Support background tasks

[tolusha]

Description

We have Task.isBackground [1] which is supposed to use for background tasks.

[1] https://github.com/eclipse-theia/theia/blob/master/packages/plugin/src/theia.d.ts#L8304

theia/packages/plugin/src/theia.d.ts

Lines 8387 to 8423 in 145f913

	/** The task's name */
	name: string;
	/** The task's definition. */
	definition: TaskDefinition;
	/** The task's scope. */
	scope?: TaskScope.Global | TaskScope.Workspace | WorkspaceFolder;
	/** The task's execution engine */
	execution?: ProcessExecution | ShellExecution;
	/** Whether the task is a background task or not. */
	isBackground?: boolean;
	/**
	* A human-readable string describing the source of this
	* shell task, e.g. 'gulp' or 'npm'.
	*/
	source?: string;
	/**
	* The task group this tasks belongs to. See TaskGroup
	* for a predefined set of available groups.
	* Defaults to undefined meaning that the task doesn't
	* belong to any special group.
	*/
	group?: TaskGroup;
	/** The presentation options. Defaults to an empty literal. */
	presentationOptions?: TaskPresentationOptions;
	/**
	* The problem matchers attached to the task. Defaults to an empty
	* array.
	*/
	problemMatchers?: string[];

Context

I try to adopt quarkus extension. This extension generates preLaunch task which is a background one. It means Theia should launch the task and then start a debug session without waiting when task is finished.

[1] https://github.com/redhat-developer/vscode-quarkus

[tsmaeder]

The todo's here are:

1. The debugger should not wait for tasks that are marked "background"
2. Problem matchers should fire events when matching certain start/end patterns. The debugger (task watcher) needs to listen to those issues and act accordingly.

[tsmaeder]

The issue is that the debugger does not start the debug session, but first waits for the background task to finish. The debugger should listen for the "task finished" event (exact name will be different, see VS Code doc), and then start the debug session.

[ShimonBenYair]

Hi @tsmaeder

I am currently working on it as part of the #5517 Support Compound tasks
I will send a pull request on few days ...