sl@0: /* Portions copyright (c) 2009 Nokia Corporation.  All rights reserved.*/
sl@0: #undef G_DISABLE_ASSERT
sl@0: #undef G_LOG_DOMAIN
sl@0: 
sl@0: #include <errno.h>
sl@0: #include <stdlib.h>
sl@0: #include <stdio.h>
sl@0: #include <string.h>
sl@0: #include <unistd.h>
sl@0: #include <sys/resource.h>
sl@0: #include <sys/time.h>
sl@0: #include <sys/poll.h>
sl@0: 
sl@0: #define TRUE 1
sl@0: #define FALSE 0
sl@0: 
sl@0: static int n_children = 3;
sl@0: static int n_active_children;
sl@0: static int n_iters = 10000;
sl@0: 
sl@0: static int write_fds[1024];
sl@0: static struct pollfd poll_fds[1024];
sl@0: 
sl@0: void
sl@0: my_pipe (int *fds)
sl@0: {
sl@0:   if (pipe(fds) < 0)
sl@0:     {
sl@0:       fprintf (stderr, "Cannot create pipe %s\n", strerror (errno));
sl@0:       exit (1);
sl@0:     }
sl@0: }
sl@0: 
sl@0: int
sl@0: read_all (int fd, char *buf, int len)
sl@0: {
sl@0:   size_t bytes_read = 0;
sl@0:   ssize_t count;
sl@0: 
sl@0:   while (bytes_read < len)
sl@0:     {
sl@0:       count = read (fd, buf + bytes_read, len - bytes_read);
sl@0:       if (count < 0)
sl@0: 	{
sl@0: 	  if (errno != EAGAIN)
sl@0: 	    return FALSE;
sl@0: 	}
sl@0:       else if (count == 0)
sl@0: 	return FALSE;
sl@0: 
sl@0:       bytes_read += count;
sl@0:     }
sl@0: 
sl@0:   return TRUE;
sl@0: }
sl@0: 
sl@0: int
sl@0: write_all (int fd, char *buf, int len)
sl@0: {
sl@0:   size_t bytes_written = 0;
sl@0:   ssize_t count;
sl@0: 
sl@0:   while (bytes_written < len)
sl@0:     {
sl@0:       count = write (fd, buf + bytes_written, len - bytes_written);
sl@0:       if (count < 0)
sl@0: 	{
sl@0: 	  if (errno != EAGAIN)
sl@0: 	    return FALSE;
sl@0: 	}
sl@0: 
sl@0:       bytes_written += count;
sl@0:     }
sl@0: 
sl@0:   return TRUE;
sl@0: }
sl@0: 
sl@0: void
sl@0: run_child (int in_fd, int out_fd)
sl@0: {
sl@0:   int i;
sl@0:   int val = 1;
sl@0: 
sl@0:   for (i = 0; i < n_iters; i++)
sl@0:     {
sl@0:       write_all (out_fd, (char *)&val, sizeof (val));
sl@0:       read_all (in_fd, (char *)&val, sizeof (val));
sl@0:     }
sl@0: 
sl@0:   val = 0;
sl@0:   write_all (out_fd, (char *)&val, sizeof (val));
sl@0: 
sl@0:   exit (0);
sl@0: }
sl@0: 
sl@0: int
sl@0: input_callback (int source, int dest)
sl@0: {
sl@0:   int val;
sl@0:   
sl@0:   if (!read_all (source, (char *)&val, sizeof(val)))
sl@0:     {
sl@0:       fprintf (stderr,"Unexpected EOF\n");
sl@0:       exit (1);
sl@0:     }
sl@0: 
sl@0:   if (val)
sl@0:     {
sl@0:       write_all (dest, (char *)&val, sizeof(val));
sl@0:       return TRUE;
sl@0:     }
sl@0:   else
sl@0:     {
sl@0:       close (source);
sl@0:       close (dest);
sl@0:       
sl@0:       n_active_children--;
sl@0:       return FALSE;
sl@0:     }
sl@0: }
sl@0: 
sl@0: void
sl@0: create_child (int pos)
sl@0: {
sl@0:   int pid;
sl@0:   int in_fds[2];
sl@0:   int out_fds[2];
sl@0:   
sl@0:   my_pipe (in_fds);
sl@0:   my_pipe (out_fds);
sl@0: 
