Skip navigation links

com.tangosol.util.filter
Class PartitionedFilter

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.filter.PartitionedFilter

All Implemented Interfaces:

Filter, EntryFilter

public class PartitionedFilter

extends Base

implements EntryFilter

Filter which limits the scope of another filter to those entries that have keys that belong to the specified partition set. <p/> This filter is intended to be used in advanced scenarios, when a caller wants to retrieve the results of parallel processing restricted to a subset of partitions. This approach may somewhat complicate the client code, but can dramatically reduce the memory footprint used by the requestor. <p/> Below are two examples of PartitionedFilter usage:

• Run a parallel query partition-by-partition:

   void executeByPartitions(NamedCache cache, Filter filter)
       {
       DistributedCacheService service =
           (DistributedCacheService) cache.getCacheService();
       int cPartitions = service.getPartitionCount();
  
       PartitionSet parts = new PartitionSet(cPartitions);
       for (int iPartition = 0; iPartition < cPartitions; iPartition++)
           {
           parts.add(iPartition);
  
           Filter filterPart = new PartitionedFilter(filter, parts);
  
           Set setEntriesPart = cache.entrySet(filterPart);
  
           // process the entries ...
  
           parts.remove(iPartition);
           }
       }
  

• Run a parallel query member-by-member:

   void executeByMembers(NamedCache cache, Filter f)
       {
       DistributedCacheService service =
           (DistributedCacheService) cache.getCacheService();
       int cPartitions = service.getPartitionCount();
  
       PartitionSet partsProcessed = new PartitionSet(cPartitions);
       for (Iterator iter = service.getStorageEnabledMembers().iterator();
               iter.hasNext();)
           {
           Member member = (Member) iter.next();
  
           PartitionSet partsMember = service.getOwnedPartitions(member);
  
           // due to a redistribution some partitions may have already been processed
           partsMember.remove(partsProcessed);
  
           Filter filterPart = new PartitionedFilter(filter, partsMember);
           Set setEntriesPart = cache.entrySet(filterPart);
  
           // process the entries ...
  
           partsProcessed.add(partsMember);
           }
  
       // due to a possible redistribution, some partitions may have been skipped
       if (!partsProcessed.isFull())
           {
           partsProcessed.invert();
           Filter filter = new PartitionedFilter(filter, partsProcessed);
  
           // process the remaining entries ...
           }
       }
  

Note 1: This filter must be the outermost filter and cannot be used as a part of any composite filter (AndFilter, OrFilter, etc.) <p/> Note 2: This filter is intended to be processed only on the client side of the partitioned cache service, so it intentionally does not implement the Serializable and PortableObject interfaces. <p/> To iterate through a query on a partition-by-partition or member-by-member basis, use the PartitionedIterator class.

Since:

Coherence 3.4

Author:

gg 2008.02.06

Constructor Summary

PartitionedFilter(Filter filter, PartitionSet partitions)
Construct a PartitionedFilter.

Method Summary

boolean	equals(Object o) Compare the PartitionedFilter with another object to determine equality.
boolean	evaluate(Object o) Apply the test to the object.
boolean	evaluateEntry(Map.Entry entry) Apply the test to a Map Entry.
Filter	getFilter() Obtain the wrapped Filter.
PartitionSet	getPartitionSet() Obtain the PartitionSet that specifies what partitions the wrapped filter will be applied to.
int	hashCode() Determine a hash value for the PartitionedFilter object according to the general Object.hashCode() contract.
String	toString() Return a human-readable description for this Filter.

Constructor Detail

PartitionedFilter

public PartitionedFilter(Filter filter,
                         PartitionSet partitions)

Construct a PartitionedFilter.

Parameters:

filter - the underlying (wrapped) filter

partitions - the subset of partitions the filter should run against

Method Detail

evaluate

public boolean evaluate(Object o)

Apply the test to the object.

Specified by:

evaluate in interface Filter

Parameters:

o - the object to test

Returns:

true if the test passes, false otherwise

evaluateEntry

public boolean evaluateEntry(Map.Entry entry)

Apply the test to a Map Entry.

Specified by:

evaluateEntry in interface EntryFilter

Parameters:

entry - the Map Entry to evaluate; never null

Returns:

true if the test passes, false otherwise

getFilter

public Filter getFilter()

Obtain the wrapped Filter.

Returns:

the wrapped filter object

getPartitionSet

public PartitionSet getPartitionSet()

Obtain the PartitionSet that specifies what partitions the wrapped filter will be applied to.

Returns:

the partition set

equals

public boolean equals(Object o)

Compare the PartitionedFilter with another object to determine equality. Two PartitionedFilter objects are considered equal iff the wrapped filters and partition sets are equal.

Returns:

true iff this PartitionedFilter and the passed object are equivalent PartitionedFilter objects

hashCode

public int hashCode()

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

Returns:

an integer hash value for this PartitionedFilter object

toString

public String toString()

Return a human-readable description for this Filter.

Returns:

a String description of the Filter

Skip navigation links