[转]使用 libevent 和 libev 提高网络应用性能

				
int main(int argc, char **argv)
{
...
    ev_init();

    /* Setup listening socket */

    event_set(&ev_accept, listen_fd, EV_READ|EV_PERSIST, on_accept, NULL);
    event_add(&ev_accept, NULL);

    /* Start the event loop. */
    event_dispatch();
}

				
#include <event.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>

#define SERVER_PORT 8080
int debug = 0;

struct client {
  int fd;
  struct bufferevent *buf_ev;
};

int setnonblock(int fd)
{
  int flags;

  flags = fcntl(fd, F_GETFL);
  flags |= O_NONBLOCK;
  fcntl(fd, F_SETFL, flags);
}

void buf_read_callback(struct bufferevent *incoming,
                       void *arg)
{
  struct evbuffer *evreturn;
  char *req;

  req = evbuffer_readline(incoming->input);
  if (req == NULL)
    return;

  evreturn = evbuffer_new();
  evbuffer_add_printf(evreturn,"You said %s\n",req);
  bufferevent_write_buffer(incoming,evreturn);
  evbuffer_free(evreturn);
  free(req);
}

void buf_write_callback(struct bufferevent *bev,
                        void *arg)
{
}

void buf_error_callback(struct bufferevent *bev,
                        short what,
                        void *arg)
{
  struct client *client = (struct client *)arg;
  bufferevent_free(client->buf_ev);
  close(client->fd);
  free(client);
}

void accept_callback(int fd,
                     short ev,
                     void *arg)
{
  int client_fd;
  struct sockaddr_in client_addr;
  socklen_t client_len = sizeof(client_addr);
  struct client *client;

  client_fd = accept(fd,
                     (struct sockaddr *)&client_addr,
                     &client_len);
  if (client_fd < 0)
    {
      warn("Client: accept() failed");
      return;
    }

  setnonblock(client_fd);

  client = calloc(1, sizeof(*client));
  if (client == NULL)
    err(1, "malloc failed");
  client->fd = client_fd;

  client->buf_ev = bufferevent_new(client_fd,
                                   buf_read_callback,
                                   buf_write_callback,
                                   buf_error_callback,
                                   client);

  bufferevent_enable(client->buf_ev, EV_READ);
}

int main(int argc,
         char **argv)
{
  int socketlisten;
  struct sockaddr_in addresslisten;
  struct event accept_event;
  int reuse = 1;

  event_init();

  socketlisten = socket(AF_INET, SOCK_STREAM, 0);

  if (socketlisten < 0)
    {
      fprintf(stderr,"Failed to create listen socket");
      return 1;
    }

  memset(&addresslisten, 0, sizeof(addresslisten));

  addresslisten.sin_family = AF_INET;
  addresslisten.sin_addr.s_addr = INADDR_ANY;
  addresslisten.sin_port = htons(SERVER_PORT);

  if (bind(socketlisten,
           (struct sockaddr *)&addresslisten,
           sizeof(addresslisten)) < 0)
    {
      fprintf(stderr,"Failed to bind");
      return 1;
    }

  if (listen(socketlisten, 5) < 0)
    {
      fprintf(stderr,"Failed to listen to socket");
      return 1;
    }

  setsockopt(socketlisten,
             SOL_SOCKET,
             SO_REUSEADDR,
             &reuse,
             sizeof(reuse));

  setnonblock(socketlisten);

  event_set(&accept_event,
            socketlisten,
            EV_READ|EV_PERSIST,
            accept_callback,
            NULL);

  event_add(&accept_event,
            NULL);

  event_dispatch();

  close(socketlisten);

  return 0;
}

				
$ telnet localhost 8080
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Hello!
You said Hello!