sl@0:   pid = fork ();
sl@0: 
sl@0:   if (pid > 0)			/* Parent */
sl@0:     {
sl@0:       close (in_fds[0]);
sl@0:       close (out_fds[1]);
sl@0: 
sl@0:       write_fds[pos] = in_fds[1];
sl@0:       poll_fds[pos].fd = out_fds[0];
sl@0:       poll_fds[pos].events = POLLIN;
sl@0:     }
sl@0:   else if (pid == 0)		/* Child */
sl@0:     {
sl@0:       close (in_fds[1]);
sl@0:       close (out_fds[0]);
sl@0: 
sl@0:       setsid ();
sl@0: 
sl@0:       run_child (in_fds[0], out_fds[1]);
sl@0:     }
sl@0:   else				/* Error */
sl@0:     {
sl@0:       fprintf (stderr,"Cannot fork: %s\n", strerror (errno));
sl@0:       exit (1);
sl@0:     }
sl@0: }
sl@0: 
sl@0: static double 
sl@0: difftimeval (struct timeval *old, struct timeval *new)
sl@0: {
sl@0:   return
sl@0:     (new->tv_sec - old->tv_sec) * 1000. + (new->tv_usec - old->tv_usec) / 1000;
sl@0: }
sl@0: 
sl@0: int 
sl@0: main (int argc, char **argv)
sl@0: {
sl@0:   int i, j;
sl@0:   struct rusage old_usage;
sl@0:   struct rusage new_usage;
sl@0:   
sl@0:   if (argc > 1)
sl@0:     n_children = atoi(argv[1]);
sl@0: 
sl@0:   if (argc > 2)
sl@0:     n_iters = atoi(argv[2]);
sl@0: 
sl@0:   printf ("Children: %d     Iters: %d\n", n_children, n_iters);
sl@0: 
sl@0:   n_active_children = n_children;
sl@0:   for (i = 0; i < n_children; i++)
sl@0:     create_child (i);
sl@0: 
sl@0:   getrusage (RUSAGE_SELF, &old_usage);
sl@0: 
sl@0:   while (n_active_children > 0)
sl@0:     {
sl@0:       int old_n_active_children = n_active_children;
sl@0: 
sl@0:       poll (poll_fds, n_active_children, -1);
sl@0: 
sl@0:       for (i=0; i<n_active_children; i++)
sl@0: 	{
sl@0: 	  if (poll_fds[i].events & (POLLIN | POLLHUP))
sl@0: 	    {
sl@0: 	      if (!input_callback (poll_fds[i].fd, write_fds[i]))
sl@0: 		write_fds[i] = -1;
sl@0: 	    }
sl@0: 	}
sl@0: 
sl@0:       if (old_n_active_children > n_active_children)
sl@0: 	{
sl@0: 	  j = 0;
sl@0: 	  for (i=0; i<old_n_active_children; i++)
sl@0: 	    {
sl@0: 	      if (write_fds[i] != -1)
sl@0: 		{
sl@0: 		  if (j < i)
sl@0: 		    {
sl@0: 		      poll_fds[j] = poll_fds[i];
sl@0: 		      write_fds[j] = write_fds[i];
sl@0: 		    }
sl@0: 		  j++;
sl@0: 		}
sl@0: 	    }
sl@0: 	}
sl@0:     }
sl@0: 
sl@0:   getrusage (RUSAGE_SELF, &new_usage);
sl@0: 
sl@0:   printf ("Elapsed user: %g\n",
sl@0: 	   difftimeval (&old_usage.ru_utime, &new_usage.ru_utime));
sl@0:   printf ("Elapsed system: %g\n",
sl@0: 	   difftimeval (&old_usage.ru_stime, &new_usage.ru_stime));
sl@0:   printf ("Elapsed total: %g\n",
sl@0: 	  difftimeval (&old_usage.ru_utime, &new_usage.ru_utime) +	   
sl@0: 	   difftimeval (&old_usage.ru_stime, &new_usage.ru_stime));
sl@0:   printf ("total / iteration: %g\n",
sl@0: 	   (difftimeval (&old_usage.ru_utime, &new_usage.ru_utime) +	   
sl@0: 	    difftimeval (&old_usage.ru_stime, &new_usage.ru_stime)) /
sl@0: 	   (n_iters * n_children));
sl@0: 
sl@0:   return 0;
sl@0: }
sl@0: