com.tangosol.util.aggregator

Class GroupAggregator<K,V,T,E,R>

java.lang.Object

com.tangosol.util.Base

com.tangosol.util.BitHelper

com.tangosol.util.ExternalizableHelper

com.tangosol.util.aggregator.GroupAggregator<K,V,T,E,R>

Type Parameters:

K - the type of the Map entry keys

V - the type of the Map entry values

T - the type of the value to extract from

E - the type of the extracted value

R - the type of the group aggregator result

All Implemented Interfaces:

ExternalizableLite, PortableObject, InvocableMap.EntryAggregator<K,V,Map<E,R>>, InvocableMap.StreamingAggregator<K,V,Map<E,Object>,Map<E,R>>, Serializable

Direct Known Subclasses:

GroupAggregator.Parallel

public class GroupAggregator<K,V,T,E,R>
extends ExternalizableHelper
implements InvocableMap.StreamingAggregator<K,V,Map<E,Object>,Map<E,R>>, ExternalizableLite, PortableObject

The GroupAggregator provides an ability to split a subset of entries in an InvocableMap into a collection of non-intersecting subsets and then aggregate them separately and independently. The splitting (grouping) is performed using the results of the underlying ValueExtractor in such a way that two entries will belong to the same group if and only if the result of the corresponding extract call produces the same value or tuple (list of values). After the entries are split into the groups, the underlying aggregator is applied separately to each group. The result of the aggregation by the GroupAggregator is a Map that has distinct values (or tuples) as keys and results of the individual aggregation as values. Additionally, those results could be further reduced using an optional Filter object.

Informally speaking, this aggregator is analogous to the SQL "group by" and "having" clauses. Note that the "having" Filter is applied independently on each server against the partial aggregation results; this generally implies that data affinity is required to ensure that all required data used to generate a given result exists within a single cache partition. In other words, the "group by" predicate should not span multiple partitions if the "having" clause is used.

The GroupAggregator is somewhat similar to the DistinctValues aggregator, which returns back a list of distinct values (tuples) without performing any additional aggregation work.

Unlike many other concrete EntryAggregator implementations that are constructed directly, instances of GroupAggregator should only be created using one of the factory methods: createInstance(extractor, aggregator), createInstance(extractor, aggregator, filter), createInstance(sMethod, aggregator) createInstance(sMethod, aggregator, filter)

Since:

Coherence 3.2

Author:

gg 2006.02.15, as 2014.11.09

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GroupAggregator.Parallel<K,V,T,E,R> Deprecated. As of Coherence 12.2.1. Use GroupAggregator instead.

Nested classes/interfaces inherited from class com.tangosol.util.ExternalizableHelper

ExternalizableHelper.DecoratedMultiBufferReadBuffer, ExternalizableHelper.DefaultObjectStreamFactory, ExternalizableHelper.FormatAwareCompressor, ExternalizableHelper.IntDecoratedObject, ExternalizableHelper.Shielded, ExternalizableHelper.ShieldedDataOutputStream, ExternalizableHelper.ShieldedInputStream, ExternalizableHelper.ShieldedObjectOutputStream, ExternalizableHelper.ShieldedOutputStream, ExternalizableHelper.SimpleXmlBeanClassCache, ExternalizableHelper.Stats, ExternalizableHelper.XmlBeanClassCache

Nested classes/interfaces inherited from class com.tangosol.util.Base

Base.LoggingWriter, Base.StackFrame

Field Summary

Fields

Modifier and Type	Field and Description
protected InvocableMap.EntryAggregator<? super K,? super V,R>	m_aggregator The underlying EntryAggregator.
protected ValueExtractor<? super T,? extends E>	m_extractor The underlying ValueExtractor.
protected Filter	m_filter The Filter object representing the "having" clause of this "group by" aggregator.
protected boolean	m_fInit Flag specifying whether this aggregator has been initialized.
protected boolean	m_fParallel Flag specifying whether parallel optimizations can be used.
protected boolean	m_fStreaming Flag specifying whether streaming optimizations can be used.
protected Map<E,Object>	m_mapResults A map of partial results to aggregate.

