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4.20 多进程实现并发服务器

要实现TCP通信服务器处理并发的任务，使用多线程或者多进程来解决。
思路：
1、一个父进程，多个子进程
2、父进程负责等待并接受客户端的连接
3、子进程：完成通信，接受一个客户端连接，就创建一个子进程用于通信

server_process.c

#include <stdio.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <wait.h>
#include <errno.h>void recyleChild(int arg) {while(1) {int ret = waitpid(-1, NULL, WNOHANG);if(ret == -1) {// 所有的子进程都回收了break;}else if(ret == 0) {// 还有子进程活着break;} else if(ret > 0){// 被回收了printf("子进程 %d 被回收了\n", ret);}}
}int main() {//不能通过父进程进行子进程的回收，使用信号的方式进程子进程的回收//子进程结束时会发送SIGCHILDstruct sigaction act;act.sa_flags = 0;sigemptyset(&act.sa_mask);//临时阻塞的信号集，信号掩码清空act.sa_handler = recyleChild;// 注册信号捕捉sigaction(SIGCHLD, &act, NULL);// 创建socketint lfd = socket(PF_INET, SOCK_STREAM, 0);if(lfd == -1){perror("socket");exit(-1);}struct sockaddr_in saddr;saddr.sin_family = AF_INET;saddr.sin_port = htons(9999);saddr.sin_addr.s_addr = INADDR_ANY;//0.0.0.0 ip地址// 绑定int ret = bind(lfd,(struct sockaddr *)&saddr, sizeof(saddr));if(ret == -1) {perror("bind");exit(-1);}// 监听ret = listen(lfd, 128);if(ret == -1) {perror("listen");exit(-1);}// 不断循环等待客户端连接while(1) {struct sockaddr_in cliaddr;int len = sizeof(cliaddr);// 接受连接int cfd = accept(lfd, (struct sockaddr*)&cliaddr, &len);if(cfd == -1) {//子进程结束，回收子进程，软中断，再回到accept会产生EINTR错误，若直接结束父进程，后续客户端将无法连接到服务端if(errno == EINTR) {continue;}perror("accept");exit(-1);}// 每一个连接进来，创建一个子进程跟客户端通信pid_t pid = fork();if(pid == 0) {// 子进程// 获取客户端的信息char cliIp[16];inet_ntop(AF_INET, &cliaddr.sin_addr.s_addr, cliIp, sizeof(cliIp));unsigned short cliPort = ntohs(cliaddr.sin_port);printf("client ip is : %s, prot is %d\n", cliIp, cliPort);// 接收客户端发来的数据char recvBuf[1024];while(1) {int len = read(cfd, &recvBuf, sizeof(recvBuf));if(len == -1) {perror("read");exit(-1);}else if(len > 0) {printf("recv client : %s\n", recvBuf);} else if(len == 0) {printf("client closed....\n");break;}write(cfd, recvBuf, strlen(recvBuf) + 1);//回写回去,+1将\0也放进去}close(cfd);exit(0);    // 退出当前子进程}}close(lfd);return 0;
}

 int cfd = accept(lfd, (struct sockaddr*)&cliaddr, &len);if(cfd == -1) {//在系统调用获取到有效连接之前，被信号打断。也就是accept本来阻塞着，程序中断去处理回收子进程。//再回来以后，accept就会产生一个EINTR错误。此时cfd == -1 ,会被判断为有误，直接exit，直接结束父进程，后续客户端将无法连接到服务端//所以这里需要加一个判断if(errno == EINTR) {continue;}perror("accept");exit(-1);}

client.c

// TCP通信的客户端
#include <stdio.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>int main() {// 1.创建套接字int fd = socket(AF_INET, SOCK_STREAM, 0);if(fd == -1) {perror("socket");exit(-1);}// 2.连接服务器端struct sockaddr_in serveraddr;serveraddr.sin_family = AF_INET;inet_pton(AF_INET, "192.168.139.132", &serveraddr.sin_addr.s_addr);serveraddr.sin_port = htons(9999);int ret = connect(fd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));if(ret == -1) {perror("connect");exit(-1);}// 3. 通信char recvBuf[1024];int i = 0;while(1) {sprintf(recvBuf, "data : %d\n", i++);// 给服务器端发送数据write(fd, recvBuf, strlen(recvBuf)+1);int len = read(fd, recvBuf, sizeof(recvBuf));if(len == -1) {perror("read");exit(-1);} else if(len > 0) {printf("recv server : %s\n", recvBuf);} else if(len == 0) {// 表示服务器端断开连接printf("server closed...");break;}sleep(1);}// 关闭连接close(fd);return 0;
}

