public void fileCacheCompleted(Path filePath, long size) {
    Pair<String, Long> pair = new Pair<>();
    // sets the region name
    String regionName = filePath.getParent().getParent().getName();
    pair.setFirst(regionName);
    pair.setSecond(size);
    fullyCachedFiles.put(filePath.getName(), pair);
  }
This method is invoked after the bucketEntry is removed from {@link BucketCache#backingMap}
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/BucketCache.java