epoll实现linux进程通信

server.c

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <unistd.h>
 #include <signal.h>
 #include <sys/epoll.h>
 #include <errno.h>

 #define UNIX_DOMAIN "/tmp/UNIX.domain"

 void handler(){

   printf("clean program start\n");
   //unlink(UNIX_DOMAIN);
   remove(UNIX_DOMAIN);
   printf("clean end.\n");
 }

 int main(void)
 {
   int lsn_fd, apt_fd;
   struct sockaddr_un srv_addr;
   struct sockaddr_un clt_addr;
   socklen_t clt_len;
   int ret;
   int i;
   char recv_buf[];
   char send_buf[];  

   signal(SIGTERM,handler);  

   //create epoll
   int epfd,eventfd;
   struct epoll_event   ev,events[];

   epfd = epoll_create();

   //create socket to bind local IP and PORT
   lsn_fd = socket(AF_UNIX, SOCK_STREAM, );
   ev.data.fd = lsn_fd;
   ev.events = EPOLLIN|EPOLLET;

   epoll_ctl(epfd,EPOLL_CTL_ADD,lsn_fd,&ev);

   if(lsn_fd < )
   {
     perror("can't create communication socket!");
     return ;
   }

   //create local IP and PORT
   srv_addr.sun_family = AF_UNIX;
   strncpy(srv_addr.sun_path, UNIX_DOMAIN, sizeof(srv_addr.sun_path) - );
   //unlink(UNIX_DOMAIN);

   //bind sockfd and sockaddr
   ret = bind(lsn_fd, (struct sockaddr*)&srv_addr, sizeof(srv_addr));
   if(ret == -)
   {
     perror("can't bind local sockaddr!");
     close(lsn_fd);
     unlink(UNIX_DOMAIN);
     return ;
   }

   //listen lsn_fd, try listen 5

   ret = listen(lsn_fd, );
   if(ret == -)
   {
     perror("can't listen client connect request");
     close(lsn_fd);
     unlink(UNIX_DOMAIN);

     return ;
   }

   clt_len = sizeof(clt_addr);
   while()
   {
     int nfds = epoll_wait(epfd,events,,);
     int i=;
     for(i=;i<nfds;++i)
     {
       if(events[i].data.fd == lsn_fd)
       {
         apt_fd = accept(lsn_fd, (struct sockaddr*)&clt_addr, &clt_len);
         if(apt_fd < ){
           perror("can't listen client connect request");
           close(lsn_fd);
           unlink(UNIX_DOMAIN);
           return ;
         }
         char lines[];
         sprintf(lines,"server data  to client\n");
         write(apt_fd, lines, );

         ev.data.fd = apt_fd;
         ev.events = EPOLLIN|EPOLLET;

         epoll_ctl(epfd,EPOLL_CTL_ADD,apt_fd,&ev);

       }
       else if (events[i].events & EPOLLIN)
       //write数据
       {
         printf("EPOLLIN\n");
         if( (eventfd = events[i].data.fd) <  )
           continue;

         int n=,ret= ;
         char line[];
         if ((ret = read(eventfd,line,)) < ){

           if(errno == ECONNRESET){
             close(eventfd);
             events[i].data.fd = -;
           }
           else
             printf("readline error\n");
         }
         else if( ret == ){
           close(eventfd);
           events[i].data.fd = -;
         }
         else if( ret >  )
         {
           line[ret] = '\0';
           printf("%s",line);
           while( ( ret = read(eventfd,line,)) >)
           {
                 line[ret] = '\0';
                 printf("%s",line);
           }
           printf("\n");
         }
       }
       else if (events[i].events & EPOLLOUT){
         //写出的数据,在EPOLLIN处理中设置fd的events为EPOLLOUT|EPOLLET时,即触发该事件
         int eventfd  = events[i].data.fd;
         char line[];
         write(eventfd,line,);

         ev.data.fd = eventfd;
         ev.events = EPOLLIN | EPOLLET;

         epoll_ctl ( epfd, EPOLL_CTL_ADD, eventfd, &ev);
       }
     }
   }

   close(apt_fd);
   close(lsn_fd);
   unlink(UNIX_DOMAIN);
   return ;
 }

client.c

 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <unistd.h>

 #define UNIX_DOMAIN "/tmp/UNIX.domain"

 int main(void)
 {
   int connect_fd;
   struct sockaddr_un srv_addr;
   char snd_buf[];
   char rcv_buf[];
   int ret;
   int i;
   connect_fd = socket(AF_UNIX, SOCK_STREAM, );

   if(connect_fd < )
   {
     perror("client create socket failed");
     return ;
   }
   srv_addr.sun_family = AF_UNIX;
   strcpy(srv_addr.sun_path, UNIX_DOMAIN);
   ret = connect(connect_fd, (struct sockaddr*)&srv_addr, sizeof(srv_addr));

   if(ret == -)
   {
     perror("connect to server failed!");
     close(connect_fd);
     unlink(UNIX_DOMAIN);
     return ;
   }

   memset(rcv_buf, , );
   int rcv_num = read(connect_fd, rcv_buf, sizeof(rcv_buf));
   printf("receive message from server (%d) :%s\n", rcv_num, rcv_buf);

   memset(snd_buf, , );
   strcpy(snd_buf, "message from client");
   printf("sizeof(snd_buf): %d\n", sizeof(snd_buf));

   printf("send data to server... ...\n");
   for(i = ; i < ; i++)
   {
     write(connect_fd, snd_buf, sizeof(snd_buf));
   }
   printf("send end!\n");
   close(connect_fd);
   return ;

 }

与网络的socket通信的区别，即socket地址有些区别，其他的一样。

sockaddr_in用于网络的socket通信，sockaddr_un用于本机上的进程之间的通信。