linux socket的IO多路复用简单例子（三）

最新推荐文章于 2023-06-02 19:14:46 发布

原创最新推荐文章于 2023-06-02 19:14:46 发布 · 1.2k 阅读

0 ·

CC 4.0 BY-SA版权

c/c++ 专栏收录该内容

21 篇文章

订阅专栏

本文介绍了一种利用poll函数实现socket服务器的方法，通过监听多个客户端连接并进行数据交互。poll函数可以监控任意数量的文件描述符，适用于高并发场景。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

通过poll函数编写socket。

原理：poll与select的过程差不多。不同的是select的fd集合有限制，而poll没有。poll使用pollfd结构来存储文件描述符。每个pollfd表示一个被监视的文件描述符，里面包含等待事件、文件描述符、实际发生的事件。等待事件需用户设置，表示期望系统检测文件描述符所发生的事件。实际发生事件是指系统监控后，在回调返回时设置。

server端：

#include <iostream>
#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <sys/shm.h>
#include <poll.h>
#include <vector>
using namespace std;

int main()
{
	int server_fd = socket(AF_INET, SOCK_STREAM, 0);
	if (server_fd == -1)
	{
		cout << "create server_fd error" << endl;
		return 0;
	}
	struct sockaddr_in serverAttr;
	serverAttr.sin_family = AF_INET;
	serverAttr.sin_port = htons(5875);
	serverAttr.sin_addr.s_addr = htonl(INADDR_ANY);
	if (bind(server_fd, (struct sockaddr*)&serverAttr, sizeof(serverAttr)) == -1)
	{
		perror("bind error");
		return 0;
	}
	if (listen(server_fd, 10) == -1)
	{
		perror("listen error");
		return 0;
	}
	int clientCnt = 0;
	struct sockaddr_in clientAttr;
	//使用数组存储pollfd，每一个pollfd结构体表示一个客户端的文件描述符
	/*
	struct pollfd
	{
		int fd;			 File descriptor to poll.
		short int events;		 Types of events poller cares about.
		short int revents;		 Types of events that actually occurred.
	};
	*/
	struct pollfd clients[1024];
	clients[0].fd = server_fd;
	//设置监控读操作
	clients[0].events = POLLIN;
	int clNum = 0;
	//初始化1024个文件描述符
	for (int i = 1; i < 1024; i++)
	{
		clients[i].fd = -1;
	}
	while (1)
	{
		/*
		int poll ( struct pollfd * fds, unsigned int nfds, int timeout);
		Poll the file descriptors described by the NFDS structures starting at
		FDS.  If TIMEOUT is nonzero and not -1, allow TIMEOUT milliseconds for
		an event to occur; if TIMEOUT is -1, block until an event occurs.
		Returns the number of file descriptors with events, zero if timed out,
		or -1 for errors.
		*/
		if (poll(clients, clNum + 1, -1) == -1)
		{
			perror("poll error");
			return 0;
		}
		//第一个是服务器的文件描述符，用来监控是有请求进来
		if (clients[0].revents & POLLIN)
		{
			socklen_t len = sizeof(clientAttr);
			int conn = accept(server_fd, (struct  sockaddr*)&clientAttr, &len);
			if (conn == -1)
			{
				perror("accept error");
				continue;
			}
			cout << "accept client :" << inet_ntoa(clientAttr.sin_addr) << ":" << clientAttr.sin_port << endl;
			//将新的请求文件描述符加到客户端数组中
			int i;
			for (i = 1; i < 1024; i++)
			{
				if (clients[i].fd == -1)
				{
					clients[i].fd = conn;
					clients[i].events = POLLIN;
					break;
				}
			}
			clNum = clNum > i ? clNum : i;
		}
		//轮询客户端fd数组
		char readBuf[1024] = {0};
		for (int i = 1; i <= clNum; i++)
		{
			memset(readBuf, 0, sizeof(readBuf));
			if (clients[i].revents & POLLIN)
			{
				//读取改客户端连接的信息
				int n = read(clients[i].fd, readBuf, 1024);
				cout << "read msg is " << readBuf << ",n=" << n << endl;
				//回复客户端
				string wrtBuf = "hello,clients[i]ient " + to_string(i);
				write(clients[i].fd, wrtBuf.c_str(), wrtBuf.length() + 1);
			}
		}
	}
	return 0;
}

参考：

http://www.cnblogs.com/Anker/p/3261006.html