C++ Thread实现简单的socket多线程通信
作者:合工大机器人实验室
起因
为什么要用C++的Thread,很简单,因为我菜
一打五用pthread实现了socket多线程通信,我之前学并发的时候没看pthread,因此代码只能看个大概,后面还是要系统学一下pthread的
服务端
多线程功能放在腾讯云服务器上,代码如下:
#include "tcpserver.h" #include <thread> #include <mutex> TcpServer server; mutex tcp_mutex; void tcpFunc(int clientfd); int main(int argc, char *argv[]) { if (server.initServer(6666) == false) { cout << "服务端初始化失败!!!" << endl; return -1; } vector<thread> tcp_vec; while (true) { if (!server.tcpAccept()) { continue; } tcp_vec.emplace_back(tcpFunc, server.m_connectfd); // thread tcpThread(tcpFunc, server.m_connectfd); // if (tcpThread.joinable()) if(tcp_vec.back().joinable()) { // cout << "Tcp thread " << tcpThread.get_id() << "is joinable!" << endl; cout << "Tcp thread " << tcp_vec.back().get_id() << " is joinable!" << endl; tcp_vec.back().detach(); } } return 0; } void tcpFunc(int clientfd) { int buf_len = 0; char buffer[1024]; while (true) { unique_lock<mutex> tcplck(tcp_mutex); memset(buffer, 0, sizeof(buffer)); if (!server.tcpRecv(clientfd, buffer, &buf_len, 5)) { cout << "接收客户端数据失败!" << endl; tcplck.unlock(); break; } cout << "服务端接收数据:" << buffer << endl; strcpy(buffer, "I am your father!"); if (!server.tcpSend(clientfd, buffer, sizeof(buffer))) { cout << "向客户端发送数据失败!" << endl; tcplck.unlock(); break; } tcplck.unlock(); usleep(100); } cout << "通信异常!" << endl; return; }
实在是很简单,贻笑大方了
有几个注意点:
- 全局变量在main函数执行完后会销毁,线程中用到了全局变量server,线程detach后要保证数据的收发,就要保持server的生存期,这里体现为在main中循环等待客户端的连接
- 要用锁锁住线程中server的操作,避免不同线程同时操作server造成混乱
- usleep(100);是为了避免不同线程争抢同一把锁而造成死锁的发生
ROS客户端
#include "tcpclient.h" #include <ros/ros.h> #include <geometry_msgs/Twist.h> TcpClient client; string send_str = "I am king of the world!"; char recv_buff[1024]; void client_callback(const geometry_msgs::Twist::ConstPtr &msg) { cout << "vel X:" << msg->linear.x << ";vel Y:" << msg->linear.y << ";angular Z:" << msg->angular.z << endl; if (!client.tcpSend(client.m_sockfd, send_str.data(), send_str.size())) { cout << "向服务端发送报文失败!" << endl; } if (!client.tcpRecv(client.m_sockfd, recv_buff, NULL, 10)) { cout << "从服务端接收报文失败!" << endl; } cout << "接收服务端报文:" << recv_buff << endl << endl; } int main(int argc, char **argv) { ros::init(argc, argv, "joystick_client"); ros::NodeHandle nh; string server_ip = "1.116.137.21"; string loop_ip = "127.0.0.1"; if (client.connectToServer(server_ip.data(), 6666) == false) { cout << "连接失败!!!" << endl; return -1; } ros::Subscriber sub = nh.subscribe("/cmd_vel", 1, client_callback); ros::spin(); }
很简单,订阅了手柄发布的话题/cmd_vel,在回调函数中和服务端通讯
话题的发布频率是10Hz,意味着和服务端通讯的频率也是10Hz
普通客户端
#include "tcp/tcpclient.h" int main(int argc, char **argv) { TcpClient client; string server_ip = "1.116.137.21"; string loop_ip = "127.0.0.1"; if (client.connectToServer(server_ip.data(), 6666) == false) { cout << "连接失败!!!" << endl; return -1; } cout << "成功连接服务器!" << endl; char buff[1024]; while (true) { memset(buff, 0, sizeof(buff)); sprintf(buff, "Ouch!"); if (!client.tcpSend(client.m_sockfd, buff, sizeof(buff))) { cout << "向服务端发送报文失败!" << endl; return -1; } memset(buff, 0, sizeof(buff)); if (!client.tcpRecv(client.m_sockfd, buff, NULL, 5)) { cout << "从服务端接收报文失败!" << endl; return -1; } cout << "接收服务端报文:" << buff << endl << endl; sleep(0.1); } return 0; }
这里sleep(0.1);是为了模拟ROS中话题的频率
sleep过长会导致服务端阻塞等待该客户端的消息,从而导致其余客户端与服务端的通信失败(如果客户端中允许的通信延时很短的话)
运行效果
云服务器上的服务端
[root@VM-4-11-centos bin]# ./server_thread
Tcp thread 140662362572544 is joinable!
服务端接收数据:I am king of the world!
服务端接收数据:I am king of the world!
服务端接收数据:I am king of the world!
服务端接收数据:I am king of the world!
Tcp thread 140662354179840 is joinable!
服务端接收数据:I am king of the world!
服务端接收数据:Ouch!
服务端接收数据:I am king of the world!
服务端接收数据:Ouch!
服务端接收数据:I am king of the world!
服务端接收数据:Ouch!
服务端接收数据:I am king of the world!
服务端接收数据:Ouch!
笔记本上的ROS客户端
redwall@redwall-G3-3500:~$ rosrun joystick_client joystick_client
[ERROR] [1656939307.244367879]: [registerPublisher] Failed to contact master at [localhost:11311]. Retrying...
[ INFO] [1656939314.923909682]: Connected to master at [localhost:11311]
vel X:0;vel Y:0;angular Z:0
接收服务端报文:I am your father!vel X:0;vel Y:0;angular Z:0
接收服务端报文:I am your father!vel X:0;vel Y:0;angular Z:0
接收服务端报文:I am your father!
虚拟机的普通客户端
- prejudice@prejudice-VirtualBox:~/socket_test/socket_for_linux/bin$ ./tcp_client 成功连接服务器!
- 接收服务端报文:I am your father!
- 接收服务端报文:I am your father!
- 接收服务端报文:I am your father!
不足
- 未考虑线程的清理
- 未考虑信号的退出处理
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