1. epoll related functions
2. epoll model code implementation
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <sys/epoll.h>
int main(int argc, const char* argv[])
{
if(argc < 2)
{
printf("eg: ./a.out port\n");
exit(1);
}
struct sockaddr_in serv_addr;
socklen_t serv_len = sizeof(serv_addr);
int port = atoi(argv[1]);
// 创建套接字
int lfd = socket(AF_INET, SOCK_STREAM, 0);
// 初始化服务器 sockaddr_in
memset(&serv_addr, 0, serv_len);
serv_addr.sin_family = AF_INET; // 地址族
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); // 监听本机所有的IP
serv_addr.sin_port = htons(port); // 设置端口
// 绑定IP和端口
bind(lfd, (struct sockaddr*)&serv_addr, serv_len);
// 设置同时监听的最大个数
listen(lfd, 36);
printf("Start accept ......\n");
struct sockaddr_in client_addr;
socklen_t cli_len = sizeof(client_addr);
// 创建epoll树根节点
int epfd = epoll_create(2000);
// 初始化epoll树
struct epoll_event ev;
ev.events = EPOLLIN;
ev.data.fd = lfd;
epoll_ctl(epfd, EPOLL_CTL_ADD, lfd, &ev);
// 存储发生变化的fd对应信息
struct epoll_event all[2000];
while(1)
{
// 使用epoll通知内核fd 文件IO检测
int ret = epoll_wait(epfd, all, sizeof(all)/sizeof(all[0]), -1);
// 遍历all数组中的前ret个元素
for(int i=0; i<ret; ++i)
{
int fd = all[i].data.fd;
// 判断是否有新连接
if(fd == lfd)
{
// 接受连接请求
int cfd = accept(lfd, (struct sockaddr*)&client_addr, &cli_len);
if(cfd == -1)
{
perror("accept error");
exit(1);
}
// 将新得到的cfd挂到树上
struct epoll_event temp;
temp.events = EPOLLIN;
temp.data.fd = cfd;
epoll_ctl(epfd, EPOLL_CTL_ADD, cfd, &temp);
// 打印客户端信息
char ip[64] = {0};
printf("New Client IP: %s, Port: %d\n",
inet_ntop(AF_INET, &client_addr.sin_addr.s_addr, ip, sizeof(ip)),
ntohs(client_addr.sin_port));
}
else
{
// 处理已经连接的客户端发送过来的数据
if(!all[i].events & EPOLLIN)
{
continue;
}
// 读数据
char buf[1024] = {0};
int len = recv(fd, buf, sizeof(buf), 0);
if(len == -1)
{
perror("recv error");
exit(1);
}
else if(len == 0)
{
printf("client disconnected ....\n");
// fd从epoll树上删除
ret = epoll_ctl(epfd, EPOLL_CTL_DEL, fd, NULL);
if(ret == -1)
{
perror("epoll_ctl - del error");
exit(1);
}
close(fd);
}
else
{
printf(" recv buf: %s\n", buf);
write(fd, buf, len);
}
}
}
}
close(lfd);
return 0;
}Further, the structure may also be stored with the file descriptor and corresponding IP and port address assigned structure ev.data.ptr. lfd corresponding server side IP address and port, the client CFD corresponding IP and port connected thereto, so linked to the red-black tree ev have the IP and port information. Because of file descriptors after epoll_wait function will change corresponding to the tree epoll_event are copied to the res array, so when traversing the res array, we can get more information.
