/// <summary>
/// Obtains and ignores the next task that the <paramref name="executor"/>
/// would otherwise execute, if one is immediately available,
/// and then retries execution of task <paramref name="runnable"/>,
/// unless the <paramref name="executor"/> is shut down, in which
/// case task <paramref name="runnable"/> is instead discarded.
/// </summary>
/// <param name="runnable">
/// The <see cref="IRunnable"/> task requested to be executed.
/// </param>
/// <param name="executor">
/// The <see cref="ThreadPoolExecutor"/> attempting to execute this
/// task.
/// </param>
public virtual void RejectedExecution(IRunnable runnable, ThreadPoolExecutor executor)
{
if (executor.IsShutdown) return;
IRunnable head;
executor.Queue.Poll(out head);
executor.Execute(runnable);
}
