package storm.trident.state;
/**
* There's 3 different kinds of state:
*
* 1. non-transactional: ignores commits, updates are permanent. no rollback. a cassandra incrementing state would be like this
* 2. repeat-transactional: idempotent as long as all batches for a txid are identical
* 3. opaque-transactional: the most general kind of state. updates are always done
* based on the previous version of the value if the current commit = latest stored commit
* Idempotent even if the batch for a txid can change.
*
* repeat transactional is idempotent for transactional spouts
* opaque transactional is idempotent for opaque or transactional spouts
*
* Trident should log warnings when state is idempotent but updates will not be idempotent
* because of spout
*/
// retrieving is encapsulated in Retrieval interface
public interface State {
void beginCommit(Long txid); // can be null for things like partitionPersist occuring off a DRPC stream
void commit(Long txid);
}