Fields inherited from class com.tangosol.util.ExternalizableHelper

CONVERTER_FROM_BINARY, CONVERTER_STRIP_INTDECO, CONVERTER_TO_BINARY, DECO_APP_1, DECO_APP_2, DECO_APP_3, DECO_CUSTOM, DECO_EXPIRY, DECO_ID_MAX, DECO_ID_MIN, DECO_JCACHE, DECO_JCACHE_SYNTHETIC, DECO_MEMCACHED, DECO_PUSHREP, DECO_QUEUE_METADATA, DECO_RSVD_1, DECO_RSVD_2, DECO_STORE, DECO_TX, DECO_VALUE, DECO_WLS, EMPTY_BINARY_ARRAY, FMT_B_ARRAY, FMT_BIN_DECO, FMT_BIN_EXT_DECO, FMT_BINARY, FMT_BOOLEAN, FMT_BYTE, FMT_DECIMAL, FMT_DOUBLE, FMT_EXT, FMT_FLOAT, FMT_IDO, FMT_INT, FMT_INTEGER, FMT_LONG, FMT_NONE, FMT_NULL, FMT_OBJ_EXT, FMT_OBJ_SER, FMT_OPT, FMT_OPT_DOUBLE, FMT_OPT_INT, FMT_OPT_LONG, FMT_SHORT, FMT_STRING, FMT_UNKNOWN, FMT_XML_BEAN, FMT_XML_SER, FORCE_RESOLVING_STREAMS, MAX_DECO_HEADER_BYTES, PROPERTY_CONFIG, s_streamfactory, TRINT_DOMAIN_SPAN, TRINT_MAX_VALUE, TRINT_MAX_VARIANCE, USE_POF_STREAMS, USE_XMLBEAN_CLASS_CACHE, XMLBEAN_CLASS_CACHE

Fields inherited from class com.tangosol.util.Base

LOG_ALWAYS, LOG_DEBUG, LOG_ERR, LOG_INFO, LOG_MAX, LOG_MIN, LOG_QUIET, LOG_WARN, POWER_0, POWER_G, POWER_K, POWER_M, POWER_T, UNIT_D, UNIT_H, UNIT_M, UNIT_MS, UNIT_NS, UNIT_S, UNIT_US

Fields inherited from interface com.tangosol.util.InvocableMap.StreamingAggregator

ALLOW_INCONSISTENCIES, BY_MEMBER, BY_PARTITION, PARALLEL, PRESENT_ONLY, RETAINS_ENTRIES, SERIAL

Constructor Summary

Constructors

Modifier	Constructor and Description
	GroupAggregator() Default constructor (necessary for the ExternalizableLite interface).
protected	GroupAggregator(ValueExtractor<? super T,? extends E> extractor, InvocableMap.EntryAggregator<? super K,? super V,R> aggregator, Filter filter) Construct a GroupAggregator based on a specified ValueExtractor and underlying EntryAggregator.

