edu.mssm.crover.odmg.objectstore
Class Transaction

java.lang.Object
  |
  +--edu.mssm.crover.odmg.objectstore.Transaction

All Implemented Interfaces:

org.odmg.Transaction

public class Transaction

extends java.lang.Object

implements org.odmg.Transaction

Field Summary

static int	READ Read lock mode.
protected com.odi.odmg.Transaction	tr
static int	UPGRADE Upgrade lock mode.
static int	WRITE Write lock mode.

Constructor Summary

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.
com.odi.odmg.Transaction	getTransaction()
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.
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

Field Detail

tr

protected com.odi.odmg.Transaction tr

READ

public static final int READ

Read lock mode.

See Also:

Constant Field Values

UPGRADE

public static final int UPGRADE

Upgrade lock mode.

See Also:

Constant Field Values

WRITE

public static final int WRITE

Write lock mode.

See Also:

Constant Field Values

Constructor Detail

Transaction

public Transaction()

Method Detail

getTransaction

public com.odi.odmg.Transaction getTransaction()

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 org.odmg.Transaction

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 org.odmg.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 org.odmg.Transaction

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 org.odmg.Transaction

Returns:

True if the transaction is open, otherwise false.

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

Specified by:

commit in interface org.odmg.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 org.odmg.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 org.odmg.Transaction

lock

public void lock(java.lang.Object obj,
                 int lockMode)
          throws org.odmg.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 org.odmg.Transaction

Parameters:

obj - The object to acquire a lock on.

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

Throws:

org.odmg.LockNotGrantedException - Is thrown if the given lock mode could not be acquired.

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 org.odmg.Transaction

Parameters:

obj - The object to acquire a lock on.

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

Returns:

True if the lock has been acquired, otherwise false.