code: private void scheduleTask(Source source, long size, Target target) {
      NodeTask nodeTask = new NodeTask(target, size);
      source.addNodeTask(nodeTask);
      target.addNodeTask(nodeTask);
      sources.add(source);
      targets.add(target);
      LOG.info("scheduled " + size + " bytes : " + source.getName() + " -> " + target.getName());
    }
docs: Pairs up given nodes in balancing plan