io.permazen.change

Class ChangeCopier

java.lang.Object

io.permazen.change.ChangeCopier

All Implemented Interfaces:

ChangeSwitch<Change<?>>

public class ChangeCopier
extends Object
implements ChangeSwitch<Change<?>>

Creates a new Change object based on an existing one where the JObjects referred to by the new Change are copies in a different transaction of the originals. This is useful to allow database change information to be accessed after the transaction in which the change occured has completed.

Each instance has an internal CopyState used to avoid redundant copies, accessible via getCopyState().

Field Summary

Fields

Modifier and Type	Field and Description
protected String	cascadeName
protected CopyState	copyState
protected JTransaction	dest
protected int	recursionLimit

Constructor Summary

Constructors

Constructor and Description
ChangeCopier() "Snapshot" constructor for when the destination transaction is the "snapshot" transaction of the transaction associated with the current thread and no copy cascade is needed
ChangeCopier(JTransaction dest) Non-cascading constructor.
ChangeCopier(JTransaction dest, String cascadeName, int recursionLimit) Primary constructor.
ChangeCopier(String cascadeName, int recursionLimit) "Snapshot" constructor for when the destination transaction is the "snapshot" transaction of the transaction associated with the current thread.

Method Summary

Modifier and Type	Method and Description
<T,E> ListFieldAdd<T,E>	caseListFieldAdd(ListFieldAdd<T,E> change) Handle a ListFieldAdd event.
<T> ListFieldClear<T>	caseListFieldClear(ListFieldClear<T> change) Handle a ListFieldClear event.
<T,E> ListFieldRemove<T,E>	caseListFieldRemove(ListFieldRemove<T,E> change) Handle a ListFieldRemove event.
<T,E> ListFieldReplace<T,E>	caseListFieldReplace(ListFieldReplace<T,E> change) Handle a ListFieldReplace event.
<T,K,V> MapFieldAdd<T,K,V>	caseMapFieldAdd(MapFieldAdd<T,K,V> change) Handle a MapFieldAdd event.
<T> MapFieldClear<T>	caseMapFieldClear(MapFieldClear<T> change) Handle a MapFieldClear event.
<T,K,V> MapFieldRemove<T,K,V>	caseMapFieldRemove(MapFieldRemove<T,K,V> change) Handle a MapFieldRemove event.
<T,K,V> MapFieldReplace<T,K,V>	caseMapFieldReplace(MapFieldReplace<T,K,V> change) Handle a MapFieldReplace event.
<T> ObjectCreate<T>	caseObjectCreate(ObjectCreate<T> change) Handle an ObjectCreate event.
<T> ObjectDelete<T>	caseObjectDelete(ObjectDelete<T> change) Handle an ObjectDelete event.
<T,E> SetFieldAdd<T,E>	caseSetFieldAdd(SetFieldAdd<T,E> change) Handle a SetFieldAdd event.
<T> SetFieldClear<T>	caseSetFieldClear(SetFieldClear<T> change) Handle a SetFieldClear event.
<T,E> SetFieldRemove<T,E>	caseSetFieldRemove(SetFieldRemove<T,E> change) Handle a SetFieldRemove event.
<T,V> SimpleFieldChange<T,V>	caseSimpleFieldChange(SimpleFieldChange<T,V> change) Handle a SimpleFieldChange event.
protected JObject	copy(JObject jobj) Copy the given JObject into the destination transaction.
String	getCascadeName() Get the configured cascade name, if any.
CopyState	getCopyState() Get the CopyState used by this instance.
JTransaction	getDestinationTransaction() Get the destination transaction configured in this instance.
void	setCopyState(CopyState copyState) Set the CopyState used by this instance.

Methods inherited from class java.lang.Object

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

Field Detail

dest

protected final JTransaction dest

cascadeName

protected final String cascadeName

recursionLimit

protected final int recursionLimit

copyState

protected CopyState copyState

Constructor Detail

ChangeCopier

public ChangeCopier(JTransaction dest)

Non-cascading constructor.

Equivalent to: ChangeCopier(dest, null, 0).

Parameters:

dest - destination transaction for copied JObjects

Throws:

IllegalArgumentException - if dest is null

ChangeCopier

public ChangeCopier(JTransaction dest,
                    String cascadeName,
                    int recursionLimit)

Primary constructor.

Parameters:

dest - destination transaction for copied JObjects

cascadeName - cascade to use when copying objects, or null to not cascade

recursionLimit - the maximum number of references to hop through, or -1 for infinity

Throws:

IllegalArgumentException - if recursionLimit is less that -1

IllegalArgumentException - if dest is null

ChangeCopier

public ChangeCopier()

"Snapshot" constructor for when the destination transaction is the "snapshot" transaction of the transaction associated with the current thread and no copy cascade is needed

This is a convenience constructor, equivalent to:

ChangeCopier(JTransaction.getCurrent().getSnapshotTransaction())

Throws:

IllegalStateException - if this is not a snapshot instance and there is no JTransaction associated with the current thread

ChangeCopier

public ChangeCopier(String cascadeName,
                    int recursionLimit)

"Snapshot" constructor for when the destination transaction is the "snapshot" transaction of the transaction associated with the current thread.

This is a convenience constructor, equivalent to:

ChangeCopier(JTransaction.getCurrent().getSnapshotTransaction(), cascadeName, recursionLimit)

Parameters:

cascadeName - cascade to use when copying objects, or null to not cascade

recursionLimit - the maximum number of cascaded references to traverse, or -1 for infinity

Throws:

IllegalArgumentException - if recursionLimit is less that -1

IllegalStateException - if this is not a snapshot instance and there is no JTransaction associated with the current thread

Method Detail

getDestinationTransaction

public JTransaction getDestinationTransaction()

Get the destination transaction configured in this instance.

