202889 - Provide a callback for creation/destruction of JSContexts

Status: RESOLVED DUPLICATE of bug 342737

(Core :: JavaScript Engine, enhancement)

Description

[David Bradley]

We could streamline and make XPConnect's code much simpler if there was a
callback provided that was called when a JSContext is created or destroyed.
Right now, XPConnect has to go through and match up its contexts with the
JSContexts and cleanup them up.

Currently XPConnect relies on clients to call XPConnect on new contexts, and
generates a assertion if that's not done. This is so it can place the
"Components" property on the global object. This could happen automatically with
such a callback.

Comment 1

[Phil Schwartau]

Reassigning; cc'ing Brendan on this request -

Comment 2

[Brendan Eich [:brendan]]

Not all contexts created in a runtime would want the Components object, though
-- how would you know which ones to skip?

/be

Comment 3

[David Bradley]

I wasn't sure how often JSContexts were created that would never be used by
XPConnect. A notification on destruction would be beneficial. Either a global
callback, or a callback provided when the context was created. This would still
make life a lot simpler for XPConnect, and eliminate much of the sync context
code that we have now. I doubt it would be much of a code size win, but it would
simplify and eliminate the need for most if not all of the sync context code
that exists in XPConnect.

Comment 4

[Aiko]

This was implemented in bug 342737, wasn't it?

Comment 5

[Igor Bukanov]

(In reply to comment #4)
> This was implemented in bug 342737, wasn't it?

Yes.

Comment 6

[David Bradley]

Should this bug really be duped? This bug was more about streamlining xpconnect's context logic. The callbacks were just one way of doing that. Given that we now have the callbacks there's work that could be done to XPConnect to change the way XPConnect sync's the contexts. It might prove to be a nice little perf win.

Comment 7

[Igor Bukanov]

> Given
> that we now have the callbacks there's work that could be done to XPConnect to
> change the way XPConnect sync's the contexts. It might prove to be a nice
> little perf win.

See bug 408539. It may not be a performance win, but at least it simplifies code a lot.