（TCP IP网络编程）实验六 epoll模型编程
一．实验目的
(1) 在理解I/O复用模型速度慢的主要原因的基础上，理解和掌握Linux下对I/O复用模型的改进和扩展——epoll模型的工作原理；
(2) 理解和掌握epoll模型中条件触发和边缘触发两者在运作机制上的区别；
(3) 分别使用epoll模型的条件触发和边缘触发实现服务器编程。
二．实验内容
(1) 使用条件触发方式实现回声服务器端(及客户端)；
(2) 使用边缘触发方式实现回声服务器端(及客户端)；
(3) 实现聊天服务器端，使其可以在连接到服务器端的所有客户端之间交换消息。按照条件触发方式和边缘触发方式分别实现epoll服务器端(及客户端)。
三．实验过程
（1）条件触发：
echo_EPLTserv.c:
#include \n" , argv[0]);
exit(1);
}
serv_sock=socket(PF_INET, SOCK_STREAM, 0);
memset(&serv_adr, 0, sizeof(serv_adr));
serv_adr.sin_family=AF_INET;
serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);
serv_adr.sin_port=htons(atoi(argv[1]));
if(bind(serv_sock, (struct sockaddr*) &serv_adr, sizeof(serv_adr))==-1)
error_handling("bind() error");
if(listen(serv_sock, 5)==-1)
error_handling("listen() error");
epfd=epoll_create(EPOLL_SIZE);
ep_events=malloc(sizeof(struct epoll_event)*EPOLL_SIZE);
event.events=EPOLLIN;
event.data.fd=serv_sock;
epoll_ctl(epfd, EPOLL_CTL_ADD, serv_sock, &event);
while(1)
{
event_cnt=epoll_wait(epfd, ep_events, EPOLL_SIZE, -1);
if(event_cnt==-1)
{
puts("epoll_wait() error");
break;
}
puts("return epoll_wait");
for(i=0; i<event_cnt; i++)
{
if(ep_events[i].data.fd==serv_sock)
{
adr_sz=sizeof(clnt_adr);
clnt_sock=accept(serv_sock, (struct sockaddr*)&clnt_adr, &adr_sz);
event.events=EPOLLIN;
event.data.fd=clnt_sock;
epoll_ctl(epfd, EPOLL_CTL_ADD, clnt_sock, &event);
printf("connected client: %d \n", clnt_sock);
}
else
{
str_len=read(ep_events[i].data.fd, buf, BUF_SIZE);
if(str_len==0) // close request!
{
epoll_ctl(epfd, EPOLL_CTL_DEL, ep_events[i].data.fd, NULL);
close(ep_events[i].data.fd);
printf("closed client: %d \n", ep_events[i].data.fd);
}
else
{
write(ep_events[i].data.fd, buf, str_len); // echo!
}
}
}
}
close(serv_sock);
close(epfd);
return 0;
}
void error_handling(char *buf)
{
fputs(buf, stderr);
fputc('\n', stderr);
exit(1);
}
echo_client.c:
#include \n" , argv[0]);
exit(1);
}
sock=socket(PF_INET, SOCK_STREAM, 0);
if(sock==-1)
error_handling("socket() error");
memset(&serv_adr, 0, sizeof(serv_adr));
serv_adr.sin_family=AF_INET;
serv_adr.sin_addr.s_addr=inet_addr(argv[1]);
serv_adr.sin_port=htons(atoi(argv[2]));
if(connect(sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr))==-1)
error_handling("connect() error!");
else
puts("Connected...........");
while(1)
{
fputs("Input message(Q to quit): ", stdout);
fgets(message, BUF_SIZE, stdin);
if(!strcmp(message,"q\n") || !strcmp(message,"Q\n"))
break;
write(sock, message, strlen(message));
str_len=read(sock, message, BUF_SIZE-1);
message[str_len]=0;
printf("Message from server: %s", message);
}
close(sock);
return 0;
}
void error_handling(char *message)
{
fputs(message, stderr);
fputc('\n', stderr);
exit(1);
}
结果：
（2）边缘触发：
echo_EPETserv.c:
#include \n" , argv[0]);
exit(1);
}
serv_sock=socket(PF_INET, SOCK_STREAM, 0);
memset(&serv_adr, 0, sizeof(serv_adr));
serv_adr.sin_family=AF_INET;
serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);
serv_adr.sin_port=htons(atoi(argv[1]));
if(bind(serv_sock, (struct sockaddr*) &serv_adr, sizeof(serv_adr))==-1)
error_handling("bind() error");
if(listen(serv_sock, 5)==-1)
error_handling("listen() error");
epfd=epoll_create(EPOLL_SIZE);
ep_events=malloc(sizeof(struct epoll_event)*EPOLL_SIZE);
setnonblockingmode(serv_sock);
event.events=EPOLLIN;
event.data.fd=serv_sock;
epoll_ctl(epfd, EPOLL_CTL_ADD, serv_sock, &event);
while(1)
{
event_cnt=epoll_wait(epfd, ep_events, EPOLL_SIZE, -1);
if(event_cnt==-1)
{
puts("epoll_wait() error");
break;
}
puts("return epoll_wait");
for(i=0; i<event_cnt; i++)
{
if(ep_events[i].data.fd==serv_sock)
{
adr_sz=sizeof(clnt_adr);
clnt_sock=accept(serv_sock, (struct sockaddr*)&clnt_adr, &adr_sz);
setnonblockingmode(clnt_sock);
event.events=EPOLLIN|EPOLLET;
event.data.fd=clnt_sock;
epoll_ctl(epfd, EPOLL_CTL_ADD, clnt_sock, &event);
printf("connected client: %d \n", clnt_sock);
}
else
{
while(1)
{
str_len=read(ep_events[i].data.fd, buf, BUF_SIZE);
if(str_len==0) // close request!
