com.tangosol.util.processor
Class ConditionalPut

java.lang.Object
  com.tangosol.util.Base
      com.tangosol.util.processor.AbstractProcessor
          com.tangosol.util.processor.ConditionalPut

All Implemented Interfaces:

ExternalizableLite, PortableObject, InvocableMap.EntryProcessor, Serializable

public class ConditionalPut
extends AbstractProcessor
implements ExternalizableLite, PortableObject

ConditionalPut is an EntryProcessor that performs an Entry.setValue operation if the specified condition is satisfied.

While the ConditionalPut processing could be implemented via direct key-based QueryMap operations, it is more efficient and enforces concurrency control without explicit locking.

For example, the following operations are functionally equivalent to methods of the ConcurrentMap interface (available with JDK 1.5).

 

   

     
InvocableMap
     
ConcurrentMap
   
   

       
filter = PresentFilter.INSTANCE;
cache.invoke(key, new ConditionalPut(filter, value);
       
cache.replace(key, value);
   
   

       
filter = new NotFilter(PresentFilter.INSTANCE);
cache.invoke(key, new ConditionalPut(filter, value));
       
cache.putIfAbsent(key, value);
   
   

       
filter = new EqualsFilter(IdentityExtractor.INSTANCE, valueOld);
cache.invoke(key, new ConditionalPut(filter, valueNew));
       
cache.replace(key, valueOld, valueNew);
   
 
 

Obviously, using more specific, fine-tuned filters (rather than ones based on the IdentityExtractor) may provide additional flexibility and efficiency allowing the put operation to be performed conditionally on values of specific attributes (or even calculations) instead of the entire object.

Since:

Coherence 3.2

Author:

gg 2006.03.15

Field Summary

protected Filter	m_filter The underlying filter.
protected boolean	m_fReturn Specifies whether or not a return value is required.
protected Object	m_oValue Specifies the new value to update an entry with.

Constructor Summary

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

ConditionalPut(Filter filter, Object oValue)
Construct a ConditionalPut that updates an entry with a new value if and only if the filter applied to the entry evaluates to true.

ConditionalPut(Filter filter, Object oValue, boolean fReturn)
Construct a ConditionalPut that updates an entry with a new value if and only if the filter applied to the entry evaluates to true.

Method Summary

boolean	equals(Object o) Compare the ConditionalPut with another object to determine equality.
int	hashCode() Determine a hash value for the ConditionalPut object according to the general Object.hashCode() contract.
Object	process(InvocableMap.Entry entry) Process a Map.Entry object.
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 ConditionalPut.
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.processor.AbstractProcessor

processAll

Field Detail

m_filter

protected Filter m_filter

The underlying filter.

m_oValue

protected Object m_oValue

Specifies the new value to update an entry with.

m_fReturn

protected boolean m_fReturn

Specifies whether or not a return value is required.

Constructor Detail

ConditionalPut

public ConditionalPut()

Default constructor (necessary for the ExternalizableLite interface).

ConditionalPut

public ConditionalPut(Filter filter,
                      Object oValue)

Construct a ConditionalPut that updates an entry with a new value if and only if the filter applied to the entry evaluates to true. The result of the process(com.tangosol.util.InvocableMap.Entry) invocation does not return any result.

Parameters:

filter - the filter to evaluate an entry

oValue - a value to update an entry with

ConditionalPut

public ConditionalPut(Filter filter,
                      Object oValue,
                      boolean fReturn)

Construct a ConditionalPut that updates an entry with a new value if and only if the filter applied to the entry evaluates to true. This processor optionally returns the current value as a result of the invocation if it has not been updated (the filter evaluated to false).

Parameters:

filter - the filter to evaluate an entry

oValue - a value to update an entry with

fReturn - specifies whether or not the processor should return the current value in case it has not been updated

Method Detail

process

public Object process(InvocableMap.Entry entry)

Process a Map.Entry object.

Specified by:

process in interface InvocableMap.EntryProcessor

Parameters:

entry - the Entry to process

Returns:

the result of the processing, if any

equals

public boolean equals(Object o)

Compare the ConditionalPut with another object to determine equality.

Returns:

true iff this ConditionalPut and the passed object are equivalent ConditionalPut processors

hashCode

public int hashCode()

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

Returns:

an integer hash value for this ConditionalPut object

toString

public String toString()

Return a human-readable description for this ConditionalPut.

Returns:

a String description of the ConditionalPut

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