#vulnerable code 
                                @Override
    public DLegerEntry get(Long index) {
        PreConditions.check(index <= legerEndIndex && index >= legerBeginIndex, DLegerException.Code.INDEX_OUT_OF_RANGE, String.format("%d should between %d-%d", index, legerBeginIndex, legerEndIndex), memberState.getLeaderId());
        SelectMmapBufferResult indexSbr = indexFileQueue.getData(index * INDEX_NUIT_SIZE, INDEX_NUIT_SIZE);
        PreConditions.check(indexSbr.getByteBuffer() != null, DLegerException.Code.DISK_ERROR, null);
        indexSbr.getByteBuffer().getInt(); //magic
        long pos = indexSbr.getByteBuffer().getLong();
        int size = indexSbr.getByteBuffer().getInt();
        indexSbr.release();
        SelectMmapBufferResult dataSbr = dataFileQueue.getData(pos, size);
        PreConditions.check(dataSbr.getByteBuffer() != null, DLegerException.Code.DISK_ERROR, null);
        DLegerEntry dLegerEntry = DLegerEntryCoder.decode(dataSbr.getByteBuffer());
        dataSbr.release();
        return dLegerEntry;
    } 
                            #location 3 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @Override
    public DLegerEntry get(Long index) {
        PreConditions.check(index <= legerEndIndex && index >= legerBeginIndex, DLegerException.Code.INDEX_OUT_OF_RANGE, String.format("%d should between %d-%d", index, legerBeginIndex, legerEndIndex), memberState.getLeaderId());
        SelectMmapBufferResult indexSbr = indexFileQueue.getData(index * INDEX_NUIT_SIZE, INDEX_NUIT_SIZE);
        PreConditions.check(indexSbr.getByteBuffer() != null, DLegerException.Code.DISK_ERROR, null);
        indexSbr.getByteBuffer().getInt(); //magic
        long pos = indexSbr.getByteBuffer().getLong();
        int size = indexSbr.getByteBuffer().getInt();
        indexSbr.release();
        SelectMmapBufferResult dataSbr = dataFileQueue.getData(pos, size);
        PreConditions.check(dataSbr.getByteBuffer() != null, DLegerException.Code.DISK_ERROR, null);
        DLegerEntry dLegerEntry = DLegerEntryCoder.decode(dataSbr.getByteBuffer());
        dLegerEntry.setPos(pos);
        dataSbr.release();
        return dLegerEntry;
    }