Oracle® Coherence Java API Reference
v3.5.3

E15583-01

com.tangosol.util.processor
Class ConditionalPut

java.lang.Object
  extended by com.tangosol.util.Base
      extended by com.tangosol.util.processor.AbstractProcessor
          extended by com.tangosol.util.processor.ConditionalPut
All Implemented Interfaces:
ExternalizableLite, PortableObject, InvocableMap.EntryProcessor, java.io.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  java.lang.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, java.lang.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, java.lang.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(java.lang.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.
 java.lang.Object process(InvocableMap.Entry entry)
          Process a Map.Entry object.
 java.util.Map processAll(java.util.Set setEntries)
          Process a Set of InvocableMap.Entry objects. This method is semantically equivalent to:
   Map mapResults = new ListMap();
   for (Iterator iter = setEntries.iterator(); iter.hasNext(); )
       {
       Entry entry = (Entry) iter.next();
       mapResults.put(entry.getKey(), process(entry));
       }
   return mapResults;
 
 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 ConditionalPut.
 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.
 

Field Detail

m_filter

protected Filter m_filter
The underlying filter.


m_oValue

protected java.lang.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,
                      java.lang.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,
                      java.lang.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 java.lang.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

processAll

public java.util.Map processAll(java.util.Set setEntries)
Process a Set of InvocableMap.Entry objects. This method is semantically equivalent to:
   Map mapResults = new ListMap();
   for (Iterator iter = setEntries.iterator(); iter.hasNext(); )
       {
       Entry entry = (Entry) iter.next();
       mapResults.put(entry.getKey(), process(entry));
       }
   return mapResults;
 

Specified by:
processAll in interface InvocableMap.EntryProcessor
Overrides:
processAll in class AbstractProcessor
Parameters:
setEntries - a read-only Set of InvocableMap.Entry objects to process
Returns:
a Map containing the results of the processing, up to one entry for each InvocableMap.Entry that was processed, keyed by the keys of the Map that were processed, with a corresponding value being the result of the processing for each key

equals

public boolean equals(java.lang.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 java.lang.String toString()
Return a human-readable description for this ConditionalPut.

Returns:
a String description of the ConditionalPut

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

Oracle® Coherence Java API Reference
v3.5.3

E15583-01

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