Bug 81706 – [BlackBerry] destruction sequence in LayerCompositingThread is confusing

• Component: WebKit BlackBerry
• Status: RESOLVED FIXED

[Joe Mason]

LayerCompositingThread's destructor looks like this:

LayerCompositingThread::~LayerCompositingThread()
{
    // Unfortunately, ThreadSafeShared<T> is hardwired to call T::~T().
    // To switch threads in case the last reference is released on the
    // WebKit thread, we send a sync message to the compositing thread.
    destroyOnCompositingThread();
}

And then destroyOnCompositingThread does a synchronous dispatch to the compositing thread to clean up the object.  It's weird to have a dispatch like this happen from within the destructor, and it's easy to miss the fact that it's synchronous and believe this is a delayed destruction.

It would be much cleaner to flip this around: have ThreadSafeShared<T> call a function called destroyOnCompositingThread, which calls "delete this", and move all the cleanup into the standard destructor.  (Also, this might let us get rid of the sync dispatch and just use a regular dispatch.)

[Joe Mason]

Created attachment 134114 [details]
patch

[Rob Buis]

Comment on attachment 134114 [details]
patch

Looks good.

[WebKit Review Bot]

Comment on attachment 134114 [details]
patch

Clearing flags on attachment: 134114

Committed r112304: <http://trac.webkit.org/changeset/112304>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.