org.exolab.castor.jdo.engine
Class AbstractDatabaseImpl

java.lang.Object
  extended by org.exolab.castor.jdo.engine.AbstractDatabaseImpl
All Implemented Interfaces:
Database
Direct Known Subclasses:
GlobalDatabaseImpl, LocalDatabaseImpl

public abstract class AbstractDatabaseImpl
extends java.lang.Object
implements Database

An implementation of the JDO database supporting explicit transaction demarcation.

Version:
$Revision: 8351 $ $Date: 2006-04-22 11:05:30 -0600 (Sat, 22 Apr 2006) $
Author:
Assaf Arkin, Bruce Snyder

Field Summary
protected  boolean _autoStore
          True if user prefer all reachable object to be stored automatically.
protected  CallbackInterceptor _callback
          The default callback interceptor for transaction.
protected  java.lang.ClassLoader _classLoader
          The class loader for application classes (may be null).
protected  TransactionContext _ctx
          The transaction context is this database was accessed with an XAResource.
protected  java.lang.String _dbName
          The name of this database.
protected  InstanceFactory _instanceFactory
          The instance factory to that creates new instances of data object.
protected  int _lockTimeout
          The lock timeout for this database.
protected  PersistenceInfoGroup _scope
          The database engine used to access the underlying SQL database.
 
Fields inherited from interface org.exolab.castor.jdo.Database
DbLocked, DBLOCKED, Exclusive, EXCLUSIVE, ReadOnly, READONLY, Shared, SHARED
 
Constructor Summary
AbstractDatabaseImpl(java.lang.String dbName, int lockTimeout, CallbackInterceptor callback, InstanceFactory instanceFactory, java.lang.ClassLoader classLoader, boolean autoStore)
          Creates an instance of this class.
 
Method Summary
abstract  void begin()
          Begin a new transaction.
abstract  void close()
          Closes the database.
abstract  void commit()
          Commits and closes the transaction.
 void create(java.lang.Object object)
          Creates a new object in persistent storage.
 CacheManager getCacheManager()
          Get's the CacheManager instance.
 java.lang.ClassLoader getClassLoader()
          Gets the current application ClassLoader's instance.
 TransactionContext getCurrentTransaction()
          Gets the current Castor transaction in use.
 java.lang.String getDatabaseName()
          Return the name of the database.
 Identity getIdentity(java.lang.Object object)
          Returns the object's identity.
abstract  java.sql.Connection getJdbcConnection()
          Gets the underlying JDBC connection.
(package private)  LockEngine getLockEngine()
          Returns the LockEngine in use by this database instance.
 OQLQuery getNamedQuery(java.lang.String name)
          Creates an OQL query based upon a named query as defined in the mapping file.
 OQLQuery getNativeQuery(java.lang.String sql, java.lang.Class<?> result)
          Creates an OQL query instance based upon a native SQL query and a returning (resulting) class.
 OQLQuery getOQLQuery()
          Creates an OQL query with no statement.
 OQLQuery getOQLQuery(java.lang.String oql)
          Creates an OQL query from the supplied statement.
 Query getQuery()
          Creates an empty query.
 PersistenceInfoGroup getScope()
           
protected  TransactionContext getTransaction()
          Returns the currently active transaction, if any.
 boolean isActive()
          Returns true if a transaction is currently active.
 boolean isAutoStore()
          Return if the current transaction is set to autoStore, it there is transaction active.
 boolean isClosed()
          Returns true if the database is closed.
 boolean isLocked(java.lang.Class cls, java.lang.Object identity)
          Returns true if the specified object is currently locked.
 boolean isPersistent(java.lang.Object object)
          Returns true if the entity is persistent.
<T> T
load(java.lang.Class<T> type, java.lang.Object identity)
          Load an object of the specified type and given identity.
<T> T
load(java.lang.Class<T> type, java.lang.Object identity, AccessMode mode)
           Load an object of the specified type and given identity.
<T> T
load(java.lang.Class<T> type, java.lang.Object identity, java.lang.Object object)
           Load an object of the specified type and given identity into a given instance of object.
protected  void loadSynchronizables()
          Load the TxSynchronizable implementations from the properties file, if not loaded before.
 void lock(java.lang.Object object)
          Acquire a soft write lock on the object.
protected  void registerSynchronizables()
          Register the TxSynchronizable implementations at the TransactionContect at end of begin().
 void remove(java.lang.Object object)
          Removes the object from persistent storage.
abstract  void rollback()
          Rolls back and closes the transaction.
 void setAutoStore(boolean autoStore)
          Indicates whether user prefer all reachable object to be stored automatically; false if user wants dependent object only to be stored.
 java.lang.String toString()
          
protected  void unregisterSynchronizables()
          Unregister the TxSynchronizable implementations at the TransactionContect after commit() or rollback().
 void update(java.lang.Object object)
          Update a data object which is queried/loaded/created in another transaction.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

_scope

protected PersistenceInfoGroup _scope
The database engine used to access the underlying SQL database.


