debug-tracker-vscode

Introduction

This extension is an API extension to help other extension track debug sessions. Other extensions can subscribe to get notifications on events occurring on debuggers they are interested in.

There have been a proliferation of debug trackers (I counted four) running within various extensions. They all cause many more event handlers for each message passing between various clients and the debug adapter, and these are generally redundant. Instead, this extension creates a single point where messages are filtered looking for events like start, stop, running, etc. Other extensions can subscript to this extension that can create more precise events.

VSCode does not provide a full complement of events. It only has an event for starting and terminating. There are things that occur prior to starting and one has to look into the messages, responses and events passing between VSCode and the debug adapter to synthesize other events. And looking at the many such trackers, the logic is sometimes incomplete. A continue event is also not generated all the time so, we have to synthesize it by looking at which commands are run that could potentially cause a continue

An extension can subscribe to all debug sessions of just the debug adapters that they are interested in. The selection of debug adapter is done via the type property used in a launch.json. For instance for vscode-cpptools, that would be cppdbg.

From a performance point of view, this extension can generate 3,000,000 events per second on a 2021 Intel MacBook Pro 16".

If we missed an event or if there is an error in our logic when synthesizing events, please let us know by filing and Issue or creating a PR.

We have versioned this API and aim to keep compatibility for the long term. If we cannot we will increment the version and will not drop support for older versions although fixes may only be done in the most recent version.

Usage

There are two ways you can use this API and both have the exact same interface. You can see the sample API here (do not use this, please get it from npm install where it will show up as exports.d.ts).

1. Install the debug-tracer-vscode npm library

   npm install debug-tracker-vscode

2. Import the library API from the extension debug-tracer-vscode and use the npm library of the same name for type definitions. You can activate the extension from your extension and acquire a shared API. Advantage of this method is that you are sharing the tracking overhead with other extensions, improving the response time to the user. You are always up to date when this extension updates. Bad thing is if we release the extension with a bug, it will affect your users. We internally will be using this method for several extensions.

3. If you do not prefer to use a shared library, you can create your own private instance by doing new DebugTracker(...). The advantage is that you are independent of another extension and you control if and when you want to move to a newer version via package.json. Disadvantage is that it does not help in reducing the number of trackers running concurrently.

Build and Debug

Pre-requisites are that you have NodeJS (npm) and vsce already installed and setup for debug sessions in VSCode. Having the command-line interface in your path for code is a plus.

1. Clone this repo and change directory into it
2. Run the following commands

   rm -f *.vsix
   npm install
   npm run compile
   vsce package

3. The above should generate a vsix files and a tgz file. The tgz file can be used to add the typings you any other extension. You will need this method until we have published everything. We are not there yet. You will need the tgz file if you are running the sample/demo from https://github.com/mcu-debug/debug-tracker-client
4. If you have code available on your command line, run the following

   code --install-extension *.vsix
   

   Of course you can debug this extension by launching a debug session and then running the command Activate Debug Tracker from the Command Palette in the in the "Extension Development Host". Once it is activated, start any debug session and observe the Debug Console of the original window.

Build the NPM library

We had trouble creating both an extension and a library from the same directory so we use build the library in an alternate directory. Somebody help us better organize this but for now, do this

cd lib
bash ./build.sh

The above generates a .tgz file that you can use to test the npm module.