Hundreds of custom configuration requests may be sent on startup before the configuration provider has registered

[sean-mcmanus]

If you have a header open on startup, it may try to request configurations for thousands of potential source files, but the configuration provider may not have registered yet and so it may not send any configuration for any of the source files, depending on the timing. It might repro more frequently on a slower machine.

[heartacker]

catch

[Colengms]

We could add some additional lifecycle messages to track when providers gets registered. That may get a little complicated when factoring in live modifications to cpp_properites.json configurations.

Another approach would be to have the response indicate it failed due to the configuration provider having not yet registered. The native side could use that as a clue to skip trying to request configurations for the remaining candidates.

We might also need a message (if there isn't one already) to notify the native side that the registration has occurred, so it can recycle the configs for existing TUs.

[sean-mcmanus]

When this issue is hit and the TU ends up falling back to header only IntelliSense, it gets "stuck" that way until a reload window, i.e. it stops requesting for configurations after the configuration provider has registered.