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Dropping Root outside Runtime.run panics #28
Description
In a project, I have a state struct that contains a glsp runtime and a struct that holds callbacks:
struct Callbacks {
//various callbacks of type: Option<Root<GFn>>
}
struct State {
callbacks: Callbacks,
runtime: Runtime,
...
}At the very end of the program, when the state is dropped, it panics with the error: a Root or Gc has outlived its originating Runtime - aborting process
I then tried manually dropping the callbacks before the end of the program, and it seems the panic occurs there, so it looks like I can't drop Roots unless I'm in a runtime environment. Is this intentional?
Activity
fleabitdev commentedon Jan 11, 2021
Thanks for the report!
This is intentional and documented. The best way to work around it is to construct your
Runtimeat the very start of yourmainfunction,runit immediately, and keep running it until the very end of yourmainfunction, as documented here.Leaving this issue open, because the rule should be documented more prominently, particularly in the rustdoc pages for
Root,GcandVal. We should probably add a more explicit warning tothe-glsp-crate.md, too. This rule used to be documented alongside theGSendmarker trait, but that trait was removed in version 0.2, so the documentation is currently a little sparse.Grinshpon commentedon Jan 11, 2021
Ah, I see, thank you!
Just curious, is there a significant performance difference in calling
runonce and keeping it active, versus calling it once or more each frame?fleabitdev commentedon Jan 12, 2021
runis basically free! It just changes the value of a thread-localOption<Rc<_>>, and then changes it back after running the closure.