				
#include <sys/types.h>

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include <event.h>
#include <evhttp.h>

void generic_request_handler(struct evhttp_request *req, void *arg)
{
  struct evbuffer *returnbuffer = evbuffer_new();

  evbuffer_add_printf(returnbuffer, "Thanks for the request!");
  evhttp_send_reply(req, HTTP_OK, "Client", returnbuffer);
  evbuffer_free(returnbuffer);
  return;
}

int main(int argc, char **argv)
{
  short          http_port = 8081;
  char          *http_addr = "192.168.0.22";
  struct evhttp *http_server = NULL;

  event_init();
  http_server = evhttp_start(http_addr, http_port);
  evhttp_set_gencb(http_server, generic_request_handler, NULL);

  fprintf(stderr, "Server started on port %d\n", http_port);
  event_dispatch();

  return(0);
}

				
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <event.h>
#include <evhttp.h>

#define RELOAD_TIMEOUT 5
#define DEFAULT_FILE "sample.html"

char *filedata;
time_t lasttime = 0;
char filename[80];
int counter = 0;

void read_file()
{
  int size = 0;
  char *data;
  struct stat buf;

  stat(filename,&buf);

  if (buf.st_mtime > lasttime)
    {
      if (counter++)
        fprintf(stderr,"Reloading file: %s",filename);
      else
        fprintf(stderr,"Loading file: %s",filename);

      FILE *f = fopen(filename, "rb");
      if (f == NULL)
        {
          fprintf(stderr,"Couldn't open file\n");
          exit(1);
        }

      fseek(f, 0, SEEK_END);
      size = ftell(f);
      fseek(f, 0, SEEK_SET);
      data = (char *)malloc(size+1);
      fread(data, sizeof(char), size, f);
      filedata = (char *)malloc(size+1);
      strcpy(filedata,data);
      fclose(f);


      fprintf(stderr," (%d bytes)\n",size);
      lasttime = buf.st_mtime;
    }
}

void load_file()
{
  struct event *loadfile_event;
  struct timeval tv;

  read_file();

  tv.tv_sec = RELOAD_TIMEOUT;
  tv.tv_usec = 0;

  loadfile_event = malloc(sizeof(struct event));

  evtimer_set(loadfile_event,
              load_file,
              loadfile_event);

  evtimer_add(loadfile_event,
              &tv);
}

void generic_request_handler(struct evhttp_request *req, void *arg)
{
  struct evbuffer *evb = evbuffer_new();

  evbuffer_add_printf(evb, "%s",filedata);
  evhttp_send_reply(req, HTTP_OK, "Client", evb);
  evbuffer_free(evb);
}

int main(int argc, char *argv[])
{
  short          http_port = 8081;
  char          *http_addr = "192.168.0.22";
  struct evhttp *http_server = NULL;

  if (argc > 1)
    {
      strcpy(filename,argv[1]);
      printf("Using %s\n",filename);
    }
  else
    {
      strcpy(filename,DEFAULT_FILE);
    }

  event_init();

  load_file();

  http_server = evhttp_start(http_addr, http_port);
  evhttp_set_gencb(http_server, generic_request_handler, NULL);

  fprintf(stderr, "Server started on port %d\n", http_port);
  event_dispatch();
}

				
$ ./basichttpfile
Loading file: sample.html (8046 bytes)
Server started on port 8081

				
$ ./basichttpfile
Loading file: sample.html (8046 bytes)
Server started on port 8081
Reloading file: sample.html (8047 bytes)
Reloading file: sample.html (8048 bytes)

				
$ ulimit -n
1024

				
my $server = IO::Socket::INET->new(
    LocalAddr       => 'localhost',
    LocalPort       => 8081,
    Proto           => 'tcp',
    ReuseAddr       => SO_REUSEADDR,
    Listen          => 1,
    Blocking        => 0,
    ) or die $@;

my $accept = event_new($server, EV_READ|EV_PERSIST, \&accept_callback);

$main->add;

event_mainloop();

				
require 'rubygems'
require 'rev'

PORT = 8081

class EchoServerConnection < Rev::TCPSocket
  def on_read(data)
    write 'You said: ' + data
  end
end

server = Rev::TCPServer.new('192.168.0.22', PORT, EchoServerConnection)
server.attach(Rev::Loop.default)

puts "Listening on localhost:#{PORT}"
Rev::Loop.default.run