A task is a quantum of work that is cancelled or executes to completion. A cancelled task skips its method execute() if that method has not yet started. Otherwise cancellation has no direct effect on the task. A task can poll task::is_cancelled() to see if cancellation was requested after it started running.
Requests cancellation of all tasks in its group and its subordinate groups.
Returns: False if the task's group already received a cancellation request; true otherwise.
|bool is_cancelled() const||
Returns: True if task's group has received a cancellation request; false otherwise.