Re: [PATCH v2] Associate target_ops with target_fileio file descriptors

[Pedro Alves <palves at redhat dot com>]

On 03/24/2015 04:36 PM, Pedro Alves wrote:
>   /* Push a new handle if no closed handles were found.  */
>   if (lowest_closed_fd == VEC_length (fileio_fh_t, fileio_fhandles))
>     {
>       fh = VEC_safe_push (fileio_fh_t, fileio_fhandles, NULL);
>       lowest_closed_fd++;
>     }

Make this:

   /* Push a new handle if no closed handles were found.  */
   if (lowest_closed_fd == VEC_length (fileio_fh_t, fileio_fhandles))
     fh = VEC_safe_push (fileio_fh_t, fileio_fhandles, NULL);

   lowest_closed_fd++;

Because there's no point in starting the next lookup at the
handle we just opened if we're reusing a slot, either.  And then
that allows getting rid of the VEC_address, by simply doing
that increment at the end:

/* Index into fileio_fhandles of the lowest handle that might be
   closed.  This permits handle reuse without searching the whole list
   each time a new file is opened.  */
static int lowest_closed_fd = 0;

static int
acquire_fileio_fd (struct target_ops *t, int fd)
{
  fileio_fh_t *fh, buf;

  gdb_assert (!is_closed_fileio_fh (fd));

  /* Search for closed handles to reuse.  */
  for (;
       VEC_iterate (fileio_fh_t, fileio_fhandles,
		    lowest_closed_fd, fh);
       lowest_closed_fd++)
    if (is_closed_fileio_fh (fh->fd))
      break;

   /* Push a new handle if no closed handles were found.  */
   if (lowest_closed_fd == VEC_length (fileio_fh_t, fileio_fhandles))
     fh = VEC_safe_push (fileio_fh_t, fileio_fhandles, NULL);

  /* Fill in the handle.  */
  fh->t = t;
  fh->fd = fd;

  /* Return its index, and start the next lookup at
     the next index.  */
  return lowest_closed_fd++;
}