ojb.server
Class TransactionImpl

java.lang.Object
  |
  +--ojb.server.TransactionImpl

All Implemented Interfaces:

Transaction

public class TransactionImpl

extends java.lang.Object

implements Transaction

Implementation of Transaction for org.odmg.Transaction.

Author:

Thomas Mahler & David Dixon-Peugh

Fields inherited from interface org.odmg.Transaction

READ, UPGRADE, WRITE

Constructor Summary

TransactionImpl(TransactionTable theTxTable, DatabaseImpl theCurrentDB)
Creates new Transaction

Method Summary

void	abort() Abort and close the transaction.
void	begin() Start a transaction.
void	checkpoint() Commit the transaction, but reopen the transaction, retaining all locks.
void	commit() Commit and close 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
void	markModified(java.lang.Object anObject) marks an object as dirty
void	register(java.lang.Object newTxObject) registers the object with this transaction recursively with all associations.
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

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

Constructor Detail

TransactionImpl

public TransactionImpl(TransactionTable theTxTable,
                       DatabaseImpl theCurrentDB)

Creates new Transaction

Parameters:

theTxTable - - Transaction table so we can manage this and other transactions.

Method Detail

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

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

markModified

public void markModified(java.lang.Object anObject)

marks an object as dirty

Parameters:

anObject - Object that was changed.

fieldName - Field name of Object that was changed.

markDelete

public void markDelete(java.lang.Object anObject)

marks an object for deletion

Parameters:

anObject - Object to be marked

register

public void register(java.lang.Object newTxObject)

registers the object with this transaction recursively with all associations.