@Override
  public void init(Map<String, Object> params) {
    if (params != null && params.containsKey(HMaster.MASTER)) {
      this.master = (MasterServices) params.get(HMaster.MASTER);
    }
  }
File cache for HFiles in the completed and currently running snapshots
hbase-server/src/main/java/org/apache/hadoop/hbase/master/snapshot/SnapshotHFileCleaner.java