What if the process of owner of the lock dies ?
How can other processes obtain the lock ?
Cheers
On Tue, Aug 9, 2016 at 8:19 AM, Liu, Ming (Ming) <ming....@esgyn.cn> wrote:
> Hi, all,
>
> I want to implement a simple 'table lock' in HBase. My current idea is for
> each table, I choose a special rowkey which NEVER be used in real data, and
> then use this row as a 'table level lock'.
>
> The getLock() will be:
>
> getLock(table, cf, cl)
> {
> rowkey = 0 ; //which never used in real data
>
> //generate a UUID, thread ID + an atomic increamental sequence number
> for example. Call it myid
> genMyid(myid);
>
> while(TRUE)
> {
> ret = table.checkAndPut ( rowkey, cf , cl , '0' , myid);
> if (ret == true ) get the lock
> return myid;
> else
> sleep and continue; //retry, maybe can retry for timeout
> here, or wait forever here
> }
> }
>
> The releaseLock() may be:
>
> releaseLock(table, cf, cl, myid)
> {
> Rowkey = 0;
> ret = checkAndPut ( rowkey , cf , cl , myid , '0' ); //If I am
> holding the lock
> if (ret == TRUE) return TRUE;
> else return FALSE;
> }
>
> So one caller get lock, and others must wait until the caller release it,
> and only the lock holder can release the lock. So if one getLock(), it can
> then modify the table, others during this period must wait.
>
> I am very new in lock implementation, so I fear there are basic problems
> in this 'design'.
> So please help me to review if there are any big issues about this idea?
> Any help will be very appreciated.
>
> Thanks a lot,
> Ming
>
