org.castor.persist

Interface TransactionContext

All Known Implementing Classes:

AbstractTransactionContext, GlobalTransactionContext, LocalTransactionContext

public interface TransactionContext

A transaction context is required in order to perform operations against the database. The transaction context is mapped to an API transaction or an XA transaction. The only way to begin a new transaction is through the creation of a new transaction context. A transaction context is created from an implementation class directly or through XAResourceImpl.

Since:

1.0

Version:

$Revision: 8660 $ $Date: 2006-04-22 11:05:30 -0600 (Sat, 22 Apr 2006) $

Author:

Assaf Arkin , Ralf Joachim, Werner Guttmann, Gregory Block

Method Summary

Methods

Modifier and Type	Method and Description
void	addTxSynchronizable(TxSynchronizable synchronizable) Register a listener which wants to synchronize its state to the state of the transaction.
void	close() Closes all Connections.
void	commit() Commits all changes and closes the transaction releasing all locks on all objects.
void	create(ClassMolder molder, Object object, OID depended) Creates a new object in persistent storage.
void	delete(Object object) Deletes the object from persistent storage.
void	expireCache(ClassMolder molder, Identity identity) Expire object from the cache.
Object	fetch(ClassMolder molder, Identity identity, AccessMode suggestedAccessMode)
ClassLoader	getClassLoader() Get the current application ClassLoader.
Connection	getConnection(LockEngine engine) Return an open connection for the specified engine.
DbMetaInfo	getConnectionInfo(LockEngine engine) Returns meta-data related to the RDBMS used.
Database	getDatabase()
int	getLockTimeout() Returns the timeout waiting to acquire a lock.
NamedNativeQuery	getNamedNativeQuery(ClassMolder molder, String name) Returns a NamedNativeQuery instance query based upon a named query as defined in the mapping file.
String	getNamedQuery(ClassMolder molder, String name) Creates an OQL query based upon a named query as defined in the mapping file.
int	getStatus() Returns the status of this transaction.
int	getTransactionTimeout() Returns the timeout of this transaction.
ObjectLock	getWaitOnLock() Returns the lock which this transaction attempts to acquire.
boolean	isAutoStore() Deprecated. Please use the 'cascading' attribute of the field mapping instead.
boolean	isCached(ClassMolder molder, Class cls, Identity identity)
boolean	isCreated(Object object) Returns true if the object is marked as created in this transaction.
boolean	isDeleted(Object object) Returns true if and only if the specified object is loaded or created in this transaction and is deleted.
boolean	isDeletedByOID(OID oid)
boolean	isDepended(OID master, Object dependent)
boolean	isLocked(Class cls, Identity identity, LockEngine lockEngine) Returns true if the object given is locked.
boolean	isOpen() Returns true if the transaction is open.
boolean	isPersistent(Object object) Returns true if the object is persistent in this transaction.
boolean	isReadOnly(Object object) Check to see whether this transaction considers an object to have been marked read-only.
boolean	isRecorded(Object object) Returns true if the object has been previously queried/loaded/updated/created in this transaction.
boolean	isUpdateCacheNeeded(Object object) Retrieves the state of the object in this transaction.
boolean	isUpdatePersistNeeded(Object object) Retrieves the state of the object in this transaction.
Iterator	iterateReadWriteObjectsInTransaction() Expose an enumeration of the commited object entries to allow TxSynchronizable to iterate through the objects.
Object	load(Identity identity, ProposedEntity proposedObject, AccessMode suggestedAccessMode) Load an object for use within the transaction.
Object	load(Identity identity, ProposedEntity proposedObject, AccessMode suggestedAccessMode, QueryResults results) Load an object for use within the transaction.
void	markCreate(ClassMolder molder, Object object, OID rootObjectOID) Walk a data object tree starting from the specified object, and mark all objects to be created.
void	markModified(Object object, boolean updatePersist, boolean updateCache)
boolean	markUpdate(ClassMolder molder, Object object, OID depended) Update a new object in persistent storage and returns the object's OID.
boolean	prepare() Prepares the transaction prior to committing it.
QueryResults	query(LockEngine engine, PersistenceQuery query, AccessMode accessMode, boolean scrollable) Perform a query using the query mechanism with the specified access mode.
void	removeTxSynchronizable(TxSynchronizable synchronizable) Unregister a listener which wants to synchronize its state to the state of the transaction.
void	rollback() Rolls back all changes and closes the transaction releasing all locks on all objects.
void	setAutoStore(boolean autoStore) Deprecated. Please use the 'cascading' attribute of the field mapping instead.
void	setCallback(CallbackInterceptor callback) Overrides the default callback interceptor by a custom interceptor for this database source.
void	setInstanceFactory(InstanceFactory factory) Overrides the default instance factory by a custom one for this database source.
void	setLockTimeout(int timeout) Sets the timeout waiting to acquire a lock.
void	setStatus(int status) Sets the status of the current transaction to the given one.
void	setTransactionTimeout(int timeout) Sets the timeout of this transaction.
void	setWaitOnLock(ObjectLock lock) Indicates which lock this transaction is waiting for.
void	update(ClassMolder molder, Object object, OID depended) Update a new object in persistent storage and returns the object's OID.
void	writeLock(Object object, int timeout) Acquire a write lock on the object.