Method Summary

Modifier and Type	Method and Description
boolean	accumulate(InvocableMap.Entry<? extends K,? extends V> entry) Accumulate one entry into the result.
int	characteristics() A bit mask representing the set of characteristics of this aggregator.
boolean	combine(Map<E,Object> partialResult) Merge another partial result into the result.
static <K,V,R> GroupAggregator<K,V,Object,Object,R>	createInstance(String sMethod, InvocableMap.EntryAggregator<K,V,R> aggregator) Create an instance of GroupAggregator based on a specified method name(s) and an EntryAggregator.
static <K,V,R> GroupAggregator<K,V,Object,Object,R>	createInstance(String sMethod, InvocableMap.EntryAggregator<K,V,R> aggregator, Filter filter) Create an instance of GroupAggregator based on a specified method name(s), an EntryAggregator and a result evaluation filter.
static <K,V,T,E,R> GroupAggregator<K,V,T,E,R>	createInstance(ValueExtractor<? super T,? extends E> extractor, InvocableMap.EntryAggregator<? super K,? super V,R> aggregator, Filter filter) Create an instance of GroupAggregator based on a specified extractor and an EntryAggregator and a result evaluation filter.
static <K,V,T,E,R> GroupAggregator<K,V,T,E,R>	createInstance(ValueExtractor<? super T,? extends E> extractor, InvocableMap.EntryAggregator<K,V,R> aggregator) Create an instance of GroupAggregator based on a specified extractor and an EntryAggregator.
protected void	ensureInitialized() Ensure that this aggregator is initialized.
boolean	equals(Object o) Compare the GroupAggregator with another object to determine equality.
Map<E,R>	finalizeResult() Return the final result of the aggregation.
InvocableMap.EntryAggregator<? super K,? super V,R>	getAggregator() Obtain the underlying EntryAggregator.
ValueExtractor<?,? extends E>	getExtractor() Obtain the underlying ValueExtractor.
Map<E,Object>	getPartialResult() Return the partial result of the aggregation.
int	hashCode() Determine a hash value for the GroupAggregator object according to the general Object.hashCode() contract.
protected boolean	isDelegateParallel() Return true if the underlying aggregator is a ParallelAwareAggregator.
protected boolean	isDelegateStreaming() Return true if the underlying aggregator is a StreamingAggregator.
protected InvocableMap.ParallelAwareAggregator<? super K,? super V,Object,R>	parallel(InvocableMap.EntryAggregator<? super K,? super V,R> aggregator) Convert the specified aggregator to ParallelAwareAggregator.
void	readExternal(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.
protected InvocableMap.StreamingAggregator<? super K,? super V,Object,R>	streaming(InvocableMap.EntryAggregator<? super K,? super V,R> aggregator) Convert the specified aggregator to StreamingAggregator.
InvocableMap.StreamingAggregator<K,V,Map<E,Object>,Map<E,R>>	supply() Create a new instance of this aggregator.
protected static <T> BinaryOperator<T>	throwingMerger()
String	toString() Return a human-readable description for this GroupAggregator.
void	writeExternal(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.

Methods inherited from class com.tangosol.util.ExternalizableHelper

asBinary, calculatePackedLength, calculatePackedLength, checkObjectInputFilter, convertUTF, decodeExpiry, decorate, decorate, decorate, decorate, decorate, decorateBinary, encodeExpiry, ensureSerializer, extractIntDecoration, fromBinary, fromBinary, fromBinary, fromBinary, fromBinary, fromBinary, fromByteArray, fromByteArray, getClass, getDecoration, getDecoration, getDecorations, getDeltaCompressor, getInputStream, getNewObjectInput, getObjectInput, getObjectOutput, getObjectStreamFactory, getOutputStream, getShieldedOutputStream, getStreamFormat, getUndecorated, getUndecorated, isDecorated, isDecorated, isIntDecorated, isIntDecorated, isResolving, isSerializable, isSerializerCompatible, isVersionCompatible, isVersionCompatible, loadClass, loadResource, main, makeTrint, readBigDecimal, readBigInteger, readBooleanArray, readByteArray, readCollection, readDate, readDoubleArray, readExternalizableLite, readExternalizableLite, readFloatArray, readInt, readInt, readIntArray2d, readLong, readLong, readMap, readMap, readObject, readObject, readSafeUTF, readSafeUTF, readSerializable, readSerializable, readStringArray, readTime, readTimestamp, readTrint, readUnsignedTrint, readUTF, readXmlBean, readXmlSerializable, readXmlSerializable, realize, removeIntDecoration, removeIntDecoration, replace, reportIncompatibleSerializers, setObjectStreamFactory, toBinary, toBinary, toByteArray, toByteArray, toByteArray, toLiteBinary, toLong, undecorate, undecorate, validateBufferSize, writeBigDecimal, writeBigInteger, writeBooleanArray, writeByteArray, writeCollection, writeDate, writeDoubleArray, writeExternalizableLite, writeFloatArray, writeInt, writeInt, writeIntArray2d, writeLong, writeLong, writeMap, writeObject, writeSafeUTF, writeSafeUTF, writeSerializable, writeStringArray, writeTime, writeTimestamp, writeTrint, writeTrint, writeUTF, writeXmlBean, writeXmlSerializable

