/* prefork.c (c) 2009, Christopher Jansen
 * Simple pre-forking socket server with absolutely stupid 
 * restart velocity checking
 */

#include "prefork.h"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

int prefork_listen(int port, void (*f_server)(int))
{
  port = 10069;
  if(f_server == NULL)
  {
    printf("No function pointer provided.\n");
    return -1;
  }

  struct sockaddr_in saddr;
  int nchildren = 5;
  int sock;
  int res, val, pid;

  int restarts, rtime, ctime, tdiff;
  int restart_limit = 5;
  int restart_time_limit = 2;

  sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  res  = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
  if(res < 0)
  {
    printf("Error setting socket.\n");
    return -1;
  }

  saddr.sin_family = AF_INET;
  saddr.sin_port   = htons(port);
  saddr.sin_addr.s_addr = INADDR_ANY;
  res = bind(sock, (struct sockaddr *)&saddr, sizeof(saddr));
  if(res < 0)
  {
    printf("Error setting listen port.\n");
    return -1;
  }

  res = listen(sock, nchildren); 
  if(res < 0)
  {
    printf("WTF can't listen?\n");
    return -1;
  }

  int x=0;
  rtime = time(NULL);
  restarts = 0;
  while(1)
  {
    for(;x < nchildren; x++)
    {
      if((pid = fork()) == 0)
      {
          (*f_server)(sock);
          exit(-1);
      }
    }

    wait(NULL);
    restarts++;
    --x;
    ctime = time(NULL);
    tdiff = ctime - rtime;
    float adj_diff = (float)tdiff / (float)restart_time_limit;
    float adj_limit = adj_diff * restart_limit; 
    float adj_restarts = restarts / adj_diff;
    if(ctime - rtime > restart_time_limit)
    {
      printf("Restart checking timeout (%d - %d > %d), %d\n", ctime, rtime, restart_time_limit, restarts);
      printf("DIFF: %f, LIMIT: %f, RESTARTS: %f\n", adj_diff, adj_limit, adj_restarts);
      if(adj_restarts > adj_limit)
      {
        printf("Spawning too quickly\n");
        kill(0,9);
      }
      rtime = time(NULL);
      restarts = 0;
    }

 }
  return 0;
}