Method ensure

future-java/src/main/java/io/trane/future/Future.java:455–455

Runs r when this future completes. @param r the Runnable to be executed. @return a future that completes with the result of this after r is executed.

(Runnable r)

   *           executed.
   */
  Future<T> ensure(Runnable r);

  /**
   * Executes the Consumer if this future completes successfully.