Method Detail

addTxSynchronizable

void addTxSynchronizable(TxSynchronizable synchronizable)

Register a listener which wants to synchronize its state to the state of the transaction.

Parameters:

synchronizable - The TxSynchronizable implementation to register.

removeTxSynchronizable

void removeTxSynchronizable(TxSynchronizable synchronizable)

Unregister a listener which wants to synchronize its state to the state of the transaction.

Parameters:

synchronizable - The TxSynchronizable implementation to unregister.

setAutoStore

void setAutoStore(boolean autoStore)

Deprecated. Please use the 'cascading' attribute of the field mapping instead.

Enable or disable autoStore. If enabled, all new objects, which are reachable from other object that are queried, loaded, created in the transaction, will be created when the transaction is committed.

Parameters:

autoStore - When set to true autoStore will be enabled.

isAutoStore

boolean isAutoStore()

Deprecated. Please use the 'cascading' attribute of the field mapping instead.

Test if autoStore option is enabled or not.

Returns:

true if autoStore option is enabled.

setCallback

void setCallback(CallbackInterceptor callback)

Overrides the default callback interceptor by a custom interceptor for this database source.

The interceptor is a callback that notifies data objects on persistent state events.

If callback interceptor is not overriden, events will be sent to data object that implements the org.exolab.castor.jdo.Persistent interface.

Parameters:

callback - The callback interceptor, disabled if null.

setInstanceFactory

void setInstanceFactory(InstanceFactory factory)

Overrides the default instance factory by a custom one for this database source.

The factory is used to obatain a new instance of data object when it is needed during loading.

Parameters:

factory - The instanceFactory to be used, disable if null.

setTransactionTimeout

void setTransactionTimeout(int timeout)

Sets the timeout of this transaction. The timeout is specified in seconds.

Parameters:

timeout - The timeout for this transaction in seconds.

getTransactionTimeout

int getTransactionTimeout()

Returns the timeout of this transaction. The timeout is specified in seconds.

Returns:

The timeout of this transaction in seconds.

setLockTimeout

void setLockTimeout(int timeout)

Sets the timeout waiting to acquire a lock. The timeout is specified in seconds.

Parameters:

timeout - The timeout waiting to acquire a lock in seconds.

getLockTimeout

int getLockTimeout()

Returns the timeout waiting to acquire a lock. The timeout is specified in seconds.

Returns:

The timeout waiting to acquire a lock in seconds.

setStatus

void setStatus(int status)

Sets the status of the current transaction to the given one.

Parameters:

status - The status to set for this transaction.

getStatus

int getStatus()

Returns the status of this transaction.

Returns:

The status of this transaction.

setWaitOnLock

void setWaitOnLock(ObjectLock lock)

Indicates which lock this transaction is waiting for. When a transaction attempts to acquire a lock it must indicate which lock it attempts to acquire in order to perform dead-lock detection. This method is called by ObjectLock before entering the temporary lock-acquire state.

Parameters:

lock - The lock which this transaction attempts to acquire

getWaitOnLock

ObjectLock getWaitOnLock()

Returns the lock which this transaction attempts to acquire.

Returns:

The lock which this transaction attempts to acquire

getConnection

Connection getConnection(LockEngine engine)
                         throws PersistenceException

Return an open connection for the specified engine. Only one connection should be created for a given engine in the same transaction.

