Implement safe plugin uninstallation

[colin-grant-work]

What it does

This PR implements several things:

1. Deployment of folders to a temp dir, with a CLI option to prevent that copying.
   • Install some unzipped plugins in your ~/.theia/extensions directory
   • Observe that during startup, messages are logged about copying those plugins.
   • Use the --uncompressed-plugins-in-place flag in the CLI
   • Observe that you don't get those startup messages.
2. Uninstallation without undeployment
   • Install some user plugins
   • Open more than one instance of Theia on the same backend
   • Open the plugin view in one instance
   • Uninstall one of your user plugins
   • Observe that the plugin's features continue to work in all instances.
   • Observe that in all instances targeting that backend, that plugin now shows a button saying 'Reload Required'
   • Click that button in one or more instances.
   • Observe that when the instances reload, the plugin is not loaded.
3. Multiple version handling
   • Follow the same steps as (2) up to 'Uninstall one of your user plugins'
   • After uninstalling the plugin, use 'Install from VSIX' to install a different version of that plugin
   • Observe that you still have the 'reload required' button
   • Click it
   • When that instance reloads, it should have access to the new version of the plugin.
4. Reimplementation of Use same tempdir for user and system compressed plugin files #10951
   • Follow testing steps from Use same tempdir for user and system compressed plugin files #10951
   • Follow testing steps from Revert "Use same tempdir for user and system compressed plugin files" #11057 with the caveat that the file should appear in your home directory, but not be decompressed.

How to test

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[msujew]

Looks good to me 👍

However, I noticed something which didn't work as described in the testing steps. "Installing" an extension by unzipping it into ~/.theia and starting the app did not copy the extension into the /tmp/vscode-unpacked directory (with and without the --uncompressed-plugins-in-place flag). It did work for zipped (.vsix) extensions as expected. Is that something I got incorrect?

Aside from that I noticed that every uninstalled extension now requires to reload before disappearing completely. While this is definitely an improvement to the way it worked previously, vscode seems to be able to decide on a case-by-case basis whether uninstalling an extension requires an app reload. But this is probably something for another PR :)

[colin-grant-work]

@msujew, thanks for taking a look!

However, I noticed something which didn't work as described in the testing steps. "Installing" an extension by unzipping it into ~/.theia and starting the app did not copy the extension into the /tmp/vscode-unpacked directory (with and without the --uncompressed-plugins-in-place flag). It did work for zipped (.vsix) extensions as expected. Is that something I got incorrect?

It should be copying all directories from the user folder. You said you unzipped into the ~/.theia/extensions (or just ~/.theia?) directory; what was your exact procedure?

Aside from that I noticed that every uninstalled extension now requires to reload before disappearing completely. While this is definitely an improvement to the way it worked previously, vscode seems to be able to decide on a case-by-case basis whether uninstalling an extension requires an app reload. But this is probably something for another PR :)

I have an idea for this, but it's harder to guarantee on the backend than the frontend, so I've left it for later :-).

[alvsan09]

It should be copying all directories from the user folder. You said you unzipped into the ~/.theia/extensions (or just ~/.theia?) directory; what was your exact procedure?

@colin-grant-work There is a typo on the instructions at the top, it should be ~/.theia/extensions as you just mentioned rather than ``~/.theia/plugins`

[colin-grant-work]

It should be copying all directories from the user folder. You said you unzipped into the ~/.theia/extensions (or just ~/.theia?) directory; what was your exact procedure?

@colin-grant-work There is a typo on the instructions at the top, it should be ~/.theia/extensions as you just mentioned rather than ``~/.theia/plugins`

Good catch. I've also fixed this behavior. @msujew, it looks like during a rebase, the actual call to copy VSCode plugins got deleted; I've brought it back in this commit

[alvsan09]

I have tested the following scenarios and they work fine! 👍

1. Tested deployment of folders to a 'tmp' directory
2. Tested loading of plugin folders in place via --uncompressed-plugins-in-place flag
3. Uninstallation without undeployment for .vsix
4. Uninstallation without undeployment for uncompressed folder extensions
5. Uninstalling and installing a different version

I am not too familiar with the code base, so I will let more experienced committers in the area to cover it.
I found a typo and mentioned it as an inline comment.

[colin-grant-work]

@tsmaeder, it might be good to have a Red Hat perspective on this, since it makes substantial changes to the way we pass around data about plugins - changing and making explicit expectations about whether versions are included as part of identifiers - and adds some state that we didn't have before. Want to make sure that we don't blow up Che, if they're still updating the version of Theia they offer.

[vince-fugnitto]

The changes work well for me 👍

I confirmed that:

• extensions can be searched.
• extensions can be installed.
• extensions can be uninstalled.
• uninstalled extensions require a reload before they are removed.
• upon reloading the application extensions can be re-installed.
• if an extensions is uninstalled, multiple clients will be notified and display reload required.
• if an extension is uninstalled, and installed through install from vsix the proper extension versions is used on reload.
• deployment of extensions works well.

[msujew]

Reconfirming my approval. With the latest changes putting an unzipped extension into the ~/.theia/plugins folder copies it to the /tmp/vscode-copied directory and activates it correctly. The behavior for the flag also works as expected 👍

[colin-grant-work]

@tsmaeder, last call here. I'll merge tomorrow if there are no objections.

[paul-marechal]

I agree that Deferred should support resolving to promises, but this introduces a bug where we may resolve to an unresolved PromiseLike but we will mark the Deferred as resolved too early.

Consider the following change:

export class Deferred<T = void> {
    state: 'resolved' | 'rejected' | 'unresolved' = 'unresolved';
    resolve: (value: T | PromiseLike<T>) => void;
    reject: (reason?: unknown) => void;

    promise: Promise<T> = new Promise<T>((resolve, reject) => {
        this.resolve = resolve;
        this.reject = reject;
    }).then(
        value => { this.state = 'resolved'; return value; },
        error => { this.state = 'rejected'; throw error; }
    );
}

[paul-marechal]

On the other hand I could be misunderstanding the role of the state property?

Is it meant to represent when resolve has been called, or when the underlying promise resolves? Doesn't look obvious.

[colin-grant-work]

Thanks everyone who reviewed!

[tsmaeder]

@colin-grant-work would have loved to chime in, but no time, unfortunately 🤷