v8::Isolate::GetCurrent() - when can it return null

[Bruce MacNaughton]

I've written a node extension that works with private data. I see from the function signature that v8::Isolate::GetCurrent() can return NULL, but I don't understand how that's possible, given that my extension is called by JavaScript and has to be running in an isolate.

The v8::Isolate::Current() function has a DCHECK_NOT_NULL, which I infer means that it shouldn't happen. But I don't know when debug checks would be enabled, so that could be a bad inference.

Does it return NULL in specific circumstances, like startup, thread termination, etc.? Can it return 

[Ben Noordhuis]

Yes. :-)

A thread "enters" and "exits" (V8 nomenclature) an isolate. Node
normally enters it and doesn't exit until the thread terminates.

v8::Isolate::TryGetCurrent() exists in case you need to handle the
eventuality of no isolate having been entered.