Parameters:

engine - The persistence engine.

Returns:

An open connection.

Throws:

PersistenceException - An error occured talking to the persistence engine.

getConnectionInfo

DbMetaInfo getConnectionInfo(LockEngine engine)
                             throws PersistenceException

Returns meta-data related to the RDBMS used.

Parameters:

engine - LockEngine instance used.

Returns:

A DbMetaInfo instance describing various features of the underlying RDBMS.

Throws:

PersistenceException - An error occured talking to the persistence engine.

fetch

Object fetch(ClassMolder molder,
           Identity identity,
           AccessMode suggestedAccessMode)
             throws PersistenceException

Throws:

PersistenceException

load

Object load(Identity identity,
          ProposedEntity proposedObject,
          AccessMode suggestedAccessMode)
            throws PersistenceException

Load an object for use within the transaction. Multiple access to the same object within the transaction will return the same object instance (except for read-only access).

This method is similar to fetch(org.exolab.castor.persist.ClassMolder, org.exolab.castor.persist.spi.Identity, org.exolab.castor.mapping.AccessMode) except that it will load the object only once within a transaction and always return the same instance.

If the object is loaded for read-only then no lock is acquired and updates to the object are not reflected at commit time. If the object is loaded for read-write then a read lock is acquired (unless timeout or deadlock detected) and the object is stored at commit time. The object is then considered persistent and may be deleted or upgraded to write lock. If the object is loaded for exclusive access then a write lock is acquired and the object is synchronized with the persistent copy.

Attempting to load the object twice in the same transaction, once with exclusive lock and once with read-write lock will result in an exception.

Parameters:

identity - The object's identity.

proposedObject - The object to fetch (single instance per transaction).

suggestedAccessMode - The access mode (see AccessMode) the values in persistent storage.

Returns:

object being loaded.

Throws:

PersistenceException - Timeout or deadlock occured attempting to acquire lock on object. The object was not found in persistent storage. An error reported by the persistence engine.

load

Object load(Identity identity,
          ProposedEntity proposedObject,
          AccessMode suggestedAccessMode,
          QueryResults results)
            throws PersistenceException

Load an object for use within the transaction. Multiple access to the same object within the transaction will return the same object instance (except for read-only access).

In addition to load(Identity,ProposedEntity,AccessMode) a QueryResults can be specified.

Parameters:

identity - The object's identity.

proposedObject - The object to fetch (single instance per transaction).

suggestedAccessMode - The access mode (see AccessMode) the values in persistent storage.

results - The QueryResult that the data to be loaded from.

Returns:

object being loaded.

Throws:

PersistenceException - Timeout or deadlock occured attempting to acquire lock on object. The object was not found in persistent storage. An error reported by the persistence engine.

query

QueryResults query(LockEngine engine,
                 PersistenceQuery query,
                 AccessMode accessMode,
                 boolean scrollable)
                   throws PersistenceException

Perform a query using the query mechanism with the specified access mode. The query is performed in this transaction, and the returned query results can only be used while this transaction is open. It is assumed that the query mechanism is compatible with the persistence engine.

Parameters:

engine - The persistence engine.

query - A query against the persistence engine.

accessMode - The access mode.

scrollable - The db cursor mode.

Returns:

A query result iterator

Throws:

PersistenceException - An error reported by the persistence engine or an invalid query.

markCreate

void markCreate(ClassMolder molder,
              Object object,
              OID rootObjectOID)
                throws PersistenceException

Walk a data object tree starting from the specified object, and mark all objects to be created.

Parameters:

molder - The class persistence molder.

object - The object to persist.

rootObjectOID - The OID of the root object to start walking.

Throws:

PersistenceException - An object with this identity already exists in persistent storage. The class is not persistent capable. An error reported by the persistence engine.

create

void create(ClassMolder molder,
          Object object,
          OID depended)
            throws PersistenceException

Creates a new object in persistent storage. The object will be persisted only if the transaction commits. If an identity is provided then duplicate identity check happens in this method, if no identity is provided then duplicate identity check occurs when the transaction completes and the object is not visible in this transaction.

Parameters:

molder - The molder of the creating class.

object - The object to persist.

depended - The master object's OID if exist.