{
epoll_ctl(epfd, EPOLL_CTL_DEL, ep_events[i].data.fd, NULL);
close(ep_events[i].data.fd);
printf("closed client: %d \n", ep_events[i].data.fd);
break;
}
else if(str_len<0)
{
if(errno==EAGAIN)
break;
}
else
{
write(ep_events[i].data.fd, buf, str_len); // echo!
}
}
}
}
}
close(serv_sock);
close(epfd);
return 0;
}
void setnonblockingmode(int fd)
{
int flag=fcntl(fd, F_GETFL, 0);
fcntl(fd, F_SETFL, flag|O_NONBLOCK);
}
void error_handling(char *buf)
{
fputs(buf, stderr);
fputc('\n', stderr);
exit(1);
}
echo_client.c:
#include \n" , argv[0]);
exit(1);
}
sock=socket(PF_INET, SOCK_STREAM, 0);
if(sock==-1)
error_handling("socket() error");
memset(&serv_adr, 0, sizeof(serv_adr));
serv_adr.sin_family=AF_INET;
serv_adr.sin_addr.s_addr=inet_addr(argv[1]);
serv_adr.sin_port=htons(atoi(argv[2]));
if(connect(sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr))==-1)
error_handling("connect() error!");
else
puts("Connected...........");
while(1)
{
fputs("Input message(Q to quit): ", stdout);
fgets(message, BUF_SIZE, stdin);
if(!strcmp(message,"q\n") || !strcmp(message,"Q\n"))
break;
write(sock, message, strlen(message));
str_len=read(sock, message, BUF_SIZE-1);
message[str_len]=0;
printf("Message from server: %s", message);
}
close(sock);
return 0;
}
void error_handling(char *message)
{
fputs(message, stderr);
fputc('\n', stderr);
exit(1);
}
结果：
（3）实验代码：
chat_EPLTserv.c:
#include \n" , argv[0]);
exit(1);
}
serv_sock=socket(PF_INET, SOCK_STREAM, 0);
memset(&serv_adr, 0, sizeof(serv_adr));
serv_adr.sin_family=AF_INET;
serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);
serv_adr.sin_port=htons(atoi(argv[1]));
if(bind(serv_sock, (struct sockaddr*) &serv_adr, sizeof(serv_adr))==-1)
error_handling("bind() error");
if(listen(serv_sock, 5)==-1)
error_handling("listen() error");
epfd=epoll_create(EPOLL_SIZE);
ep_events=malloc(sizeof(struct epoll_event)*EPOLL_SIZE);
event.events=EPOLLIN;
event.data.fd=serv_sock;
epoll_ctl(epfd, EPOLL_CTL_ADD, serv_sock, &event);
while(1)
{
event_cnt=epoll_wait(epfd, ep_events, EPOLL_SIZE, -1);
if(event_cnt==-1)
{
break;
}
for(i=0; i<event_cnt; i++)
{
if(ep_events[i].data.fd==serv_sock)
{
adr_sz=sizeof(clnt_adr);
clnt_sock=accept(serv_sock, (struct sockaddr*)&clnt_adr, &adr_sz);
event.events=EPOLLIN;
event.data.fd=clnt_sock;
epoll_ctl(epfd, EPOLL_CTL_ADD, clnt_sock, &event);
clnt_socks[clnt_cnt++]=clnt_sock;
printf("connected client: %d \n", clnt_sock);
}
else
{
str_len=read(ep_events[i].data.fd, buf, BUF_SIZE);
if(str_len==0)
{
epoll_ctl(epfd, EPOLL_CTL_DEL, ep_events[i].data.fd, NULL);
close(ep_events[i].data.fd);
printf("closed client: %d \n", ep_events[i].data.fd);
for(i=0; i<clnt_cnt; i++)
{
if(clnt_sock==clnt_socks[i])
{
while(i++<clnt_cnt-1)
clnt_socks[i]=clnt_socks[i+1];
break;
}
}
clnt_cnt--;
}
else
{
send_msg(buf, str_len);
}
}
}
}
close(serv_sock);
close(epfd);
return 0;
}
void send_msg(char * msg, int len) // send to all
{
int i;
for(i=0; i<clnt_cnt; i++)
write(clnt_socks[i], msg, len);
}
void error_handling(char *buf)
{
fputs(buf, stderr);
fputc('\n', stderr);
exit(1);
}
chat_client.c:
#include \n" , argv[0]);
exit(1);
}
sprintf(name, "[%s]", argv[3]);
sock=socket(PF_INET, SOCK_STREAM, 0);
