Add onTaskProvide and onTaskResolve activation events

Author: SchoofsKelvin

src/vs/vscode.d.ts

@@ -6931,6 +6931,10 @@ declare module 'vscode' {
 		/**
 		 * Register a task provider.
 		 *
+		 * When looking for tasks, VS Code fires an `onTaskProvide:taskType` activation event.
+		 * When a task is being resolved, VS Code fires an `onTaskResolve:taskType` activation event.
+		 * Your extension can listen to these events to make sure the task provider is available.
+		 *
 		 * @param type The task kind type this provider is registered for.
 		 * @param provider A task provider.
 		 * @return A {@link Disposable} that unregisters this provider when being disposed.
@@ -10928,6 +10932,10 @@ declare module 'vscode' {
 		 *
 		 * @deprecated Use the corresponding function on the `tasks` namespace instead
 		 *
+		 * When looking for tasks, VS Code fires an `onTaskProvide:taskType` activation event.
+		 * When a task is being resolved, VS Code fires an `onTaskResolve:taskType` activation event.
+		 * Your extension can listen to these events to make sure the task provider is available.
+		 *
 		 * @param type The task kind type this provider is registered for.
 		 * @param provider A task provider.
 		 * @return A {@link Disposable} that unregisters this provider when being disposed.

src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts

@@ -607,6 +607,9 @@ export abstract class AbstractTaskService extends Disposable implements ITaskSer
 			return;
 		}
 		await Promise.all([this.extensionService.activateByEvent('onCommand:workbench.action.tasks.runTask'), this.extensionService.whenInstalledExtensionsRegistered()]);
+		if (configuringTask.type) {
+			await Promise.all([this.extensionService.activateByEvent(`onTaskResolve:${configuringTask.type}`), this.extensionService.whenInstalledExtensionsRegistered()]);
+		}
 		let matchingProvider: ITaskProvider | undefined;
 		let matchingProviderUnavailable: boolean = false;
 		for (const [handle, provider] of this._providers) {
@@ -1677,12 +1680,19 @@ export abstract class AbstractTaskService extends Disposable implements ITaskSer
 
 	private getGroupedTasks(type?: string): Promise<TaskMap> {
 		const needsRecentTasksMigration = this.needsRecentTasksMigration();
+		const isProvideTasksEnabled = this.isProvideTasksEnabled();
 		return Promise.all([this.extensionService.activateByEvent('onCommand:workbench.action.tasks.runTask'), this.extensionService.whenInstalledExtensionsRegistered()]).then(() => {
 			let validTypes: IStringDictionary<boolean> = Object.create(null);
-			TaskDefinitionRegistry.all().forEach(definition => validTypes[definition.taskType] = true);
 			validTypes['shell'] = true;
 			validTypes['process'] = true;
-			return new Promise<TaskSet[]>(resolve => {
+			const activationPromises: Promise<void>[] = [];
+			TaskDefinitionRegistry.all().forEach(({ taskType }) => {
+				validTypes[taskType] = true;
+				if (isProvideTasksEnabled && (type === undefined || type === taskType)) {
+					activationPromises.push(this.extensionService.activateByEvent(`onTaskProvide:${taskType}`));
+				}
+			});
+			return Promise.all(activationPromises).then(() => new Promise<TaskSet[]>(resolve => {
 				let result: TaskSet[] = [];
 				let counter: number = 0;
 				let done = (value: TaskSet | undefined) => {
@@ -1736,7 +1746,7 @@ export abstract class AbstractTaskService extends Disposable implements ITaskSer
 				} else {
 					resolve(result);
 				}
-			});
+			}));
 		}).then((contributedTaskSets) => {
 			let result: TaskMap = new TaskMap();
 			let contributedTasks: TaskMap = new TaskMap();

src/vs/workbench/services/extensions/common/extensionsRegistry.ts

@@ -309,6 +309,16 @@ export const schema: IJSONSchema = {
 						body: 'onCustomEditor:${9:viewType}',
 						description: nls.localize('vscode.extension.activationEvents.onCustomEditor', 'An activation event emitted whenever the specified custom editor becomes visible.'),
 					},
+					{
+						label: 'onTaskProvide',
+						description: nls.localize('vscode.extension.activationEvents.onTaskProvide', 'An activation event emitted whenever VS Code is looking for tasks of a given (or any) type.'),
+						body: 'onTaskResolve:${1:taskType}'
+					},
+					{
+						label: 'onTaskResolve',
+						description: nls.localize('vscode.extension.activationEvents.onTaskResolve', 'An activation event emitted whenever a task with the given type gets resolved.'),
+						body: 'onTaskResolve:${1:taskType}'
+					},
 					{
 						label: 'onNotebook',
 						body: 'onNotebook:${1:type}',