_ctx

protected TransactionContext _ctx
The transaction context is this database was accessed with an XAResource.


_lockTimeout

protected int _lockTimeout
The lock timeout for this database. Zero for immediate timeout, an infinite value for no timeout. The timeout is specified in seconds.


_callback

protected CallbackInterceptor _callback
The default callback interceptor for transaction.


_instanceFactory

protected InstanceFactory _instanceFactory
The instance factory to that creates new instances of data object.


_dbName

protected java.lang.String _dbName
The name of this database.


_autoStore

protected boolean _autoStore
True if user prefer all reachable object to be stored automatically. False if user want only dependent object to be stored.


_classLoader

protected java.lang.ClassLoader _classLoader
The class loader for application classes (may be null).

Constructor Detail

AbstractDatabaseImpl

public AbstractDatabaseImpl(java.lang.String dbName,
                            int lockTimeout,
                            CallbackInterceptor callback,
                            InstanceFactory instanceFactory,
                            java.lang.ClassLoader classLoader,
                            boolean autoStore)
                     throws DatabaseNotFoundException
Creates an instance of this class.

Parameters:
dbName - Name of the database.
lockTimeout - Lock timeout to use.
callback - Callback interceptors.
instanceFactory - Instance factory.
classLoader - Current class loader.
autoStore - True if auto storing is enabled.
Throws:
DatabaseNotFoundException - If there's no database configuration for the given name.
Method Detail

getLockEngine

LockEngine getLockEngine()
Returns the LockEngine in use by this database instance.

Returns:
the LockEngine in use by this database instance.

getScope

public PersistenceInfoGroup getScope()
Specified by:
getScope in interface Database

setAutoStore

public void setAutoStore(boolean autoStore)
Indicates whether user prefer all reachable object to be stored automatically; false if user wants dependent object only to be stored.

Specified by:
setAutoStore in interface Database
Parameters:
autoStore - True to indicate that 'autoStore' mode should be used.

isAutoStore

public boolean isAutoStore()
Return if the current transaction is set to autoStore, it there is transaction active. If there is no active transaction, return if the next transaction will be set to autoStore.

Specified by:
isAutoStore in interface Database
Returns:
True if 'auto-store' mode is in use.

getClassLoader

public java.lang.ClassLoader getClassLoader()
Gets the current application ClassLoader's instance.

Specified by:
getClassLoader in interface Database
Returns:
the current ClassLoader's instance, or null if not provided

getDatabaseName

public java.lang.String getDatabaseName()
Return the name of the database.

Specified by:
getDatabaseName in interface Database
Returns:
Name of the database.

close

public abstract void close()
                    throws PersistenceException
Closes the database. If a client transaction is in progress the transaction will be rolled back and an exception thrown. If an app-server transaction is in progress, the transaction will commit/rollback when triggered by the application server.

Specified by:
close in interface Database
Throws:
PersistenceException - An error occured while attempting to close the database

isClosed

public boolean isClosed()
Returns true if the database is closed.

Specified by:
isClosed in interface Database
Returns:
True if the database is closed

isLocked

public boolean isLocked(java.lang.Class cls,
                        java.lang.Object identity)
                 throws PersistenceException
Returns true if the specified object is currently locked.

Specified by:
isLocked in interface Database
Parameters:
cls - Class instance.
identity - Object identity.
Returns:
True if the object specified is locked; false otherwise.
Throws:
PersistenceException

load

public <T> T load(java.lang.Class<T> type,
                  java.lang.Object identity)
       throws PersistenceException
Load an object of the specified type and given identity. Once loaded the object is persistent. Calling this method with the same identity in the same transaction will return the same object. This method is equivalent to a query that returns a single object. If the identity spans on more than one field, all of the identity fields can be wrapped in a Complex object.

Specified by:
load in interface Database
Parameters:
type - The object's type
identity - The object's identity
Returns:
The object instance.
Throws:
ObjectNotFoundException - No object of the given type and identity was found in persistent storage
LockNotGrantedException - Timeout or deadlock occured attempting to acquire a lock on the object
TransactionNotInProgressException - Method called while transaction is not in progress
PersistenceException - An error reported by the persistence engine

load

public <T> T load(java.lang.Class<T> type,
                  java.lang.Object identity,
                  java.lang.Object object)
       throws PersistenceException

Load an object of the specified type and given identity into a given instance of object. Once loaded the object is persistent. Calling this method with the same identity in the same transaction will return the same object. This method is equivalent to a query that returns a single object. If the identity spans on more than one field, all of the identity fields can be wrapped in a Complex object.

