/** @return the total bytes on each storage tier */ public Map<String, Long> getTotalBytesOnTiers() { Map<String, Long> ret = new HashMap<String, Long>(); synchronized (mWorkers) { for (MasterWorkerInfo worker : mWorkers) { for (Map.Entry<String, Long> entry : worker.getTotalBytesOnTiers().entrySet()) { Long total = ret.get(entry.getKey()); ret.put(entry.getKey(), (total == null ? 0L : total) + entry.getValue()); } } } return ret; }