Method shrink

src/common/resources.cpp:1288–1318

bool Resources::shrink(Resource* resource, const Value::Scalar& target)
{
  if (resource->scalar() <= target) {
    return true; // Already within target.
  }

  // Some `disk` resources (e.g. MOUNT disk) are indivisible.
  // We use a containement check to verify this. Specifically,
  // if it contains a smaller version of itself, then it can
  // safely be chopped into a smaller amount.
  //
  // NOTE: If additional types of resources become indivisible,
  // this code needs updating!
  if (resource->has_disk()) {
    Resource original = *resource;

    Value::Scalar oldScalar = resource->scalar();
    *resource->mutable_scalar() = target;

    if (mesos::contains(original, *resource)) {
      return true;
    }

    // Restore the old value.
    *resource->mutable_scalar() = std::move(oldScalar);
    return false;
  }

  *resource->mutable_scalar() = target;
  return true;
}


Resources Resources::getReservationAncestor(