Add onStartupFinished plugin activation event

[vinokurig]

What it does

Add onStartupFinished plugin activation event

fixes #8488

How to test

1. Clone any Theia plugin e.g https://github.com/eclipse/che-theia-samples/tree/master/samples/hello-world-backend-plugin
2. Change the activation event in its package.json from * to onStartupFinished
3. Start the plugin.

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

[tsmaeder]

I was wondering why the event should be sent at this location and not another. What parts of the system need to be ready in order for startup to be finished? Not saying it's the wrong place, I just want to understand your thinking.

[azatsarynnyy]

I've verified it according to "How to test" steps. Works well, but I have some concerns about the activation order.

Why not emit it after a star(*) activation

theia/packages/plugin-ext/src/plugin/plugin-manager.ts

Line 219 in d974eb0

await this.$activateByEvent('*');

as it's in VSCode
https://github.com/microsoft/vscode/blob/0e297b112830bd5be9cf51a848d9314c3887ec42/src/vs/workbench/api/common/extHostExtensionService.ts#L475

Isn't it too early emitting onStartupFinished during hosted-plugin initialization?
Won't it happen eager than a star(*) activation?

[azatsarynnyy]

Or another variant. As HostedPluginSupport is FrontendApplicationContribution, wouldn't it better to emit the event on some of the FrontendApplicationContribution's callbacks, e.g. onStart or onDidInitializeLayout?

[vinokurig]

@tsmaeder @azatsarynnyy I think I've found a better place for this event :). Now it is called on application's ready state which suites the event's documentation.

[azatsarynnyy]

I believe emitting on appState.reachedState('ready') looks late enough as for onStartupFinished.

[akosyakov]

Did you check VS Code source code to learn the real semantic of this event and align it?

[vinokurig]

@akosyakov
vscode handles this event after the * events and the workspaceContains events: https://github.com/microsoft/vscode/blob/7e0c1aa76e4ce162679409828af17535d50a4424/src/vs/workbench/api/common/extHostExtensionService.ts#L472-L476
Do you think it is better to handle this event after the workspaceContains events here?

theia/packages/plugin-ext/src/hosted/browser/hosted-plugin.ts

Lines 415 to 422 in 8bf15dc

	this.activateByWorkspaceContains(manager, plugin);
	}
	} catch (e) {
	console.error(`Failed to start plugins for '${host}' host`, e);
	}
	})());
	}
	await Promise.all(thenable);

[akosyakov]

yes, i think it should mean the same

[vinokurig]

@akosyakov Done

[jeluard]

@vinokurig I can see the following error message with latest master:

root ERROR [hosted-plugin: 93564] Unsupported activation events: onStartupFinished, please open an issue: https://github.com/eclipse-theia/theia/issues/new

Is there something specific to do to avoid that?

[vinokurig]

@jeluard Thank you for reporting the issue, the PR above fixes this problem.