4.22 多线程实现并发服务器

客户端代码：

// TCP通信的客户端
#include <stdio.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>int main() {// 1.创建套接字int fd = socket(AF_INET, SOCK_STREAM, 0);if(fd == -1) {perror("socket");exit(-1);}// 2.连接服务器端struct sockaddr_in serveraddr;serveraddr.sin_family = AF_INET;inet_pton(AF_INET, "192.168.139.133", &serveraddr.sin_addr.s_addr);serveraddr.sin_port = htons(9999);int ret = connect(fd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));if(ret == -1) {perror("connect");exit(-1);}// 3. 通信char recvBuf[1024];int i = 0;while(1) {sprintf(recvBuf, "data : %d\n", i++);// 给服务器端发送数据write(fd, recvBuf, strlen(recvBuf)+1);int len = read(fd, recvBuf, sizeof(recvBuf));if(len == -1) {perror("read");exit(-1);} else if(len > 0) {printf("recv server : %s\n", recvBuf);} else if(len == 0) {// 表示服务器端断开连接printf("server closed...");break;}sleep(1);}// 关闭连接close(fd);return 0;
}

服务端代码：

#include <stdio.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>struct sockInfo {int fd; // 通信的文件描述符struct sockaddr_in addr;pthread_t tid;  // 线程号
};struct sockInfo sockinfos[128];void * working(void * arg) {// 子线程和客户端通信   cfd 客户端的信息 线程号// 获取客户端的信息struct sockInfo * pinfo = (struct sockInfo *)arg;char cliIp[16];inet_ntop(AF_INET, &pinfo->addr.sin_addr.s_addr, cliIp, sizeof(cliIp));unsigned short cliPort = ntohs(pinfo->addr.sin_port);printf("client ip is : %s, prot is %d\n", cliIp, cliPort);// 接收客户端发来的数据char recvBuf[1024];while(1) {int len = read(pinfo->fd, &recvBuf, sizeof(recvBuf));if(len == -1) {perror("read");exit(-1);}else if(len > 0) {printf("recv client : %s\n", recvBuf);} else if(len == 0) {printf("client closed....\n");break;}write(pinfo->fd, recvBuf, strlen(recvBuf) + 1);}close(pinfo->fd);return NULL;
}int main() {// 创建socketint lfd = socket(PF_INET, SOCK_STREAM, 0);if(lfd == -1){perror("socket");exit(-1);}struct sockaddr_in saddr;saddr.sin_family = AF_INET;saddr.sin_port = htons(9999);saddr.sin_addr.s_addr = INADDR_ANY;// 绑定int ret = bind(lfd,(struct sockaddr *)&saddr, sizeof(saddr));if(ret == -1) {perror("bind");exit(-1);}// 监听ret = listen(lfd, 128);if(ret == -1) {perror("listen");exit(-1);}// 初始化数据int max = sizeof(sockinfos) / sizeof(sockinfos[0]);for(int i = 0; i < max; i++) {bzero(&sockinfos[i], sizeof(sockinfos[i]));sockinfos[i].fd = -1;//表示该文件描述符可用sockinfos[i].tid = -1;}// 循环等待客户端连接，一旦一个客户端连接进来，就创建一个子线程进行通信while(1) {struct sockaddr_in cliaddr;int len = sizeof(cliaddr);// 接受连接int cfd = accept(lfd, (struct sockaddr*)&cliaddr, &len);struct sockInfo * pinfo;for(int i = 0; i < max; i++) {// 从这个数组中找到一个可以用的sockInfo元素if(sockinfos[i].fd == -1) {pinfo = &sockinfos[i];break;}if(i == max - 1) {sleep(1);i--;}}pinfo->fd = cfd;memcpy(&pinfo->addr, &cliaddr, len);// 创建子线程pthread_create(&pinfo->tid, NULL, working, pinfo);pthread_detach(pinfo->tid);}close(lfd);return 0;
}