3. epoll level trigger mode
Example:
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <sys/epoll.h>
int main(int argc, const char* argv[])
{
if(argc < 2)
{
printf("eg: ./a.out port\n");
exit(1);
}
struct sockaddr_in serv_addr;
socklen_t serv_len = sizeof(serv_addr);
int port = atoi(argv[1]);
// 创建套接字
int lfd = socket(AF_INET, SOCK_STREAM, 0);
// 初始化服务器 sockaddr_in
memset(&serv_addr, 0, serv_len);
serv_addr.sin_family = AF_INET; // 地址族
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); // 监听本机所有的IP
serv_addr.sin_port = htons(port); // 设置端口
// 绑定IP和端口
bind(lfd, (struct sockaddr*)&serv_addr, serv_len);
// 设置同时监听的最大个数
listen(lfd, 36);
printf("Start accept ......\n");
struct sockaddr_in client_addr;
socklen_t cli_len = sizeof(client_addr);
// 创建epoll树根节点
int epfd = epoll_create(2000);
// 初始化epoll树
struct epoll_event ev;
ev.events = EPOLLIN;
ev.data.fd = lfd;
epoll_ctl(epfd, EPOLL_CTL_ADD, lfd, &ev);
struct epoll_event all[2000];
while(1)
{
// 使用epoll通知内核fd 文件IO检测
int ret = epoll_wait(epfd, all, sizeof(all)/sizeof(all[0]), -1);
printf("================== epoll_wait =============\n");
// 遍历all数组中的前ret个元素
for(int i=0; i<ret; ++i)
{
int fd = all[i].data.fd;
// 判断是否有新连接
if(fd == lfd)
{
// 接受连接请求
int cfd = accept(lfd, (struct sockaddr*)&client_addr, &cli_len);
if(cfd == -1)
{
perror("accept error");
exit(1);
}
// 将新得到的cfd挂到树上
struct epoll_event temp;
temp.events = EPOLLIN;
temp.data.fd = cfd;
epoll_ctl(epfd, EPOLL_CTL_ADD, cfd, &temp);
// 打印客户端信息
char ip[64] = {0};
printf("New Client IP: %s, Port: %d\n",
inet_ntop(AF_INET, &client_addr.sin_addr.s_addr, ip, sizeof(ip)),
ntohs(client_addr.sin_port));
}
else
{
// 处理已经连接的客户端发送过来的数据
if(!all[i].events & EPOLLIN)
{
continue;
}
// 读数据
char buf[5] = {0};
int len = recv(fd, buf, sizeof(buf), 0);
if(len == -1)
{
perror("recv error");
exit(1);
}
else if(len == 0)
{
printf("client disconnected ....\n");
// fd从epoll树上删除
ret = epoll_ctl(epfd, EPOLL_CTL_DEL, fd, NULL);
if(ret == -1)
{
perror("epoll_ctl - del error");
exit(1);
}
close(fd);
}
else
{
// printf(" recv buf: %s\n", buf);
write(STDOUT_FILENO, buf, len);
write(fd, buf, len);
}
}
}
}
close(lfd);
return 0;
}Note: Since the end of buf no '\ 0', so if you use printf garbled, so here with write.
Results of the:
4. epoll edge-triggered mode
Example:
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <sys/epoll.h>
int main(int argc, const char* argv[])
{
if(argc < 2)
{
printf("eg: ./a.out port\n");
exit(1);
}
struct sockaddr_in serv_addr;
socklen_t serv_len = sizeof(serv_addr);
int port = atoi(argv[1]);
// 创建套接字
int lfd = socket(AF_INET, SOCK_STREAM, 0);
// 初始化服务器 sockaddr_in
memset(&serv_addr, 0, serv_len);
serv_addr.sin_family = AF_INET; // 地址族
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); // 监听本机所有的IP
serv_addr.sin_port = htons(port); // 设置端口
// 绑定IP和端口
bind(lfd, (struct sockaddr*)&serv_addr, serv_len);
// 设置同时监听的最大个数
listen(lfd, 36);
printf("Start accept ......\n");
struct sockaddr_in client_addr;
