public static boolean isCompactionInProgress(String dir, String storeId) {
    return new File(dir, storeId + COMPACTION_LOG_SUFFIX).exists();
  }
Used to determine whether compaction is in progress.
@param dir the directory where the compaction log is expected to exist (if any).
@param storeId the ID of the store under compaction.
@return whether compaction is in progress for the store.
ambry-store/src/main/java/com/github/ambry/store/CompactionLog.java