Methods inherited from class com.tangosol.util.BitHelper

countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, rotateLeft, rotateLeft, rotateLeft, rotateRight, rotateRight, rotateRight, toBitString, toBitString, toBitString, toBytes, toBytes, toBytes, toBytes, toInt, toInt, toLong

Methods inherited from class com.tangosol.util.Base

azzert, azzert, azzert, azzertFailed, breakLines, breakLines, capitalize, checkNotEmpty, checkNotNull, checkRange, computeSafeWaitTime, decimalValue, dup, dup, ensureBigDecimal, ensureClassLoader, ensureRuntimeException, ensureRuntimeException, equals, equalsDeep, err, err, err, err, err, escape, formatDateTime, getCallerStackFrame, getCommonMonitor, getCommonMonitor, getCommonMonitor, getContextClassLoader, getContextClassLoader, getDeepMessage, getErr, getLastSafeTimeMillis, getLog, getMaxDecDigits, getMaxHexDigits, getOriginalException, getOut, getProcessRandom, getRandom, getRandomBinary, getRandomBinary, getRandomString, getSafeTimeMillis, getStackFrame, getStackFrames, getStackTrace, getStackTrace, getThreadFactory, getTimeZone, getUpTimeMillis, hashCode, hexValue, indentString, indentString, isDecimal, isHex, isLogEcho, isOctal, log, log, log, log, log, makeInteger, makeLong, makeThread, mod, mod, octalValue, out, out, out, out, out, pad, parseBandwidth, parseBandwidth, parseDelimitedString, parseHex, parseHex, parseMemorySize, parseMemorySize, parsePercentage, parseTime, parseTime, parseTimeNanos, parseTimeNanos, printStackTrace, randomize, randomize, randomize, randomize, read, read, read, read, read, read, read, replace, setErr, setLog, setLogEcho, setOut, sleep, toBandwidthString, toBandwidthString, toCharEscape, toCrc, toCrc, toCrc, toCrc, toCrc, toDecString, toDelimitedString, toDelimitedString, toDelimitedString, toDelimitedString, toHex, toHex, toHexDump, toHexEscape, toHexEscape, toHexEscape, toHexEscape, toHexString, toMemorySizeString, toMemorySizeString, toQuotedCharEscape, toQuotedStringEscape, toSqlString, toString, toString, toStringEscape, toUnicodeEscape, trace, trace, trace, trace, trace, trace, trace, trace, trace, truncateString, truncateString, wait

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.tangosol.util.InvocableMap.StreamingAggregator

accumulate, aggregate, isAllowInconsistencies, isByMember, isByPartition, isParallel, isPresentOnly, isRetainsEntries, isSerial

Field Detail

m_extractor

protected ValueExtractor<? super T,? extends E> m_extractor

The underlying ValueExtractor.

m_aggregator

protected InvocableMap.EntryAggregator<? super K,? super V,R> m_aggregator

The underlying EntryAggregator.

m_filter

protected Filter m_filter

The Filter object representing the "having" clause of this "group by" aggregator.

m_fInit

protected transient boolean m_fInit

Flag specifying whether this aggregator has been initialized.

m_fStreaming

protected transient boolean m_fStreaming

Flag specifying whether streaming optimizations can be used.

m_fParallel

protected transient boolean m_fParallel

Flag specifying whether parallel optimizations can be used.

m_mapResults

protected transient Map<E,Object> m_mapResults

A map of partial results to aggregate.

Constructor Detail

GroupAggregator

public GroupAggregator()

Default constructor (necessary for the ExternalizableLite interface).

GroupAggregator

protected GroupAggregator(ValueExtractor<? super T,? extends E> extractor,
                          InvocableMap.EntryAggregator<? super K,? super V,R> aggregator,
                          Filter filter)

Construct a GroupAggregator based on a specified ValueExtractor and underlying EntryAggregator.

Parameters:

extractor - a ValueExtractor object that is used to split InvocableMap entries into non-intersecting subsets; may not be null

aggregator - an EntryAggregator object; may not be null

filter - an optional Filter object used to filter out results of individual group aggregation results

Method Detail

supply

public InvocableMap.StreamingAggregator<K,V,Map<E,Object>,Map<E,R>> supply()

Description copied from interface: InvocableMap.StreamingAggregator

Create a new instance of this aggregator.