Specified by:
load in interface Database
Parameters:
type - The object's type
identity - The object's identity
object - The object instance to be loaded into
Returns:
The object instance.
Throws:
ObjectNotFoundException - No object of the given type and identity was found in persistent storage
LockNotGrantedException - Timeout or deadlock occured attempting to acquire a lock on the object
TransactionNotInProgressException - Method called while transaction is not in progress
PersistenceException - An error reported by the persistence engine

load

public <T> T load(java.lang.Class<T> type,
                  java.lang.Object identity,
                  AccessMode mode)
       throws PersistenceException

Load an object of the specified type and given identity. Once loaded the object is persistent. Calling this method with the same identity in the same transaction will return the same object. This method is equivalent to a query that returns a single object.

Specified by:
load in interface Database
Parameters:
type - The object's type
identity - The object's identity
mode - The access mode
Returns:
The object instance.
Throws:
ObjectNotFoundException - No object of the given type and identity was found in persistent storage
LockNotGrantedException - Timeout or deadlock occured attempting to acquire a lock on the object
TransactionNotInProgressException - Method called while transaction is not in progress
PersistenceException - An error reported by the persistence engine

create

public void create(java.lang.Object object)
            throws PersistenceException
Creates a new object in persistent storage. The object will be persisted only if the transaction commits.

If the object has an identity then duplicate identity check happens in this method, and the object is visible to queries in this transaction. If the identity is null, duplicate identity check occurs when the transaction completes and the object is not visible to queries until the transaction commits.

Specified by:
create in interface Database
Parameters:
object - The object to create
Throws:
TransactionNotInProgressException - Method called while transaction is not in progress
DuplicateIdentityException - An object with this identity already exists in persistent storage
ClassNotPersistenceCapableException - The class is not persistent capable
PersistenceException - An error reported by the persistence engine

getCacheManager

public CacheManager getCacheManager()
Get's the CacheManager instance. Call getCacheManager for every Database-instances.

Specified by:
getCacheManager in interface Database
Returns:
the CacheManager-instance.

update

public void update(java.lang.Object object)
            throws PersistenceException
Update a data object which is queried/loaded/created in another transaction. This method is used only for long transaction support. Calling this method for data object queried/loaded/created in the same transaction results in Exception.

For example, the data object may be sent to a client application and dispayed to a user. After that the objects is being modified in the client application, the object returns back and is update to the database in the second transaction.

See Long Transaction on Castor website.

Specified by:
update in interface Database
Parameters:
object - The object to create
Throws:
TransactionNotInProgressException - Method called while transaction is not in progress
ClassNotPersistenceCapableException - The class is not persistent capable
PersistenceException - An error reported by the persistence engine

remove

public void remove(java.lang.Object object)
            throws PersistenceException
Removes the object from persistent storage. The deletion will take effect only if the transaction is committed, but the object is no longer visible to queries in the current transaction and locks for access from other transactions will block until this transaction completes.

Specified by:
remove in interface Database
Parameters:
object - The object to remove
Throws:
TransactionNotInProgressException - Method called while transaction is not in progress
ObjectNotPersistentException - The object has not been queried or created in this transaction
LockNotGrantedException - Timeout or deadlock occured attempting to acquire a lock on the object
PersistenceException - An error reported by the persistence engine

isPersistent

public boolean isPersistent(java.lang.Object object)
Returns true if the entity is persistent. An entity is persistent if it was created or loaded but not removed in this transaction. If the entity was created or loaded in another transaction, or there is no open transaction, this method returns false.

Specified by:
isPersistent in interface Database
Parameters:
object - The entity.
Returns:
True if entity is persistent in this transaction.

getIdentity

public Identity getIdentity(java.lang.Object object)
                     throws PersistenceException
Returns the object's identity. The identity will be determined by calling the getters of the fields defined as identities in the mapping. If a mapping for the objects class could not be found a ClassNotPersistenceCapableException will be thrown. Null is only returned if the objects identity is null. It is not required to have an active transaction when using this method.

Note: Prior to 0.9.9.1 release of castor the identity could only be determined if the object took part in the transaction. If this was not the case, the previous implementation also returned null.

Specified by:
getIdentity in interface Database
Parameters:
object - The object.
Returns:
The object's identity, or null.
Throws:
PersistenceException - The class is not persistent capable.

lock

public void lock(java.lang.Object object)
          throws PersistenceException
Acquire a soft 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.

A soft lock is acquired in memory, not in the database. To acquire a lock in the database, use the locked access mode.

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 timeout has elapsed or a deadlock has been detected, an exception will be thrown but the current lock will be retained.

