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Fix bug when gc-cons-percentage is bumped to 0.8

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Problem reported by Michael Heerdegen (Bug#37321).
* src/alloc.c (gc_threshold): New static var.
(bump_consing_until_gc): Change args from DIFF to THRESHOLD and
PERCENTAGE.  All uses changed.  When accounting for a changed
gc-cons-percentage, do not assume that total_bytes_of_live_objects
returns the same value now that it did the last time we were
called.
This commit is contained in:
Paul Eggert 2019-09-07 18:08:12 -07:00
parent 8e93e6da7c
commit b6b7c7fc98
1 changed files with 28 additions and 17 deletions
Download patch file Download diff file Expand all files Collapse all files

45
src/alloc.c
View file

@ -297,6 +297,10 @@ static ptrdiff_t pure_bytes_used_non_lisp;
static intptr_t garbage_collection_inhibited;
/* The GC threshold in bytes, the last time it was calculated
from gc-cons-threshold and gc-cons-percentage. */
static intmax_t gc_threshold;
/* If nonzero, this is a warning delivered by malloc and not yet
displayed. */
@ -5808,15 +5812,28 @@ consing_threshold (intmax_t threshold, Lisp_Object percentage)
}
}
/* Increment consing_until_gc by DIFF, avoiding overflow. */
/* Adjust consing_until_gc, assuming gc-cons-threshold is THRESHOLD and
gc-cons-percentage is PERCENTAGE. */
static Lisp_Object
bump_consing_until_gc (intmax_t diff)
bump_consing_until_gc (intmax_t threshold, Lisp_Object percentage)
{
/* If consing_until_gc is negative leave it alone, since this prevents
negative integer overflow and a GC would have been done soon anyway. */
if (0 <= consing_until_gc
&& INT_ADD_WRAPV (consing_until_gc, diff, &consing_until_gc))
consing_until_gc = INTMAX_MAX;
if (0 <= consing_until_gc)
{
threshold = consing_threshold (threshold, percentage);
intmax_t sum;
if (INT_ADD_WRAPV (consing_until_gc, threshold - gc_threshold, &sum))
{
/* Scale the threshold down so that consing_until_gc does
not overflow. */
sum = INTMAX_MAX;
threshold = INTMAX_MAX - consing_until_gc + gc_threshold;
}
consing_until_gc = sum;
gc_threshold = threshold;
}
return Qnil;
}
@ -5825,13 +5842,10 @@ static Lisp_Object
watch_gc_cons_threshold (Lisp_Object symbol, Lisp_Object newval,
Lisp_Object operation, Lisp_Object where)
{
Lisp_Object percentage = Vgc_cons_percentage;
intmax_t threshold;
intmax_t diff = (INTEGERP (newval) && integer_to_intmax (newval, &threshold)
? (consing_threshold (threshold, percentage)
- consing_threshold (gc_cons_threshold, percentage))
: 0);
return bump_consing_until_gc (diff);
if (! (INTEGERP (newval) && integer_to_intmax (newval, &threshold)))
return Qnil;
return bump_consing_until_gc (threshold, Vgc_cons_percentage);
}
/* Watch changes to gc-cons-percentage. */
@ -5839,10 +5853,7 @@ static Lisp_Object
watch_gc_cons_percentage (Lisp_Object symbol, Lisp_Object newval,
Lisp_Object operation, Lisp_Object where)
{
intmax_t threshold = gc_cons_threshold;
intmax_t diff = (consing_threshold (threshold, newval)
- consing_threshold (threshold, Vgc_cons_percentage));
return bump_consing_until_gc (diff);
return bump_consing_until_gc (gc_cons_threshold, newval);
}
/* Subroutine of Fgarbage_collect that does most of the work. */
@ -5987,8 +5998,8 @@ garbage_collect_1 (struct gcstat *gcst)
unblock_input ();
consing_until_gc = consing_threshold (gc_cons_threshold,
Vgc_cons_percentage);
consing_until_gc = gc_threshold
= consing_threshold (gc_cons_threshold, Vgc_cons_percentage);
if (garbage_collection_messages && NILP (Vmemory_full))
{