libevent库的使用--定时器的使用实例

#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)