Add cancel task (#17038)

* Add cancel task

* remove unneeded exports

src/services/sqlTasksService.ts

@@ -5,7 +5,7 @@
 
 import * as vscode from 'vscode';
 import SqlToolsServiceClient from '../languageservice/serviceclient';
-import { NotificationType } from 'vscode-languageclient';
+import { NotificationType, RequestType } from 'vscode-languageclient';
 import { TaskExecutionMode } from 'vscode-mssql';
 import { Deferred } from '../protocol';
 import * as utils from '../models/utils';
@@ -43,14 +43,22 @@ export interface TaskInfo {
     isCancelable: boolean;
 }
 
-export namespace TaskStatusChangedNotification {
+namespace TaskStatusChangedNotification {
     export const type = new NotificationType<TaskProgressInfo, void>('tasks/statuschanged');
 }
 
-export namespace TaskCreatedNotification {
+namespace TaskCreatedNotification {
     export const type = new NotificationType<TaskInfo, void>('tasks/newtaskcreated');
 }
 
+interface CancelTaskParams {
+    taskId: string;
+}
+
+namespace CancelTaskRequest {
+    export const type = new RequestType<CancelTaskParams, boolean, void, void>('tasks/canceltask');
+}
+
 type ActiveTaskInfo = {
     taskInfo: TaskInfo,
     progressCallback: ProgressCallback,
@@ -71,6 +79,13 @@ export class SqlTasksService {
         this._client.onNotification(TaskStatusChangedNotification.type, taskProgressInfo => this.handleTaskChangedNotification(taskProgressInfo));
     }
 
+    private cancelTask(taskId: string): Thenable<boolean> {
+        const params: CancelTaskParams = {
+            taskId
+        };
+        return this._client.sendRequest(CancelTaskRequest.type, params);
+    }
+
     /**
      * Handles a new task being created. This will start up a progress notification toast for the task and set up
      * callbacks to update the status of that task as it runs.
@@ -91,10 +106,13 @@ export class SqlTasksService {
             {
                 location: vscode.ProgressLocation.Notification,
                 title: taskInfo.name,
-                cancellable: false
+                cancellable: taskInfo.isCancelable
             },
-            async (progress, _token): Promise<void> => {
+            async (progress, token): Promise<void> => {
                 newTaskInfo.progressCallback = value => progress.report(value);
+                token.onCancellationRequested(() => {
+                    this.cancelTask(taskInfo.taskId);
+                });
                 await newTaskInfo.completionPromise;
             }
         );
@@ -118,7 +136,12 @@ export class SqlTasksService {
             // Task is completed, complete the progress notification and display a final toast informing the
             // user of the final status.
             this._activeTasks.delete(taskProgressInfo.taskId);
+            if (taskProgressInfo.status === TaskStatus.Canceled) {
+                taskInfo.completionPromise.reject(new Error('Task cancelled'));
+            } else {
                 taskInfo.completionPromise.resolve();
+            }
+
             // Only include the message if it isn't the same as the task status string we already have - some (but not all) task status
             // notifications include this string as the message
             const taskMessage = taskProgressInfo.message && taskProgressInfo.message.toLowerCase() !== taskStatusString.toLowerCase() ?