[infinispan-dev] SysAdmin operations for recovering transactions

[Mircea Markus]

On 18 Mar 2011, at 12:32, Manik Surtani <manik at jboss.org> wrote:

> 
> On 18 Mar 2011, at 12:13, Mircea Markus wrote:
> 
>> Hi,
>> 
>> It's about the stage where TM's recovery  process finds a in-doubt transaction and notifies the sys admin about it: what hooks does ISPN provide to the sys admin in order to "fix" the tx.
>> E.g. step >= 3.3 : http://community.jboss.org/servlet/JiveServlet/showImage/102-16552-14-11811/3_non_originator_failure.png
>> 
>> Here is what I have in mind:
>> 
>> Expose (JMX) two operations:
>> 
>>   //all the params together fully describe a xid.
>>   replayTx(byte[] txBranch, byte[] txId, int formatId); 
>>   forceRollbackTx(byte[] txBranch, byte[] txId, int formatId);
> 
> You expect a sysadmin to type a byte array into a JMX console?  :-)  You might get death threats from sysadmins... 
I imagine untraceble threats, right?
String then...
> 
>> Here is how these two ops would work:
>> A. replayTx 
>>    1. the node has locally the PrepareCommand associated with that XID
>> 	- re-issues a prepare: TransactionXAResource.prepare
>> 	- if successful re-issues a commit: TransactionXAResource.commit
>>        -if failure happens at any step the user is informed and she/he can re-do the JMX call
>> 	- if success the recovery information is removed from the cluster (async)
>>    2. the node doesn't have the PrepareCommand associated with that XID
>> 	- broadcast ReplayTxCommand (Xid)
>>        - when a node receives ReplayTxCommand
>> 		- if doesn't have a PreparedCommand associated with the Xid ignores it
>> 		- if has a PreparedCommand...
>> 			- is it the first in the view that has it [1]? 
> 
> How does a node know the answer to this question?  Is the list of nodes that holds the prepare replay info stored on the PrepareCommand?
No, [1] explains it
> 
>> 				- yes. Execute A.1then returns result to node that broadcasted ReplayTxCommand. This is guaranteed to happen on at most[2] one node in the cluster
>> 				- no. Ignores it.
>> 	- if success the recovery information is removed from the cluster (async)
>> B.rollbackTx
>>   - node broadcasts RollbackCommand
>>   - each node that has the PrepareCommand forces a rollback
>>   - each node that doesn't have the PreparedCommand ignores it
>>   - if success the recovery information is removed from the cluster (async)
>> 
>> Cheers,
>> Mircea
>> 
>> [1] this is determined by building the set of nodes on which tx spreads, based on tx's state. Then determine the first in the view. 
>> [2] it is possible not to happen on any node as the PrepareCommand might had been removed from all nodes in between (node failures, expiration from the recovery cache). 
>> 
>> 
>> 
>> 
>> 
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> 
> --
> Manik Surtani
> manik at jboss.org
> twitter.com/maniksurtani
> 
> Lead, Infinispan
> http://www.infinispan.org
> 
> 
> 
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