org.apache.ojb.odmg
Class TransactionImpl

java.lang.Object
  org.apache.ojb.odmg.TransactionImpl

All Implemented Interfaces:

org.apache.ojb.broker.util.configuration.Configurable, HasBroker, org.apache.ojb.broker.accesslayer.MaterializationListener, Transaction, TransactionExt

Direct Known Subclasses:

J2EETransactionImpl

public class TransactionImpl

extends java.lang.Object

implements Transaction, org.apache.ojb.broker.accesslayer.MaterializationListener, org.apache.ojb.broker.util.configuration.Configurable, TransactionExt

Implementation of Transaction for org.odmg.Transaction.

Version:

$Id: TransactionImpl.java,v 1.53 2004/02/10 15:28:18 arminw Exp $

Author:

Thomas Mahler & David Dixon-Peugh, Matthew Baird, Armin Waibel

Field Summary

Fields inherited from interface org.odmg.Transaction

READ, UPGRADE, WRITE

Constructor Summary

TransactionImpl(DatabaseImpl theCurrentDB)
Creates new Transaction

Method Summary

void	abort() Abort and close the transaction.
void	afterMaterialization(org.apache.ojb.broker.accesslayer.IndirectionHandler handler, java.lang.Object materializedObject) this callback is invoked after an Object is materialized within an IndirectionHandler.
void	beforeMaterialization(org.apache.ojb.broker.accesslayer.IndirectionHandler handler, Identity oid) this callback is invoked before an Object is materialized within an IndirectionHandler.
void	begin() Start a transaction.
void	checkpoint() Commit the transaction, but reopen the transaction, retaining all locks.
void	commit() Commit and close the transaction.
void	configure(org.apache.ojb.broker.util.configuration.Configuration config)
void	flush() Calling flush flushes persistent object modifications made within the ODMG transaction since the last checkpoint to the underlying database transaction, but does commit the database transaction.
DatabaseImpl	getAssociatedDatabase() Returns the associated database
PersistenceBroker	getBroker() Gets the broker associated with the transaction.
java.lang.String	getGUID()
java.lang.Object	getObjectByIdentity(Identity id) Get object by identity.
boolean	isDeleted(Identity id) Checks if the object with the given identity has been deleted within the transaction.
boolean	isOpen() Determine whether the transaction is open or not.
void	join() Attach the caller's thread to this Transaction and detach the thread from any former Transaction the thread may have been associated with.
void	leave() Detach the caller's thread from this Transaction , but do not attach the thread to another Transaction .
void	lock(java.lang.Object obj, int lockMode) Upgrade the lock on the given object to the given lock mode.
void	markDelete(java.lang.Object anObject) marks an object for deletion without locking the object.
void	markDirty(java.lang.Object anObject) marks an object as dirty without locking the object.
void	setImplicitLocking(boolean value) This method can be used to activate or deactivate the implicit locking mechanism for the current transaction.
boolean	tryLock(java.lang.Object obj, int lockMode) Upgrade the lock on the given object to the given lock mode.

Methods inherited from class java.lang.Object

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

Constructor Detail

TransactionImpl

public TransactionImpl(DatabaseImpl theCurrentDB)

Creates new Transaction

Parameters:

theCurrentDB - - create a transaction that is associated with the database.

Method Detail

getAssociatedDatabase

public DatabaseImpl getAssociatedDatabase()

Returns the associated database

isOpen

public boolean isOpen()

Determine whether the transaction is open or not. A transaction is open if a call has been made to begin , but a subsequent call to either commit or abort has not been made.

Specified by:

isOpen in interface Transaction

Returns:

True if the transaction is open, otherwise false.

join

public void join()

Attach the caller's thread to this Transaction and detach the thread from any former Transaction the thread may have been associated with.

Specified by:

join in interface Transaction

lock

public void lock(java.lang.Object obj,
                 int lockMode)
          throws LockNotGrantedException

Upgrade the lock on the given object to the given lock mode. The call has no effect if the object's current lock is already at or above that level of lock mode.

Specified by:

lock in interface Transaction

Parameters:

obj - object to acquire a lock on.

lockMode - lock mode to acquire. The lock modes are READ , UPGRADE , and WRITE .

Throws:

LockNotGrantedException - Description of Exception

leave

public void leave()

Detach the caller's thread from this Transaction , but do not attach the thread to another Transaction .

Specified by:

leave in interface Transaction

checkpoint

public void checkpoint()

Commit the transaction, but reopen the transaction, retaining all locks. Calling checkpoint commits persistent object modifications made within the transaction since the last checkpoint to the database. The transaction retains all locks it held on those objects at the time the checkpoint was invoked.

Specified by:

checkpoint in interface Transaction

flush

public void flush()

Description copied from interface: TransactionExt

Calling flush flushes persistent object modifications made within the ODMG transaction since the last checkpoint to the underlying database transaction, but does commit the database transaction. The ODMG transaction retains all locks it held on those objects at the time the flush was invoked.

This method is very similair to Transaction.checkpoint().

