目录
1 -> connect的断线重连
客户端会面临服务器崩溃的情况,我们可以试着写一个客户端重连的代码,模拟并理解一些客户端行为,比如游戏客户端等。
TcpClient.cc
采用状态机,实现一个简单的tcp client可以实现重连效果。
#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
using namespace std;
void Usage(const std::string& process)
{
std::cout << "Usage: " << process << " server_ip server_port" << std::endl;
}
enum class Status // C++11 强类型枚举
{
NEW, // 新建状态,就是单纯的连接
CONNECTING, // 正在连接,仅仅方便查询conn状态
CONNECTED, // 连接或者重连成功
DISCONNECTED, // 重连失败
CLOSED // 连接失败,经历重连,无法连接
};
class ClientConnection
{
public:
ClientConnection(uint16_t serverport, const std::string& serverip)
: _sockfd(-1),
_serverport(serverport),
_serverip(serverip),
_retry_interval(1),
_max_retries(5),
_status(Status::NEW)
{
}
void Connect()
{
// 1. 创建socket
_sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (_sockfd < 0)
{
cerr << "socket error" << endl;
exit(1);
}
// 2. 要不要bind?必须要有Ip和Port, 需要bind,但是不需要用户显示的bind,client系统随机端口
// 发起连接的时候,client会被OS自动进行本地绑定
// 2. connect
struct sockaddr_in server;
memset(&server, 0, sizeof(server));
server.sin_family = AF_INET;
server.sin_port = htons(_serverport);
// p:process(进程), n(网络) -- 不太准确,但是好记忆
inet_pton(AF_INET, _serverip.c_str(), &server.sin_addr); // 1. 字符串ip->4字节IP 2. 网络序列
int n = connect(_sockfd, (struct sockaddr*)&server, sizeof(server)); // 自动进行bind哦!
if (n < 0)
{
Disconnect(); // 恢复_sockfd的默认值,是连接没有成功,不代表sockfd创建没有成功
_status = Status::DISCONNECTED; // 没有连接成功
return;
}
_status = Status::CONNECTED; // 连接成功
}
int SocketFd()
{
return _sockfd;
}
void Reconnect()
{
_status = Status::CONNECTING; // 正在重连
int count = 0;
while (count < _max_retries)
{
Connect(); // 重连
if (_status == Status::CONNECTED)
{
return;
}
sleep(_retry_interval);
count++;
std::cout << "重连次数: " << count << ", 最大上限: " << _max_retries << std::endl;
}
_status = Status::CLOSED; // 重连失败,可以关闭了
}
void Disconnect()
{
if (_sockfd != -1)
{
close(_sockfd);
_status = Status::CLOSED;
_sockfd = -1;
}
}
Status GetStatus()
{
return _status;
}
void Process()
{
// 简单的IO即可
while (true)
{
string inbuffer;
cout << "Please Enter# ";
getline(cin, inbuffer);
if (inbuffer.empty())
continue;
ssize_t n = write(_sockfd, inbuffer.c_str(), inbuffer.size());
if (n > 0)
{
char buffer[1024];
ssize_t m = read(_sockfd, buffer, sizeof(buffer) - 1);
if (m > 0)
{
buffer[m] = 0;
cout << "echo messsge -> " << buffer << endl;
}
else if (m == 0) // 这里证明server端掉线了
{
_status = Status::DISCONNECTED;
break;
}
else
{
std::cout << "read m : " << m << "errno: " << errno << "errno string: " << strerror(errno) << std::endl;
_status = Status::CLOSED;
break;
}
}
else
{
std::cout << "write n : " << n << "errno: " << errno << "errno string: " << strerror(errno) << std::endl;
_status = Status::CLOSED;
break;
}
}
}
~ClientConnection()
{
Disconnect();
}
private:
int _sockfd;
uint16_t _serverport; // server port 端口号
std::string _serverip; // server ip地址
int _retry_interval; // 重试时间间隔
int _max_retries; // 重试次数
Status _status; // 连接状态
};
class TcpClient
{
public:
TcpClient(uint16_t serverport, const std::string& serverip) : _conn(serverport, serverip)
{
}
void Execute()
{
while (true)
{
switch (_conn.GetStatus())
{
case Status::NEW:
_conn.Connect();
break;
case Status::CONNECTED:
std::cout << "连接成功, 开始进行通信." << std::endl;
_conn.Process();
break;
case Status::DISCONNECTED:
std::cout << "连接失败或者对方掉线,开始重连." << std::endl;
_conn.Reconnect();
break;
case Status::CLOSED:
_conn.Disconnect();
std::cout << "重连失败, 退出." << std::endl;
return; // 退出
default:
break;
}
}
}
~TcpClient()
{
}
private:
ClientConnection _conn; // 简单组合起来即可
};
// class Tcp
// ./tcp_client serverip serverport
int main(int argc, char* argv[])
{
if (argc != 3)
{
Usage(argv[0]);
return 1;
}
std::string serverip = argv[1];
uint16_t serverport = stoi(argv[2]);
TcpClient client(serverport, serverip);
client.Execute();
return 0;
}
感谢各位大佬支持!!!
互三啦!!!