1 /* Functions for memory limit warnings.
  2    Copyright (C) 1990, 1992, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
  3                  2008, 2009, 2010  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 <setjmp.h>
 23 #include "lisp.h"
 24 #endif
 25 
 26 #ifndef emacs
 27 #include <stddef.h>
 28 typedef size_t SIZE;
 29 typedef void *POINTER;
 30 #define EXCEEDS_LISP_PTR(x) 0
 31 #endif
 32 
 33 #include "mem-limits.h"
 34 
 35 #ifdef HAVE_GETRLIMIT
 36 #include <sys/resource.h>
 37 #endif
 38 
 39 /*
 40   Level number of warnings already issued.
 41   0 -- no warnings issued.
 42   1 -- 75% warning already issued.
 43   2 -- 85% warning already issued.
 44   3 -- 95% warning issued; keep warning frequently.
 45 */
 46 enum warnlevel { not_warned, warned_75, warned_85, warned_95 };
 47 
 48 static enum warnlevel warnlevel;
 49 
 50 /* Function to call to issue a warning;
 51    0 means don't issue them.  */
 52 static void (*warn_function) ();
 53 
 54 /* Start of data space; can be changed by calling malloc_init.  */
 55 static POINTER data_space_start;
 56 
 57 /* Number of bytes of writable memory we can expect to be able to get.  */
 58 static unsigned long lim_data;
 59 
 60 
 61 #ifdef NO_LIM_DATA
 62 static void
 63 get_lim_data ()
 64 {
 65   lim_data = -1;
 66 }
 67 #else /* not NO_LIM_DATA */
 68 
 69 #if defined (HAVE_GETRLIMIT) && defined (RLIMIT_AS)
 70 static void
 71 get_lim_data ()
 72 {
 73   struct rlimit rlimit;
 74 
 75   getrlimit (RLIMIT_AS, &rlimit);
 76   if (rlimit.rlim_cur == RLIM_INFINITY)
 77     lim_data = -1;
 78   else
 79     lim_data = rlimit.rlim_cur;
 80 }
 81 
 82 #else /* not HAVE_GETRLIMIT */
 83 
 84 #ifdef USG
 85 
 86 static void
 87 get_lim_data ()
 88 {
 89   extern long ulimit ();
 90 
 91   lim_data = -1;
 92 
 93   /* Use the ulimit call, if we seem to have it.  */
 94 #if !defined (ULIMIT_BREAK_VALUE) || defined (GNU_LINUX)
 95   lim_data = ulimit (3, 0);
 96 #endif
 97 
 98   /* If that didn't work, just use the macro's value.  */
 99 #ifdef ULIMIT_BREAK_VALUE
100   if (lim_data == -1)
101     lim_data = ULIMIT_BREAK_VALUE;
102 #endif
103 
104   lim_data -= (long) data_space_start;
105 }
106 
107 #else /* not USG */
108 #ifdef WINDOWSNT
109 
110 static void
111 get_lim_data ()
112 {
113   extern unsigned long reserved_heap_size;
114   lim_data = reserved_heap_size;
115 }
116 
117 #else
118 #if !defined (BSD4_2) && !defined (__osf__)
119 
120 #ifdef MSDOS
121 void
122 get_lim_data ()
123 {
124   _go32_dpmi_meminfo info;
125   unsigned long lim1, lim2;
126 
127   _go32_dpmi_get_free_memory_information (&info);
128   /* DPMI server of Windows NT and its descendants reports in
129      info.available_memory a much lower amount that is really
130      available, which causes bogus "past 95% of memory limit"
131      warnings.  Try to overcome that via circumstantial evidence.  */
132   lim1 = info.available_memory;
133   lim2 = info.available_physical_pages;
134   /* DPMI Spec: "Fields that are unavailable will hold -1."  */
135   if ((long)lim1 == -1L)
136     lim1 = 0;
137   if ((long)lim2 == -1L)
138     lim2 = 0;
139   else
140     lim2 *= 4096;
141   /* Surely, the available memory is at least what we have physically
142      available, right?  */
143   if (lim1 >= lim2)
144     lim_data = lim1;
145   else
146     lim_data = lim2;
147   /* Don't believe they will give us more that 0.5 GB.   */
148   if (lim_data > 512U * 1024U * 1024U)
149     lim_data = 512U * 1024U * 1024U;
150 }
151 
152 unsigned long
153 ret_lim_data ()
154 {
155   get_lim_data ();
156   return lim_data;
157 }
158 #else /* not MSDOS */
159 static void
160 get_lim_data ()
161 {
162   lim_data = vlimit (LIM_DATA, -1);
163 }
164 #endif /* not MSDOS */
