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   unsigned long lim1, lim2;
 125
 126   _go32_dpmi_get_free_memory_information (&info);
 127   /* DPMI server of Windows NT and its descendants reports in
 128      info.available_memory a much lower amount that is really
 129      available, which causes bogus "past 95% of memory limit"
 130      warnings.  Try to overcome that via circumstantial evidence.  */
 131   lim1 = info.available_memory;
 132   lim2 = info.available_physical_pages;
 133   /* DPMI Spec: "Fields that are unavailable will hold -1."  */
 134   if ((long)lim1 == -1L)
 135     lim1 = 0;
 136   if ((long)lim2 == -1L)
 137     lim2 = 0;
 138   else
 139     lim2 *= 4096;
 140   /* Surely, the available memory is at least what we have physically
 141      available, right?  */
 142   if (lim1 >= lim2)
 143     lim_data = lim1;
 144   else
 145     lim_data = lim2;
 146   /* Don't believe they will give us more that 0.5 GB.   */
 147   if (lim_data > 512U * 1024U * 1024U)
 148     lim_data = 512U * 1024U * 1024U;
 149 }
 150 #else /* not MSDOS */
 151 static void
 152 get_lim_data ()
 153 {
 154   lim_data = vlimit (LIM_DATA, -1);
 155 }
 156 #endif /* not MSDOS */
 157
 158 #else /* BSD4_2 */
 159
 160 static void
 161 get_lim_data ()
 162 {
 163   struct rlimit XXrlimit;
 164
 165   getrlimit (RLIMIT_DATA, &XXrlimit);
 166 #ifdef RLIM_INFINITY
 167   lim_data = XXrlimit.rlim_cur & RLIM_INFINITY; /* soft limit */
 168 #else
 169   lim_data = XXrlimit.rlim_cur; /* soft limit */
 170 #endif
 171 }
 172 #endif /* BSD4_2 */
 173 #endif /* not WINDOWSNT */
 174 #endif /* not USG */
 175 #endif /* not HAVE_GETRLIMIT */
 176 #endif /* not NO_LIM_DATA */
 177 \f
 178 /* Verify amount of memory available, complaining if we're near the end. */
 179
 180 static void
 181 check_memory_limits ()
 182 {
 183 #ifdef REL_ALLOC
 184   extern POINTER (*real_morecore) ();
 185 #endif
 186   extern POINTER (*__morecore) ();
 187
 188   register POINTER cp;
 189   unsigned long five_percent;
 190   unsigned long data_size;
 191   enum warnlevel new_warnlevel;
 192
 193   if (lim_data == 0)
 194     get_lim_data ();
 195   five_percent = lim_data / 20;
 196
 197   /* Find current end of memory and issue warning if getting near max */
 198 #ifdef REL_ALLOC
 199   if (real_morecore)
 200     cp = (char *) (*real_morecore) (0);
 201   else
 202 #endif
 203   cp = (char *) (*__morecore) (0);
 204   data_size = (char *) cp - (char *) data_space_start;
 205
 206   if (!warn_function)
 207     return;
 208
 209   /* What level of warning does current memory usage demand?  */
 210   new_warnlevel
 211     = (data_size > five_percent * 19) ? warned_95
 212     : (data_size > five_percent * 17) ? warned_85
 213     : (data_size > five_percent * 15) ? warned_75
 214     : not_warned;
 215
 216   /* If we have gone up a level, give the appropriate warning.  */
 217   if (new_warnlevel > warnlevel || new_warnlevel == warned_95)
 218     {
 219       warnlevel = new_warnlevel;
 220       switch (warnlevel)
 221         {
 222         case warned_75:
 223           (*warn_function) ("Warning: past 75% of memory limit");
 224           break;
 225
 226         case warned_85:
 227           (*warn_function) ("Warning: past 85% of memory limit");
 228           break;
 229
 230         case warned_95:
 231           (*warn_function) ("Warning: past 95% of memory limit");
 232         }
 233     }
 234   /* Handle going down in usage levels, with some hysteresis.  */
 235   else
 236     {
 237       /* If we go down below 70% full, issue another 75% warning
 238          when we go up again.  */
 239       if (data_size < five_percent * 14)
 240         warnlevel = not_warned;
 241       /* If we go down below 80% full, issue another 85% warning
 242          when we go up again.  */
 243       else if (warnlevel > warned_75 && data_size < five_percent * 16)
 244         warnlevel = warned_75;
 245       /* If we go down below 90% full, issue another 95% warning
 246          when we go up again.  */
 247       else if (warnlevel > warned_85 && data_size < five_percent * 18)
 248         warnlevel = warned_85;
 249     }
 250
 251   if (EXCEEDS_LISP_PTR (cp))
 252     (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
 253 }
 254 \f
 255 /* Enable memory usage warnings.
 256    START says where the end of pure storage is.
 257    WARNFUN specifies the function to call to issue a warning.  */
 258
 259 void
 260 memory_warnings (start, warnfun)
 261      POINTER start;
 262      void (*warnfun) ();
 263 {
 264   extern void (* __after_morecore_hook) ();     /* From gmalloc.c */
 265
 266   if (start)
 267     data_space_start = start;
 268   else
 269     data_space_start = start_of_data ();
 270
 271   warn_function = warnfun;
 272   __after_morecore_hook = check_memory_limits;
 273
 274   /* Force data limit to be recalculated on each run.  */
 275   lim_data = 0;
 276 }
 277
 278 /* arch-tag: eab04eda-1f69-447a-8d9f-95f0a3983ca5
 279    (do not change this comment) */