com.sleepycat.collections
Class CurrentTransaction

java.lang.Object
  com.sleepycat.collections.CurrentTransaction

public class CurrentTransaction
extends Object

Provides access to the current transaction for the current thread within the context of a Berkeley DB environment. This class provides explicit transaction control beyond that provided by the TransactionRunner class. However, both methods of transaction control manage per-thread transactions.

Author:

Mark Hayes

Method Summary

Transaction	abortTransaction() Aborts the transaction that is active for the current thread for this environment and makes the parent transaction (if any) the current transaction.
Transaction	beginTransaction(TransactionConfig config) Begins a new transaction for this environment and associates it with the current thread.
Transaction	commitTransaction() Commits the transaction that is active for the current thread for this environment and makes the parent transaction (if any) the current transaction.
Environment	getEnvironment() Returns the underlying Berkeley DB environment.
static CurrentTransaction	getInstance(Environment env) Gets the CurrentTransaction accessor for a specified Berkeley DB environment.
Transaction	getTransaction() Returns the transaction associated with the current thread for this environment, or null if no transaction is active.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getInstance

public static CurrentTransaction getInstance(Environment env)

Gets the CurrentTransaction accessor for a specified Berkeley DB environment. This method always returns the same reference when called more than once with the same environment parameter.

Parameters:

env - is an open Berkeley DB environment.

Returns:

the CurrentTransaction accessor for the given environment, or null if the environment is not transactional.

getEnvironment

public final Environment getEnvironment()

Returns the underlying Berkeley DB environment.

getTransaction

public final Transaction getTransaction()

Returns the transaction associated with the current thread for this environment, or null if no transaction is active.

beginTransaction

public final Transaction beginTransaction(TransactionConfig config)
                                   throws DatabaseException

Begins a new transaction for this environment and associates it with the current thread. If a transaction is already active for this environment and thread, a nested transaction will be created.

Parameters:

config - the transaction configuration used for calling Environment.beginTransaction(com.sleepycat.je.Transaction, com.sleepycat.je.TransactionConfig), or null to use the default configuration.

Returns:

the new transaction.

Throws:

InsufficientReplicasException - if the Master in a replicated environment could not contact a quorum of replicas as determined by the Durability.ReplicaAckPolicy.

ReplicaConsistencyException - if a replica in a replicated environment cannot become consistent within the timeout period.

EnvironmentFailureException - if an unexpected, internal or environment-wide failure occurs.

DatabaseException - if the transaction cannot be started, in which case any existing transaction is not affected.

IllegalStateException - if a transaction is already active and nested transactions are not supported by the environment.

commitTransaction

public final Transaction commitTransaction()
                                    throws DatabaseException,
                                           IllegalStateException

Commits the transaction that is active for the current thread for this environment and makes the parent transaction (if any) the current transaction.

Returns:

the parent transaction or null if the committed transaction was not nested.

Throws:

InsufficientReplicasException - if the master in a replicated environment could not contact a quorum of replicas as determined by the Durability.ReplicaAckPolicy. The application must abort the transaction and can choose to retry it.

InsufficientAcksException - if the master in a replicated environment did not receive enough replica acknowledgments, although the commit succeeded locally.

ReplicaWriteException - if a write operation was performed with this transaction, but this node is now a Replica.

OperationFailureException - if this exception occurred earlier and caused the transaction to be invalidated.

EnvironmentFailureException - if an unexpected, internal or environment-wide failure occurs.

DatabaseException - if an error occurs committing the transaction. The transaction will still be closed and the parent transaction will become the current transaction.

IllegalStateException - if no transaction is active for the current thread for this environment.

abortTransaction

public final Transaction abortTransaction()
                                   throws DatabaseException,
                                          IllegalStateException

Aborts the transaction that is active for the current thread for this environment and makes the parent transaction (if any) the current transaction.

Returns:

the parent transaction or null if the aborted transaction was not nested.

Throws:

EnvironmentFailureException - if an unexpected, internal or environment-wide failure occurs.

DatabaseException - if an error occurs aborting the transaction. The transaction will still be closed and the parent transaction will become the current transaction.

IllegalStateException - if no transaction is active for the current thread for this environment.