com.antelmann.db
Interface DBTransaction

All Known Implementing Classes:

AbstractDBTransaction, SQLTransaction

public interface DBTransaction

a transaction controlls access to all resources of a Database through DBClassStore instances. A Thread accessing resources must own the monitor on the active transaction. To ensure thread-save consistency on a transaction, a thread must maintain ownership over the transaction throughout the duration of a transaction.

Author:

Holger Antelmann

See Also:

Database, TransactionListener

Method Summary

void	abort() aborts this transaction; requires ownership of this instance.
boolean	addTransactionListener(TransactionListener listener)
void	begin() sets the transaction to active and allows access to the Resources provided that the calling thread holds the lock on this instance.
void	commit() commits all data within the transaction scope to the underlying database; requires ownership of this instance.
Database<?>	getDatabase() gives access to the associated Database
TransactionListener[]	getTransactionListeners()
boolean	isActive() if true, a transaction is currently in progress and has not been committed or aborted, yet.
boolean	isReadOnly() informs whether the currently running transaction is configured to be read-only.
boolean	removeTransactionListener(TransactionListener listener)
void	setNextToReadOnly(boolean flag) allows to configure the next transaction to be read-only.

Method Detail

addTransactionListener

boolean addTransactionListener(TransactionListener listener)

removeTransactionListener

boolean removeTransactionListener(TransactionListener listener)

getTransactionListeners

TransactionListener[] getTransactionListeners()

getDatabase

Database<?> getDatabase()

gives access to the associated Database

begin

void begin()
           throws TransactionException

sets the transaction to active and allows access to the Resources provided that the calling thread holds the lock on this instance.

Throws:

TransactionException - if the transaction is already active or if the transaction is in transition

See Also:

TransactionListener.transactionAborted(DBTransaction), TransactionListener.transactionCommitted(DBTransaction)

commit

void commit()
            throws TransactionException,
                   DatabaseException

commits all data within the transaction scope to the underlying database; requires ownership of this instance.

Throws:

TransactionException - if the transaction is already active

DatabaseException - if the transaction could not be committed to the underlying service

abort

void abort()
           throws TransactionException,
                  DatabaseException

aborts this transaction; requires ownership of this instance.

Throws:

TransactionException - if the transaction is already active

DatabaseException - if the transaction could not be aborted from the underlying service

isActive

boolean isActive()

if true, a transaction is currently in progress and has not been committed or aborted, yet. Access to resources is only save if this method returns true and the calling thread holds the lock on this instance. In order to rely on the return value after the method returns, an ownership of the calling thread on this DBTransaction is required.

isReadOnly

boolean isReadOnly()

informs whether the currently running transaction is configured to be read-only. If there is no active transaction, the return value will determine whether the next transaction to be started is going to be read-only. This setting only applies for the current/next transaction, not for subsequent ones. Some given database implementation may, however, configure every transaction to be read-only (or read-write) while altering this setting may not be supported. setNextToReadOnly(boolean)

setNextToReadOnly

void setNextToReadOnly(boolean flag)
                       throws TransactionException,
                              UnsupportedOperationException

allows to configure the next transaction to be read-only. This call must be repeated before every transaction that is to be read-only, as after each commit/abort this setting is reset to false.

Parameters:

flag - if true, the next transaction will run read-only; if false, the next transaction will be read-write

Throws:

TransactionException - if a transaction is currently active

UnsupportedOperationException

See Also:

isReadOnly()