mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-07-24 11:44:31 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 8

Jack Jansen hit a bug in the new dict code, reported on python-dev.

Browse source 
dictresize() was too aggressive about never ever resizing small dicts.
If a small dict is entirely full, it needs to rebuild it despite that
it won't actually resize it, in order to purge old dummy entries thus
creating at least one virgin slot (lookdict assumes at least one such
exists).

Also took the opportunity to add some high-level comments to dictresize.
This commit is contained in:
Tim Peters 2001-05-23 23:33:57 +00:00
parent a5ca7dd71a
commit 0c6010be75
2 changed files with 43 additions and 9 deletions
Download patch file Download diff file Expand all files Collapse all files

37
Objects/dictobject.c
View file

@ -395,14 +395,15 @@ actually be smaller than the old one.
static int
dictresize(dictobject *mp, int minused)
{
register int newsize, newpoly;
register dictentry *oldtable = mp->ma_table;
register dictentry *newtable;
register dictentry *ep;
register int i;
int newsize, newpoly;
dictentry *oldtable, *newtable, *ep;
int i;
int is_oldtable_malloced;
dictentry small_copy[MINSIZE];
assert(minused >= 0);
assert(oldtable != NULL);
/* Find the smallest table size > minused, and its poly[] entry. */
newpoly = 0;
newsize = MINSIZE;
for (i = 0; i < sizeof(polys)/sizeof(polys[0]); ++i) {
@ -419,10 +420,26 @@ dictresize(dictobject *mp, int minused)
PyErr_NoMemory();
return -1;
}
/* Get space for a new table. */
oldtable = mp->ma_table;
assert(oldtable != NULL);
is_oldtable_malloced = oldtable != mp->ma_smalltable;
if (newsize == MINSIZE) {
/* Either a large table is shrinking, or we can't get any
smaller. */
newtable = mp->ma_smalltable;
if (newtable == oldtable)
return 0;
if (newtable == oldtable) {
if (mp->ma_fill < mp->ma_size)
return 0;
/* The small table is entirely full. We're not
going to resise it, but need to rebuild it
anyway to purge old dummy entries. */
assert(mp->ma_fill > mp->ma_used); /* a dummy exists */
memcpy(small_copy, oldtable, sizeof(small_copy));
oldtable = small_copy;
}
}
else {
newtable = PyMem_NEW(dictentry, newsize);
@ -431,6 +448,8 @@ dictresize(dictobject *mp, int minused)
return -1;
}
}
/* Make the dict empty, using the new table. */
assert(newtable != oldtable);
mp->ma_table = newtable;
mp->ma_size = newsize;
@ -455,7 +474,7 @@ dictresize(dictobject *mp, int minused)
/* else key == value == NULL: nothing to do */
}
if (oldtable != mp->ma_smalltable)
if (is_oldtable_malloced)
PyMem_DEL(oldtable);
return 0;
}