SnapshotTransaction (Permazen 4.1.9 API)

java.lang.Object
- io.permazen.core.Transaction
- - io.permazen.core.SnapshotTransaction

All Implemented Interfaces:

Closeable, AutoCloseable
```
public class SnapshotTransaction
extends Transaction
implements Closeable
```
A "snapshot" Transaction that persists indefinitely.
SnapshotTransactions hold a "snapshot" of some portion of the state of a Transaction for later use. Each SnapshotTransaction contains its own set of "snapshot" objects.
SnapshotTransactions can never be closed (i.e., committed or rolled-back); they persist in memory until no longer referenced. Transaction.Callbacks may be registered but they will never be invoked.
SnapshotTransactions can be based on an arbitrary KVStore; see Database.createSnapshotTransaction().

See Also:

Transaction.createSnapshotTransaction(), Database.createSnapshotTransaction(), SnapshotJTransaction

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

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and 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 snapshot transaction's state.
`boolean`	`isSnapshot()` Determine whether this instance is a `SnapshotTransaction`.
`boolean`	`isValid()` Determine whether this transaction is still valid.
`void`	`reset()` Delete all objects contained in this snapshot transaction.
`void`	`rollback()` Roll back this transaction.

Methods inherited from class io.permazen.core.Transaction
addCreateListener, addDeleteListener, addFieldChangeListener, addListFieldChangeListener, addMapFieldChangeListener, addSetFieldChangeListener, addSimpleFieldChangeListener, addVersionChangeListener, adjustCounterField, copy, create, create, create, create, createSnapshotTransaction, delete, deleteSchemaVersion, exists, followReferencePath, generateId, getAll, getAll, getDatabase, getKey, getKey, getKVTransaction, getSchema, getSchemas, getSchemaVersion, getTypeDescription, getUserObject, invertReferencePath, isReadOnly, isRollbackOnly, queryCompositeIndex, queryCompositeIndex2, queryCompositeIndex3, queryCompositeIndex4, queryIndex, queryListElementIndex, queryMapValueIndex, queryVersion, readCounterField, readListField, readMapField, readSetField, readSimpleField, removeCreateListener, removeDeleteListener, removeFieldChangeListener, removeListFieldChangeListener, removeMapFieldChangeListener, removeSetFieldChangeListener, removeSimpleFieldChangeListener, removeVersionChangeListener, setListeners, setReadOnly, setRollbackOnly, setTimeout, setUserObject, snapshotListeners, updateSchemaVersion, writeCounterField, writeSimpleField

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - isSnapshot
```
public boolean isSnapshot()
```
    Description copied from class: Transaction
    
    Determine whether this instance is a SnapshotTransaction.
    
    Overrides:
    
    isSnapshot in class Transaction
    
    Returns:
    
    true if this instance is a SnapshotTransaction, otherwise false
  - getKVStore
```
public KVStore getKVStore()
```
    Get the underlying KVStore that holds this snapshot transaction's state.
    
    Returns:
    
    underlying KVStore
  - reset
```
public void reset()
```
    Delete all objects contained in this snapshot transaction.
    Upon return, the underlying key/value store will still contain meta-data, but no objects.
  - commit
```
public void commit()
```
    Commit this transaction.
    SnapshotTransactions 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.
    SnapshotTransactions 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 SnapshotTransaction will by definition never be invoked. Therefore, this method simply discards callback.
    
    Overrides:
    
    addCallback in class Transaction
    
    Parameters:
    
    callback - callback to invoke
  - isValid
```
public boolean isValid()
```
    Determine whether this transaction is still valid.
    SnapshotTransactions are always valid.
    
    Overrides:
    
    isValid in class Transaction
    
    Returns:
    
    true always
  - close
```
public void close()
```
    Close this instance and release any resources associated with it.
    The implementation in SnapshotTransaction closes the underlying KVStore if it is a CloseableKVStore, otherwise it does nothing.
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable

Class SnapshotTransaction

Nested Class Summary

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

Field Summary

Fields inherited from class io.permazen.core.Transaction

Method Summary

Methods inherited from class io.permazen.core.Transaction

Methods inherited from class java.lang.Object

Method Detail

isSnapshot

getKVStore

reset

commit

rollback

addCallback

isValid

close