com.tangosol.util.filter
Class MapEventFilter

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

All Implemented Interfaces:

ExternalizableLite, PortableObject, Filter, Serializable

public class MapEventFilter
extends ExternalizableHelper
implements Filter, ExternalizableLite, PortableObject

Filter which evaluates the content of a MapEvent object according to the specified criteria. This filter is intended to be used by various ObservableMap listeners that are interested in particular subsets of MapEvent notifications emitted by the map.

Usage examples:

• a filter that evaluates to true if an Employee object is inserted into a cache with a value of Married property set to true.

     new MapEventFilter(MapEventFilter.E_INSERT,
         new EqualsFilter("isMarried", Boolean.TRUE));
   

• a filter that evaluates to true if any object is removed from a cache.

     new MapEventFilter(MapEventFilter.E_DELETE);
   

• a filter that evaluates to true if there is an update to an Employee object where either an old or new value of LastName property equals to "Smith"

     new MapEventFilter(MapEventFilter.E_UPDATE,
         new EqualsFilter("LastName", "Smith"));
   

• a filter that is used to keep a cached keySet result based on some map filter up-to-date.

     final Set    setKeys   = new HashSet();
     final Filter filterEvt = new MapEventFilter(filterMap);
     MapListener listener = new
     map.addMapListener(listener, filterEvt, true);
     setKeys.addAll(map.keySet(filterMap));
   

Since:

Coherence 2.3

Author:

gg 2003.09.22

See Also:

ValueChangeEventFilter

Field Summary

static int	E_ALL This value indicates that all events should be evaluated.
static int	E_DELETED This value indicates that ENTRY_DELETED events should be evaluated.
static int	E_INSERTED This value indicates that ENTRY_INSERTED events should be evaluated.
static int	E_KEYSET This value indicates that all events that would affect the result of a QueryMap.keySet(com.tangosol.util.Filter) query should be evaluated.
static int	E_UPDATED This value indicates that ENTRY_UPDATED events should be evaluated.
static int	E_UPDATED_ENTERED This value indicates that ENTRY_UPDATED events should be evaluated, but only if filter evaluation is false for the old value and true for the new value.
static int	E_UPDATED_LEFT This value indicates that ENTRY_UPDATED events should be evaluated, but only if filter evaluation is true for the old value and false for the new value.
static int	E_UPDATED_WITHIN This value indicates that ENTRY_UPDATED events should be evaluated, but only if filter evaluation is true for both the old and the new value.
protected Filter	m_filter The event value(s) filter.
protected int	m_nMask The event mask.

Constructor Summary

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

MapEventFilter(Filter filter)
Construct a MapEventFilter that evaluates MapEvent objects that would affect the results of a keySet filter issued by a previous call to QueryMap.keySet(com.tangosol.util.Filter).

MapEventFilter(int nMask)
Construct a MapEventFilter that evaluates MapEvent objects based on the specified combination of event types.

MapEventFilter(int nMask, Filter filter)
Construct a MapEventFilter that evaluates MapEvent objects based on the specified combination of event types.

Method Summary

boolean	equals(Object o) Compare the MapEventFilter with another object to determine equality.
boolean	evaluate(Object o) Apply the test to the object.
int	getEventMask() Obtain the event mask.
Filter	getFilter() Obtain the Filter object used to evaluate the event value(s).
int	hashCode() Determine a hash value for the MapEventFilter object according to the general Object.hashCode() contract.
void	readExternal(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.
String	toString() Return a human-readable description for this Filter.
void	writeExternal(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, toBitString, toBitString, toBitString

Field Detail

E_INSERTED

public static final int E_INSERTED

This value indicates that ENTRY_INSERTED events should be evaluated. The event will be fired if there is no filter specified or the filter evaluates to true for a new value.

See Also:

Constant Field Values

E_UPDATED

public static final int E_UPDATED

This value indicates that ENTRY_UPDATED events should be evaluated. The event will be fired if there is no filter specified or the filter evaluates to true when applied to either old or new value.

