Transaction remake in Infinispan 5.1

It’s up to you as an user to decide weather you want to define a cache as transactional or not. By default, infinispan caches are non transactional. A cache can be made transactional by changing the transactionMode attribute:

transactionMode can only take two values: TRANSACTIONAL and NON_TRANSACTIONAL. Same thing can be also achieved programatically:

Important:for transactional caches it is required to configure a TransactionManagerLookup.

The autoCommit attribute was added in order to assure backward compatibility. If a cache is transactional and autoCommit is enabled (defaults to true) then any call that is performed outside of a transaction’s scope is transparently wrapped within a transaction. In other words Infinispan adds the logic for starting a transaction before the call and committing it after the call. So if your code accesses a cache both transactionally and non-transactionally, all you have to do when migrating to Infinispan 5.1 is mark the cache as transactional and enable autoCommit (that’s actually enabled by default, so just don’t disable it :) The autoCommit feature can be managed through configuration:

or programatically:

With optimistic transactions locks are being acquired at transaction prepare time and are only being held up to the point the transaction commits (or rollbacks). This is different from the 5.0 default locking model where local locks are being acquire on writes and cluster locks are being acquired during prepare time. Optimistic transactions can be enabled in the configuration file:

or programatically:

By default, a transactional cache is optimistic.

From a lock acquisition perspective, pessimistic transactions obtain locks on keys at the time the key is written. E.g.

When cache.put(k1,v1) returns k1 is locked and no other transaction running anywhere in the cluster can write to it. Reading k1 is still possible. The lock on k1 is released when the transaction completes (commits or rollbacks).

Pessimistic transactions can be enabled in the configuration file:

or programatically:

From a use case perspective, optimistic transactions should be used when there’s not a lot of contention between multiple transactions running at the same time. That is because the optimistic transactions rollback if data has changed between the time it was read and the time it was committed (writeSkewCheck). On the other hand, pessimistic transactions might be a better fit when there is high contention on the keys and transaction rollbacks are less desirable. Pessimistic transactions are more costly by their nature: each write operation potentially involves a RPC for lock acquisition.

This major transaction rework has opened the way for several other transaction related improvements:

Stay tuned! Mircea