emacs / src / vm-limit.c

/* Functions for memory limit warnings.
   Copyright (C) 1990, 1992, 2002, 2003, 2004,
                 2005, 2006 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.  */

#ifdef emacs
#include <config.h>
#include "lisp.h"
#endif

#ifndef emacs
#include <stddef.h>
typedef size_t SIZE;
typedef void *POINTER;
#define EXCEEDS_LISP_PTR(x) 0
#endif

#include "mem-limits.h"

#ifdef HAVE_GETRLIMIT
#include <sys/resource.h>
#endif

/*
  Level number of warnings already issued.
  0 -- no warnings issued.
  1 -- 75% warning already issued.
  2 -- 85% warning already issued.
  3 -- 95% warning issued; keep warning frequently.
*/
enum warnlevel { not_warned, warned_75, warned_85, warned_95 };

static enum warnlevel warnlevel;

/* Function to call to issue a warning;
   0 means don't issue them.  */
static void (*warn_function) ();

/* Start of data space; can be changed by calling malloc_init.  */
static POINTER data_space_start;

/* Number of bytes of writable memory we can expect to be able to get.  */
static unsigned long lim_data;


#ifdef NO_LIM_DATA
static void
get_lim_data ()
{
  lim_data = -1;
}
#else /* not NO_LIM_DATA */

#ifdef USG

static void
get_lim_data ()
{
  extern long ulimit ();

  lim_data = -1;

  /* Use the ulimit call, if we seem to have it.  */
#if !defined (ULIMIT_BREAK_VALUE) || defined (GNU_LINUX)
  lim_data = ulimit (3, 0);
#endif

  /* If that didn't work, just use the macro's value.  */
#ifdef ULIMIT_BREAK_VALUE
  if (lim_data == -1)
    lim_data = ULIMIT_BREAK_VALUE;
#endif

  lim_data -= (long) data_space_start;
}

#else /* not USG */
#ifdef WINDOWSNT

static void
get_lim_data ()
{
  extern unsigned long reserved_heap_size;
  lim_data = reserved_heap_size;
}

#else
#if !defined (BSD4_2) && !defined (__osf__)

#ifdef MSDOS
void
get_lim_data ()
{
  _go32_dpmi_meminfo info;

  _go32_dpmi_get_free_memory_information (&info);
  lim_data = info.available_memory;
}
#else /* not MSDOS */
static void
get_lim_data ()
{
  lim_data = vlimit (LIM_DATA, -1);
}
#endif /* not MSDOS */

#else /* BSD4_2 */

static void
get_lim_data ()
{
  struct rlimit XXrlimit;

  getrlimit (RLIMIT_DATA, &XXrlimit);
#ifdef RLIM_INFINITY
  lim_data = XXrlimit.rlim_cur & RLIM_INFINITY; /* soft limit */
#else
  lim_data = XXrlimit.rlim_cur;	/* soft limit */
#endif
}
#endif /* BSD4_2 */
#endif /* not WINDOWSNT */
#endif /* not USG */
#endif /* not NO_LIM_DATA */

/* Verify amount of memory available, complaining if we're near the end. */

static void
check_memory_limits ()
{
#ifdef REL_ALLOC
  extern POINTER (*real_morecore) ();
#endif
  extern POINTER (*__morecore) ();


  register POINTER cp;
  unsigned long five_percent;
  unsigned long data_size;
  enum warnlevel new_warnlevel;

#ifdef HAVE_GETRLIMIT
  struct rlimit rlimit;

  getrlimit (RLIMIT_AS, &rlimit);

  if (RLIM_INFINITY == rlimit.rlim_max)
    return;

  /* This is a nonsensical case, but it happens -- rms.  */
  if (rlimit.rlim_cur > rlimit.rlim_max)
    return;

  five_percent = rlimit.rlim_max / 20;
  data_size = rlimit.rlim_cur;

#else /* not HAVE_GETRLIMIT */

  if (lim_data == 0)
    get_lim_data ();
  five_percent = lim_data / 20;

  /* Find current end of memory and issue warning if getting near max */
#ifdef REL_ALLOC
  if (real_morecore)
    cp = (char *) (*real_morecore) (0);
  else
#endif
  cp = (char *) (*__morecore) (0);
  data_size = (char *) cp - (char *) data_space_start;

#endif /* not HAVE_GETRLIMIT */

  if (!warn_function)
    return;

  /* What level of warning does current memory usage demand?  */
  if (data_size > five_percent * 19)
    new_warnlevel = warned_95;
  else if (data_size > five_percent * 17)
    new_warnlevel = warned_85;
  else if (data_size > five_percent * 15)
    new_warnlevel = warned_75;
  else
    new_warnlevel = not_warned;

  /* If we have gone up a level, give the appropriate warning.  */
  if (new_warnlevel > warnlevel || new_warnlevel == warned_95)
    {
      warnlevel = new_warnlevel;
      switch (warnlevel)
	{
	case warned_75:
	  (*warn_function) ("Warning: past 75% of memory limit");
	  break;

	case warned_85:
	  (*warn_function) ("Warning: past 85% of memory limit");
	  break;

	case warned_95:
	  (*warn_function) ("Warning: past 95% of memory limit");
	}
    }
  /* Handle going down in usage levels, with some hysteresis.  */
  else
    {
      /* If we go down below 70% full, issue another 75% warning
	 when we go up again.  */
      if (data_size < five_percent * 14)
	warnlevel = not_warned;
      /* If we go down below 80% full, issue another 85% warning
	 when we go up again.  */
      else if (warnlevel > warned_75 && data_size < five_percent * 16)
	warnlevel = warned_75;
      /* If we go down below 90% full, issue another 95% warning
	 when we go up again.  */
      else if (warnlevel > warned_85 && data_size < five_percent * 18)
	warnlevel = warned_85;
    }

  if (EXCEEDS_LISP_PTR (cp))
    (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
}

/* Enable memory usage warnings.
   START says where the end of pure storage is.
   WARNFUN specifies the function to call to issue a warning.  */

void
memory_warnings (start, warnfun)
     POINTER start;
     void (*warnfun) ();
{
  extern void (* __after_morecore_hook) ();     /* From gmalloc.c */

  if (start)
    data_space_start = start;
  else
    data_space_start = start_of_data ();

  warn_function = warnfun;
  __after_morecore_hook = check_memory_limits;

  /* Force data limit to be recalculated on each run.  */
  lim_data = 0;
}

/* arch-tag: eab04eda-1f69-447a-8d9f-95f0a3983ca5
   (do not change this comment) */
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