Specified by:

flush in interface TransactionExt

See Also:

TransactionExt.flush()

markDelete

public void markDelete(java.lang.Object anObject)

Description copied from interface: TransactionExt

marks an object for deletion without locking the object.

Specified by:

markDelete in interface TransactionExt

Parameters:

anObject - Object to be marked

See Also:

TransactionExt.markDelete(java.lang.Object)

markDirty

public void markDirty(java.lang.Object anObject)

Description copied from interface: TransactionExt

marks an object as dirty without locking the object.

Specified by:

markDirty in interface TransactionExt

Parameters:

anObject - Object to be marked

See Also:

TransactionExt.markDirty(java.lang.Object)

tryLock

public boolean tryLock(java.lang.Object obj,
                       int lockMode)

Upgrade the lock on the given object to the given lock mode. Method tryLock is the same as lock except it returns a boolean indicating whether the lock was granted instead of generating an exception.

Specified by:

tryLock in interface Transaction

Parameters:

obj - Description of Parameter

lockMode - Description of Parameter

Returns:

Description of the Returned Value , UPGRADE , and WRITE .

commit

public void commit()

Commit and close the transaction. Calling commit commits to the database all persistent object modifications within the transaction and releases any locks held by the transaction. A persistent object modification is an update of any field of an existing persistent object, or an update or creation of a new named object in the database. If a persistent object modification results in a reference from an existing persistent object to a transient object, the transient object is moved to the database, and all references to it updated accordingly. Note that the act of moving a transient object to the database may create still more persistent references to transient objects, so its referents must be examined and moved as well. This process continues until the database contains no references to transient objects, a condition that is guaranteed as part of transaction commit. Committing a transaction does not remove from memory transient objects created during the transaction. The updateObjectList contains a list of all objects for which this transaction has write privledge to. We need to update these objects.

Specified by:

commit in interface Transaction

abort

public void abort()

Abort and close the transaction. Calling abort abandons all persistent object modifications and releases the associated locks. Aborting a transaction does not restore the state of modified transient objects

Specified by:

abort in interface Transaction

begin

public void begin()

Start a transaction. Calling begin multiple times on the same transaction object, without an intervening call to commit or abort , causes the exception TransactionInProgressException to be thrown on the second and subsequent calls. Operations executed before a transaction has been opened, or before reopening after a transaction is aborted or committed, have undefined results; these may throw a TransactionNotInProgressException exception.

Specified by:

begin in interface Transaction

getGUID

public java.lang.String getGUID()

getObjectByIdentity

public java.lang.Object getObjectByIdentity(Identity id)
                                     throws PersistenceBrokerException

Get object by identity. First lookup among objects registered in the transaction, then in persistent storage.

Parameters:

id - The identity

Returns:

The object

Throws:

PersistenceBrokerException

isDeleted

public boolean isDeleted(Identity id)

Checks if the object with the given identity has been deleted within the transaction.

Parameters:

id - The identity

Returns:

true if the object has been deleted

Throws:

PersistenceBrokerException

beforeMaterialization

public void beforeMaterialization(org.apache.ojb.broker.accesslayer.IndirectionHandler handler,
                                  Identity oid)

this callback is invoked before an Object is materialized within an IndirectionHandler.

Specified by:

beforeMaterialization in interface org.apache.ojb.broker.accesslayer.MaterializationListener

Parameters:

handler - the invoking handler

oid - the identity of the object to be materialized

afterMaterialization

public void afterMaterialization(org.apache.ojb.broker.accesslayer.IndirectionHandler handler,
                                 java.lang.Object materializedObject)

this callback is invoked after an Object is materialized within an IndirectionHandler. this callback allows to defer registration of objects until it's really neccessary.

Specified by:

afterMaterialization in interface org.apache.ojb.broker.accesslayer.MaterializationListener

Parameters:

handler - the invoking handler

materializedObject - the materialized Object

getBroker

public PersistenceBroker getBroker()

Gets the broker associated with the transaction. MBAIRD: only return the associated broker if the transaction is open, if it's closed, throw a TransactionNotInProgressException. If we allow brokers to be reaquired by an already closed transaction, there is a very good chance the broker will be leaked as the doClose() method of transactionImpl will never be called and thus the broker will never be closed and returned to the pool.

Specified by:

getBroker in interface HasBroker

Returns:

Returns a PersistenceBroker

Throws:

TransactionNotInProgressException - is the transaction is not open;

configure

public void configure(org.apache.ojb.broker.util.configuration.Configuration config)
               throws org.apache.ojb.broker.util.configuration.ConfigurationException

Specified by:

configure in interface org.apache.ojb.broker.util.configuration.Configurable

Throws:

org.apache.ojb.broker.util.configuration.ConfigurationException

setImplicitLocking

public void setImplicitLocking(boolean value)

Description copied from interface: TransactionExt

This method can be used to activate or deactivate the implicit locking mechanism for the current transaction. turning of implicit locking may improve performance but requires additional care to make sure all changed objects are properly registered to the transaction.

Specified by:

setImplicitLocking in interface TransactionExt

Parameters:

value - if set to true implicit locking is enabled, if false, implicit locking is disabled.

See Also:

TransactionExt.setImplicitLocking(boolean)