Throws:

PersistenceException - An object with this identity already exists in persistent storage. The class is not persistent capable. An error reported by the persistence engine.

markUpdate

boolean markUpdate(ClassMolder molder,
                 Object object,
                 OID depended)
                   throws PersistenceException

Update a new object in persistent storage and returns the object's OID. The object will be persisted only if the transaction commits. If an identity is provided then duplicate identity check happens in this method, if no identity is provided then duplicate identity check occurs when the transaction completes and the object is not visible in this transaction.

Update will also mark objects to be created if the TIMESTAMP equals to NO_TIMESTAMP.

Parameters:

molder - The object's molder.

object - The object to persist.

depended - The master objects of the specified object to be created if exisit.

Returns:

true if the object is marked to be created.

Throws:

PersistenceException - An object with this identity already exists in persistent storage. The class is not persistent capable. Dirty checking mechanism may immediately report that the object was modified in the database during the long transaction. An error reported by the persistence engine.

update

void update(ClassMolder molder,
          Object object,
          OID depended)
            throws PersistenceException

Update a new object in persistent storage and returns the object's OID. The object will be persisted only if the transaction commits. If an identity is provided then duplicate identity check happens in this method, if no identity is provided then duplicate identity check occurs when the transaction completes and the object is not visible in this transaction.

Update will also mark objects to be created if the TIMESTAMP equals to NO_TIMESTAMP.

Parameters:

molder - The object's molder.

object - The object to persist.

depended - The master objects of the specified object to be created if exisit.

Throws:

PersistenceException - An object with this identity already exists in persistent storage. The class is not persistent capable. Dirty checking mechanism may immediately report that the object was modified in the database during the long transaction. An error reported by the persistence engine.

delete

void delete(Object object)
            throws PersistenceException

Deletes the object from persistent storage. The deletion will take effect only if the transaction is committed, but the object is no longer viewable for the current transaction and locks for access from other transactions will block until this transaction completes. A write lock is acquired in order to assure the object can be deleted.

Parameters:

object - The object to delete from persistent storage.

Throws:

PersistenceException - The object has not been queried or created in this transaction. Timeout or deadlock occured attempting to acquire lock on object. An error reported by the persistence engine.

writeLock

void writeLock(Object object,
             int timeout)
               throws PersistenceException

Acquire a write lock on the object. Read locks are implicitly available when the object is queried. A write lock is only granted for objects that are created or deleted or for objects loaded in exclusive mode - this method can obtain such a lock explicitly. If the object already has a write lock in this transaction or a read lock in this transaction but no read lock in any other transaction, a write lock is obtained. If this object has a read lock in any other transaction this method will block until the other transaction will release its lock. If the specified timeout has elapsed or a deadlock has been detected, an exception will be thrown but the current lock will be retained.

Parameters:

object - The object to lock.

timeout - Timeout waiting to acquire lock, specified in seconds, zero for no waiting, negative to use the default timeout for this transaction.

Throws:

PersistenceException - The object has not been queried or created in this transaction. Timeout or deadlock occured attempting to acquire lock on object. An error reported by the persistence engine.

markModified

void markModified(Object object,
                boolean updatePersist,
                boolean updateCache)

prepare

boolean prepare()
                throws TransactionAbortedException

Prepares the transaction prior to committing it. Indicates whether the transaction is read-only (i.e. no modified objects), can commit, or an error has occured and the transaction must be rolled back. This method performs actual storage into the persistence storage. Multiple calls to this method can be done, and do not release locks, allowing checkpoint to occur. An IllegalStateException is thrown if transaction is not in the proper state to perform this operation.

Returns:

True if the transaction can commit, false if the transaction is read only

Throws:

TransactionAbortedException - The transaction has been aborted due to inconsistency, duplicate object identity, error with the persistence engine or any other reason.

commit

void commit()
            throws TransactionAbortedException

Commits all changes and closes the transaction releasing all locks on all objects. All objects are now transient. Must be called after a call to prepare() has returned successfully. Throws an IllegalStateException when called without calling prepare() first.

Throws:

TransactionAbortedException - The transaction has been aborted due to inconsistency, duplicate object identity, error with the persistence engine or any other reason.

rollback

void rollback()

Rolls back all changes and closes the transaction releasing all locks on all objects. All objects are now transient, if they were queried in this transaction. This method may be called at any point during the transaction. Throws an IllegalStateException if transaction is not in the proper state to perform this operation.

close

void close()
           throws TransactionAbortedException

Closes all Connections. Must be called before the end of the transaction in EJB environment or after commit in standalone case. Throws an IllegalStateException if this method has been called after the end of the transaction.

