Subj : Re: The new changes to atom safety in garbage collection
To   : netscape.public.mozilla.jseng
From : Brendan Eich <brendan@meer.net>
Date : Wed Jul 30 2003 06:52 pm

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Brendan Eich wrote:

> Steven C. Cole wrote:
>
>> Here's my question: Is the "keep atoms" flag also set in other places 
>> where it's not safe to GC them?  In other words, can we go back to 
>> calling the "official" api JS_GC() call from our out-of-memory hooks 
>> (which can happen in resolve hooks or any of the other object hooks), 
>> and remove the "restricted GC" routine that I wrote? 
>
> That's a great idea -- thanks.  We just need the resolve code in 
> js_LookupProperty to farble rt->gcKeepAtoms.  I'm hopeful that's the 
> last place, but I haven't checked.  If you know of other cases where 
> JSClass or JSObjectOps callbacks might be unable to trigger a GC 
> without collecting an atom in use, hit me. 


Try this patch.

/be

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Index: jsobj.c
===================================================================
RCS file: /cvsroot/mozilla/js/src/jsobj.c,v
retrieving revision 3.148
diff -p -u -8 -u -r3.148 jsobj.c
--- jsobj.c	26 Jul 2003 22:37:09 -0000	3.148
+++ jsobj.c	31 Jul 2003 00:47:59 -0000
@@ -2313,19 +2313,24 @@ js_LookupProperty(JSContext *cx, JSObjec
                             (cx->fp->flags & JSFRAME_ASSIGNING)) {
                             flags |= JSRESOLVE_ASSIGNING;
                         }
                     }
                     obj2 = (clasp->flags & JSCLASS_NEW_RESOLVE_GETS_START)
                            ? start
                            : NULL;
                     JS_UNLOCK_OBJ(cx, obj);
+
+                    /* Protect id and all atoms from a GC nested in resolve. */
+                    JS_KEEP_ATOMS(cx->runtime);
                     ok = newresolve(cx, obj, ID_TO_VALUE(id), flags, &obj2);
+                    JS_UNKEEP_ATOMS(cx->runtime);
                     if (!ok)
                         goto cleanup;
+
                     JS_LOCK_OBJ(cx, obj);
                     SET_OBJ_INFO(obj, file, line);
                     if (obj2) {
                         /* Resolved: juggle locks and lookup id again. */
                         if (obj2 != obj) {
                             JS_UNLOCK_OBJ(cx, obj);
                             JS_LOCK_OBJ(cx, obj2);
                         }

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