1131801 - remove use of parent in XPCWrappedNative's RescueOrphans

Status: RESOLVED FIXED

(Core :: XPConnect, defect)

Description

[Steve Fink [:sfink] [:s:]]

Split out from bug 805052, item 12: RescueOrphans in XPCWrappedNative, which has a cross-compartment wrapper as parent??

Comment 1

[Boris Zbarsky [:bzbarsky]]

OK, so RescueOrphans is meant to deal with an XPCWrappedNative whose parent gets reparented.

For an XPCWrappedNative to have an interesting (non-global-object) parent, it needs to have a PreCreate hook.

We have the following PreCreate hooks in our codebase:

1) nsDOMConstructorSH::PreCreate, which calls nsDOMConstructor::PreCreate, which does SetParentToWindow(win, parentObj), so the parent always ends up being a window.

2) nsEventTargetSH::PreCreate which does:

   *parentObj = native_parent ? native_parent->GetGlobalJSObject() : globalObj;

where native_parent is an nsIScriptGlobalObject and globalObj is the aGlobalObj that was passed in.

3) nsDOMClassInfo::PreCreate, which does "*parentObj = globalObj;".

4) ComponentsSH::PreCreate, which does:

  *parentObj = self->GetScope()->GetGlobalJSObject();

5)  BackstagePass::PreCreate which sets *parentObj to global->GetGlobalJSObject(), where global is an nsIGlobalObject.

That's it.  So the parent always ends up being a global, and those of course never get reparented.

Given that, we can just kill off RescueOrphans entirely.

Comment 2

[Boris Zbarsky [:bzbarsky]]

Attachment: part 1. Get rid of the now-unnecessary RescueOrphans function

Comment 3

[Boris Zbarsky [:bzbarsky]]

Attachment: part 2. Get rid of the now-useless RescueOrphansInScope

Comment 4

[Boris Zbarsky [:bzbarsky]]

Attachment: part 3. Get rid of the now-unused ReparentWrapperIfFound

Comment 5

[Boris Zbarsky [:bzbarsky]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/d71b934c28ee
https://hg.mozilla.org/integration/mozilla-inbound/rev/be654bd9e20d
https://hg.mozilla.org/integration/mozilla-inbound/rev/32176c758b4d

Comment 6

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

Backed out in for bustage:
https://hg.mozilla.org/integration/mozilla-inbound/rev/945a30df1b0a
https://hg.mozilla.org/integration/mozilla-inbound/rev/238076a16f5a
https://hg.mozilla.org/integration/mozilla-inbound/rev/fa2a3978652a

https://treeherder.mozilla.org/logviewer.html#?job_id=6597859&repo=mozilla-inbound

Comment 7

[Boris Zbarsky [:bzbarsky]]

The problem was bug 1117242.  Repushed:

https://hg.mozilla.org/integration/mozilla-inbound/rev/7a3153f07028
https://hg.mozilla.org/integration/mozilla-inbound/rev/9a66f24829d9
https://hg.mozilla.org/integration/mozilla-inbound/rev/af5f70c0286a

Comment 8

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/7a3153f07028
https://hg.mozilla.org/mozilla-central/rev/9a66f24829d9
https://hg.mozilla.org/mozilla-central/rev/af5f70c0286a