See Also:

Constant Field Values

E_DELETED

public static final int E_DELETED

This value indicates that ENTRY_DELETED events should be evaluated. The event will be fired if there is no filter specified or the filter evaluates to true for an old value.

See Also:

Constant Field Values

E_UPDATED_ENTERED

public static final int E_UPDATED_ENTERED

This value indicates that ENTRY_UPDATED events should be evaluated, but only if filter evaluation is false for the old value and true for the new value. This corresponds to an item that was not in a keySet filter result changing such that it would now be in that keySet filter result.

Since:

Coherence 3.1

See Also:

Constant Field Values

E_UPDATED_LEFT

public static final int E_UPDATED_LEFT

This value indicates that ENTRY_UPDATED events should be evaluated, but only if filter evaluation is true for the old value and false for the new value. This corresponds to an item that was in a keySet filter result changing such that it would no longer be in that keySet filter result.

Since:

Coherence 3.1

See Also:

Constant Field Values

E_UPDATED_WITHIN

public static final int E_UPDATED_WITHIN

This value indicates that ENTRY_UPDATED events should be evaluated, but only if filter evaluation is true for both the old and the new value. This corresponds to an item that was in a keySet filter result changing but not leaving the keySet filter result.

Since:

Coherence 3.1

See Also:

Constant Field Values

E_ALL

public static final int E_ALL

This value indicates that all events should be evaluated.

See Also:

Constant Field Values

E_KEYSET

public static final int E_KEYSET

This value indicates that all events that would affect the result of a QueryMap.keySet(com.tangosol.util.Filter) query should be evaluated.

Since:

Coherence 3.1

See Also:

Constant Field Values

m_nMask

protected int m_nMask

The event mask.

m_filter

protected Filter m_filter

The event value(s) filter.

Constructor Detail

MapEventFilter

public MapEventFilter()

Default constructor (necessary for the ExternalizableLite interface).

MapEventFilter

public MapEventFilter(int nMask)

Construct a MapEventFilter that evaluates MapEvent objects based on the specified combination of event types.

Using this constructor is equivalent to: new MapEventFilter(nMask, null);

Parameters:

nMask - any combination of E_INSERTED, E_UPDATED and E_DELETED, E_UPDATED_ENTERED, E_UPDATED_WITHIN, E_UPDATED_LEFT

Since:

Coherence 3.1

MapEventFilter

public MapEventFilter(Filter filter)

Construct a MapEventFilter that evaluates MapEvent objects that would affect the results of a keySet filter issued by a previous call to QueryMap.keySet(com.tangosol.util.Filter). It is possible to easily implement continuous query functionality.

Using this constructor is equivalent to: new MapEventFilter(E_KEYSET, filter);

Parameters:

filter - the filter passed previously to a keySet() query method

Since:

Coherence 3.1

MapEventFilter

public MapEventFilter(int nMask,
                      Filter filter)

Construct a MapEventFilter that evaluates MapEvent objects based on the specified combination of event types.

Parameters:

nMask - combination of any of the E_* values

filter - (optional) the filter used for evaluating event values

Method Detail

evaluate

public boolean evaluate(Object o)

Apply the test to the object.

Specified by:

evaluate in interface Filter

Returns:

true if the test passes, false otherwise

Throws:

ClassCastException - if the specified object is not an instance of MapEvent

getEventMask

public int getEventMask()

Obtain the event mask. The mask value is concatenation of any of the E_* values.

Returns:

the event mask

getFilter

public Filter getFilter()

Obtain the Filter object used to evaluate the event value(s).

Returns:

the filter used to evaluate the event value(s)

equals

public boolean equals(Object o)

Compare the MapEventFilter with another object to determine equality.

Returns:

true iff this MapEventFilter and the passed object are equivalent filters

hashCode

public int hashCode()

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

Returns:

an integer hash value for this MapEventFilter object

toString

public String toString()

Return a human-readable description for this Filter.

Returns:

a String description of the Filter

readExternal

public void readExternal(DataInput in)
                  throws 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:

IOException - if an I/O exception occurs

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

writeExternal

public void writeExternal(DataOutput out)
                   throws 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:

IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws 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:

IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws 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:

IOException - if an I/O error occurs