Debug: fix debt around preLaunchTask

fixes #31674

src/vs/workbench/parts/debug/electron-browser/debugService.ts

@@ -38,7 +38,7 @@ import { ViewModel } from 'vs/workbench/parts/debug/common/debugViewModel';
 import * as debugactions from 'vs/workbench/parts/debug/browser/debugActions';
 import { ConfigurationManager } from 'vs/workbench/parts/debug/electron-browser/debugConfigurationManager';
 import { ToggleMarkersPanelAction } from 'vs/workbench/parts/markers/browser/markersPanelActions';
-import { ITaskService, TaskEvent, TaskType, TaskServiceEvents, ITaskSummary } from 'vs/workbench/parts/tasks/common/taskService';
+import { ITaskService, TaskServiceEvents, ITaskSummary } from 'vs/workbench/parts/tasks/common/taskService';
 import { TaskError } from 'vs/workbench/parts/tasks/common/taskSystem';
 import { VIEWLET_ID as EXPLORER_VIEWLET_ID } from 'vs/workbench/parts/files/common/files';
 import { IViewletService } from 'vs/workbench/services/viewlet/browser/viewlet';
@@ -75,7 +75,6 @@ export class DebugService implements debug.IDebugService {
 	private allSessionIds: Set<string>;
 	private configurationManager: ConfigurationManager;
 	private customTelemetryService: ITelemetryService;
-	private lastTaskEvent: TaskEvent;
 	private toDispose: lifecycle.IDisposable[];
 	private toDisposeOnSessionEnd: Map<string, lifecycle.IDisposable[]>;
 	private inDebugMode: IContextKey<boolean>;
@@ -135,24 +134,8 @@ export class DebugService implements debug.IDebugService {
 
 	private registerListeners(lifecycleService: ILifecycleService): void {
 		this.toDispose.push(this.fileService.onFileChanges(e => this.onFileChanges(e)));
-
-		if (this.taskService) {
-			this.toDispose.push(this.taskService.addListener(TaskServiceEvents.Active, (e: TaskEvent) => {
-				this.lastTaskEvent = e;
-			}));
-			this.toDispose.push(this.taskService.addListener(TaskServiceEvents.Inactive, (e: TaskEvent) => {
-				if (e.type === TaskType.SingleRun) {
-					this.lastTaskEvent = null;
-				}
-			}));
-			this.toDispose.push(this.taskService.addListener(TaskServiceEvents.Terminated, (e: TaskEvent) => {
-				this.lastTaskEvent = null;
-			}));
-		}
-
 		lifecycleService.onShutdown(this.store, this);
 		lifecycleService.onShutdown(this.dispose, this);
-
 		this.toDispose.push(this.broadcastService.onBroadcast(this.onBroadcast, this));
 	}
 
@@ -907,30 +890,20 @@ export class DebugService implements debug.IDebugService {
 				return TPromise.wrapError(errors.create(nls.localize('DebugTaskNotFound', "Could not find the preLaunchTask \'{0}\'.", taskName)));
 			}
 
+			return this.taskService.getActiveTasks().then(tasks => {
+				if (tasks.filter(t => t._id === task._id).length) {
 					// task is already running - nothing to do.
-			if (this.lastTaskEvent && this.lastTaskEvent.taskId === task._id) {
 					return TPromise.as(null);
 				}
 
-			if (this.lastTaskEvent) {
-				// there is a different task running currently.
-				return TPromise.wrapError(errors.create(nls.localize('differentTaskRunning', "The task '{0}' is already running. Cannot run pre-launch task '{1}'.", this.lastTaskEvent.taskName, taskName)));
-			}
-
-			// no task running, execute the preLaunchTask.
-			const taskPromise = this.taskService.run(task).then(result => {
-				this.lastTaskEvent = null;
-				return result;
-			}, err => {
-				this.lastTaskEvent = null;
-			});
-
+				const taskPromise = this.taskService.run(task);
 				if (task.isBackground) {
 					return new TPromise((c, e) => this.taskService.addOneTimeListener(TaskServiceEvents.Inactive, () => c(null)));
 				}
 
 				return taskPromise;
 			});
+		});
 	}
 
 	public sourceIsNotAvailable(uri: uri): void {