using System;
using System.Text;

//NOTE: cache for less GC operations
public static class TempBuffer
{
  static byte[][] tmp_bufs = new byte[][] { new byte[512], new byte[512], new byte[512] };
  static int tmp_buf_counter = 0;
  static public int stats_max_buf = 0;

  static public byte[] Get(int size)
  {
    var buf = Get();
    if(size > buf.Length)
    {
      Array.Resize(ref buf, size);
      Update(buf);
    }
    return buf;
  }

  static byte[] Get()
  {
    var buf = tmp_bufs[tmp_buf_counter % 3];
    ++tmp_buf_counter;
    return buf;
  }

  static void Update(byte[] buf)
  {
    var idx = (tmp_buf_counter-1) % 3;
    //for debug
    //var curr = tmp_bufs[idx];
    //if(curr != buf)
    //  Log.Debug(curr.Length + " VS " + buf.Length);
    tmp_bufs[idx] = buf;
    stats_max_buf = stats_max_buf < buf.Length ? buf.Length : stats_max_buf;
  }

  static public void Cleanup()
  {
    for(int i = 0; i < tmp_bufs.Length; ++i)
      System.Array.Clear(tmp_bufs[i], 0, tmp_bufs[i].Length);
  }
}

public static class TempStringBuffer
{
  static public StringBuilder[] tmp_bufs = new StringBuilder[] { new StringBuilder(), new StringBuilder() };
  static int tmp_buf_counter = 0;

  static public StringBuilder Get()
  {
    var buf = tmp_bufs[tmp_buf_counter % 2];
    buf.Length = 0;
    ++tmp_buf_counter;
    return buf;
  }

  static public string Concat(string s1, string s2)
  {
    return Get().Append(s1).Append(s2).ToString();
  }

  static public string Concat(string s1, string s2, string s3)
  {
    return Get().Append(s1).Append(s2).Append(s3).ToString();
  }

  static public string Concat(string s1, string s2, string s3, string s4)
  {
    return Get().Append(s1).Append(s2).Append(s3).Append(s4).ToString();
  }
}