C#实现异步阻塞TCP

// This class creates a single large buffer which can be divided up
// and assigned to SocketAsyncEventArgs objects for use with each
// socket I/O operation. 
// This enables bufffers to be easily reused and guards against
// fragmenting heap memory.
//
// The operations exposed on the BufferManager class are not thread safe.
public class BufferManager
{
    //buffer缓冲区大小
    private int m_numBytes;
    //缓冲区
    private byte[] m_buffer;
    private Stack<int> m_freeIndexPool;
    private int m_currentIndex;
    private int m_bufferSize;
 
    public BufferManager(int totalBytes, int bufferSize)
    {
        m_numBytes = totalBytes;
        m_currentIndex = 0;
        m_bufferSize = bufferSize;
        m_freeIndexPool = new Stack<int>();
    }
 
    /// <summary>
    /// 给buffer分配缓冲区
    /// </summary>
    public void InitBuffer()
    {
        m_buffer = new byte[m_numBytes];
    }
 
    /// <summary>
    ///  将buffer添加到args的IO缓冲区中，并设置offset
    /// </summary>
    /// <param name="args"></param>
    /// <returns></returns>
    public bool SetBuffer(SocketAsyncEventArgs args)
    {
        if (m_freeIndexPool.Count > 0)
        {
            args.SetBuffer(m_buffer, m_freeIndexPool.Pop(), m_bufferSize);
        }
        else
        {
            if ((m_numBytes - m_bufferSize) < m_currentIndex)
            {
                return false;
            }
            args.SetBuffer(m_buffer, m_currentIndex, m_bufferSize);
            m_currentIndex += m_bufferSize;
        }
        return true;
    }
 
    /// <summary>
    /// 将buffer从args的IO缓冲区中释放
    /// </summary>
    /// <param name="args"></param>
    public void FreeBuffer(SocketAsyncEventArgs args)
    {
        m_freeIndexPool.Push(args.Offset);
        args.SetBuffer(null, 0, 0);
    }
 
    /// <summary>
    /// 释放全部buffer缓存
    /// </summary>
    public void FreeAllBuffer()
    {
        m_freeIndexPool.Clear();
        m_currentIndex = 0;
        m_buffer = null;
    }
}　//