private Path getNewPath() throws IOException {
    this.filenum.set(Math.max(getFilenum() + 1, EnvironmentEdgeManager.currentTime()));
    Path newPath = getCurrentFileName();
    return newPath;
  }
retrieve the next path to use for writing. Increments the internal filenum.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/AbstractFSWAL.java