Returns:

destination transaction

getCascadeName

public String getCascadeName()

Get the configured cascade name, if any.

Returns:

configured cascade name, or null if none

setCopyState

public void setCopyState(CopyState copyState)

Set the CopyState used by this instance.

Parameters:

copyState - copy state

Throws:

IllegalArgumentException - if copyState is null

getCopyState

public CopyState getCopyState()

Get the CopyState used by this instance.

Returns:

associated copy state

caseObjectCreate

public <T> ObjectCreate<T> caseObjectCreate(ObjectCreate<T> change)

Description copied from interface: ChangeSwitch

Handle an ObjectCreate event.

Specified by:

caseObjectCreate in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

Parameters:

change - visiting change

Returns:

visitor return value

caseObjectDelete

public <T> ObjectDelete<T> caseObjectDelete(ObjectDelete<T> change)

Description copied from interface: ChangeSwitch

Handle an ObjectDelete event.

Specified by:

caseObjectDelete in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

Parameters:

change - visiting change

Returns:

visitor return value

caseListFieldAdd

public <T,E> ListFieldAdd<T,E> caseListFieldAdd(ListFieldAdd<T,E> change)

Description copied from interface: ChangeSwitch

Handle a ListFieldAdd event.

Specified by:

caseListFieldAdd in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

E - changed list element type

Parameters:

change - visiting change

Returns:

visitor return value

caseListFieldClear

public <T> ListFieldClear<T> caseListFieldClear(ListFieldClear<T> change)

Description copied from interface: ChangeSwitch

Handle a ListFieldClear event.

Specified by:

caseListFieldClear in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

Parameters:

change - visiting change

Returns:

visitor return value

caseListFieldRemove

public <T,E> ListFieldRemove<T,E> caseListFieldRemove(ListFieldRemove<T,E> change)

Description copied from interface: ChangeSwitch

Handle a ListFieldRemove event.

Specified by:

caseListFieldRemove in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

E - changed list element type

Parameters:

change - visiting change

Returns:

visitor return value

caseListFieldReplace

public <T,E> ListFieldReplace<T,E> caseListFieldReplace(ListFieldReplace<T,E> change)

Description copied from interface: ChangeSwitch

Handle a ListFieldReplace event.

Specified by:

caseListFieldReplace in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

E - changed list element type

Parameters:

change - visiting change

Returns:

visitor return value

caseMapFieldAdd

public <T,K,V> MapFieldAdd<T,K,V> caseMapFieldAdd(MapFieldAdd<T,K,V> change)

Description copied from interface: ChangeSwitch

Handle a MapFieldAdd event.

Specified by:

caseMapFieldAdd in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

K - changed map key type

V - changed map value type

Parameters:

change - visiting change

Returns:

visitor return value

caseMapFieldClear

public <T> MapFieldClear<T> caseMapFieldClear(MapFieldClear<T> change)

Description copied from interface: ChangeSwitch

Handle a MapFieldClear event.

Specified by:

caseMapFieldClear in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

Parameters:

change - visiting change

Returns:

visitor return value

caseMapFieldRemove

public <T,K,V> MapFieldRemove<T,K,V> caseMapFieldRemove(MapFieldRemove<T,K,V> change)

Description copied from interface: ChangeSwitch

Handle a MapFieldRemove event.

Specified by:

caseMapFieldRemove in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

K - changed map key type

V - changed map value type

Parameters:

change - visiting change

Returns:

visitor return value

caseMapFieldReplace

public <T,K,V> MapFieldReplace<T,K,V> caseMapFieldReplace(MapFieldReplace<T,K,V> change)

Description copied from interface: ChangeSwitch

Handle a MapFieldReplace event.

Specified by:

caseMapFieldReplace in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

K - changed map key type

V - changed map value type

Parameters:

change - visiting change

Returns:

visitor return value

caseSetFieldAdd

public <T,E> SetFieldAdd<T,E> caseSetFieldAdd(SetFieldAdd<T,E> change)

Description copied from interface: ChangeSwitch

Handle a SetFieldAdd event.

Specified by:

caseSetFieldAdd in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

E - changed set element type

Parameters:

change - visiting change

Returns:

visitor return value

caseSetFieldClear

public <T> SetFieldClear<T> caseSetFieldClear(SetFieldClear<T> change)

Description copied from interface: ChangeSwitch

Handle a SetFieldClear event.

Specified by:

caseSetFieldClear in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

Parameters:

change - visiting change

Returns:

visitor return value

caseSetFieldRemove

public <T,E> SetFieldRemove<T,E> caseSetFieldRemove(SetFieldRemove<T,E> change)

Description copied from interface: ChangeSwitch

Handle a SetFieldRemove event.

Specified by:

caseSetFieldRemove in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

E - changed set element type

Parameters:

change - visiting change

Returns:

visitor return value

caseSimpleFieldChange

public <T,V> SimpleFieldChange<T,V> caseSimpleFieldChange(SimpleFieldChange<T,V> change)

Description copied from interface: ChangeSwitch

Handle a SimpleFieldChange event.

Specified by:

caseSimpleFieldChange in interface ChangeSwitch<Change<?>>

Type Parameters:

T - changed object type

V - changed field type

Parameters:

change - visiting change

Returns:

visitor return value

copy

protected JObject copy(JObject jobj)

Copy the given JObject into the destination transaction.

The implementation in ChangeCopier copies jobj and objects reachable via the configured copy cascade, unless jobj does not exist, in which case it is not copied (but the corresponding JObject is still returned). Subclasses may override as needed.

Parameters:

jobj - original object

Returns:

copied object in dest

Throws:

IllegalArgumentException - if jobj is null