Throws:

TransactionAbortedException - The transaction has been aborted due to inconsistency, duplicate object identity, error with the persistence engine or any other reason.

iterateReadWriteObjectsInTransaction

Iterator iterateReadWriteObjectsInTransaction()

Expose an enumeration of the commited object entries to allow TxSynchronizable to iterate through the objects.

Returns:

Iterator of modifiable (read-write) object entries.

isCreated

boolean isCreated(Object object)

Returns true if the object is marked as created in this transaction. Note that this does not find objects in the 'transitional' state of creating. Primarily intended to be used by tests.

Parameters:

object - The object to test the state of in this transaction.

Returns:

true if the object is marked as created within this transaction.

isUpdateCacheNeeded

boolean isUpdateCacheNeeded(Object object)

Retrieves the state of the object in this transaction. Specifically, in this case, that the object requires a cache update.

Parameters:

object - The object to test the state of in this transaction.

Returns:

true if the object is recorded in this transaction with the requested state.

isUpdatePersistNeeded

boolean isUpdatePersistNeeded(Object object)

Retrieves the state of the object in this transaction. Specifically, in this case, that the object requires a persistence update.

Parameters:

object - The object to test the state of in this transaction.

Returns:

true if the object is recorded in this transaction with the requested state.

isPersistent

boolean isPersistent(Object object)

Returns true if the object is persistent in this transaction.

Parameters:

object - The object.

Returns:

true if persistent in transaction.

isRecorded

boolean isRecorded(Object object)

Returns true if the object has been previously queried/loaded/updated/created in this transaction.

Parameters:

object - The object to investigate.

Returns:

true if recorded in this transaction.

isDepended

boolean isDepended(OID master,
                 Object dependent)

isOpen

boolean isOpen()

Returns true if the transaction is open.

Returns:

true if the transaction is open.

isDeleted

boolean isDeleted(Object object)

Returns true if and only if the specified object is loaded or created in this transaction and is deleted.

Parameters:

object - The object to test the state of in this transaction.

Returns:

true if the object is deleted.

isDeletedByOID

boolean isDeletedByOID(OID oid)

isReadOnly

boolean isReadOnly(Object object)

Check to see whether this transaction considers an object to have been marked read-only.

Parameters:

object - The object to test for read-only status

Returns:

true if the object is marked read-only in this transaction; otherwise, false.

isCached

boolean isCached(ClassMolder molder,
               Class cls,
               Identity identity)
                 throws PersistenceException

Throws:

PersistenceException

expireCache

void expireCache(ClassMolder molder,
               Identity identity)
                 throws PersistenceException

Expire object from the cache. Objects expired from the cache will be read from persistent storage, as opposed to being read from the cache, during subsequent load/query operations.

Parameters:

molder - The class persistence molder.

identity - The object's identity.

Throws:

PersistenceException - If identity is null or any problem that happens during expiration of cache values.

getClassLoader

ClassLoader getClassLoader()

Get the current application ClassLoader.

Returns:

the current ClassLoader's instance. null if none has been provided

getDatabase

Database getDatabase()

isLocked

boolean isLocked(Class cls,
               Identity identity,
               LockEngine lockEngine)

Returns true if the object given is locked.

Parameters:

cls - Class instance of the object to be investigated.

identity - Identity of the object to be investigated.

lockEngine - Current LcokEngine instance

Returns:

True if the object in question is locked.

getNamedQuery

String getNamedQuery(ClassMolder molder,
                   String name)
                     throws QueryException

Creates an OQL query based upon a named query as defined in the mapping file.

Parameters:

molder - Specific class molder.

name - Name of the (named) query to create.

Returns:

An OQL query

Throws:

QueryException - If the named query can not be found

getNamedNativeQuery

NamedNativeQuery getNamedNativeQuery(ClassMolder molder,
                                   String name)
                                     throws QueryException

Returns a NamedNativeQuery instance query based upon a named query as defined in the mapping file.

Parameters:

molder - Specific class molder.

name - Name of the (named) query to create.

Returns:

A NamedNativeQuery instance.

Throws:

QueryException - If the named query can not be found.