socklen_t cli_len = sizeof(client_addr);
// 创建epoll树根节点
int epfd = epoll_create(2000);
// 初始化epoll树
struct epoll_event ev;
// 设置边沿触发
ev.events = EPOLLIN | EPOLLET;
ev.data.fd = lfd;
epoll_ctl(epfd, EPOLL_CTL_ADD, lfd, &ev);
struct epoll_event all[2000];
while(1)
{
// 使用epoll通知内核fd 文件IO检测
int ret = epoll_wait(epfd, all, sizeof(all)/sizeof(all[0]), -1);
printf("================== epoll_wait =============\n");
// 遍历all数组中的前ret个元素
for(int i=0; i<ret; ++i)
{
int fd = all[i].data.fd;
// 判断是否有新连接
if(fd == lfd)
{
// 接受连接请求
int cfd = accept(lfd, (struct sockaddr*)&client_addr, &cli_len);
if(cfd == -1)
{
perror("accept error");
exit(1);
}
// 将新得到的cfd挂到树上
struct epoll_event temp;
// 设置边沿触发
temp.events = EPOLLIN | EPOLLET;
temp.data.fd = cfd;
epoll_ctl(epfd, EPOLL_CTL_ADD, cfd, &temp);
// 打印客户端信息
char ip[64] = {0};
printf("New Client IP: %s, Port: %d\n",
inet_ntop(AF_INET, &client_addr.sin_addr.s_addr, ip, sizeof(ip)),
ntohs(client_addr.sin_port));
}
else
{
// 处理已经连接的客户端发送过来的数据
if(!all[i].events & EPOLLIN)
{
continue;
}
// 读数据
char buf[5] = {0};
int len = recv(fd, buf, sizeof(buf), 0);
if(len == -1)
{
perror("recv error");
exit(1);
}
else if(len == 0)
{
printf("client disconnected ....\n");
// fd从epoll树上删除
ret = epoll_ctl(epfd, EPOLL_CTL_DEL, fd, NULL);
if(ret == -1)
{
perror("epoll_ctl - del error");
exit(1);
}
close(fd);
}
else
{
// printf(" recv buf: %s\n", buf);
write(STDOUT_FILENO, buf, len);
write(fd, buf, len);
}
}
}
}
close(lfd);
return 0;
}Results of the:
5. epoll edge triggered non-blocking
If set to a non-blocking, then, after the read data buffer, read again, then -1 is returned, and errno is automatically set to EAGAIN. Whether it is set to blocking or non-blocking, when returns 0, expressed client disconnects.
Example:
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <sys/epoll.h>
#include <fcntl.h>
#include <errno.h>
int main(int argc, const char* argv[])
{
if(argc < 2)
{
printf("eg: ./a.out port\n");
exit(1);
}
struct sockaddr_in serv_addr;
socklen_t serv_len = sizeof(serv_addr);
int port = atoi(argv[1]);
// 创建套接字
int lfd = socket(AF_INET, SOCK_STREAM, 0);
// 初始化服务器 sockaddr_in
memset(&serv_addr, 0, serv_len);
serv_addr.sin_family = AF_INET; // 地址族
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); // 监听本机所有的IP
serv_addr.sin_port = htons(port); // 设置端口
// 绑定IP和端口
bind(lfd, (struct sockaddr*)&serv_addr, serv_len);
// 设置同时监听的最大个数
listen(lfd, 36);
printf("Start accept ......\n");
struct sockaddr_in client_addr;
socklen_t cli_len = sizeof(client_addr);
// 创建epoll树根节点
int epfd = epoll_create(2000);
// 初始化epoll树
struct epoll_event ev;
// 设置边沿触发
ev.events = EPOLLIN;
ev.data.fd = lfd;
epoll_ctl(epfd, EPOLL_CTL_ADD, lfd, &ev);
struct epoll_event all[2000];
while(1)
{
// 使用epoll通知内核fd 文件IO检测
int ret = epoll_wait(epfd, all, sizeof(all)/sizeof(all[0]), -1);
printf("================== epoll_wait =============\n");
// 遍历all数组中的前ret个元素
for(int i=0; i<ret; ++i)
{
int fd = all[i].data.fd;
// 判断是否有新连接
if(fd == lfd)
{
