mono/mcs/class/corlib/System.Collections.Concurrent/ConcurrentStack.cs

#if NET_4_0
// ConcurrentStack.cs
//
// Copyright (c) 2008 Jérémie "Garuma" Laval
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
//

using System;
using System.Threading;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.Serialization;

namespace System.Collections.Concurrent
{
	
	
	public class ConcurrentStack<T> : IProducerConsumerCollection<T>, IEnumerable<T>,
	                                  ICollection, IEnumerable
	{
		class Node
		{
			public T Value = default (T);
			public Node Next = null;
		}
		
		Node head = null;
		
		int count;
		
		public ConcurrentStack ()
		{
		}
		
		public ConcurrentStack (IEnumerable<T> enumerable)
		{
			foreach (T item in enumerable) 
				Push (item);
		}
		
		bool IProducerConsumerCollection<T>.TryAdd (T elem)
		{
			Push (elem);
			return true;
		}
		
		public void Push (T element)
		{
			Node temp = new Node ();
			temp.Value = element;
			do {
			  temp.Next = head;
			} while (Interlocked.CompareExchange (ref head, temp, temp.Next) != temp.Next);
			
			Interlocked.Increment (ref count);
		}

		public void PushRange (T[] values)
		{
			PushRange (values, 0, values.Length);
		}
		
		public void PushRange (T[] values, int start, int length)
		{
			Node insert = null;
			Node first = null;
			
			for (int i = start; i < length; i++) {
				Node temp = new Node ();
				temp.Value = values[i];
				temp.Next = insert;
				insert = temp;
				
				if (first == null)
					first = temp;
			}
			
			do {
				first.Next = head;
			} while (Interlocked.CompareExchange (ref head, insert, first.Next) != first.Next);
			
			Interlocked.Add (ref count, length);
		}
		
		public bool TryPop (out T value)
		{
			Node temp;
			do {
				temp = head;
				// The stak is empty
				if (temp == null) {
					value = default (T);
					return false;
				}
			} while (Interlocked.CompareExchange (ref head, temp.Next, temp) != temp);
			
			Interlocked.Decrement (ref count);
			
			value = temp.Value;
			return true;
		}

		public int TryPopRange (T[] values)
		{
			return TryPopRange (values, 0, values.Length);
		}

		public int TryPopRange (T[] values, int startIndex, int count)
		{
			Node temp;
			Node end;
			
			do {
				temp = head;
				if (temp == null)
					return -1;
				end = temp;
				for (int j = 0; j < count - 1; j++) {
					end = end.Next;
					if (end == null)
						break;
				}
			} while (Interlocked.CompareExchange (ref head, end, temp) != temp);
			
			int i;
			for (i = startIndex; i < count && temp != null; i++) {
				values[i] = temp.Value;
				temp = temp.Next;
			}
			
			return i - 1;
		}
		
		public bool TryPeek (out T value)
		{
			Node myHead = head;
			if (myHead == null) {
				value = default (T);
				return false;
			}
			value = myHead.Value;
			return true;
		}
		
		public void Clear ()
		{
			// This is not satisfactory
			count = 0;
			head = null;
		}
		
		IEnumerator IEnumerable.GetEnumerator ()
		{
			return (IEnumerator)InternalGetEnumerator ();
		}
		
		IEnumerator<T> IEnumerable<T>.GetEnumerator ()
		{
			return InternalGetEnumerator ();
		}
		
		public IEnumerator<T> GetEnumerator ()
		{
			return InternalGetEnumerator ();
		}
		
		IEnumerator<T> InternalGetEnumerator ()
		{
			Node my_head = head;
			if (my_head == null) {
				yield break;
			} else {
				do {
					yield return my_head.Value;
				} while ((my_head = my_head.Next) != null);
			}
		}
		
		void ICollection.CopyTo (Array array, int index)
		{
			T[] dest = array as T[];
			if (dest == null)
				return;
			CopyTo (dest, index);
		}
		
		public void CopyTo (T[] dest, int index)
		{
			IEnumerator<T> e = InternalGetEnumerator ();
			int i = index;
			while (e.MoveNext ()) {
				dest[i++] = e.Current;
			}
		}
		
		bool ICollection.IsSynchronized {
			get { return true; }
		}
		
		bool IProducerConsumerCollection<T>.TryTake (out T item)
		{
			return TryPop (out item);
		}
		
		object syncRoot = new object ();
		object ICollection.SyncRoot {
			get { return syncRoot; }
		}
		
		public T[] ToArray ()
		{
			T[] dest = new T [count];
			CopyTo (dest, 0);
			return dest;
		}
		
		public int Count {
			get {
				return count;
			}
		}
		
		public bool IsEmpty {
			get {
				return count == 0;
			}
		}
	}
}
#endif