ask user to terminate or restart a task if it is actve

- offer users the flexibility of terminating or restarting a task, if
the user tries to run a task that is actively running.

packages/task/src/browser/task-service.ts

@@ -409,6 +409,40 @@ export class TaskService implements TaskConfigurationClient {
     }
 
     async runTask(task: TaskConfiguration, option?: RunTaskOption): Promise<TaskInfo | undefined> {
+        const runningTasksInfo: TaskInfo[] = await this.getRunningTasks();
+
+        // check if the task is active
+        const matchedRunningTaskInfo = runningTasksInfo.find(taskInfo => {
+            const taskConfig = taskInfo.config;
+            return this.taskDefinitionRegistry.compareTasks(taskConfig, task);
+        });
+        if (matchedRunningTaskInfo) { // the task is active
+            const taskName = this.taskNameResolver.resolve(task);
+            const taskId = matchedRunningTaskInfo.taskId;
+            const terminalId = matchedRunningTaskInfo.terminalId;
+            let terminal: TerminalWidget | undefined;
+            if (terminalId) {
+                terminal = this.terminalService.getById(this.getTerminalWidgetId(terminalId));
+                if (terminal) {
+                    terminal.show(); // bring the terminal to the top
+                }
+            }
+            this.messageService.info(`The task \'${taskName}\' is already active`, 'Terminate Task', 'Restart Task').then(actionTask => {
+                if (actionTask) {
+                    this.taskServer.kill(taskId);
+                    if (actionTask === 'Restart Task' && terminal) {
+                        terminal.close();
+                        this.doRunTask(task, option);
+                    }
+                }
+            });
+            return;
+        } else { // run task as the task is not active
+            return this.doRunTask(task, option);
+        }
+    }
+
+    private async doRunTask(task: TaskConfiguration, option?: RunTaskOption): Promise<TaskInfo | undefined> {
         if (option && option.customization) {
             const taskDefinition = this.taskDefinitionRegistry.getDefinition(task);
             if (taskDefinition) { // use the customization object to override the task config
@@ -648,7 +682,7 @@ export class TaskService implements TaskConfigurationClient {
             TERMINAL_WIDGET_FACTORY_ID,
             <TerminalWidgetFactoryOptions>{
                 created: new Date().toString(),
-                id: 'terminal-' + processId,
+                id: this.getTerminalWidgetId(processId),
                 title: taskInfo
                     ? `Task: ${taskInfo.config.label}`
                     : `Task: #${taskId}`,
@@ -660,6 +694,10 @@ export class TaskService implements TaskConfigurationClient {
         widget.start(processId);
     }
 
+    private getTerminalWidgetId(terminalId: number): string {
+        return `${TERMINAL_WIDGET_FACTORY_ID}-${terminalId}`;
+    }
+
     async configure(task: TaskConfiguration): Promise<void> {
         await this.taskConfigurations.configure(task);
     }