ConcurrentStack.cs

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// 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.
//
//

#if NET_4_0

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

namespace System.Collections.Concurrent
{
    
    [System.Diagnostics.DebuggerDisplay ("Count = {Count}")]
    [System.Diagnostics.DebuggerTypeProxy (typeof (CollectionDebuggerView<>))]
    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> collection)
        {
            foreach (T item in collection) 
                Push (item);
        }
        
        bool IProducerConsumerCollection<T>.TryAdd (T elem)
        {
            Push (elem);
            return true;
        }
        
        public void Push (T item)
        {
            Node temp = new Node ();
            temp.Value = item;
            do {
              temp.Next = head;
            } while (AotInterlocked.CompareExchange (ref head, temp, temp.Next) != temp.Next);
            
            Interlocked.Increment (ref count);
        }

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

            return true;
        }

        public int TryPopRange (T[] items)
        {
            if (items == null)
                throw new ArgumentNullException ("items");
            return TryPopRange (items, 0, items.Length);
        }

        public int TryPopRange (T[] items, int startIndex, int count)
        {
            if (items == null)
                throw new ArgumentNullException ("items");
            if (startIndex < 0 || startIndex >= items.Length)
                throw new ArgumentOutOfRangeException ("startIndex");
            if (count < 0)
                throw new ArgumentOutOfRangeException ("count");
            if (startIndex + count > items.Length)
                throw new ArgumentException ("startIndex + count is greater than the length of items.");

            Node temp;
            Node end;
            
            do {
                temp = head;
                if (temp == null)
                    return -1;
                end = temp;
                for (int j = 0; j < count; j++) {
                    end = end.Next;
                    if (end == null)
                        break;
                }
            } while (AotInterlocked.CompareExchange (ref head, end, temp) != temp);
            
            int i;
            for (i = startIndex; i < startIndex + count && temp != null; i++) {
                items[i] = temp.Value;
                end = temp;
                temp = temp.Next;
            }
            Interlocked.Add (ref this.count, -(i - startIndex));
            
            return i - startIndex;
        }
        
        public bool TryPeek (out T result)
        {
            Node myHead = head;
            if (myHead == null) {
                result = default (T);
                return false;
            }
            result = myHead.Value;
            return true;
        }
        
        public void Clear ()
        {
            // This is not satisfactory
            count = 0;
            head = null;
        }
        
        IEnumerator IEnumerable.GetEnumerator ()
        {
            return (IEnumerator)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)
        {
            if (array == null)
                throw new ArgumentNullException ("array");
            if (array.Rank > 1)
                throw new ArgumentException ("The array can't be multidimensional");
            if (array.GetLowerBound (0) != 0)
                throw new ArgumentException ("The array needs to be 0-based");

            T[] dest = array as T[];
            if (dest == null)
                throw new ArgumentException ("The array cannot be cast to the collection element type", "array");
            CopyTo (dest, index);
        }
        
        public void CopyTo (T[] array, int index)
        {
            if (array == null)
                throw new ArgumentNullException ("array");
            if (index < 0)
                throw new ArgumentOutOfRangeException ("index");
            if (index >= array.Length)
                throw new ArgumentException ("index is equals or greather than array length", "index");

            IEnumerator<T> e = InternalGetEnumerator ();
            int i = index;
            while (e.MoveNext ()) {
                if (i == array.Length - index)
                    throw new ArgumentException ("The number of elememts in the collection exceeds the capacity of array", "array");
                array[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 ()
        {
            return new List<T> (this).ToArray ();
        }
        
        public int Count {
            get {
                return count;
            }
        }
        
        public bool IsEmpty {
            get {
                return count == 0;
            }
        }
    }
}
#endif