Specified by:

supply in interface InvocableMap.StreamingAggregator<K,V,Map<E,Object>,Map<E,R>>

Returns:

a StreamAggregator

accumulate

public boolean accumulate(InvocableMap.Entry<? extends K,? extends V> entry)

Description copied from interface: InvocableMap.StreamingAggregator

Accumulate one entry into the result.

Specified by:

accumulate in interface InvocableMap.StreamingAggregator<K,V,Map<E,Object>,Map<E,R>>

Parameters:

entry - the entry to accumulate into the aggregation result

Returns:

true to continue the aggregation, and false to signal to the caller that the result is ready and the aggregation can be short-circuited

combine

public boolean combine(Map<E,Object> partialResult)

Description copied from interface: InvocableMap.StreamingAggregator

Merge another partial result into the result.

Specified by:

combine in interface InvocableMap.StreamingAggregator<K,V,Map<E,Object>,Map<E,R>>

Parameters:

partialResult - the partial result to merge

Returns:

true to continue the aggregation, and false to signal to the caller that the result is ready and the aggregation can be short-circuited

getPartialResult

public Map<E,Object> getPartialResult()

Description copied from interface: InvocableMap.StreamingAggregator

Return the partial result of the aggregation.

Specified by:

getPartialResult in interface InvocableMap.StreamingAggregator<K,V,Map<E,Object>,Map<E,R>>

Returns:

the partial result of the aggregation

finalizeResult

public Map<E,R> finalizeResult()

Description copied from interface: InvocableMap.StreamingAggregator

Return the final result of the aggregation.

Specified by:

finalizeResult in interface InvocableMap.StreamingAggregator<K,V,Map<E,Object>,Map<E,R>>

Returns:

the final result of the aggregation

characteristics

public int characteristics()

Description copied from interface: InvocableMap.StreamingAggregator

A bit mask representing the set of characteristics of this aggregator.

Be default, characteristics are a combination of InvocableMap.StreamingAggregator.PARALLEL and InvocableMap.StreamingAggregator.RETAINS_ENTRIES, which is sub-optimal and should be overridden by the aggregator implementation if the aggregator does not need to retain entries (which is often the case).

Specified by:

characteristics in interface InvocableMap.StreamingAggregator<K,V,Map<E,Object>,Map<E,R>>

Returns:

a bit mask representing the set of characteristics of this aggregator

See Also:

InvocableMap.StreamingAggregator.PARALLEL, InvocableMap.StreamingAggregator.SERIAL, InvocableMap.StreamingAggregator.BY_MEMBER, InvocableMap.StreamingAggregator.BY_PARTITION, InvocableMap.StreamingAggregator.RETAINS_ENTRIES, InvocableMap.StreamingAggregator.PRESENT_ONLY

getExtractor

public ValueExtractor<?,? extends E> getExtractor()

Obtain the underlying ValueExtractor.

Returns:

the underlying ValueExtractor

getAggregator

public InvocableMap.EntryAggregator<? super K,? super V,R> getAggregator()

Obtain the underlying EntryAggregator.

Returns:

the underlying EntryAggregator

ensureInitialized

protected void ensureInitialized()

Ensure that this aggregator is initialized.

streaming

protected InvocableMap.StreamingAggregator<? super K,? super V,Object,R> streaming(InvocableMap.EntryAggregator<? super K,? super V,R> aggregator)

Convert the specified aggregator to StreamingAggregator.

Parameters:

aggregator - the aggregator to convert

Returns:

an instance of a StreamingAggregator

parallel

protected InvocableMap.ParallelAwareAggregator<? super K,? super V,Object,R> parallel(InvocableMap.EntryAggregator<? super K,? super V,R> aggregator)

Convert the specified aggregator to ParallelAwareAggregator.

Parameters:

aggregator - the aggregator to convert

Returns:

an instance of a ParallelAwareAggregator

isDelegateStreaming

protected boolean isDelegateStreaming()

Return true if the underlying aggregator is a StreamingAggregator.

Returns:

true if the underlying aggregator is a StreamingAggregator

isDelegateParallel

protected boolean isDelegateParallel()

Return true if the underlying aggregator is a ParallelAwareAggregator.

