rotateSecrets.scala

    def secrets: Secrets ={
      val s = cacheBuffer.last
      if (s.current.expired) rotateSecrets.last
      else s
    }
    /**
    *Checks if the secret is knows. Rotates if the secret is the new secret.
    **/
    def find(f: Secret=>Boolean): Option[Secret] = {
      val lastSecrets = cacheBuffer.last

      if( f(lastSecrets.current)) Some(lastSecrets.current)
      else if ( f(lastSecrets.previous)) Some(lastSecrets.previous)
      else if ( f(rotateSecrets.current) Some(cacheBuffer.last.current)
      else None
    }

    private def rotateSecrets: Secrets = {
      if (cacheBuffer.last.current != newBuffer.last.current)
        // take out a lock
        mutex.lock {
          if (cacheBuffer.last.current != newBuffer.last.current) {
            val s = cacheBuffer.last.current
            val n = newBuffer.last
            val newSecrets = Secrets(n,s)
            cacheBuffer.append(newSecrets)
          }
        }
      cacheBuffer.last
    }