Question

好的，我需要一些帮助。当发送出需要可靠性的数据包时，它会被传递给ReliabilityLayer。从那里，ReliabilityLayer将该数据包添加到列表中，然后将其写入SocketLayer一次。然后，ReliabilityLayer生成一个具有2个定时器的线程。当数据包仍在列表中时，第一个定时器每250ms连续将数据包发送到SocketLayer。第二个计时器是超时时间。它会在2秒后引发异常。 ReliabilityLayer挂钩到数据包接收事件，当ACK数据包返回包含ReliabilityLayer数据包列表中数据包的校验和时，它应该删除它，允许线程退出。问题是多线程...跨线程访问列表给了我随机的空指针和其他问题。所以我必须以某种方式使其线程安全或重新思考这一切。我想知道是否有人可以帮助我？感谢

public void Write(NetworkPacket packet, ClientInfo client, Action<byte[], EndPoint> action)
        {
            if (CSL)
                throw new Exception("ReliabilityLayer loaded for client use.");

            if (!packet.Command.RequiresReliability())
                throw new ArgumentException("Packet does not require reliability.");

            //Add the packet to the reliability list
            packetList.Add(packet);

            //Send the packet to the socket layer.
            action.Invoke(packet.RawData, client.EndPoint);

            new Thread(() =>
            {
                Stopwatch timeout = new Stopwatch();
                Stopwatch timer = new Stopwatch();
                timer.Start();
                timeout.Start();
                while (packetList.Contains(packet))
                {
                    //Still no response from the remote connection -> send another packet
                    if (timer.ElapsedMilliseconds > 256)
                    {
                        action.Invoke(packet.RawData, client.EndPoint);
                        timer.Restart();
                    }

                    //No response after 2 seconds -> throw exception
                    if (timeout.ElapsedMilliseconds > 2048)
                    {
                        throw new Exception("Client has not responded to the request.");
                    }
                }
            }).Start();
        }

        private void ssl_OnPacketReceived(object sender, ServerPacketEventArgs e)
        {
            if (e.Packet.Command != Command.Ack)
                return;

            //Find matching packet in the packetList
            NetworkPacket packet = packetList.Find(pkt => pkt.Checksum == e.Packet.Data[0]); //e.Packet.Data[0] is the checksum of the packet that was send out.
            if (packet != null)
            {
                //Remove it to allow thread to exit
                packetList.Remove(packet);
            }
        }

Answer 1

解决问题的最简单方法是使用lock（）“保护”对List的任何调用。您可以查看here如何操作。
简而言之，解释如下：
你应该按照方式“保护”不是线程安全的操作

private object private_obj_to_be_used = new object();

lock(private_obj_to_be_used)
{
   /// not thread safe operation goes here<br/>
}

请注意，您不仅要“保护”插入或移除，还要读取。或者您可以检查是否有适合您的“并发”课程。

数据包可靠性多线程错误

1 个答案: