Support arbitrary data to be looped from one debug session to a restarted session

[weinand]

I noticed that we sometimes have to hardcode a "port" in a launch config if we want to use the same port in restarted debug sessions. Here is an example from the MERN Starter Recipe (see https://github.com/weinand/vscode-recipes/tree/master/MERN-Starter):

"protocol": "inspector",
"runtimeExecutable": "nodemon",
"runtimeArgs": [
    "--inspect=9222"
],
"port": 9222,
"restart": true,    

The ugly thing about this is the redundancy (and potential inconsistency) between the protocol, runtimeArgs, and port attributes. If the value of protocol is changed to legacy, the values for runtimeArgs and port must be changed as well, otherwise a problematic inconsistency will occur.

It would be preferable if we could just use this:

"protocol": "inspector",
"runtimeExecutable": "nodemon",
"restart": true,    

In this case the debug adapter picks a random port and passes it with the correct 'inspect' or 'debug' option to the runtime.

The problem is how this "port" can be looped from the DA back to VS Code and then to the next session.

I suggest that we support a generic mechanism for passing arbitrary data from one debug session to the next by extending the type of the restartattribute of the TerminatedRequest from "boolean" to "any".

VS Code will loop this restart value unmodified and uninterpreted from one session to a restarted next session as the (already existing) __restart attribute of the launchRequest.

[weinand]

@isidorn I've modified the DAP for this.

[weinand]

@roblourens I've verified that node-debug2 still works after this protocol- and frontend-change.

You might want to adapt node-debug2. Here is what I did in node-debug:

I'm now sending the debug port as part of the TerminatedEvent:

			if (this._restartMode && !this._inShutdown) {
				this.sendEvent(new TerminatedEvent({ port: this._port }));
			} else {

and in the launchRequest handler I'm processing the __restart attribute as follows:

		if (args.__restart && typeof args.__restart.port === 'number') {
			this._attach(response, args.__restart.port, undefined, args.timeout);
			return;
		}

[roblourens]

This should be hooked up on the vscode side right? When I send TerminatedEvent with an object, __restart doesn't come back on the launch config object. Even with 'legacy', as a result, nodemon debugging is not working very well unless the port is specified.

[roblourens]

Actually this works in 1.12, filing an issue.

[weinand]

When using the "inspector" protocol the restarts stops on entry: microsoft/vscode-node-debug2#114