Package com.tangosol.util

Interface TransactionMap.Validator

All Known Implementing Classes:

SimpleValidator

Enclosing interface:

TransactionMap

public static interface TransactionMap.Validator

A callback interface used by TransactionMap implementations.

By providing an implementation of this interface, it is possible to provide alternative strategies for verifying the correctness of concurrent execution of transactions.

Method Summary

Modifier and Type	Method	Description
void	enlist(TransactionMap mapTx, Object oKey)	Enlist the resource with the specified transaction.
TransactionMap.Validator	getNextValidator()	Retrive the next Validator.
void	setNextValidator(TransactionMap.Validator v)	Set the next Validator.
void	validate(TransactionMap mapTx, Set setInsert, Set setUpdate, Set setDelete, Set setRead, Set setPhantom)	Validate that the content of the TransactionMap is "fit" to be committed into the base map.

Method Detail

enlist

void enlist(TransactionMap mapTx,
            Object oKey)

Enlist the resource with the specified transaction.

This method is invoked for all resources that are "used" by the transaction immediately before the resource value is copied into the local map.

It is this method's responsibility to call a next Validator in the validation chain (i.e. getNextValidator().enlist(map, okey);)

Parameters:

mapTx - the TransactionMap to enlist the resource with

oKey - the resource key to be enlisted with the transaction

validate

void validate(TransactionMap mapTx,
              Set setInsert,
              Set setUpdate,
              Set setDelete,
              Set setRead,
              Set setPhantom)
       throws ConcurrentModificationException

Validate that the content of the TransactionMap is "fit" to be committed into the base map.

This method is invoked during "prepare" phase after all the resources involved in this transaction are successfully locked at the base map. The Validator is expected to retrieve the "old" and "new" values (using map.get(oKey), map.getBaseMap().get(oKey)) and use the information gathered during "enlist" calls to make the determination whether or not commit should be allowed to proceed.

To force a roll back it should throw an exception indicating the reason this transaction cannot be committed. When that happens, the sets are expected to hold just the keys of the "offending" resources.

It is this method's responsibility to call a next Validator in the validation chain (i.e. getNextValidator().validate(map, setI, setU, setD, setR, setF);)

Parameters:

mapTx - the TransactionMap that is being prepared

setInsert - the set of inserted resources

setUpdate - the set of updated resources

setDelete - the set of deleted resources

setRead - the set of read resources. It is always empty for TRANSACTION_GET_COMMITTED isolation level.

setPhantom - the set of phantom resources, that is resources that were added to the base map, but were not known to the transaction. This set can be not empty only for TRANSACTION_GET_SERIALIZED isolation level.

Throws:

ConcurrentModificationException - if the validator detects an unresolveable conflict between the resources

getNextValidator

TransactionMap.Validator getNextValidator()

Retrive the next Validator.

Returns:

the next Validator

setNextValidator

void setNextValidator(TransactionMap.Validator v)

Set the next Validator. Note: This method cannot be called while in the middle of a validation (commit) phase.

Parameters:

v - the Validator to be added

Throws:

IllegalStateException - if the next validator cannot be changed