当需要同时监听多个文件描述符时，就需要I/O复用函数，I/O复用函数有select、poll、epoll，今天主要使用poll函数。
成都创新互联是由多位在大型网络公司、广告设计公司的优秀设计人员和策划人员组成的一个具有丰富经验的团队，其中包括网站策划、网页美工、网站程序员、网页设计师、平面广告设计师、网络营销人员及形象策划。承接：成都网站设计、成都做网站、网站改版、网页设计制作、网站建设与维护、网络推广、数据库开发,以高性价比制作企业网站、行业门户平台等全方位的服务。
poll()接受一个指向结构'struct pollfd'列表的指针，其中包括了你想测试的文件描述符和事件。事件由一个在结构中事件域的比特掩码确定。当前的结构在调用后将被填写并在事件发生后返回。
函数原型：
#includeint poll(struct pollfd *fds, nfds_t nfds, int timeout); struct pollfd{ int fd; /*file descriptor*/ short events; /*requested events*/ short revents; /*returned events*/ }
函数参数：fds是要监听的fd的数组，nfds是数组个数，timeout 超时时间 -1是阻塞；
函数说用：通过传入的events的类型去判断返回的类型是否一致，如果一致就该干事了。
events：
常量 | 说明 |
POLLIN | 普通或优先级带数据可读 |
POLLRDNORM | 普通数据可读 |
POLLRDBAND | 优先级带数据可读 |
POLLPRI | 高优先级数据可读 |
POLLOUT | 普通数据可写 |
POLLWRNORM | 普通数据可写 |
POLLWRBAND | 优先级带数据可写 |
POLLERR | 发生错误 |
POLLHUP | 发生挂起 |
POLLNVAL | 描述字不是一个打开的文件 |
接下来是是一个服务器监听两个socket的例子：
服务器代码：
#include#include #include #include #include #include #include #include #include #include #define MAX_POLLFD_NUM 2 //#define SERVER_CONN_IP1 "1.1.1.1" //#define SERVER_CONN_IP2 "1.1.1.1" #define DEFAULT_PORT 8000 #define BUFF_MAX 1024 typedef void(*Server_Rrocess_Thread_Fun)(void *arg); /*thread process function define */ typedef struct sever_thread_fun{ Server_Rrocess_Thread_Fun Server_Process_Client_Conn1; Server_Rrocess_Thread_Fun Server_Process_Client_Conn2; }Poll_Server_Process_Clinet_FUN_t; /*connect 1 thread function*/ void *Poll_Conn1_Process(void *arg) { unsigned char ucBufArr[BUFF_MAX] = {0}; unsigned long ulSize = 0; int connect_fd ; printf("come pthread conn1 fun to proess conn1\n"); if( (connect_fd = accept( *(int*)arg, (struct sockaddr*)NULL, NULL)) == -1){ printf("accept socket error: %s(errno: %d)",strerror(errno),errno); } ulSize = recv(connect_fd, ucBufArr, BUFF_MAX, 0); if(send(connect_fd, "Hello,you are connected 1!\n", 26,0) == -1) perror("send error"); ucBufArr[ulSize] = '\0'; //sleep(20); printf("recv msg from client: %s\n", ucBufArr); close(connect_fd); pthread_exit((void*)1); } /*connect 1 thread function*/ void *Poll_Conn2_Process(void *arg) { unsigned char ucBufArr[BUFF_MAX] = {0}; unsigned long ulSize = 0; int connect_fd ; printf("come pthread conn2 fun to proess conn2\n"); if( (connect_fd = accept( *(int*)arg, (struct sockaddr*)NULL, NULL)) == -1){ printf("accept socket error: %s(errno: %d)",strerror(errno),errno); } ulSize = recv(connect_fd, ucBufArr, BUFF_MAX, 0); if(send(connect_fd, "Hello,you are connected 2!\n", 26,0) == -1) perror("send error"); ucBufArr[ulSize] = '\0'; // sleep(20); printf("recv msg from client: %s\n", ucBufArr); close(connect_fd); pthread_exit((void*)2); } int main() { int poll_ret = 0; pthread_t thread_conn1; pthread_t thread_conn2; /*socket var*/ int server_socket_fd_conn1; int server_socket_fd_conn2; struct sockaddr_in servaddr_conn1; struct sockaddr_in serveraddr_conn2; /*poll var*/ struct pollfd pollfd_arr[MAX_POLLFD_NUM]; /*init thread fun*/ Poll_Server_Process_Clinet_FUN_t server_conn_handel; server_conn_handel.Server_Process_Client_Conn1 = Poll_Conn1_Process; server_conn_handel.Server_Process_Client_Conn2 = Poll_Conn2_Process; /*create two server socket*/ if( (server_socket_fd_conn1 = socket(AF_INET, SOCK_STREAM, 0)) == -1 ){ printf("create socket conn1 error: %s(errno: %d)\n",strerror(errno),errno); exit(0); } if( (server_socket_fd_conn2 = socket(AF_INET, SOCK_STREAM, 0)) == -1 ){ printf("create socket conn2 error: %s(errno: %d)\n",strerror(errno),errno); exit(0); } /*init socket 1 for conn1*/ memset(&servaddr_conn1, 