Package io.permazen.core

Class DetachedTransaction

java.lang.Object

io.permazen.core.Transaction

io.permazen.core.DetachedTransaction

All Implemented Interfaces:

Closeable, AutoCloseable

public class DetachedTransaction
extends Transaction
implements Closeable

A Transaction that is not actually connected to a persistent database, but instead exists just to hold objects in memory.

DetachedTransactions are typically used to hold a "snapshot" some portion of a normal Transaction for later use. As with all transactions, each DetachedTransaction contains its own object data.

DetachedTransactions cannot be committed or rolled-back; they just persist in memory until no longer needed. Transaction.Callbacks may be registered, but they will never be invoked.

DetachedTransactions can be based on an arbitrary KVStore; see Database.createDetachedTransaction(). + *

Lifecycle Management

Instances of this class should be close()'d when no longer needed to release any associated resources.

See Also:

• Transaction.createDetachedTransaction()
• Database.createDetachedTransaction()
• DetachedPermazenTransaction

Nested Class Summary

Nested classes/interfaces inherited from class io.permazen.core.Transaction

Transaction.Callback, Transaction.CallbackAdapter, Transaction.ListenerSet

Field Summary

Fields inherited from class io.permazen.core.Transaction

log

Method Summary

Modifier and Type	Method	Description
void	addCallback(Transaction.Callback callback)	Register a transaction callback to be invoked when this transaction completes.
void	close()	Close this instance and release any resources associated with it.
void	commit()	Commit this transaction.
KVStore	getKVStore()	Get the underlying KVStore that holds this detached transaction's state.
boolean	isDetached()	Determine whether this instance is a DetachedTransaction.
boolean	isOpen()	Determine whether this transaction is still open.
void	reset()	Delete all objects contained in this detached transaction.
void	rollback()	Roll back this transaction.

Methods inherited from class io.permazen.core.Transaction

addCreateListener, addDeleteListener, addFieldChangeListener, addListFieldChangeListener, addMapFieldChangeListener, addSchema, addSchemaChangeListener, addSetFieldChangeListener, addSimpleFieldChangeListener, adjustCounterField, copy, create, create, create, create, createDetachedTransaction, createSnapshotTransaction, delete, exists, followReferencePath, generateId, getAll, getAll, getDatabase, getFieldDescription, getKey, getKVTransaction, getObjDescription, getObjType, getSchema, getSchemaBundle, getTypeDescription, getTypeName, getUserObject, invertReferencePath, isReadOnly, isRollbackOnly, migrateSchema, queryCompositeIndex2, queryCompositeIndex3, queryCompositeIndex4, queryIndex, queryListElementIndex, queryMapValueIndex, querySchemaIndex, querySimpleIndex, readCounterField, readListField, readMapField, readSetField, readSimpleField, removeCreateListener, removeDeleteListener, removeFieldChangeListener, removeListFieldChangeListener, removeMapFieldChangeListener, removeSchema, removeSchemaChangeListener, removeSetFieldChangeListener, removeSimpleFieldChangeListener, setListeners, setReadOnly, setRollbackOnly, setTimeout, setUserObject, snapshotListeners, withWeakConsistency, writeCounterField, writeSimpleField

Methods inherited from class java.lang.Object

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

Method Details

isDetached

public boolean isDetached()

Description copied from class: Transaction

Determine whether this instance is a DetachedTransaction.

Overrides:

isDetached in class Transaction

Returns:

true if this instance is a DetachedTransaction, otherwise false

getKVStore

public KVStore getKVStore()

Get the underlying KVStore that holds this detached transaction's state.

Returns:

underlying KVStore

reset

public void reset()

Delete all objects contained in this detached transaction.

Upon return, the underlying key/value store will still contain meta-data, but no objects.

commit

public void commit()

Commit this transaction.

DetachedTransactions do not support this method and will always throw UnsupportedOperationException.

Overrides:

commit in class Transaction

Throws:

UnsupportedOperationException - always

rollback

public void rollback()

Roll back this transaction.

DetachedTransactions do not support this method and will always throw UnsupportedOperationException.

Overrides:

rollback in class Transaction

Throws:

UnsupportedOperationException - always

addCallback

public void addCallback(Transaction.Callback callback)

Register a transaction callback to be invoked when this transaction completes.

Transaction.Callbacks registered with a DetachedTransaction will by definition never be invoked. Therefore, this method simply discards callback.

Overrides:

addCallback in class Transaction

Parameters:

callback - callback to invoke

isOpen

public boolean isOpen()

Determine whether this transaction is still open.

DetachedTransactions are always open.

Overrides:

isOpen in class Transaction

Returns:

true always

close

public void close()

Close this instance and release any resources associated with it.

The implementation in DetachedTransaction closes the underlying KVStore if it is a CloseableKVStore, otherwise it does nothing.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable