Bug 80549 – [MutationObservers] Enforce a consistent order of MutationRecord delivery

• Status: RESOLVED
• Resolution: FIXED
• Component: New Bugs

[Adam Klein]

[MutationObservers] Enforce a consistent order of MutationRecord delivery

[Adam Klein]

Created attachment 130713 [details]
Patch

[Adam Klein]

The exact ordering is currently specified in http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#concept-mo-invoke, but I've suggested a change to the algorithm to match this patch in http://lists.w3.org/Archives/Public/www-dom/2012JanMar/0145.html.

[Adam Klein]

This is now ready for review.

[Ojan Vafai]

Comment on attachment 130713 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=130713&action=review

> Source/WebCore/dom/WebKitMutationObserver.h:98
> +    int m_priority;

Are you at all worried about overflow? At the least, this should probably be unsigned, no?

[Adam Klein]

Comment on attachment 130713 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=130713&action=review

>> Source/WebCore/dom/WebKitMutationObserver.h:98
>> +    int m_priority;
> 
> Are you at all worried about overflow? At the least, this should probably be unsigned, no?

I find it unlikely that a renderer would behave reasonably having created 2 billion mutation observers. Making it unsigned doesn't help much (if you've already created 2 billion, why not another 2 billion?).

If you think this is something that we should worry about, perhaps a completely different implementation (something better matching the spec, perhaps) could be in order: keeping a list of all living mutation observers, and iterating over that for delivery. But that will behave poorly if we have lots of observers only a few of which are active at a time.

[Adam Klein]

Comment on attachment 130713 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=130713&action=review

>>> Source/WebCore/dom/WebKitMutationObserver.h:98
>>> +    int m_priority;
>> 
>> Are you at all worried about overflow? At the least, this should probably be unsigned, no?
> 
> I find it unlikely that a renderer would behave reasonably having created 2 billion mutation observers. Making it unsigned doesn't help much (if you've already created 2 billion, why not another 2 billion?).
> 
> If you think this is something that we should worry about, perhaps a completely different implementation (something better matching the spec, perhaps) could be in order: keeping a list of all living mutation observers, and iterating over that for delivery. But that will behave poorly if we have lots of observers only a few of which are active at a time.

As per offline discussion, making this unsigned and punting overflow.

[Adam Klein]

Created attachment 131378 [details]
Patch for landing

[WebKit Review Bot]

Comment on attachment 131378 [details]
Patch for landing

Clearing flags on attachment: 131378

Committed r110465: <http://trac.webkit.org/changeset/110465>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.

[Adam Klein]

*** Bug 79710 has been marked as a duplicate of this bug. ***