src/vm-limit.c

   1 /* Functions for memory limit warnings.
   2    Copyright (C) 1990, 1992, 2001, 2002, 2003, 2004,
   3                  2005, 2006, 2007, 2008  Free Software Foundation, Inc.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs; see the file COPYING.  If not, write to
  19 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  20 Boston, MA 02110-1301, USA.  */
  21
  22 #ifdef emacs
  23 #include <config.h>
  24 #include "lisp.h"
  25 #endif
  26
  27 #ifndef emacs
  28 #include <stddef.h>
  29 typedef size_t SIZE;
  30 typedef void *POINTER;
  31 #define EXCEEDS_LISP_PTR(x) 0
  32 #endif
  33
  34 #include "mem-limits.h"
  35
  36 #ifdef HAVE_GETRLIMIT
  37 #include <sys/resource.h>
  38 #endif
  39
  40 /*
  41   Level number of warnings already issued.
  42   0 -- no warnings issued.
  43   1 -- 75% warning already issued.
  44   2 -- 85% warning already issued.
  45   3 -- 95% warning issued; keep warning frequently.
  46 */
  47 enum warnlevel { not_warned, warned_75, warned_85, warned_95 };
  48
  49 static enum warnlevel warnlevel;
  50
  51 /* Function to call to issue a warning;
  52    0 means don't issue them.  */
  53 static void (*warn_function) ();
  54
  55 /* Start of data space; can be changed by calling malloc_init.  */
  56 static POINTER data_space_start;
  57
  58 /* Number of bytes of writable memory we can expect to be able to get.  */
  59 static unsigned long lim_data;
  60 \f
  61
  62 #ifdef NO_LIM_DATA
  63 static void
  64 get_lim_data ()
  65 {
  66   lim_data = -1;
  67 }
  68 #else /* not NO_LIM_DATA */
  69
  70 #if defined (HAVE_GETRLIMIT) && defined (RLIMIT_AS)
  71 static void
  72 get_lim_data ()
  73 {
  74   struct rlimit rlimit;
  75
  76   getrlimit (RLIMIT_AS, &rlimit);
  77   if (rlimit.rlim_cur == RLIM_INFINITY)
  78     lim_data = -1;
  79   else
  80     lim_data = rlimit.rlim_cur;
  81 }
  82
  83 #else /* not HAVE_GETRLIMIT */
  84
  85 #ifdef USG
  86
  87 static void
  88 get_lim_data ()
  89 {
  90   extern long ulimit ();
  91
  92   lim_data = -1;
  93
  94   /* Use the ulimit call, if we seem to have it.  */
  95 #if !defined (ULIMIT_BREAK_VALUE) || defined (GNU_LINUX)
  96   lim_data = ulimit (3, 0);
  97 #endif
  98
  99   /* If that didn't work, just use the macro's value.  */
 100 #ifdef ULIMIT_BREAK_VALUE
 101   if (lim_data == -1)
 102     lim_data = ULIMIT_BREAK_VALUE;
 103 #endif
 104
 105   lim_data -= (long) data_space_start;
 106 }
 107
 108 #else /* not USG */
 109 #ifdef WINDOWSNT
 110
 111 static void
 112 get_lim_data ()
 113 {
 114   extern unsigned long reserved_heap_size;
 115   lim_data = reserved_heap_size;
 116 }
 117
 118 #else
 119 #if !defined (BSD4_2) && !defined (__osf__)
 120
 121 #ifdef MSDOS
 122 void
 123 get_lim_data ()
 124 {
 125   _go32_dpmi_meminfo info;
 126
 127   _go32_dpmi_get_free_memory_information (&info);
 128   lim_data = info.available_memory;
 129 }
 130 #else /* not MSDOS */
 131 static void
 132 get_lim_data ()
 133 {
 134   lim_data = vlimit (LIM_DATA, -1);
 135 }
 136 #endif /* not MSDOS */
 137
 138 #else /* BSD4_2 */
 139
 140 static void
 141 get_lim_data ()
 142 {
 143   struct rlimit XXrlimit;
 144
 145   getrlimit (RLIMIT_DATA, &XXrlimit);
 146 #ifdef RLIM_INFINITY
 147   lim_data = XXrlimit.rlim_cur & RLIM_INFINITY; /* soft limit */
 148 #else
 149   lim_data = XXrlimit.rlim_cur; /* soft limit */
 150 #endif
 151 }
 152 #endif /* BSD4_2 */
 153 #endif /* not WINDOWSNT */
 154 #endif /* not USG */
 155 #endif /* not HAVE_GETRLIMIT */
 156 #endif /* not NO_LIM_DATA */
 157 \f
 158 /* Verify amount of memory available, complaining if we're near the end. */
 159
 160 static void
 161 check_memory_limits ()
 162 {
 163 #ifdef REL_ALLOC
 164   extern POINTER (*real_morecore) ();
 165 #endif
 166   extern POINTER (*__morecore) ();
 167
 168   register POINTER cp;
 169   unsigned long five_percent;
 170   unsigned long data_size;
 171   enum warnlevel new_warnlevel;
 172
 173   if (lim_data == 0)
 174     get_lim_data ();
 175   five_percent = lim_data / 20;
 176
 177   /* Find current end of memory and issue warning if getting near max */
 178 #ifdef REL_ALLOC
 179   if (real_morecore)
 180     cp = (char *) (*real_morecore) (0);
 181   else
 182 #endif
 183   cp = (char *) (*__morecore) (0);
 184   data_size = (char *) cp - (char *) data_space_start;
 185
 186   if (!warn_function)
 187     return;
 188
 189   /* What level of warning does current memory usage demand?  */
 190   new_warnlevel
 191     = (data_size > five_percent * 19) ? warned_95
 192     : (data_size > five_percent * 17) ? warned_85
 193     : (data_size > five_percent * 15) ? warned_75
 194     : not_warned;
 195
 196   /* If we have gone up a level, give the appropriate warning.  */
 197   if (new_warnlevel > warnlevel || new_warnlevel == warned_95)
 198     {
 199       warnlevel = new_warnlevel;
 200       switch (warnlevel)
 201         {
 202         case warned_75:
 203           (*warn_function) ("Warning: past 75% of memory limit");
 204           break;
 205
 206         case warned_85:
 207           (*warn_function) ("Warning: past 85% of memory limit");
 208           break;
 209
 210         case warned_95:
 211           (*warn_function) ("Warning: past 95% of memory limit");
 212         }
 213     }
 214   /* Handle going down in usage levels, with some hysteresis.  */
 215   else
 216     {
 217       /* If we go down below 70% full, issue another 75% warning
 218          when we go up again.  */
 219       if (data_size < five_percent * 14)
 220         warnlevel = not_warned;
 221       /* If we go down below 80% full, issue another 85% warning
 222          when we go up again.  */
 223       else if (warnlevel > warned_75 && data_size < five_percent * 16)
 224         warnlevel = warned_75;
 225       /* If we go down below 90% full, issue another 95% warning
 226          when we go up again.  */
 227       else if (warnlevel > warned_85 && data_size < five_percent * 18)
 228         warnlevel = warned_85;
 229     }
 230
 231   if (EXCEEDS_LISP_PTR (cp))
 232     (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
 233 }
 234 \f
 235 /* Enable memory usage warnings.
 236    START says where the end of pure storage is.
 237    WARNFUN specifies the function to call to issue a warning.  */
 238
 239 void
 240 memory_warnings (start, warnfun)
 241      POINTER start;
 242      void (*warnfun) ();
 243 {
 244   extern void (* __after_morecore_hook) ();     /* From gmalloc.c */
 245
 246   if (start)
 247     data_space_start = start;
 248   else
 249     data_space_start = start_of_data ();
 250
 251   warn_function = warnfun;
 252   __after_morecore_hook = check_memory_limits;
 253
 254   /* Force data limit to be recalculated on each run.  */
 255   lim_data = 0;
 256 }
 257
 258 /* arch-tag: eab04eda-1f69-447a-8d9f-95f0a3983ca5
 259    (do not change this comment) */