Package com.tangosol.util.processor

Class ConditionalRemove<K,V>

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.processor.AbstractProcessor<K,V,V>
com.tangosol.util.processor.ConditionalRemove<K,V>
All Implemented Interfaces:
ExternalizableLite, PortableObject, InvocableMap.EntryProcessor<K,V,V>, Serializable
public class ConditionalRemove<K,V> extends AbstractProcessor<K,V,V> implements ExternalizableLite, PortableObject
ConditionalRemove is an EntryProcessor that performs an Entry.remove operation if the specified condition is satisfied.

While the ConditionalRemove 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 similar, but the InvocableMap versions (a) perform significantly better for partitioned caches; (b) provide all necessary concurrency control (which is ommited from the QueryMap examples):

Compare InvocableMap and QueryMap
InvocableMap QueryMap
cache.invoke(key, new ConditionalRemove(filter)); (*) if (filter.evaluate(cache.get(key)) cache.remove(key);
cache.invokeAll(setKeys, new ConditionalRemove(filter)); for (Object key : setKeys) if (filter.evaluate(cache.get(key)) cache.remove(key);
cache.invokeAll(filter1, new ConditionalRemove(filter2); for (Object key : cache.setKeys(filter1)) if (filter2.evaluate(cache.get(key)) cache.remove(key);
cache.invokeAll(filter, new ConditionalRemove(AlwaysFilter.INSTANCE)); Set setKeys = cache.keySet(filter); cache.keySet().removeAll(setKeys);
(*) If the filter is assigned as the following: filter = new EqualsFilter(IdentityExtractor.INSTANCE, oValue);
this operation also becomes functionally equivalent to the remove method of the ConcurrentMap interface (available with JDK 1.5).
Since:
Coherence 3.2
Author:
gg 2006.03.15
See Also:

  • Field Details

    • m_filter

      protected Filter m_filter
      The underlying filter.

    • m_fReturn

      protected boolean m_fReturn
      Specifies whether or not a return value is required.

  • Constructor Details

    • ConditionalRemove

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

    • ConditionalRemove

      public ConditionalRemove(Filter filter)
      Construct a ConditionalRemove processor that removes an InvocableMap entry 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

    • ConditionalRemove

      public ConditionalRemove(Filter filter, boolean fReturn)
      Construct a ConditionalRemove processor that removes an InvocableMap entry if and only if the filter applied to the entry evaluates to true. This processor may optionally return the current value as a result of the invocation if it has not been removed (the filter evaluated to false).
      Parameters:
      filter - the filter to evaluate an entry
      fReturn - specifies whether or not the processor should return the current value if it has not been removed

  • 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 ConditionalRemove with another object to determine equality.
      Overrides:
      equals in class Object
      Returns:
      true iff this ConditionalRemove and the passed object are equivalent ConditionalRemove

    • hashCode

      public int hashCode()
      Determine a hash value for the ConditionalRemove object according to the general Object.hashCode() contract.
      Overrides:
      hashCode in class Object
      Returns:
      an integer hash value for this ConditionalRemove object

    • toString

      public String toString()
      Return a human-readable description for this ConditionalRemove.
      Overrides:
      toString in class Object
      Returns:
      a String description of the ConditionalRemove processor

    • 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