Linux socket编程实战（非阻塞）

#Linux socket编程实战（非阻塞）| 来源: 网络整理| 查看: 265

socket在创建的时候默认是阻塞的，要想设置为非阻塞的有以下几种方法：

1.ioctl 和 fcntl 设置已经创建socket的fd

ioctl用于设备控制

#include int ioctl(int fd, unsigned long request, ...);

fcntl用于文件控制

#include #include int fcntl(int fd, int cmd, ... /* arg */ );

通过下面方式设置：

flags = fcntl(sfd, F_GETFL); flags |= O_NONBLOCK; fcntl(sfd, F_SETFL, flags);

2.在创建socket的时候设置

int fd = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, 0);

3.accept4

int accept4(int sockfd, struct sockaddr *addr,socklen_t *addrlen, int flags);

flags 设置成 SOCK_NONBLOCK，这种方式是在服务端。

服务端设置5秒后再接收数据：

#include #include #include #include #include #include int main(int argc, char* argv[]){ int fd = socket(AF_INET, SOCK_STREAM, 0); if(fd < 0){ printf("create socket failed!, errno=%d\n",errno); } struct sockaddr_in addr; addr.sin_family = AF_INET; addr.sin_addr.s_addr = htonl(INADDR_ANY); addr.sin_port = htons(8080); int ret; ret = bind(fd, (struct sockaddr*) &addr, sizeof(addr)); if(ret == -1){ printf("bind failed!, errno=%d",errno); close(fd); } ret = listen(fd, SOMAXCONN); if(ret == -1){ printf("listen failed!, errno=%d",errno); } struct sockaddr_in clientaddr; socklen_t clientaddrlen = sizeof(clientaddr); int afd = accept(fd, (struct sockaddr*) &clientaddr, &clientaddrlen); if(afd != -1){ printf("A client connected!,ip=%s,port=%d\n",inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port)); char buf[256] = {0}; sleep(5); ret = recv(afd, buf, 256, 0); if(ret > 0){ printf("recv %d byte:%s\n",ret,buf); } else if(ret == -1){ printf("recv error!,errno=%d\n",errno); } else{ printf("client disconnect!\n"); } } else{ printf("accept failed!,errno=%d\n",errno); } }

客户端设置非阻塞，验证一下send非阻塞的现象：

#include #include #include #include #include #include #include #include #include int main(int argc, char* argv[]){ if(argc != 3){ printf("please input IP port\n"); } char* ip = argv[1]; unsigned int port = atoi(argv[2]); int fd = socket(AF_INET, SOCK_STREAM, 0); if(fd < 0){ printf("create socket failed!, errno=%d\n",errno); } struct sockaddr_in addr; addr.sin_family = AF_INET; addr.sin_addr.s_addr = inet_addr(ip); addr.sin_port = htons(port); int ret; ret = connect(fd, (struct sockaddr*) &addr, sizeof(addr)); if(ret == -1){ printf("connect failed!, errno=%d",errno); } else{ //连接成功后将fd设置为非阻塞 int flags = fcntl(fd, F_GETFL); flags |= O_NONBLOCK; ret = fcntl(fd, F_SETFL, flags); if(ret == -1){ printf("set O_NONBLOCK failed!,errno=%d\n",errno); } char *buf = "hello, I am a client!"; int cnt = 0; while(1){ ret = send(fd, buf, strlen(buf), 0); if(ret > 0){ cnt++; printf("send %d byte:%s,cnt = %d\n",ret,buf,cnt); } else if(ret == -1){ if(errno == EAGAIN){ printf("send try again\n"); sleep(1); continue; } else printf("send error!,errno=%d\n",errno); } else{ printf("server disconnect!\n"); } } } }

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