org.apache.commons.transaction.memory
Class PessimisticMapWrapper

java.lang.Object
  org.apache.commons.transaction.memory.TransactionalMapWrapper
      org.apache.commons.transaction.memory.PessimisticMapWrapper

All Implemented Interfaces:

java.util.Map, javax.transaction.Status

public class PessimisticMapWrapper
extends TransactionalMapWrapper

Wrapper that adds transactional control to all kinds of maps that implement the Map interface. By using pessimistic transaction control (blocking locks) this wrapper has better isolation than TransactionalMapWrapper, but also has less possible concurrency and may even deadlock. A commit, however, will never fail.
Start a transaction by calling startTransaction(). Then perform the normal actions on the map and finally either call TransactionalMapWrapper.commitTransaction() to make your changes permanent or TransactionalMapWrapper.rollbackTransaction() to undo them.
Caution: Do not modify values retrieved by TransactionalMapWrapper.get(Object) as this will circumvent the transactional mechanism. Rather clone the value or copy it in a way you see fit and store it back using put(Object, Object).
Note: This wrapper guarantees isolation level SERIALIZABLE.

Version:

$Revision$

See Also:

TransactionalMapWrapper, OptimisticMapWrapper

Nested Class Summary

class

PessimisticMapWrapper.LockingTxContext

Nested classes/interfaces inherited from class org.apache.commons.transaction.memory.TransactionalMapWrapper

TransactionalMapWrapper.HashEntry, TransactionalMapWrapper.TxContext

Nested classes/interfaces inherited from interface java.util.Map

java.util.Map.Entry<K,V>

Field Summary

protected static java.lang.Object	GLOBAL_LOCK
protected ReadWriteLockManager	lockManager
protected static int	READ
protected long	readTimeOut
protected static int	WRITE

Fields inherited from class org.apache.commons.transaction.memory.TransactionalMapWrapper

mapFactory, setFactory, wrapped

Fields inherited from interface javax.transaction.Status

STATUS_ACTIVE, STATUS_COMMITTED, STATUS_COMMITTING, STATUS_MARKED_ROLLBACK, STATUS_NO_TRANSACTION, STATUS_PREPARED, STATUS_PREPARING, STATUS_ROLLEDBACK, STATUS_ROLLING_BACK, STATUS_UNKNOWN

Constructor Summary

PessimisticMapWrapper(java.util.Map wrapped, LoggerFacade logger)
Creates a new pessimistic transactional map wrapper.

PessimisticMapWrapper(java.util.Map wrapped, MapFactory mapFactory, SetFactory setFactory, LoggerFacade logger)
Creates a new pessimistic transactional map wrapper.

Method Summary

protected void	assureGlobalReadLock()
protected void	assureWriteLock(java.lang.Object key)
java.util.Set	entrySet()
java.util.Set	keySet()
java.lang.Object	put(java.lang.Object key, java.lang.Object value)
java.lang.Object	remove(java.lang.Object key)
void	startTransaction() Starts a new transaction and associates it with the current thread.
java.util.Collection	values()

Methods inherited from class org.apache.commons.transaction.memory.TransactionalMapWrapper

clear, commitTransaction, containsKey, containsValue, get, getActiveTx, getTransactionState, isEmpty, isReadOnly, isTransactionMarkedForRollback, markTransactionForRollback, putAll, resumeTransaction, rollbackTransaction, setActiveTx, size, suspendTransaction

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

equals, hashCode

Field Detail

READ

protected static final int READ

See Also:

Constant Field Values

WRITE

protected static final int WRITE

See Also:

Constant Field Values

GLOBAL_LOCK

protected static final java.lang.Object GLOBAL_LOCK

lockManager

protected ReadWriteLockManager lockManager

readTimeOut

protected long readTimeOut

Constructor Detail

PessimisticMapWrapper

public PessimisticMapWrapper(java.util.Map wrapped,
                             LoggerFacade logger)

Creates a new pessimistic transactional map wrapper. Temporary maps and sets to store transactional data will be instances of HashMap and HashSet.

Parameters:

wrapped - map to be wrapped

logger - generic logger used for all kinds of logging

PessimisticMapWrapper

public PessimisticMapWrapper(java.util.Map wrapped,
                             MapFactory mapFactory,
                             SetFactory setFactory,
                             LoggerFacade logger)

Creates a new pessimistic transactional map wrapper. Temporary maps and sets to store transactional data will be created and disposed using MapFactory and SetFactory.

Parameters:

wrapped - map to be wrapped

mapFactory - factory for temporary maps

setFactory - factory for temporary sets

logger - generic logger used for all kinds of logging

Method Detail

startTransaction

public void startTransaction()

Description copied from class: TransactionalMapWrapper

Starts a new transaction and associates it with the current thread. All subsequent changes in the same thread made to the map are invisible from other threads until TransactionalMapWrapper.commitTransaction() is called. Use TransactionalMapWrapper.rollbackTransaction() to discard your changes. After calling either method there will be no transaction associated to the current thread any longer.

Caution: Be careful to finally call one of those methods, as otherwise the transaction will lurk around for ever.

Overrides:

startTransaction in class TransactionalMapWrapper

See Also:

TransactionalMapWrapper.commitTransaction(), TransactionalMapWrapper.rollbackTransaction()

values

public java.util.Collection values()

Specified by:

values in interface java.util.Map

Overrides:

values in class TransactionalMapWrapper

See Also:

Map.values()

entrySet

public java.util.Set entrySet()

Specified by:

entrySet in interface java.util.Map

Overrides:

entrySet in class TransactionalMapWrapper

See Also:

Map.entrySet()

keySet

public java.util.Set keySet()

Specified by:

keySet in interface java.util.Map

Overrides:

keySet in class TransactionalMapWrapper

See Also:

Map.keySet()

remove

public java.lang.Object remove(java.lang.Object key)

Specified by:

remove in interface java.util.Map

Overrides:

remove in class TransactionalMapWrapper

See Also:

Map.remove(java.lang.Object)

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)

Specified by:

put in interface java.util.Map

Overrides:

put in class TransactionalMapWrapper

See Also:

Map.put(java.lang.Object, java.lang.Object)

assureWriteLock

protected void assureWriteLock(java.lang.Object key)

assureGlobalReadLock

protected void assureGlobalReadLock()