src/vm-limit.c

   1 /* Functions for memory limit warnings.
   2    Copyright (C) 1990, 1992, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
   3                  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 of the License, or
  10 (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifdef emacs
  21 #include <config.h>
  22 #include "lisp.h"
  23 #endif
  24
  25 #ifndef emacs
  26 #include <stddef.h>
  27 typedef size_t SIZE;
  28 typedef void *POINTER;
  29 #define EXCEEDS_LISP_PTR(x) 0
  30 #endif
  31
  32 #include "mem-limits.h"
  33
  34 #ifdef HAVE_GETRLIMIT
  35 #include <sys/resource.h>
  36 #endif
  37
  38 /*
  39   Level number of warnings already issued.
  40   0 -- no warnings issued.
  41   1 -- 75% warning already issued.
  42   2 -- 85% warning already issued.
  43   3 -- 95% warning issued; keep warning frequently.
  44 */
  45 enum warnlevel { not_warned, warned_75, warned_85, warned_95 };
  46
  47 static enum warnlevel warnlevel;
  48
  49 /* Function to call to issue a warning;
  50    0 means don't issue them.  */
  51 static void (*warn_function) ();
  52
  53 /* Start of data space; can be changed by calling malloc_init.  */
  54 static POINTER data_space_start;
  55
  56 /* Number of bytes of writable memory we can expect to be able to get.  */
  57 static unsigned long lim_data;
  58 \f
  59
  60 #ifdef NO_LIM_DATA
  61 static void
  62 get_lim_data ()
  63 {
  64   lim_data = -1;
  65 }
  66 #else /* not NO_LIM_DATA */
  67
  68 #if defined (HAVE_GETRLIMIT) && defined (RLIMIT_AS)
  69 static void
  70 get_lim_data ()
  71 {
  72   struct rlimit rlimit;
  73
  74   getrlimit (RLIMIT_AS, &rlimit);
  75   if (rlimit.rlim_cur == RLIM_INFINITY)
  76     lim_data = -1;
  77   else
  78     lim_data = rlimit.rlim_cur;
  79 }
  80
  81 #else /* not HAVE_GETRLIMIT */
  82
  83 #ifdef USG
  84
  85 static void
  86 get_lim_data ()
  87 {
  88   extern long ulimit ();
  89
  90   lim_data = -1;
  91
  92   /* Use the ulimit call, if we seem to have it.  */
  93 #if !defined (ULIMIT_BREAK_VALUE) || defined (GNU_LINUX)
  94   lim_data = ulimit (3, 0);
  95 #endif
  96
  97   /* If that didn't work, just use the macro's value.  */
  98 #ifdef ULIMIT_BREAK_VALUE
  99   if (lim_data == -1)
 100     lim_data = ULIMIT_BREAK_VALUE;
 101 #endif
 102
 103   lim_data -= (long) data_space_start;
 104 }
 105
 106 #else /* not USG */
 107 #ifdef WINDOWSNT
 108
 109 static void
 110 get_lim_data ()
 111 {
 112   extern unsigned long reserved_heap_size;
 113   lim_data = reserved_heap_size;
 114 }
 115
 116 #else
 117 #if !defined (BSD4_2) && !defined (__osf__)
 118
 119 #ifdef MSDOS
 120 void
 121 get_lim_data ()
 122 {
 123   _go32_dpmi_meminfo info;
 124
 125   _go32_dpmi_get_free_memory_information (&info);
 126   lim_data = info.available_memory;
 127 }
 128 #else /* not MSDOS */
 129 static void
 130 get_lim_data ()
 131 {
 132   lim_data = vlimit (LIM_DATA, -1);
 133 }
 134 #endif /* not MSDOS */
 135
 136 #else /* BSD4_2 */
 137
 138 static void
 139 get_lim_data ()
 140 {
 141   struct rlimit XXrlimit;
 142
 143   getrlimit (RLIMIT_DATA, &XXrlimit);
 144 #ifdef RLIM_INFINITY
 145   lim_data = XXrlimit.rlim_cur & RLIM_INFINITY; /* soft limit */
 146 #else
 147   lim_data = XXrlimit.rlim_cur; /* soft limit */
 148 #endif
 149 }
 150 #endif /* BSD4_2 */
 151 #endif /* not WINDOWSNT */
 152 #endif /* not USG */
 153 #endif /* not HAVE_GETRLIMIT */
 154 #endif /* not NO_LIM_DATA */
 155 \f
 156 /* Verify amount of memory available, complaining if we're near the end. */
 157
 158 static void
 159 check_memory_limits ()
 160 {
 161 #ifdef REL_ALLOC
 162   extern POINTER (*real_morecore) ();
 163 #endif
 164   extern POINTER (*__morecore) ();
 165
 166   register POINTER cp;
 167   unsigned long five_percent;
 168   unsigned long data_size;
 169   enum warnlevel new_warnlevel;
 170
 171   if (lim_data == 0)
 172     get_lim_data ();
 173   five_percent = lim_data / 20;
 174
 175   /* Find current end of memory and issue warning if getting near max */
 176 #ifdef REL_ALLOC
 177   if (real_morecore)
 178     cp = (char *) (*real_morecore) (0);
 179   else
 180 #endif
 181   cp = (char *) (*__morecore) (0);
 182   data_size = (char *) cp - (char *) data_space_start;
 183
 184   if (!warn_function)
 185     return;
 186
 187   /* What level of warning does current memory usage demand?  */
 188   new_warnlevel
 189     = (data_size > five_percent * 19) ? warned_95
 190     : (data_size > five_percent * 17) ? warned_85
 191     : (data_size > five_percent * 15) ? warned_75
 192     : not_warned;
 193
 194   /* If we have gone up a level, give the appropriate warning.  */
 195   if (new_warnlevel > warnlevel || new_warnlevel == warned_95)
 196     {
 197       warnlevel = new_warnlevel;
 198       switch (warnlevel)
 199         {
 200         case warned_75:
 201           (*warn_function) ("Warning: past 75% of memory limit");
 202           break;
 203
 204         case warned_85:
 205           (*warn_function) ("Warning: past 85% of memory limit");
 206           break;
 207
 208         case warned_95:
 209           (*warn_function) ("Warning: past 95% of memory limit");
 210         }
 211     }
 212   /* Handle going down in usage levels, with some hysteresis.  */
 213   else
 214     {
 215       /* If we go down below 70% full, issue another 75% warning
 216          when we go up again.  */
 217       if (data_size < five_percent * 14)
 218         warnlevel = not_warned;
 219       /* If we go down below 80% full, issue another 85% warning
 220          when we go up again.  */
 221       else if (warnlevel > warned_75 && data_size < five_percent * 16)
 222         warnlevel = warned_75;
 223       /* If we go down below 90% full, issue another 95% warning
 224          when we go up again.  */
 225       else if (warnlevel > warned_85 && data_size < five_percent * 18)
 226         warnlevel = warned_85;
 227     }
 228
 229   if (EXCEEDS_LISP_PTR (cp))
 230     (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
 231 }
 232 \f
 233 /* Enable memory usage warnings.
 234    START says where the end of pure storage is.
 235    WARNFUN specifies the function to call to issue a warning.  */
 236
 237 void
 238 memory_warnings (start, warnfun)
 239      POINTER start;
 240      void (*warnfun) ();
 241 {
 242   extern void (* __after_morecore_hook) ();     /* From gmalloc.c */
 243
 244   if (start)
 245     data_space_start = start;
 246   else
 247     data_space_start = start_of_data ();
 248
 249   warn_function = warnfun;
 250   __after_morecore_hook = check_memory_limits;
 251
 252   /* Force data limit to be recalculated on each run.  */
 253   lim_data = 0;
 254 }
 255
 256 /* arch-tag: eab04eda-1f69-447a-8d9f-95f0a3983ca5
 257    (do not change this comment) */