Package com.tangosol.util.processor

Class 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:
    Serialized Form

    • Field Detail

      • 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 Detail

      • 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 Detail

      • 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
        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