[infinispan-dev] Issue about propagation of the RollbackCommand in Infinispan 5.2.0

[Sebastiano Peluso]

Hi all,

I have a question about the propagation of the RollbackCommand in 
Infinispan 5.2.0 when I use the Optimistic locking scheme and the 
Distribution clustering mode.

In particular I have noticed that a RollbackCommand command for a 
transaction T is propagated on a set of nodes S even if T's coordinator 
has never sent and it will never send a PrepareCommand command to nodes 
in S.

I try to make clear the issue by the following example.
  Suppose you have a transaction T executing on node N0 and T writes on 
keys k0, k1, k2,...., km (m+1 keys) until it reaches the prepare phase. 
In addition node Ni, with i=0,...,m+1, is the ki's primary owner. If at 
prepare time, during the lock acquisition on the local node N0 (see 
visitPrepareCommand method in OptimisticLockingInterceptor class) T 
fails to acquire the lock on k0, an exception is thrown (e.g. 
TimeoutException) and T will be rolled back. In this case, when T starts 
the rollback phase, it seems to me that a RollbackCommand command is 
multicast to all nodes Nj, with j=1,...,d, if k0 is sorted after kj 
during the local lock acquisition (see acquireAllLocks method in 
OptimisticLockingInterceptor), because:

  - shouldInvokeRemoteCommand method on the TxInvocationContext returns 
true (see BaseRpcInterceptor class);
  - getAffectedKeys on the TxInvocationContext returns the set {k1,..., 
kd} (see visitRollbackCommand in DistributionInterceptor class).

Is it correct?

If I'm not wrong, which is the design choice behind this implementation?

Thank you.

Best regards,

    Sebastiano Peluso

-- 
Sebastiano Peluso, PhD student

Department of Computer, Control and Management Engineering
Sapienza University of Rome
Via Ariosto 25, 00185, Rome, Italy
Tel. +39 06 77274108
Webpage http://www.dis.uniroma1.it/~peluso

Distributed Systems Group, INESC-ID
Instituto Superior Técnico
Rua Alves Redol 9, 1000-029, Lisbon, Portugal
Webpage http://www.gsd.inesc-id.pt/~peluso