Queue

using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;

public class Queue<v> : iQueue<v> {

    public List<v> list;
    int cursor, current, max, flag;
    const int reduce = 5;

    public Queue() {
        list = new List<v>();
        cursor = -1;
        current = 0;
        max = 0;
        flag = -1;
    }

    private object locker = new object();
    public bool Dequeue(ref v data) {
        lock (locker)
            if (max > 0) {
                if ((current + 1) - (cursor + 1) == max + 1 || max - current > 0)
                    cursor++;
                else
                    cursor = 0;

                data = list[cursor];
                max--;
                return true;
            } else
                return false;
    }

    private int count = 0;
    public void Enqueue(v data) {
        lock (locker) {

            if (current == list.Count)
                list.Add(data);
            else
                list[current] = data;

            if (cursor > -1 && current - cursor - max == 1) {
                flag = current;
                current = 0;
            } else {
                current++;
                while (cursor < current && current <= flag)
                    current++;
            }

            max++;

            if (max + Math.Max(current, cursor) < list.Count) {
                if (++count == reduce) {
                    list.RemoveAt(list.Count - 1);
                    list.TrimExcess();
                    count -= reduce;
                }
            } else
                count = 0;
        }
    }

    public bool Peek(ref v data) {
        lock (locker)
            if (max > 0) {
                int index = cursor;
                if ((current + 1) - (cursor + 1) == max + 1 || max - current > 0)
                    index++;
                else
                    index = 0;

                data = list[index];
                return true;
            } else
                return false;
    }
}

public interface iQueue<v> {
    void Enqueue(v data);
    bool Dequeue(ref v data);
    bool Peek(ref v data);
}