org.castor.persist

Interface TransactionContext

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.
Version:
$Revision: 6230 $ $Date: 2006-04-22 11:05:30 -0600 (Sat, 22 Apr 2006) $
Authors:
Assaf Arkin
Ralf Joachim
Werner Guttmann
Gregory Block
Since:
1.0

Method Summary

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.
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()
Test if autoStore option is enabled or not.
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 is previously queried/loaded/update/create 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)
Enable or disable autoStore.
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 Details

addTxSynchronizable

public 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.

close

public 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.

commit

public 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.

create

public 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.

delete

public 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.

expireCache

public 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.

fetch

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

getClassLoader

public ClassLoader getClassLoader()
Get the current application ClassLoader.
Returns:
the current ClassLoader's instance. null if none has been provided

getConnection

public 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

public 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.

getDatabase

public Database getDatabase()

getLockTimeout

public 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.

getNamedQuery

public 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

getStatus

public int getStatus()
Returns the status of this transaction.
Returns:
The status of this transaction.

getTransactionTimeout

public int getTransactionTimeout()
Returns the timeout of this transaction. The timeout is specified in seconds.
Returns:
The timeout of this transaction in seconds.

getWaitOnLock

public ObjectLock getWaitOnLock()
Returns the lock which this transaction attempts to acquire.
Returns:
The lock which this transaction attempts to acquire

isAutoStore

public boolean isAutoStore()
Test if autoStore option is enabled or not.
Returns:
true if autoStore option is enabled.

isCached

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

isCreated

public 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.

isDeleted

public 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

public boolean isDeletedByOID(OID oid)

isDepended

public boolean isDepended(OID master,
                          Object dependent)

isLocked

public 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.

isOpen

public boolean isOpen()
Returns true if the transaction is open.
Returns:
true if the transaction is open.

isPersistent

public boolean isPersistent(Object object)
Returns true if the object is persistent in this transaction.
Parameters:
object - The object.
Returns:
true if persistent in transaction.

isReadOnly

public 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.

isRecorded

public boolean isRecorded(Object object)
Returns true if the object is previously queried/loaded/update/create in this transaction
Parameters:
object - The object.
Returns:
true if recorded in this transaction.

isUpdateCacheNeeded

public 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

public 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.

iterateReadWriteObjectsInTransaction

public 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.

load

public 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(ClassMolder,Identity,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

public 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.

markCreate

public 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.

markModified

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

markUpdate

public 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.

prepare

public 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.

query

public 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.

removeTxSynchronizable

public 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.

rollback

public 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.

setAutoStore

public void setAutoStore(boolean autoStore)
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.

setCallback

public 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

public 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.

setLockTimeout

public 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.

setStatus

public void setStatus(int status)
Sets the status of the current transaction to the given one.
Parameters:
status - The status to set for this transaction.

setTransactionTimeout

public 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.

setWaitOnLock

public 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

update

public 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.

writeLock

public 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.

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