Cancellation token passed to `provideReferences` is never cancelled

[lukehoban]

• VSCode Version: 0.10.11
• OS Version: OS X

The cancellation token passed to vscode.ReferenceProvider#provideReferences appears to not get cancelled ever - and in particular, not get cancelled when the Find References panel is closed by the user.

Since Find References can require an expensive compute operation to be needed, this is particularly unfortunate. In the vscode-go extension, this user command spawns a process which can in pathological cases take more than a minute (and use 100% of multiple cores). A user can easily do Find References multiple times (because they see no results being returned), causing multiple of these processes to be spawned.

Are there any documented semantics for the cancelation token's passed to these higher level language service APIs? Is there some case where the provideReferences cancellation token will actually be cancelled?

[joaomoreno]

I don't get the cancellation event when using the Escape key, only when pressing the x of the references widget.