development-notes.md

Development Notes 2019-12-27, Bob Dubner

This folder is for developing the cbl-dbg extension.

First, of course, you have to have Visual Studio Code installed

Making sure you have the correct software installed so that you can install additional correct software is the usual infinite regress bookended in insanity. I no longer recall how I got bootstrapped in; I think I installed snap (or maybe it was already present on Ubuntu) and then used

sudo snap install --classic code
sudo snap install --classic code-insiders

for the regular and bleeding-edge versions of Visual Studio Code. You probably don't need the bleeding-edge code-insiders version.

I don't at what point npm was installed. I do know that getting vsce to work involved running

npm install -g vsce

When this folder is initially cloned from a git repository, it is necessary to run

npm install

to appease the Microsoft software development demons. (It appears to create a necessary massive folder called "node_modules". I don't know what else it might be doing.)

Everything is installed. Now what?

Creating the VSIX extension installation file is accomplished by running

vsce package

The resulting cbl-dbg-x.x.x.vsix package needs to be installed on a user's system. This can be done by launching Visual Studio Code and displaying the Extensions pane (Ctrl+Shift+X), then clicking the three-dot "More actions" item, and then selecting "Install from VSIX...".

You can also get there via the Command Palette (Ctrl+Shift+P) and finding "Extensions: Install from VSIX...", which you can find by typing "VSIX".

It's also possible to install the VSIX package from the command line:

code --install-extension cbl-dbg-x.x.x.vsix

With the cbl-dbg extension installed and enabled, you need to look elsewhere for the cbl-dgb-template folder for the starting point for compiling and debugging actual COBOL code.

Oh, you want to do development on the extension?

You have guts. Either that, or you are me, and you are trying to remember what you did in the first place.

Here's where you are going to be going: When you are actively debugging the debugger, there will be not one, not two, but three Visual Studio Code instances running.

The debugging adapter, which is likely what you are most interested in changing, will be running from this folder as the Server configuration.

The extension package, which acts as a bridge between a user and the debugging adapter, will be running as a second instance in this folder as the Extension configuration.

The extension configuration launches a third instance of Visual Studio Code. You'll use that one to open the folder containing the test program that will be debugged by the debugging adapter. At this writing, this development-notes.md file is in a folder named CamelCobolExt/cbl-gdb. Some suitable test programs can be found in CamelCobolExt/samples.

The three launch configurations

Take a look at this project's launch.json file.

The "Extension" configuration

The key thing about the Extension configuration is that it launches execPath, which means yet another copy of Visual Studio Code.

The "Server" configuration

The Server configuration launches the debug adapter in Server mode, which is determined by the presences of the "args": [ "--server=4711" ], parameter. In this mode, it listens for an attempt to connect on port 4711, rather than doing the usual extension thing. (The "usual extension thing" is defined by the "cbl-gdb" configuration in the extensions package.json file, also found in this folder.)

The Client configuration

The Client configuration controls what happens when the third instance of Visual Studio Code, the one launched by the Extensions configuration, is used to F5/Start Debugging. Here is the launch.json file I've been using for targets used for debugging the debug adapter:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Attach to debugServer",
            "type": "node",
            "request": "attach",
            "cwd": "${workspaceFolder}",
            "debugServer": 4711,
            "solibs":"${env:PRIM_LIBRARY_PATH}",
            "target": "${input:attachtopid}",
        },
        {
            "name": "Attach to COBOL debugger",
            "type": "cbl-gdb",
            "request": "attach",
            "cwd":"${workspaceFolder}",
            "solibs":"${env:PRIM_LIBRARY_PATH}",
            "target": "${input:attachtopid}",
        }
    ],
    "inputs": [
        {
            "id": "attachtopid",
            "type": "promptString",
            "description": "Enter the PID to attach to",
            "default": ""
        }
    ]
}

Note how the Attach to debugServer configuration expects to connect to a server instance through the matching port 4711.

The Attach to COBOL debugger isn't used during sessions when one is debugging the debugger, but it is an example of how one uses the debug adapter extension once it is packaged up and installed.

It should be mentioned that the "inputs" section defines the attachtopid input, which causes Visual Studio Code to ask the user for the PID that is going to be debugged after gdb attaches to it.

Here's launch.json for a specific program to run when debugging the debugging adapter. This is copied from the sample/optfde01 program elsewhere in the source code repository for this VSIX package:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Build ${file} with cobc/cobst, debug with debugServer",
            "type": "node",
            "request": "launch",
            "skipFiles": ["<node_internals>/**"],
            "preLaunchTask": "make",
            "program": "${workspaceRoot}/optfde01",
            "cwd": "${workspaceFolder}",
            "arguments": "",
            "debugServer": 4711
        },
        {
            "name": "cobc/cobst build and debug",
            "type": "cbl-gdb",
            "request": "launch",
            "preLaunchTask": "make",
            "program": "${workspaceFolder}/optfde01",
            "cwd": "${workspaceFolder}",
            "arguments": ""
        }

    ]
}