The debugger's API mode added a lot of extra complexity to the debugger client for minimal value. It also had a bunch of bugs, and unnecessarily tied alternate debugger clients to the command line client implementation. Deleting it.
Differential Revision: D912729
There was a race in the debugger protocol tests which send bad commands to the proxy and expect it to disconnect. If the proxy thread was fast enough it would mark the client as stopped, and we'd skip trying to get a new message after sending the bad command. This means missing one line of output in very rare cases. I've put in a wait to ensure that the client settles in the stopped state before continuing, to remove the race.
Cleanup a lot of hangs with either the debugger client or server in a variety of error conditions, mostly related to communication errors or the client or server exiting unexpectedly. One of the biggest fixes is that all cases where the client was left in a state where Ctrl-C wouldn't work have been fixed.
Remove lots of little snippets of dead code. If you see a function (or small set of functions/fields) deleted then it was actually dead.
I debated whether to keep throwing DebuggerClientExitException on the server, and I decided to keep it. I think it's reasonable that if you've got the server stopped and you quit the debugger that the request gets terminated rather than continuing to run.
I also considered a big change to the way Ctrl-C works, but ended up staying with what was there with just a bit of cleanup. We need to guard against people banging on Ctrl-C, which is a reasonable behavior, and I think it feels pretty reasonable with the updated message.
Finally, added many comments about how this stuff works.