Could you recommend some guides about Epoll on Linux [closed]
Here's an introduction to Epoll, a pretty basic tutorial: http://blog.kovyrin.net/2006/04/13/epoll-asynchronous-network-programming/
A more complete example can be found here: https://banu.com/blog/2/how-to-use-epoll-a-complete-example-in-c/
Also, the man pages
#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <sys/epoll.h>#define PORT 1500 #define MAX_CON (1200)static struct epoll_event *events;int main(int argc, char *argv[]){ fd_set master; fd_set read_fds; struct sockaddr_in serveraddr; struct sockaddr_in clientaddr; int fdmax; int listener; int newfd; char buf[1024]; int nbytes; int addrlen; int yes; int epfd = -1; int res = -1; struct epoll_event ev; int i=0; int index = 0; int client_fd = -1; int SnumOfConnection = 0; time_t Sstart, Send; if((listener = socket(AF_INET, SOCK_STREAM, 0)) == -1) { perror("Server-socket() error lol!"); exit(1); } if(setsockopt(listener, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) { perror("Server-setsockopt() error lol!"); exit(1); } serveraddr.sin_family = AF_INET; serveraddr.sin_addr.s_addr = INADDR_ANY; serveraddr.sin_port = htons(PORT); memset(&(serveraddr.sin_zero), '\0', 8); if(bind(listener, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) == -1) { perror("Server-bind() error lol!"); exit(1); } if(listen(listener, 10) == -1) { perror("Server-listen() error lol!"); exit(1); } fdmax = listener; /* so far, it's this one*/ events = calloc(MAX_CON, sizeof(struct epoll_event)); if ((epfd = epoll_create(MAX_CON)) == -1) { perror("epoll_create"); exit(1); } ev.events = EPOLLIN; ev.data.fd = fdmax; if (epoll_ctl(epfd, EPOLL_CTL_ADD, fdmax, &ev) < 0) { perror("epoll_ctl"); exit(1); } //time(&start); for(;;) { res = epoll_wait(epfd, events, MAX_CON, -1); client_fd = events[index].data.fd; for (index = 0; index < MAX_CON; index++) { if(client_fd == listener) { addrlen = sizeof(clientaddr); if((newfd = accept(listener, (struct sockaddr *)&clientaddr, &addrlen)) == -1) { perror("Server-accept() error lol!"); } else { // printf("Server-accept() is OK...\n"); ev.events = EPOLLIN; ev.data.fd = newfd; if (epoll_ctl(epfd, EPOLL_CTL_ADD, newfd, &ev) < 0) { perror("epoll_ctl"); exit(1); } } break; } else { if (events[index].events & EPOLLHUP) { if (epoll_ctl(epfd, EPOLL_CTL_DEL, client_fd, &ev) < 0) { perror("epoll_ctl"); } close(client_fd); break; } if (events[index].events & EPOLLIN) { if((nbytes = recv(client_fd, buf, sizeof(buf), 0)) <= 0) { if(nbytes == 0) { // printf("socket %d hung up\n", client_fd); } else { printf("recv() error lol! %d", client_fd); perror(""); } if (epoll_ctl(epfd, EPOLL_CTL_DEL, client_fd, &ev) < 0) { perror("epoll_ctl"); } close(client_fd); } else { if(send(client_fd, buf, nbytes, 0) == -1) perror("send() error lol!"); } break; } } } } return 0;}I wrote this program for testing and I was able to connect more than 80k connections and I find average system load only to 0.27%.