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com.tangosol.util.filter
Class FilterTrigger

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.BitHelper
com.tangosol.util.ExternalizableHelper
com.tangosol.util.filter.FilterTrigger

All Implemented Interfaces:

ExternalizableLite, PortableObject, MapTrigger, java.io.Serializable

public class FilterTrigger

extends ExternalizableHelper

implements MapTrigger, ExternalizableLite, PortableObject

A generic Filter-based MapTrigger implementation. If an evaluation of the Entry object representing a pending change fails (returns false), then one of the following actions is taken:

• ACTION_ROLLBACK - an IllegalArgumentException is thrown by the trigger to reject the operation that would result in this change (default);
• ACTION_IGNORE - the change is ignored and the Entry's value is reset to the original value returned by the Entry.getOriginalValue() method;
• ACTION_REMOVE - the entry is removed from the underlying backing map using the Entry.remove(true) call.

Note: This trigger never prevents entries from being removed.

Since:

Coherence 3.4

Author:

gg 2008.03.11

Nested Class Summary

Nested classes/interfaces inherited from interface com.tangosol.util.MapTrigger

MapTrigger.Entry

Field Summary

static int	ACTION_IGNORE Evaluation failure results in restoring the original Entry's value.
static int	ACTION_REMOVE Evaluation failure results in a removal of the entry.
static int	ACTION_ROLLBACK Evaluation failure results in an IllegalArgumentException thrown by the trigger.
protected Filter	m_filter The underlying filter.
protected int	m_nAction The action code.

Constructor Summary

FilterTrigger()
Default constructor (necessary for the ExternalizableLite interface).

FilterTrigger(Filter filter)
Construct a FilterTrigger based on the specified Filter object and ACTION_ROLLBACK.

FilterTrigger(Filter filter, int nAction)
Construct a FilterTrigger based on the specified Filter object and the action constant.

Method Summary

boolean	equals(java.lang.Object o) Compare the FilterTrigger with another object to determine equality.
int	getAction() Obtain the action code for this FilterTrigger.
Filter	getFilter() Obtain the underlying Filter.
int	hashCode() Determine a hash value for the FilterTrigger object according to the general Object.hashCode() contract.
void	process(MapTrigger.Entry entry) This method is called before the result of a mutating operation represented by the specified Entry object is committed into the underlying map.
void	readExternal(java.io.DataInput in) Restore the contents of this object by loading the object's state from the passed DataInput object.
void	readExternal(PofReader in) Restore the contents of a user type instance by reading its state using the specified PofReader object.
java.lang.String	toString() Return a human-readable description for this FilterTrigger.
void	writeExternal(java.io.DataOutput out) Save the contents of this object by storing the object's state into the passed DataOutput object.
void	writeExternal(PofWriter out) Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Methods inherited from class com.tangosol.util.BitHelper

countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, rotateLeft, rotateLeft, rotateLeft, rotateRight, rotateRight, rotateRight, toBitString, toBitString, toBitString

Field Detail

ACTION_ROLLBACK

public static final int ACTION_ROLLBACK

Evaluation failure results in an IllegalArgumentException thrown by the trigger.

See Also:

Constant Field Values

ACTION_IGNORE

public static final int ACTION_IGNORE

Evaluation failure results in restoring the original Entry's value.

See Also:

Constant Field Values

ACTION_REMOVE

public static final int ACTION_REMOVE

Evaluation failure results in a removal of the entry.

See Also:

Constant Field Values

m_filter

protected Filter m_filter

The underlying filter.

m_nAction

protected int m_nAction

The action code.

Constructor Detail

FilterTrigger

public FilterTrigger()

Default constructor (necessary for the ExternalizableLite interface).

FilterTrigger

public FilterTrigger(Filter filter)

Construct a FilterTrigger based on the specified Filter object and ACTION_ROLLBACK.

Parameters:

filter - the underlying Filter

FilterTrigger

public FilterTrigger(Filter filter,
                     int nAction)

Construct a FilterTrigger based on the specified Filter object and the action constant.

Parameters:

filter - the underlying Filter

nAction - one of the ACTION_* constants

Method Detail

process

public void process(MapTrigger.Entry entry)

This method is called before the result of a mutating operation represented by the specified Entry object is committed into the underlying map.

An implementation of this method can evaluate the change by analyzing the original and the new value, and can perform any of the following:

• override the requested change by calling InvocableMap.Entry.setValue(java.lang.Object) with a different value;
• undo the pending change by resetting the entry value to the original value obtained from MapTrigger.Entry.getOriginalValue();
• remove the entry from the underlying map by calling InvocableMap.Entry.remove(boolean);
• reject the pending change by throwing a RuntimeException, which will prevent any changes from being committed, and will result in the exception being thrown from the operation that attempted to modify the map; or
• do nothing, thus allowing the pending change to be committed to the underlying map.

Specified by:

process in interface MapTrigger

Parameters:

entry - a MapTrigger.Entry object that represents the pending change to be committed to the map, as well as the original state of the Entry

getFilter

public Filter getFilter()

Obtain the underlying Filter.

Returns:

the underlying Filter object

getAction

public int getAction()

Obtain the action code for this FilterTrigger.

Returns:

one of the ACTION_* constants

readExternal

public void readExternal(java.io.DataInput in)
                  throws java.io.IOException

Restore the contents of this object by loading the object's state from the passed DataInput object.

Specified by:

readExternal in interface ExternalizableLite

Parameters:

in - the DataInput stream to read data from in order to restore the state of this object

Throws:

java.io.IOException - if an I/O exception occurs

java.io.NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

writeExternal

public void writeExternal(java.io.DataOutput out)
                   throws java.io.IOException

Save the contents of this object by storing the object's state into the passed DataOutput object.

Specified by:

writeExternal in interface ExternalizableLite

Parameters:

out - the DataOutput stream to write the state of this object to

Throws:

java.io.IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws java.io.IOException

Restore the contents of a user type instance by reading its state using the specified PofReader object.

Specified by:

readExternal in interface PortableObject

Parameters:

in - the PofReader from which to read the object's state

Throws:

java.io.IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws java.io.IOException

Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Specified by:

writeExternal in interface PortableObject

Parameters:

out - the PofWriter to which to write the object's state

Throws:

java.io.IOException - if an I/O error occurs

equals

public boolean equals(java.lang.Object o)

Compare the FilterTrigger with another object to determine equality. Two FilterTrigger objects are considered equal iff the wrapped filters and action codes are equal.

Returns:

true iff this FilterTrigger and the passed object are equivalent FilterTrigger objects

hashCode

public int hashCode()

Determine a hash value for the FilterTrigger object according to the general Object.hashCode() contract.

Returns:

an integer hash value for this FilterTrigger object

toString

public java.lang.String toString()

Return a human-readable description for this FilterTrigger.

Returns:

a String description of the FilterTrigger

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