Do not allow GlobalHandles::Create to reuse destoryed nodes (ones from free l...

Do not allow GlobalHandles::Create to reuse destoryed nodes (ones from free list)
while performing GlobalHandles::PostGarbageCollectionProcessing as those might be already deleted (in C++ sense).


Committed: http://code.google.com/p/v8/source/detail?r=2724

[Mads Ager (chromium), 2009-08-19 17:32:07]

http://codereview.chromium.org/173060/diff/5/6
File src/global-handles.cc (right):

http://codereview.chromium.org/173060/diff/5/6#newcode162
Line 162: set_first_free(NULL);
Doesn't this leak the nodes on the free list?  Shouldn't you traverse the free
list and free the nodes before you set first free to NULL?

[antonm, 2009-08-19 17:39:32]

http://codereview.chromium.org/173060/diff/5/6
File src/global-handles.cc (right):

http://codereview.chromium.org/173060/diff/5/6#newcode162
Line 162: set_first_free(NULL);
On 2009/08/19 17:32:07, Mads Ager wrote:
> Doesn't this leak the nodes on the free list?  Shouldn't you traverse the free
> list and free the nodes before you set first free to NULL?

I don't think so.  To the best of my knowledge we don't use first_free_ pointer
while cleaning up the list---destroyed nodes are spotted while traversing the
whole list (fyi, I've experimented w/ other approaches, but they buy us nothing
for DOM performance).  Does that sound reasonable?

And just an observation: DESTROYED nodes could 'leak' both before and with my
patch if you destroy node already traversed, but they should be cleaned up on
next path.

[Mads Ager (chromium), 2009-08-19 18:32:01]

LGTM

I get it now.  Nodes are added to the free_list when the global handle is
explictly Disposed through the API.  The actual nodes are delete in the post GC
processing.

Thanks for the additional explanation. :-)