Package com.tangosol.util.processor

Class ConditionalPut<K,V>

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.processor.AbstractProcessor<K,V,V>
com.tangosol.util.processor.ConditionalPut<K,V>
All Implemented Interfaces:
ExternalizableLite, PortableObject, InvocableMap.EntryProcessor<K,V,V>, Serializable
public class ConditionalPut<K,V> extends AbstractProcessor<K,V,V> 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).

Compare InvocableMap and ConcurrentMap
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
See Also:

  • Field Details

    • m_filter

      protected Filter m_filter
      The underlying filter.

    • m_value

      protected V m_value
      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 Details

    • ConditionalPut

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

    • ConditionalPut

      public ConditionalPut(Filter filter, V value)
      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<K, V>) invocation does not return any result.
      Parameters:
      filter - the filter to evaluate an entry
      value - a value to update an entry with

    • ConditionalPut

      public ConditionalPut(Filter filter, V value, 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
      value - 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 Details

    • process

      public V process(InvocableMap.Entry<K,V> entry)
      Process a Map.Entry object.

      Note: if this method throws an exception, all modifications to the supplied entry or any other entries retrieved via the BackingMapContext.getBackingMapEntry(java.lang.Object) API will be rolled back leaving all underlying values unchanged.

      Specified by:
      process in interface InvocableMap.EntryProcessor<K,V,V>
      Parameters:
      entry - the Entry to process
      Returns:
      the result of the processing, if any

    • processAll

      public Map<K,V> processAll(Set<? extends InvocableMap.Entry<K,V>> 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;

      Note: if processAll() call throws an exception, only the entries that were removed from the setEntries would be considered successfully processed and the corresponding changes made to the underlying Map; changes made to the remaining entries or any other entries obtained from BackingMapContext.getBackingMapEntry(java.lang.Object) will not be processed. Note: As of Coherence 12.2.1, this method simply delegates to the default processAll implementation in InvocableMap.EntryProcessor.

      Specified by:
      processAll in interface InvocableMap.EntryProcessor<K,V,V>
      Overrides:
      processAll in class AbstractProcessor<K,V,V>
      Parameters:
      setEntries - a 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(Object o)
      Compare the ConditionalPut with another object to determine equality.
      Overrides:
      equals in class Object
      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.
      Overrides:
      hashCode in class Object
      Returns:
      an integer hash value for this ConditionalPut object

    • toString

      public String toString()
      Return a human-readable description for this ConditionalPut.
      Overrides:
      toString in class Object
      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

    • 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