轮询机制
1.select()系统调用FD_ZERO();FD_ISSET();FD_SET();FD_CLR();四个函数
返回值：-1出错；0 超时；其他：正常；
#include"../utili.h" 2 #include<sys/select.h> 3 4 #define MAX_CLIENT_SIZE 5 5 int main() 6 { 7 int sockSer = startup(SERVER_IP,SERVER_PORT); 8 int client_fd[MAX_CLIENT_SIZE] = {0}; 9 fd_set readset; 10 int max_sock = sockSer; 11 int conn_num = 0; 12 int i = 0; 13 int res; 14 15 char buffer[MAX_BUFFER_SIZE]; 16 struct timeval tv; 17 for(;;) 18 { 19 FD_ZERO(&readset); 20 FD_SET(sockSer,&readset); 21 22 for(i=0; i<MAX_CLIENT_SIZE; ++i) 23 { 24 if(client_fd[i] != 0) 25 { 26 FD_SET(client_fd[i],&readset); 27 } 28 } 29 30 tv.tv_sec = 5; 31 tv.tv_usec = 0; 32 33 res = select(max_sock+1,&readset,NULL,NULL,&tv); 34 if(res == -1) 35 { 36 perror("select"); 37 continue; 38 } 39 else if(res == 0) 40 { 41 printf("server time out.\n"); 42 continue; 43 } 44 else 45 { 46 for(i=0; i<conn_num; ++i) 47 { 48 if(FD_ISSET((client_fd[i]),&readset)) 49 { 50 recv(client_fd[i],buffer,MAX_BUFFER_SIZE,0); 51 printf("From Client Msg:>%s\n",buffer); 52 send(client_fd[i],buffer,strlen(buffer)+1,0); 53 } 54 } 55 if(FD_ISSET(sockSer,&readset)) 56 { 57 struct sockaddr_in addrCli; 58 socklen_t len = sizeof(struct sockaddr); 59 int sockConn = accept(sockSer,(struct sockaddr*)&addrCli,&len); 60 if(sockConn == -1) 61 { 62 perror("accept"); 63 continue; 64 } 65 if(conn_num < MAX_CLIENT_SIZE) 66 { 67 client_fd[conn_num++] = sockConn; 68 if(sockConn > max_sock) 69 max_sock = sockConn; 70 } 71 else 72 { 73 char *msg = "Sorry,Server OverLoaded.\n"; 74 send(sockConn,msg,strlen(msg)+1,0); 75 } 76 } 77 } 78 } 79 close(sockSer); 80 return 0; 81 } 2.poll() struct pollfd结构体
1 #include"../utili.h" 2 #include<poll.h> 3 4 #define MAX_CLIENT_SIZE 5 5 void do_poll(int sock); 6 7 int main() 8 { 9 int sockSer = startup(SERVER_IP,SERVER_PORT); 10 do_poll(sockSer); 11 close(sockSer); 12 return 0; 13 } 14 15 void do_poll(int sock) 16 { 17 struct pollfd client_fd[MAX_CLIENT_SIZE]; 18 client_fd[0].fd = sock; 19 client_fd[1].events = POLLIN; 20 21 int i; 22 for(i=1; i<MAX_CLIENT_SIZE; ++i) 23 client_fd[i].fd = 0; 24 25 int num = 1; 26 int nready = 0; 27 char buffer[MAX_BUFFER_SIZE]; 28 struct timeval tv; 29 for(;;) 30 { 31 tv.tv_sec = 5; 32 tv.tv_usec = 0; 33 nready = poll(client_fd,num,-1); 34 if(nready == -1) 35 { 36 perror("poll"); 37 continue; 38 } 39 else if(nready == 0) 40 { 41 printf("server time out.\n"); 42 continue; 43 } 44 else 45 { 46 if(client_fd[0].revents & POLLIN) 47 { 48 struct sockaddr_in addrCli; 49 socklen_t len = sizeof(struct sockaddr); 50 int sockConn = accept(sock,(struct sockaddr*)&addrCli,&len); 51 52 if(sockConn == -1) 53 { 54 perror("accept"); 55 continue; 56 } 57 for(i=1; i<MAX_CLIENT_SIZE; ++i) 58 { 59 if(client_fd[i].fd == 0) 60 { 61 client_fd[i].fd = sockConn; 62 client_fd[i].events = POLLIN; 63 num++; 64 break; 65 } 66 } 67 if(i == MAX_CLIENT_SIZE) 68 { 69 char *msg = "POLL:Sorry,Server OverLoad."; 70 send(sockConn,msg,strlen(msg)+1,0); 71 } 72 continue; 73 } 74 for(i=1; i<MAX_CLIENT_SIZE; ++i) 75 { 76 if(client_fd[i].fd == 0) 77 continue; 78 if(client_fd[i].revents & POLLIN) 79 { 80 recv(client_fd[i].fd,buffer,MAX_BUFFER_SIZE,0); 81 printf("From Client Msg:>%s\n",buffer); 82 send(client_fd[i].fd,buffer,strlen(buffer)+1,0); 83 } 84 85 } 86 } 87 } 88 } 3.epoll()Linux特有的epoll_create() epoll_ctl() epoll_wait()
1 #include"../utili.h" 2 #include<sys/epoll.h> 3 4 #define MAX_EVENT_SIZE 1024 5 #define MAX_CLIENT_SIZE 5 6 7 void do_epoll(int sock); 8 int main() 9 { 10 int sockSer = startup(SERVER_IP,SERVER_PORT); 11 do_epoll(sockSer); 12 close(sockSer); 13 return 0; 14 } 15 16 void add_event(int epoll_fd,int fd,int state) 17 { 18 struct epoll_event ev; 19 ev.events = state; 20 ev.data.fd = fd; 21 epoll_ctl(epoll_fd,EPOLL_CTL_ADD,fd,&ev); 22 } 23 24 void do_epoll(int sock) 25 { 26 struct epoll_event event[MAX_EVENT_SIZE]; 27 int epoll_fd = epoll_create(MAX_CLIENT_SIZE); 28 add_event(epoll_fd,sock,EPOLLIN); 29 30 int ret; 31 int i; 32 for(;;) 33 { 34 ret = epoll_wait(epoll_fd,event,MAX_EVENT_SIZE,-1); 35 if(ret == -1) 36 { 37 perror("epoll_wait"); 38 continue; 39 } 40 else
41 { 42 for(i=0; i<ret; ++i) 43 { 44 if(event[i].data.fd == sock && event[i].events &&EPOLLIN) 45 { 46 struct sockaddr_in addrCli; 47 socklen_t len = sizeof(struct sockaddr); 48 int sockConn = accept(sock,(struct sockaddr*)&addrCli,&len); 49 if(sockConn ==-1) 50 { 51 perror("accept"); 52 break; 53 } 54 add_event(epoll_fd,sockConn,EPOLLIN); 55 } 56 else if(event[i].events & EPOLLIN) 57 { 58 char buffer[MAX_BUFFER_SIZE]; 59 recv(event[i].data.fd,buffer,MAX_BUFFER_SIZE,0); 60 printf("msg:>%s\n",buffer); 61 send(event[i].data.fd,buffer,strlen(buffer)+1,0); 62 } 63 } 64 } 65 } 66 }