Returns:

true if the underlying aggregator is a ParallelAwareAggregator

throwingMerger

protected static <T> BinaryOperator<T> throwingMerger()

readExternal

public void readExternal(DataInput in)
                  throws IOException

Description copied from interface: ExternalizableLite

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

Description copied from interface: ExternalizableLite

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

Description copied from interface: PortableObject

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

Description copied from interface: PortableObject

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

equals

public boolean equals(Object o)

Compare the GroupAggregator with another object to determine equality.

Overrides:

equals in class Object

Returns:

true iff this GroupAggregator and the passed object are equivalent

hashCode

public int hashCode()

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

Overrides:

hashCode in class Object

Returns:

an integer hash value for this GroupAggregator object

toString

public String toString()

Return a human-readable description for this GroupAggregator.

Overrides:

toString in class Object

Returns:

a String description of the GroupAggregator

createInstance

public static <K,V,R> GroupAggregator<K,V,Object,Object,R> createInstance(String sMethod,
                                                                          InvocableMap.EntryAggregator<K,V,R> aggregator)

Create an instance of GroupAggregator based on a specified method name(s) and an EntryAggregator.
If the specified underlying aggregator is an instance of ParallelAwareAggregator, then a parallel-aware instance of the GroupAggregator will be created. Otherwise, the resulting GroupAggregator will not be parallel-aware and could be ill-suited for aggregations run against large partitioned caches.

Parameters:

sMethod - a method name or a comma-delimited sequence of names that results in a ReflectionExtractor or a MultiExtractor that will be used to split InvocableMap entries into distinct groups

aggregator - an underlying EntryAggregator

createInstance

public static <K,V,R> GroupAggregator<K,V,Object,Object,R> createInstance(String sMethod,
                                                                          InvocableMap.EntryAggregator<K,V,R> aggregator,
                                                                          Filter filter)

Create an instance of GroupAggregator based on a specified method name(s), an EntryAggregator and a result evaluation filter.
If the specified underlying aggregator is an instance of ParallelAwareAggregator, then a parallel-aware instance of the GroupAggregator will be created. Otherwise, the resulting GroupAggregator will not be parallel-aware and could be ill-suited for aggregations run against large partitioned caches.

Parameters:

sMethod - a method name or a comma-delimited sequence of names that results in a ReflectionExtractor or a MultiExtractor that will be used to split InvocableMap entries into distinct groups

aggregator - an underlying EntryAggregator

filter - an optional Filter object that will be used to evaluate results of each individual group aggregation

createInstance

public static <K,V,T,E,R> GroupAggregator<K,V,T,E,R> createInstance(ValueExtractor<? super T,? extends E> extractor,
                                                                    InvocableMap.EntryAggregator<K,V,R> aggregator)

Create an instance of GroupAggregator based on a specified extractor and an EntryAggregator.
If the specified aggregator is an instance of ParallelAwareAggregator, then a parallel-aware instance of the GroupAggregator will be created. Otherwise, the resulting GroupAggregator will not be parallel-aware and could be ill-suited for aggregations run against large partitioned caches.

Parameters:

extractor - a ValueExtractor that will be used to split a set of InvocableMap entries into distinct groups

aggregator - an underlying EntryAggregator

createInstance

public static <K,V,T,E,R> GroupAggregator<K,V,T,E,R> createInstance(ValueExtractor<? super T,? extends E> extractor,
                                                                    InvocableMap.EntryAggregator<? super K,? super V,R> aggregator,
                                                                    Filter filter)

Create an instance of GroupAggregator based on a specified extractor and an EntryAggregator and a result evaluation filter.
If the specified aggregator is an instance of ParallelAwareAggregator, then a parallel-aware instance of the GroupAggregator will be created. Otherwise, the resulting GroupAggregator will not be parallel-aware and could be ill-suited for aggregations run against large partitioned caches.

Parameters:

extractor - a ValueExtractor that will be used to split a set of InvocableMap entries into distinct groups

aggregator - an underlying EntryAggregator

filter - an optional Filter object used to filter out results of individual group aggregation results