The FailPoint interface allows waiters to be interrupted while waiting on a fail point in FailPoint::pauseWhileSet() and FailPoint::waitForTimesEntered(). These two functions currently accept OperationContext but the interruptible sleep function is really part of the base class Interruptible::sleepFor(). These functions currently do not support callers that might want to pass in other classes derived from Interruptible (such as Interruptible::notInterruptible).