namespace System.Threading.Tasks
{
	internal class SimpleConcurrentBag<T>
	{
		private readonly IConcurrentDeque<T>[] deques;

		private readonly bool unique;

		private int index = -1;

		[ThreadStatic]
		private int stealIndex;

		public SimpleConcurrentBag(int num)
		{
			deques = new CyclicDeque<T>[num];
			for (int i = 0; i < deques.Length; i++)
			{
				deques[i] = new CyclicDeque<T>();
			}
			unique = num <= 1;
		}

		public int GetNextIndex()
		{
			return Interlocked.Increment(ref index);
		}

		public bool TryTake(int index, out T value)
		{
			value = default(T);
			return deques[index].PopBottom(out value) == PopResult.Succeed;
		}

		public bool TrySteal(int index, out T value)
		{
			value = default(T);
			if (unique)
			{
				return false;
			}
			for (int round = 0; round < 3; round++)
			{
				if (stealIndex == index)
				{
					stealIndex = (stealIndex + 1) % deques.Length;
				}
				if (deques[stealIndex = (stealIndex + 1) % deques.Length].PopTop(out value) == PopResult.Succeed)
				{
					return true;
				}
			}
			return false;
		}

		public void Add(int index, T value)
		{
			deques[index].PushBottom(value);
		}
	}
}