epoll边缘触发(epoll et) 源代码例子
来源:互联网 发布:matcher java 编辑:程序博客网 时间:2024/03/29 05:41
在利用epoll编写网络应用程序,特别是服务器的时候。为了得到最优的效果,一般采用边缘触发(epoll ET)的方式。由于边缘触发,epoll_wait只有在套接字状态发生变化的时候才会返回。所以要对套接字(socket)进行循环accept,read,write;直到套接字的缓冲区空(read,accept)或者填满(write)为止。当read返回的字节数小于要读的字节数,或者返回EAGAIN的时候,认为缓存区为空了。由于网络上已经有很多epollet如何处理epollin事件的例子,所以下面是本人只提供测试如何处理epollout事件的代码。
int opt;
opt = fcntl(sockFd, F_GETFL); if (opt< 0) { printf("fcntl(F_GETFL) fail."); exit(-1); } opt |= O_NONBLOCK; if (fcntl(sockFd, F_SETFL, opt) < 0) { printf("fcntl(F_SETFL) fail."); exit(-1); }
close(g_srv_fd); fprintf(stderr, "receiv sig int"); sleep(5); exit(0);
int snd_len = write(fd, out_buf+offset, buf_len-offset); int tmp_len; if (snd_len==(buf_len-offset)) { do { tmp_len = write(fd, out_buf+offset+snd_len, buf_len-offset-snd_len); if (tmp_len>0 && tmp_len<(buf_len-offset-snd_len)) { snd_len += tmp_len; break; } if(tmp_len == -1) { break; } snd_len += tmp_len; } while(tmp_len>0); } if (((snd_len==-1||tmp_len==-1) && errno ==EAGAIN) || snd_len<buf_len-offset) { fprintf(stderr, "snd receiv eagin or snd_len<out_len\r\n"); } fprintf(stderr, "snd ret:%d\r\n", snd_len); return snd_len;
char *p_out_buf=g_out_buf; int tmp_offset; int i; for(i=0; i<REPEAT_NUM;i++) { tmp_offset+=snprintf(p_out_buf+tmp_offset,OUT_BUF_SIZE-tmp_offset,"%d:%s\r\n", i,in_buf); } g_out_buf_len =tmp_offset; g_out_buf_offset = 0; g_has_write_buf = 0; g_out_buf_offset +=write_out_buf(fd, g_out_buf, g_out_buf_len,g_out_buf_offset); fprintf(stderr, "write_out_buf len:%d wret:%d\r\n", g_out_buf_len, g_out_buf_offset); if (g_out_buf_offset<g_out_buf_len) { g_has_write_buf=1; }
int serverFd;
serverFd = socket(AF_INET, SOCK_STREAM, 0); g_srv_fd = serverFd;
setnonblocking(serverFd); signal(SIGPIPE, SIG_IGN); signal(SIGINT, handle_sig);
int epFd = epoll_create(EPOLL_SIZE); struct epoll_event ev, evs[EVENT_ARR]; ev.data.fd = serverFd; ev.events = EPOLLIN | EPOLLET; epoll_ctl(epFd, EPOLL_CTL_ADD, serverFd, &ev);
struct sockaddr_in serverAddr; socklen_t serverLen = sizeof(struct sockaddr_in); serverAddr.sin_addr.s_addr = htonl(INADDR_ANY); serverAddr.sin_port = htons(PORT); if (bind(serverFd, (struct sockaddr *) &serverAddr, serverLen)) { printf("bind() fail.\n"); exit(-1); }
if (listen(serverFd, BACK_QUEUE)) { printf("Listen fail.\n"); exit(-1); }
int clientFd; struct sockaddr_in clientAddr; socklen_t clientLen; char buf[BUF_SIZE];
int i = 0; while (1) {
