public  IBufferAllocator<int> IntBufferAllocator {
+            get {
+                return _intAllocator;
+            }
+
+            set {
+                if (value == null) {
+                    throw new ArgumentNullException("value");
+                }
+
+                _intAllocator = value;
+            }
+        }
+
+        public IBufferAllocator<IntPtr> IntPtrBufferAllocator {
+            get {
+                return _intPtrAllocator;
+            }
+
+            set {
+                if (value == null) {
+                    throw new ArgumentNullException("value");
+                }
+
+                _intPtrAllocator = value;
+            }
+        }
+
+        public void TrimMemory() {
+            if (_charAllocator != null) {
+                _charAllocator.ReleaseAllBuffers();
+            }
+
+            if (_intAllocator != null) {
+                _intAllocator.ReleaseAllBuffers();
+            }
+
+            if (_intPtrAllocator != null) {
+                _intPtrAllocator.ReleaseAllBuffers();
+            }
+        }
+    }
+}