void switchToCompactionMode() throws IOException {
    ourReadersCache.remove(myPath);
    ourFileChannelCache.remove(myPath);

    // in compaction mode use faster reader
    if (myCompressedAppendableFile != null) {
      myCompactionModeReader = new ReaderOverCompressedFile(myCompressedAppendableFile);
    }
    else {
      myCompactionModeReader = new FileReader(myPath);
    }

    myCompactionMode = true;
  }
void switchToCompactionMode()