Specified by:
lock in interface Database
Parameters:
object - The object to lock
Throws:
TransactionNotInProgressException - Method called while transaction is not in progress
ObjectNotPersistentException - The object has not been queried or created in this transaction
LockNotGrantedException - Timeout or deadlock occured attempting to acquire a lock on the object
PersistenceException - An error reported by the persistence engine

getOQLQuery

public OQLQuery getOQLQuery()
Creates an OQL query with no statement. OQLQuery.create(java.lang.String) must be called before the query can be executed.

Specified by:
getOQLQuery in interface Database
Returns:
An OQL query

getNamedQuery

public final OQLQuery getNamedQuery(java.lang.String name)
                             throws PersistenceException
Creates an OQL query based upon a named query as defined in the mapping file. OQLQuery.create(java.lang.String)

Specified by:
getNamedQuery in interface Database
Parameters:
name - Name of the (named) query to create.
Returns:
An OQL query
Throws:
PersistenceException

getNativeQuery

public final OQLQuery getNativeQuery(java.lang.String sql,
                                     java.lang.Class<?> result)
                              throws PersistenceException
Creates an OQL query instance based upon a native SQL query and a returning (resulting) class.

Specified by:
getNativeQuery in interface Database
Parameters:
sql - Native SQL query to be used.
result - Class that is result of the query.
Returns:
An OQL query
Throws:
PersistenceException

getOQLQuery

public OQLQuery getOQLQuery(java.lang.String oql)
                     throws PersistenceException
Creates an OQL query from the supplied statement.

Specified by:
getOQLQuery in interface Database
Parameters:
oql - An OQL query statement
Returns:
An OQL query
Throws:
PersistenceException

getQuery

public Query getQuery()
Creates an empty query. The query must be created before it can be executed.

Specified by:
getQuery in interface Database
Returns:
A query

getTransaction

protected TransactionContext getTransaction()
                                     throws TransactionNotInProgressException
Returns the currently active transaction, if any.

Returns:
The current active transaction.
Throws:
TransactionNotInProgressException - If there's no active transaction.

begin

public abstract void begin()
                    throws PersistenceException
Begin a new transaction. A transaction must be open in order to query and persist objects.

Specified by:
begin in interface Database
Throws:
PersistenceException - A transaction is already open on this database, or an error reported by the persistence engine

commit

public abstract void commit()
                     throws TransactionNotInProgressException,
                            TransactionAbortedException
Commits and closes the transaction. All changes made to persistent objects during the transaction are made persistent; objects created during the transaction are made durable; and, objects removed during the transaction are removed from the database.

In other words, any modifications to any data objects which are queried/loaded/created/update to this database is automatically stored to the database and visible to subsequence transactions. (ie. update is solely used for long transaction support and should not be called for any data object queried/loaded/created in the this transaction.)

If the transaction cannot commit, the entire transaction rolls back and a TransactionAbortedException exception is thrown.

After this method returns, the transaction is closed and all persistent objects are transient. Using Database.begin() to open a new transaction will not restore objects to their persistent stage.

Specified by:
commit in interface Database
Throws:
TransactionNotInProgressException - Method called while transaction is not in progress
TransactionAbortedException - The transaction cannot commit and has been rolled back

rollback

public abstract void rollback()
                       throws TransactionNotInProgressException
Rolls back and closes the transaction. All changes made to persistent objects during the transaction are lost, objects created during the transaction are not made durable and objects removed during the transaction continue to exist.

Specified by:
rollback in interface Database
Throws:
TransactionNotInProgressException - Method called while transaction is not in progress

isActive

public boolean isActive()
Returns true if a transaction is currently active.

Specified by:
isActive in interface Database
Returns:
True if a transaction is active

toString

public java.lang.String toString()

Overrides:
toString in class java.lang.Object

getJdbcConnection

public abstract java.sql.Connection getJdbcConnection()
                                               throws PersistenceException
Gets the underlying JDBC connection. This is for advanced use only. Please make sure that you never close this Connection instance, as it will be closed by Castor.

Specified by:
getJdbcConnection in interface Database
Returns:
the underlying JDBC connection, if present; otherwise null
Throws:
PersistenceException - If the underlying JDBC connection cannot be obtained.

loadSynchronizables

protected void loadSynchronizables()
Load the TxSynchronizable implementations from the properties file, if not loaded before.


registerSynchronizables

protected void registerSynchronizables()
Register the TxSynchronizable implementations at the TransactionContect at end of begin().


unregisterSynchronizables

protected void unregisterSynchronizables()
Unregister the TxSynchronizable implementations at the TransactionContect after commit() or rollback().


getCurrentTransaction

public TransactionContext getCurrentTransaction()
                                         throws TransactionNotInProgressException
Gets the current Castor transaction in use.

Returns:
the current Castor
Throws:
TransactionNotInProgressException - If there's no transaction in progress.


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