help, try to use HBase's checkAndPut() to implement distribution lock

[Liu, Ming (Ming)]

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