summaryrefslogtreecommitdiff
path: root/src/vm-limit.c
blob: ab102e32623321ca3d2a12bf36eb4a51d61635f1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
/* Functions for memory limit warnings.
   Copyright (C) 1990, 1992, 2001-2015 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>
#include <unistd.h> /* for 'environ', on AIX */
#include "lisp.h"

#ifdef MSDOS
#include "dosfns.h"
extern int etext;
#endif

/* Some systems need this before <sys/resource.h>.  */
#include <sys/types.h>

#ifdef HAVE_SYS_RESOURCE_H
# include <sys/time.h>
# include <sys/resource.h>
#else
# if HAVE_SYS_VLIMIT_H
#  include <sys/vlimit.h>	/* Obsolete, says glibc */
# endif
#endif

/* Start of data.  It is OK if this is approximate; it's used only as
   a heuristic.  */
#ifdef DATA_START
# define data_start ((char *) DATA_START)
#else
extern char data_start[];
# ifndef HAVE_DATA_START
/* Initialize to nonzero, so that it's put into data and not bss.
   Link this file's object code first, so that this symbol is near the
   start of data.  */
char data_start[1] = { 1 };
# endif
#endif

/* From gmalloc.c.  */
extern void (* __after_morecore_hook) (void);
extern void *(*__morecore) (ptrdiff_t);

/* From ralloc.c.  */
#ifdef REL_ALLOC
extern void *(*real_morecore) (ptrdiff_t);
#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) (const char *);

/* Start of data space; can be changed by calling memory_warnings.  */
static char *data_space_start;

/* Number of bytes of writable memory we can expect to be able to get.  */
static size_t lim_data;

#ifdef HAVE_GETRLIMIT

# ifndef RLIMIT_AS
#  define RLIMIT_AS RLIMIT_DATA
# endif

static void
get_lim_data (void)
{
  /* Set LIM_DATA to the minimum of the maximum object size and the
     maximum address space.  Don't bother to check for values like
     RLIM_INFINITY since in practice they are not much less than SIZE_MAX.  */
  struct rlimit rlimit;
  lim_data
    = (getrlimit (RLIMIT_AS, &rlimit) == 0 && rlimit.rlim_cur <= SIZE_MAX
       ? rlimit.rlim_cur
       : SIZE_MAX);
}

#elif defined WINDOWSNT

#include "w32heap.h"

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

#elif defined MSDOS

void
get_lim_data (void)
{
  unsigned long totalram, freeram, totalswap, freeswap;

  dos_memory_info (&totalram, &freeram, &totalswap, &freeswap);
  lim_data = freeram;
  /* Don't believe they will give us more that 0.5 GB.   */
  if (lim_data > 512U * 1024U * 1024U)
    lim_data = 512U * 1024U * 1024U;
}

unsigned long
ret_lim_data (void)
{
  get_lim_data ();
  return lim_data;
}
#else
# error "get_lim_data not implemented on this machine"
#endif

/* Verify amount of memory available, complaining if we're near the end. */

static void
check_memory_limits (void)
{
#ifndef REL_ALLOC
  void *(*real_morecore) (ptrdiff_t) = 0;
#endif

  char *cp;
  size_t five_percent;
  size_t data_size;
  enum warnlevel new_warnlevel;

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

  /* Find current end of memory and issue warning if getting near max */
  cp = (real_morecore ? real_morecore : __morecore) (0);
  data_size = cp - data_space_start;

  if (!warn_function)
    return;

  /* What level of warning does current memory usage demand?  */
  new_warnlevel
    = (data_size > five_percent * 19) ? warned_95
    : (data_size > five_percent * 17) ? warned_85
    : (data_size > five_percent * 15) ? warned_75
    : 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;
    }
}

/* 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 (void *start, void (*warnfun) (const char *))
{
  data_space_start = start ? start : data_start;

  warn_function = warnfun;
  __after_morecore_hook = check_memory_limits;

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