165 
166 #else /* BSD4_2 */
167 
168 static void
169 get_lim_data ()
170 {
171   struct rlimit XXrlimit;
172 
173   getrlimit (RLIMIT_DATA, &XXrlimit);
174 #ifdef RLIM_INFINITY
175   lim_data = XXrlimit.rlim_cur & RLIM_INFINITY; /* soft limit */
176 #else
177   lim_data = XXrlimit.rlim_cur; /* soft limit */
178 #endif
179 }
180 #endif /* BSD4_2 */
181 #endif /* not WINDOWSNT */
182 #endif /* not USG */
183 #endif /* not HAVE_GETRLIMIT */
184 #endif /* not NO_LIM_DATA */
185 
186 /* Verify amount of memory available, complaining if we're near the end. */
187 
188 static void
189 check_memory_limits ()
190 {
191 #ifdef REL_ALLOC
192   extern POINTER (*real_morecore) ();
193 #endif
194   extern POINTER (*__morecore) ();
195 
196   register POINTER cp;
197   unsigned long five_percent;
198   unsigned long data_size;
199   enum warnlevel new_warnlevel;
200 
201   if (lim_data == 0)
202     get_lim_data ();
203   five_percent = lim_data / 20;
204 
205   /* Find current end of memory and issue warning if getting near max */
206 #ifdef REL_ALLOC
207   if (real_morecore)
208     cp = (char *) (*real_morecore) (0);
209   else
210 #endif
211   cp = (char *) (*__morecore) (0);
212   data_size = (char *) cp - (char *) data_space_start;
213 
214   if (!warn_function)
215     return;
216 
217   /* What level of warning does current memory usage demand?  */
218   new_warnlevel
219     = (data_size > five_percent * 19) ? warned_95
220     : (data_size > five_percent * 17) ? warned_85
221     : (data_size > five_percent * 15) ? warned_75
222     : not_warned;
223 
224   /* If we have gone up a level, give the appropriate warning.  */
225   if (new_warnlevel > warnlevel || new_warnlevel == warned_95)
226     {
227       warnlevel = new_warnlevel;
228       switch (warnlevel)
229         {
230         case warned_75:
231           (*warn_function) ("Warning: past 75% of memory limit");
232           break;
233 
234         case warned_85:
235           (*warn_function) ("Warning: past 85% of memory limit");
236           break;
237 
238         case warned_95:
239           (*warn_function) ("Warning: past 95% of memory limit");
240         }
241     }
242   /* Handle going down in usage levels, with some hysteresis.  */
243   else
244     {
245       /* If we go down below 70% full, issue another 75% warning
246          when we go up again.  */
247       if (data_size < five_percent * 14)
248         warnlevel = not_warned;
249       /* If we go down below 80% full, issue another 85% warning
250          when we go up again.  */
251       else if (warnlevel > warned_75 && data_size < five_percent * 16)
252         warnlevel = warned_75;
253       /* If we go down below 90% full, issue another 95% warning
254          when we go up again.  */
255       else if (warnlevel > warned_85 && data_size < five_percent * 18)
256         warnlevel = warned_85;
257     }
258 
259   if (EXCEEDS_LISP_PTR (cp))
260     (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
261 }
262 
263 /* Enable memory usage warnings.
264    START says where the end of pure storage is.
265    WARNFUN specifies the function to call to issue a warning.  */
266 
267 void
268 memory_warnings (start, warnfun)
269      POINTER start;
270      void (*warnfun) ();
271 {
272   extern void (* __after_morecore_hook) ();     /* From gmalloc.c */
273 
274   if (start)
275     data_space_start = start;
276   else
277     data_space_start = start_of_data ();
278 
279   warn_function = warnfun;
280   __after_morecore_hook = check_memory_limits;
281 
282   /* Force data limit to be recalculated on each run.  */
283   lim_data = 0;
284 }
285 
286 /* arch-tag: eab04eda-1f69-447a-8d9f-95f0a3983ca5
287    (do not change this comment) */