private void unpreblow(OplogFile olf, long maxSize) {
    synchronized (/* olf */lock) {
      if (!olf.RAFClosed && !olf.unpreblown) {
        olf.unpreblown = true;
        if (olf.currSize < maxSize) {
          try {
            olf.raf.setLength(olf.currSize);
          } catch (IOException ignore) {
          }
        }
      }
    }
  }
Returns true if added file was crf; false if drf
geode-core/src/main/java/org/apache/geode/internal/cache/Oplog.java