public ResourceUsage addDirectMemory(long amount, String description) {
    return add(DIRECT_MEMORY, amount, description)
      .add(OFF_HEAP_MEMORY, amount, description);
  }
Requests {@code amount} bytes of direct memory that will exist outside the JVM heap.
planetiler-core/src/main/java/com/onthegomap/planetiler/util/ResourceUsage.java