using System;
using System.Threading;
using JD.Collections.Details;
using JD.Kernel.Classes;

namespace JD.Serializers
{
    public class StringRecycler : Singleton<StringRecycler>
    {
        private readonly object m_lock = new object();
        private readonly FastHash<string> m_strings = new FastHash<string>();
        private int m_usageCount;

        public IDisposable Use()
        {
            Interlocked.Increment(ref m_usageCount);
            return new DisposableHelper(Unuse);
        }

        private void Unuse()
        {
            if (Interlocked.Decrement(ref m_usageCount) == 0)
            {
                lock (m_lock)
                {
                    m_strings.Clear();
                }
            }
        }

        public string Intern(string value)
        {
            if (value == null || m_usageCount == 0)
            {
                return value;
            }

            lock (m_lock)
            {
                m_strings.TryAdd(ref value);
            }

            return value;
        }
    }
}