Boost: ASIO library application in RedHat Enterprise 5 (3)

Since ASIO uses epoll as the network core, to understand epoll, let's take a look at how libev works.

Compared with the huge boost dependency of ASIO, libev is compact, lightweight, and efficient.

Column demo

Client:

#include "stdio.h"#include "stdlib.h"#include <iostream>#include "netinet/in.h"#include "sys/socket.h"#include "sys/types.h"#include "sys/wait.h"#include "arpa/inet.h"#include "string.h"int _clientsock;struct sockaddr_in c_addr;int main(int argc, char *argv[]){        int port = atoi(argv[1]);        _clientsock = socket(AF_INET,SOCK_STREAM,0);        c_addr.sin_family=AF_INET;        c_addr.sin_port=htons(port);//6001);        c_addr.sin_addr.s_addr=inet_addr("127.0.0.1");        connect(_clientsock,(struct sockaddr*)&c_addr,sizeof(struct sockaddr));        //char str[32]="123456";        static int x = 0;        while(1)//x < 3)        {          char str[32]="123456";          char c[32];          sprintf(c,"%d\n",x);          strcat(str,c);          send(_clientsock,str,strlen(str)+1,0);          char buffer[128]={'\0'};          recv(_clientsock,buffer,128,0);          printf(buffer);          x++;          //sleep(1000);          getchar();        }        //char buffer[128]={'\0'};        //recv(_clientsock,buffer,128,0);        //printf(buffer);        //close(_clientsock);        getchar();        return 0;}

Echoserver. cpp

Compile command: G ++-g-o echoserver-levechoserver. cpp

It is not clear which static or dynamic library is connected to libev.

#include <stdio.h>#include <string.h>#include <stdlib.h>#include <errno.h>#include <unistd.h>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#include <pthread.h>#include "arpa/inet.h"#include <ev.h>#define MAXLEN 1023#define PORT 9999#define ADDR_IP "127.0.0.1"int socket_init();void accept_callback(struct ev_loop *loop, ev_io *w, int revents);void recv_callback(struct ev_loop *loop, ev_io *w, int revents);void write_callback(struct ev_loop *loop, ev_io *w, int revents);int main(int argc ,char** argv){ int listen; ev_io ev_io_watcher; listen=socket_init(); struct ev_loop *loop = ev_loop_new(EVBACKEND_EPOLL); ev_io_init(&ev_io_watcher, accept_callback,listen, EV_READ); ev_io_start(loop,&ev_io_watcher);  ev_loop(loop,0); ev_loop_destroy(loop); return 0; } int socket_init(){ struct sockaddr_in my_addr; int listener; if ((listener = socket(AF_INET, SOCK_STREAM, 0)) == -1)  {  perror("socket");  exit(1); }  else {  printf("SOCKET CREATE SUCCESS!/n"); } //setnonblocking(listener); int so_reuseaddr=1; setsockopt(listener,SOL_SOCKET,SO_REUSEADDR,&so_reuseaddr,sizeof(so_reuseaddr)); bzero(&my_addr, sizeof(my_addr)); my_addr.sin_family = PF_INET; my_addr.sin_port = htons(PORT); my_addr.sin_addr.s_addr = inet_addr(ADDR_IP); if (bind(listener, (struct sockaddr *) &my_addr, sizeof(struct sockaddr))== -1)  {  perror("bind error!/n");  exit(1); }  else {  printf("IP BIND SUCCESS,IP:%s/n",ADDR_IP); } if (listen(listener, 1024) == -1)  {  perror("listen error!/n");  exit(1); }  else {  printf("LISTEN SUCCESS,PORT:%d/n",PORT); } return listener;} void accept_callback(struct ev_loop *loop, ev_io *w, int revents){ int newfd; struct sockaddr_in sin; socklen_t addrlen = sizeof(struct sockaddr); ev_io* accept_watcher=(ev_io*)malloc(sizeof(ev_io)); while ((newfd = accept(w->fd, (struct sockaddr *)&sin, &addrlen)) < 0) {  if (errno == EAGAIN || errno == EWOULDBLOCK)   {   //these are transient, so don't log anything.   continue;   }  else  {   printf("accept error.[%s]/n", strerror(errno));   break;  } } ev_io_init(accept_watcher,recv_callback,newfd,EV_READ); ev_io_start(loop,accept_watcher); printf("accept callback : fd :%d/n",accept_watcher->fd); }void recv_callback(struct ev_loop *loop, ev_io *w, int revents){ char buffer[1024]={0}; int ret =0; //ev_io write_event;loop: ret=recv(w->fd,buffer,MAXLEN,0); if(ret > 0) {  printf("recv message :%s  /n",buffer);   } else if(ret ==0) {  printf("remote socket closed!socket fd: %d/n",w->fd);  close(w->fd);  ev_io_stop(loop, w);  free(w);  return; } else {  if(errno == EAGAIN ||errno == EWOULDBLOCK)  {    goto loop;  }  else  {   printf("ret :%d ,close socket fd : %d/n",ret,w->fd);   close(w->fd);   ev_io_stop(loop, w);   free(w);   return;  } } int fd=w->fd; ev_io_stop(loop,  w); ev_io_init(w,write_callback,fd,EV_WRITE); ev_io_start(loop,w); printf("socket fd : %d, turn read 2 write loop! ",fd); }void write_callback(struct ev_loop *loop, ev_io *w, int revents){ char buffer[1024]={0}; //ev_io read_event; snprintf(buffer,1023,"this is a test!"); write(w->fd,buffer,strlen(buffer)); int fd=w->fd; ev_io_stop(loop,  w); ev_io_init(w,recv_callback,fd,EV_READ); ev_io_start(loop,w);}