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/* Functions for memory limit warnings.
Copyright (C) 1990, 1992, 2001-2023 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 <https://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
#ifdef HAVE_MALLOC_H
# include <malloc.h>
#endif
#ifndef DOUG_LEA_MALLOC
# ifndef __MALLOC_HOOK_VOLATILE
# define __MALLOC_HOOK_VOLATILE volatile
# endif
extern void *(*__morecore) (ptrdiff_t);
extern void (*__MALLOC_HOOK_VOLATILE __after_morecore_hook) (void);
#endif
/* 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 than 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;
static char const *const warn_diagnostic[] =
{
"Warning: past 75% of memory limit",
"Warning: past 85% of memory limit",
"Warning: past 95% of memory limit"
};
warn_function (warn_diagnostic[warnlevel - 1]);
}
/* 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;
}
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