// 接受连接请求
int cfd = accept(lfd, (struct sockaddr*)&client_addr, &cli_len);
if(cfd == -1)
{
perror("accept error");
exit(1);
}
// 设置文件cfd为非阻塞模式
int flag = fcntl(cfd, F_GETFL);
flag |= O_NONBLOCK;
fcntl(cfd, F_SETFL, flag);
// 将新得到的cfd挂到树上
struct epoll_event temp;
// 设置边沿触发
temp.events = EPOLLIN | EPOLLET;
temp.data.fd = cfd;
epoll_ctl(epfd, EPOLL_CTL_ADD, cfd, &temp);
// 打印客户端信息
char ip[64] = {0};
printf("New Client IP: %s, Port: %d\n",
inet_ntop(AF_INET, &client_addr.sin_addr.s_addr, ip, sizeof(ip)),
ntohs(client_addr.sin_port));
}
else
{
// 处理已经连接的客户端发送过来的数据
if(!all[i].events & EPOLLIN)
{
continue;
}
// 读数据
char buf[5] = {0};
int len;
// 循环读数据
while( (len = recv(fd, buf, sizeof(buf), 0)) > 0 )
{
// 数据打印到终端
write(STDOUT_FILENO, buf, len);
// 发送给客户端
send(fd, buf, len, 0);
}
if(len == 0)
{
printf("客户端断开了连接\n");
ret = epoll_ctl(epfd, EPOLL_CTL_DEL, fd, NULL);
if(ret == -1)
{
perror("epoll_ctl - del error");
exit(1);
}
close(fd);
}
else if(len == -1)
{
if(errno == EAGAIN)
{
printf("缓冲区数据已经读完\n");
}
else
{
printf("recv error----\n");
exit(1);
}
}
}
}
}
close(lfd);
return 0;
}Results of the:
6. 1024 file descriptors breakthrough
7. udp communication flow
8. udp server-side code implemented
Example:
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <arpa/inet.h>
int main(int argc, const char* argv[])
{
// 创建套接字
int fd = socket(AF_INET, SOCK_DGRAM, 0);
if(fd == -1)
{
perror("socket error");
exit(1);
}
// fd绑定本地的IP和端口
struct sockaddr_in serv;
memset(&serv, 0, sizeof(serv));
serv.sin_family = AF_INET;
serv.sin_port = htons(8765);
serv.sin_addr.s_addr = htonl(INADDR_ANY);
int ret = bind(fd, (struct sockaddr*)&serv, sizeof(serv));
if(ret == -1)
{
perror("bind error");
exit(1);
}
struct sockaddr_in client;
socklen_t cli_len = sizeof(client);
// 通信
char buf[1024] = {0};
while(1)
{
int recvlen = recvfrom(fd, buf, sizeof(buf), 0,
(struct sockaddr*)&client, &cli_len);
if(recvlen == -1)
{
perror("recvform error");
exit(1);
}
printf("recv buf: %s\n", buf);
char ip[64] = {0};
printf("New Client IP: %s, Port: %d\n",
inet_ntop(AF_INET, &client.sin_addr.s_addr, ip, sizeof(ip)),
ntohs(client.sin_port));
// 给客户端发送数据
sendto(fd, buf, strlen(buf)+1, 0, (struct sockaddr*)&client, sizeof(client));
}
close(fd);
return 0;
}9. udp client code implemented
Example:
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <arpa/inet.h>
int main(int argc, const char* argv[])
{
// create socket
int fd = socket(AF_INET, SOCK_DGRAM, 0);
if(fd == -1)
{
perror("socket error");
exit(1);
}
// 初始化服务器的IP和端口
struct sockaddr_in serv;
memset(&serv, 0, sizeof(serv));
serv.sin_family = AF_INET;
serv.sin_port = htons(8765);
inet_pton(AF_INET, "127.0.0.1", &serv.sin_addr.s_addr);
// 通信
while(1)
{
char buf[1024] = {0};
fgets(buf, sizeof(buf), stdin);
// 数据的发送 - server - IP port
sendto(fd, buf, strlen(buf)+1, 0, (struct sockaddr*)&serv, sizeof(serv));
// 等待服务器发送数据过来
recvfrom(fd, buf, sizeof(buf), 0, NULL, NULL);
printf("recv buf: %s\n", buf);
}
close(fd);
return 0;
}