Bug 22380 – Fix WorkerContext refcounting

• Status: RESOLVED
• Resolution: FIXED
• Component: WebCore JavaScript

[Alexey Proskuryakov]

WorkerContext is not currently destroyed when its thread finishes, because its JS wrapper holds a reference to it. We need to clear destroy the JS heap before the thread finishes.

[Alexey Proskuryakov]

Created attachment 25311 [details]
proposed patch

[Darin Adler]

Comment on attachment 25311 [details]
proposed patch

> +    , m_script(new WorkerScriptController(this))

For future consideration: We want to try to avoid bare "new" calls almost everywhere. For single-owner classes, I think a create function that returns auto_ptr is a good design. We can change OwnPtr so it has a constructor that takes an auto_ptr, if it doesn't already have one. For reference counted classes a create function that returns PassRefPtr is obviously our approach.

> +    workerContext->clearScript();
> +    ASSERT(workerContext->refCount() == 1);

I think you should add a comment here explaining why there's a guarantee that no one else is holding a reference. Our usual aim with reference-counted objects is to make the "shutdown" operation be something other than destruction, and always allow someone to prolong the lifetime of the object a bit, just to keep a pointer valid. I know we don't always use reference counting that way, but I think it merits a comment when we're not.

By the way, can you use the hasOneRef() function here instead?

r=me

[Alexey Proskuryakov]

Committed revision 38626.

Added a comment that hopefully clarifies the behavior a little, and changed to hasOneRef, which is better.