On Thu, Sep 20, 2012 at 8:32 PM, kaka chen <[email protected]> wrote:
> Hi All:
> Can someone explain the handle BADVERSION at setData() method in
> RecoverableZookeeper.java, I am very confused. The meta data is MAGIC(1
> BYTE) + LENGTH_FIELD(4 BYTE) + ID + DATA, but the parsing is very strange,
> and why to compare id with data? Please help me, thanks!
>
> case BADVERSION:
> // try to verify whether the previous setData success or not
> try{
> Stat stat = new Stat();
> byte[] revData = zk.getData(path, false, stat);
> int idLength = Bytes.toInt(revData, ID_LENGTH_SIZE);
> int dataLength = revData.length-ID_LENGTH_SIZE-idLength;
> int dataOffset = ID_LENGTH_SIZE+idLength;
>
> if(Bytes.compareTo(revData, ID_LENGTH_SIZE, id.length,
> revData, dataOffset, dataLength) == 0) {
I don't know. The above looks wong to me. Maybe if I read more of
RecoverableZooKeeper, it'd make sense (but I doubt it).
Se we tried to setData but the version proffered was wrong; someone
else had changed it on us.
Is there a broader context?
St.Ack
> // the bad version is caused by previous successful setData
> return stat;
> }
> } catch(KeeperException keeperException){
> // the ZK is not reliable at this moment. just throwing
> exception
> throw keeperException;
> }
>
> Kaka Chen