0, sizeof(servaddr_conn1)); servaddr_conn1.sin_family = AF_INET; servaddr_conn1.sin_addr.s_addr = htonl(INADDR_ANY); servaddr_conn1.sin_port = htons(DEFAULT_PORT); // if( inet_pton(AF_INET, SERVER_CONN_IP1, &servaddr_conn1.sin_addr.s_addr) <= 0){ // printf("inet_pton error for %s\n",SERVER_CONN_IP1); // exit(0); // } /*init socket 2 for conn2*/ memset(&serveraddr_conn2, 0, sizeof(serveraddr_conn2)); serveraddr_conn2.sin_family = AF_INET; serveraddr_conn2.sin_addr.s_addr = htonl(INADDR_ANY); serveraddr_conn2.sin_port = htons(DEFAULT_PORT+1); // if( inet_pton(AF_INET, SERVER_CONN_IP2, &serveraddr_conn2.sin_addr.s_addr) <= 0){ // printf("inet_pton error for %s\n",SERVER_CONN_IP2); // exit(0); // } /*bind connect 1 socket*/ if( bind(server_socket_fd_conn1, (struct sockaddr*)&servaddr_conn1, sizeof(servaddr_conn1)) == -1){ printf("bind socket error1: %s(errno: %d)\n",strerror(errno),errno); exit(0); } /*bind connect 2 socket*/ if( bind(server_socket_fd_conn2, (struct sockaddr*)&serveraddr_conn2, sizeof(serveraddr_conn2)) == -1){ printf("bind socket error2: %s(errno: %d)\n",strerror(errno),errno); exit(0); } /*listen connect 1*/ if( listen(server_socket_fd_conn1, 10) == -1){ printf("listen socket error: %s(errno: %d)\n",strerror(errno),errno); exit(0); } /*listen connect 2*/ if( listen(server_socket_fd_conn2, 10) == -1){ printf("listen socket error: %s(errno: %d)\n",strerror(errno),errno); exit(0); } pollfd_arr[0].events = POLLRDNORM;/*only read event*/ pollfd_arr[0].fd = server_socket_fd_conn1; pollfd_arr[1].events = POLLRDNORM;/*only read event*/ pollfd_arr[1].fd = server_socket_fd_conn2; while(1) { poll_ret = poll( pollfd_arr, MAX_POLLFD_NUM,-1); if( pollfd_arr[0].revents & POLLRDNORM ) { /*connect 1 process task*/ pthread_create( &thread_conn1, NULL, server_conn_handel.Server_Process_Client_Conn1, (void *)(&pollfd_arr[0].fd)); } if( pollfd_arr[1].revents & POLLRDNORM ) { /*connect 2 process task*/ pthread_create( &thread_conn2, NULL, server_conn_handel.Server_Process_Client_Conn2, (void *)(&pollfd_arr[1].fd)); } sleep(1); } return 0; }
客户端代码：
#include#include #include #include #include #include #include #define BUFF_MAX 1024 #define DEFAULT_PORT 8000 int main(int argc, char** argv) { int sockfd, n,rec_len; char recvline[BUFF_MAX], sendline[BUFF_MAX]; char buf[BUFF_MAX]; struct sockaddr_in servaddr; if( argc != 2){ printf("usage: ./client \n"); exit(0); } /*create socket*/ if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){ printf("create socket error: %s(errno: %d)\n", strerror(errno),errno); exit(0); } memset(&servaddr, 0, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(DEFAULT_PORT/*+1/);/*DEFAULT_PORT is connect 1 to server,DEFAULT_PORT+1 is connect 2 to server*/ /*string ip to int ip*/ if( inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0){ printf("inet_pton error for %s\n",argv[1]); exit(0); } /*connect server*/ if( connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0){ printf("connect error: %s(errno: %d)\n",strerror(errno),errno); exit(0); } printf("send msg to server: \n"); fgets(sendline, BUFF_MAX, stdin); /*write data to sockfd*/ if( send(sockfd, sendline, strlen(sendline), 0) < 0) { printf("send msg error: %s(errno: %d)\n", strerror(errno), errno); exit(0); } /*read socket data*/ if((rec_len = recv(sockfd, buf, BUFF_MAX,0)) == -1) { perror("recv error"); exit(1); } buf[rec_len] = '\0'; printf("Received : %s \n",buf); /*colse socket*/ close(sockfd); exit(0); }
解释：服务器端监听 ip 127.0.0.1 port 8000和ip 127.0.0.1 port 8001
结果演示：
