Marius Vollmer wrote:
Han-Wen Nienhuys <[EMAIL PROTECTED]> writes:
I think the right fix is to change the weak hashtable marking
algorithm to properly cope with circular references like this. I will
try this and then come back to you.
Interesting. How would you go about doing that?
The marking would would rougly look like this (some special cases are
not considered, like improper alists):
mark OBJ:
if mark of OBJ is set:
return
set mark of OBJ
if OBJ is a weak vector
put it on POSTPONED_OBJECTS
else
mark references of OBJ
gc:
POSTPONED_OBJECTS = '()
mark all root references
while POSTPONED_OBJECTS not empty
OBJS = POSTPONED_OBJECTS
POSTPONED_OBJECTS = '()
mark_weak_vector all OBJS
sweep
mark_weak_vector OBJ:
for all elements ELT of OBJ:
for all pairs P on list ELT:
if P is marked, break
ITEM = car of P
if ITEM is a pair:
if (OBJ has weak keys and car of ITEM is unmarked)
or (OBJ has weak values and cdr of ITEM is unmarked)
remove P from ELT
what happens if the weak (c[ad]r ITEM) is marked through a postponed
weak vector that you haven't processed yet? Then P is removed
erroneously, or am I missing something?
--
Han-Wen Nienhuys - [EMAIL PROTECTED] - http://www.xs4all.nl/~hanwen
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