memset(&serv_addr, 0, sizeof(serv_addr));
serv_addr.sin_family=AF_INET;
serv_addr.sin_addr.s_addr=inet_addr(argv[1]);
serv_addr.sin_port=htons(atoi(argv[2]));
if(connect(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr))==-1)
error_handling("connect() error");
pthread_create(&snd_thread, NULL, send_msg, (void*)&sock);
pthread_create(&rcv_thread, NULL, recv_msg, (void*)&sock);
pthread_join(snd_thread, &thread_return);
pthread_join(rcv_thread, &thread_return);
close(sock);
return 0;
}
void * send_msg(void * arg) // send thread main
{
int sock=*((int*)arg);
char name_msg[NAME_SIZE+BUF_SIZE];
while(1)
{
fgets(msg, BUF_SIZE, stdin);
if(!strcmp(msg,"q\n")||!strcmp(msg,"Q\n"))
{
close(sock);
exit(0);
}
sprintf(name_msg,"%s %s", name, msg);
write(sock, name_msg, strlen(name_msg));
}
return NULL;
}
void * recv_msg(void * arg) // read thread main
{
int sock=*((int*)arg);
char name_msg[NAME_SIZE+BUF_SIZE];
int str_len;
while(1)
{
str_len=read(sock, name_msg, NAME_SIZE+BUF_SIZE-1);
if(str_len==-1)
return (void*)-1;
name_msg[str_len]=0;
fputs(name_msg, stdout);
}
return NULL;
}
void error_handling(char *msg)
{
fputs(msg, stderr);
fputc('\n', stderr);
exit(1);
}
结果：
chat_EPETserv.c:
#include \n" , argv[0]);
exit(1);
}
serv_sock=socket(PF_INET, SOCK_STREAM, 0);
memset(&serv_adr, 0, sizeof(serv_adr));
serv_adr.sin_family=AF_INET;
serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);
serv_adr.sin_port=htons(atoi(argv[1]));
if(bind(serv_sock, (struct sockaddr*) &serv_adr, sizeof(serv_adr))==-1)
error_handling("bind() error");
if(listen(serv_sock, 5)==-1)
error_handling("listen() error");
epfd=epoll_create(EPOLL_SIZE);
ep_events=malloc(sizeof(struct epoll_event)*EPOLL_SIZE);
setnonblockingmode(serv_sock);
event.events=EPOLLIN;
event.data.fd=serv_sock;
epoll_ctl(epfd, EPOLL_CTL_ADD, serv_sock, &event);
while(1)
{
event_cnt=epoll_wait(epfd, ep_events, EPOLL_SIZE, -1);
if(event_cnt==-1)
{
puts("epoll_wait() error");
break;
}
puts("return epoll_wait");
for(i=0; i<event_cnt; i++)
{
if(ep_events[i].data.fd==serv_sock)
{
adr_sz=sizeof(clnt_adr);
clnt_sock=accept(serv_sock, (struct sockaddr*)&clnt_adr, &adr_sz);
setnonblockingmode(clnt_sock);
event.events=EPOLLIN|EPOLLET;
event.data.fd=clnt_sock;
epoll_ctl(epfd, EPOLL_CTL_ADD, clnt_sock, &event);
clnt_socks[clnt_cnt++]=clnt_sock;
printf("connected client: %d \n", clnt_sock);
}
else
{
while(1)
{
str_len=read(ep_events[i].data.fd, buf, BUF_SIZE);
if(str_len==0) // close request!
{
epoll_ctl(epfd, EPOLL_CTL_DEL, ep_events[i].data.fd, NULL);
close(ep_events[i].data.fd);
for(i=0; i<clnt_cnt; i++)
{
if(ep_events[i].data.fd==clnt_socks[i])
{
while(i++<clnt_cnt-1)
clnt_socks[i]=clnt_socks[i+1];
break;
}
}
clnt_cnt--;
printf("closed client: %d \n", ep_events[i].data.fd);
break;
}
else if(str_len<0)
{
if(errno==EAGAIN)
break;
}
else
{
send_msg(buf, str_len);
}
}
}
}
}
close(serv_sock);
close(epfd);
return 0;
}
void send_msg(char * msg, int len) // send to all
{
int i;
for(i=0; i<clnt_cnt; i++)
write(clnt_socks[i], msg, len);
}
void setnonblockingmode(int fd)
{
int flag=fcntl(fd, F_GETFL, 0);
fcntl(fd, F_SETFL, flag|O_NONBLOCK);
}
void error_handling(char *buf)
{
fputs(buf, stderr);
fputc('\n', stderr);
exit(1);
}
结果：