int nfds = epoll_wait(epFd, evs, EVENT_ARR, -1); for (i = 0; i < nfds; i++) { if (evs[i].data.fd == serverFd && (evs[i].events & EPOLLIN)) { //epollet需要循环对监听的套接字accept,直到返回EAGAIN do { if ((clientFd = accept(serverFd,(struct sockaddr *) &clientAddr, &clientLen))< 0) { printf("accept fail.\n"); break; } printf("Connect from %s:%d\n", inet_ntoa(clientAddr.sin_addr), htons(clientAddr.sin_port)); setnonblocking(clientFd); ev.data.fd = clientFd; //注意,为了效率,这里直接对EPOLLIN,EPOLLOUT事件监听 ev.events = EPOLLIN | EPOLLET | EPOLLOUT; //ev.events = EPOLLIN; epoll_ctl(epFd, EPOLL_CTL_ADD, clientFd,& ev); } while(clientFd>0); } else if (evs[i].events & EPOLLIN) { fprintf(stderr, "epollin event fd:%d\n", clientFd); if ((clientFd = evs[i].data.fd) > 0) { //epollet需要对套接字循环的读,直到len < BUF_SIZE,或者len<=0返回 int len = read(clientFd, buf, BUF_SIZE); fprintf(stderr, "read fd:%d len:%d\n", clientFd, len); if (len == BUF_SIZE) { do { process_write(clientFd, buf, len); if (len < BUF_SIZE) { fprintf(stderr, "len <bufsize %d<%d\n", len, BUF_SIZE); break; } len = read(clientFd, buf, BUF_SIZE); fprintf(stderr, "read2 fd:%d len:%d\n", clientFd, len); } while (len> 0); if (len == 0) { epoll_ctl(epFd, EPOLL_CTL_DEL, clientFd, &ev); close(clientFd); evs[i].data.fd = -1; fprintf(stderr, "close fd:%d\n", clientFd); } else if (len == -1 && errno != EAGAIN) { fprintf(stderr, " fd:%d\n", clientFd); epoll_ctl(epFd, EPOLL_CTL_DEL, clientFd, &ev); close(clientFd); evs[i].data.fd = -1; } } else if (len > 0&& len < BUF_SIZE) { process_write(clientFd, buf, len); } else if (len == 0 || (len == -1&& errno != EAGAIN)) { epoll_ctl(epFd, EPOLL_CTL_DEL, clientFd,& ev); close(clientFd); evs[i].data.fd = -1; fprintf(stderr, "close fd:%d\n", clientFd); }
} } else if(evs[i].events & EPOLLOUT) { //监听到epollout时间,说明发送缓冲去可以写,那继续上一次的写操作 clientFd = evs[i].data.fd; fprintf(stderr, "receive epoll out fd:%d\n", clientFd); if(g_has_write_buf) { g_out_buf_offset +=write_out_buf(clientFd, g_out_buf, g_out_buf_len,g_out_buf_offset); fprintf(stderr, "write len :%d writed:%d\n",g_out_buf_len,g_out_buf_offset); if(g_out_buf_offset==g_out_buf_len) { g_has_write_buf = 0; } } } else { printf("other event.\n"); } } }
return 0;
#include< stdio.h>
#include< stdlib.h>
#include< unistd.h>
#include< fcntl.h>
#include< arpa/inet.h>
#include< netinet/in.h>
#include< sys/epoll.h>
#include< errno.h>
#include< sys/types.h>
#include< sys/socket.h>
#include< signal.h>
#define EPOLL_SIZE 10
#define EVENT_ARR 20
#define BACK_QUEUE 10
#define PORT 18001
#define BUF_SIZE 16
#define REPEAT_NUM 20000
#define OUT_BUF_SIZE 32*REPEAT_NUM
int g_srv_fd;
//由于有可能不能一次write所有的内容,所以需要全局变量保存内容的长度,内容输出到那里,
//在监听到epollout事件后继续上一次的发送
char g_out_buf[OUT_BUF_SIZE];//保存输出的内容
int g_out_buf_offset; //保存输出到那里
int g_out_buf_len; //保存输出内容的长度
int g_has_write_buf; //保存是否要写输出内容
void setnonblocking(int sockFd)
{
}
void handle_sig(int signum)
{
}
int write_out_buf(int fd, char *out_buf,int buf_len,int offset)
{
}
//
void process_write(int fd, char *in_buf,int buf_len)
{
}
int main()
{
}
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