Class ReducerAggregator<K,V,T,E>

java.lang.Object

com.tangosol.util.Base

com.tangosol.util.BitHelper

com.tangosol.util.ExternalizableHelper

com.tangosol.util.aggregator.AbstractAggregator<K,V,T,E,Map<K,E>>

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

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

All Implemented Interfaces:

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

public class ReducerAggregator<K,V,T,E>
extends AbstractAggregator<K,V,T,E,Map<K,E>>

The ReducerAggregator is used to implement functionality similar to CacheMap.getAll(Collection) API. Instead of returning the complete set of values, it will return a portion of value attributes based on the provided ValueExtractor.

This aggregator could be used in combination with MultiExtractor allowing one to collect tuples that are a subset of the attributes of each object stored in the cache.

Author:

djl 2009.03.02

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class ExternalizableHelper

ExternalizableHelper.DecoratedMultiBufferReadBuffer, ExternalizableHelper.DecorationAware, 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 Base

Base.LoggingWriter

Nested classes/interfaces inherited from interface InvocableMap.StreamingAggregator

InvocableMap.StreamingAggregator.RetractionResult

Field Summary

Fields

Modifier and Type	Field	Description
protected Map<K,E>	m_map	The resulting map of reduced values.

Fields inherited from class AbstractAggregator

m_fParallel

Fields inherited from class ExternalizableHelper

BINARY_SIZE, CHUNK_SIZE, CHUNK_THRESHOLD, CONVERTER_FROM_BINARY, CONVERTER_STRIP_INTDECO, CONVERTER_TO_BINARY, DECO_APP_1, DECO_APP_2, DECO_APP_3, DECO_BACKUP, DECO_CUSTOM, DECO_EXPIRY, DECO_ID_MAX, DECO_ID_MIN, DECO_JCACHE, DECO_JCACHE_SYNTHETIC, DECO_MEMCACHED, DECO_PUSHREP, DECO_RSVD_1, DECO_STORE, DECO_TOPLINK, DECO_TX, DECO_VALUE, DECO_VECTOR, 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, LAMBDA_SERIALIZATION, MAX_DECO_HEADER_BYTES, MAX_MEMCACHED_PASS_THROUGH_FORMAT_DEPTH, PACKED_INT_SIZE, PACKED_LONG_SIZE, PROPERTY_CONFIG, s_streamfactory, s_tloInEHDeserialize, TRINT_DOMAIN_SPAN, TRINT_MAX_VALUE, TRINT_MAX_VARIANCE, USE_POF_STREAMS, USE_XMLBEAN_CLASS_CACHE, XMLBEAN_CLASS_CACHE

Fields inherited from class Base

DEFAULT_LOAD_FACTOR, LOG_ALWAYS, LOG_CONFIG, 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 InvocableMap.StreamingAggregator

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

Constructor Summary

Constructors

Constructor	Description
ReducerAggregator()	Default constructor (necessary for the ExternalizableLite interface).
ReducerAggregator(ValueExtractor<? super T, ? extends E> extractor)	Construct a ReducerAggregator based on the specified extractor.
ReducerAggregator(String sMethod)	Construct a ReducerAggregator based on the specified method name.

Method Summary

Modifier and Type	Method	Description
int	characteristics()	A bit mask representing the set of characteristics of this aggregator.
protected Map<K,E>	ensureMap()	Return a map that can be used to store reduced values, creating it if one has not already been created.
protected Map<K,E>	finalizeResult(boolean fFinal)	Obtain the result of the aggregation.
protected void	init(boolean fFinal)	Initialize the aggregation result.
protected void	process(Object o, boolean fFinal)	Incorporate one aggregatable value into the result.
void	processEntry(InvocableMap.Entry<? extends K, ? extends V> entry)	Incorporate one aggregatable entry into the result.
void	restoreState(Object oState)	Restore a maintenance-state snapshot into this empty supplied instance.
InvocableMap.StreamingAggregator.RetractionResult	retract(InvocableMap.Entry<? extends K, ? extends V> entry)	Retract the contribution of a single entry from the aggregation result.
Object	snapshotState()	Return a detached, serializer-compatible snapshot of the state required to continue incremental maintenance.
InvocableMap.StreamingAggregator<K,V,Object,Map<K,E>>	supply()	Create a new instance of this aggregator.
InvocableMap.StreamingAggregator.RetractionResult	update(InvocableMap.Entry<? extends K, ? extends V> entry)	Replace the contribution of an entry that was present before and remains present after a map update.

Methods inherited from class AbstractAggregator

accumulate, accumulate, combine, ensureInitialized, equals, finalizeResult, getPartialResult, getValueExtractor, hashCode, isReplacementRequired, readExternal, readExternal, remove, replace, toString, writeExternal, writeExternal

Methods inherited from class ExternalizableHelper

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

Methods inherited from class 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 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, getStackTrace, getThreadFactory, getTimeZone, getUpTimeMillis, hashCode, hexValue, indentString, indentString, isDecimal, isHex, isLogEcho, isOctal, log, log, log, log, log, makeInteger, makeLong, makeThread, mergeArray, mergeBooleanArray, mergeByteArray, mergeCharArray, mergeDoubleArray, mergeFloatArray, mergeIntArray, mergeLongArray, mod, mod, newHashMap, newHashMap, newHashSet, newHashSet, 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 Object

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

Methods inherited from interface InvocableMap.StreamingAggregator

aggregate, finalizeResult, getMaintenanceStatus, isAllowInconsistencies, isByMember, isByPartition, isContinuous, isParallel, isPresentOnly, isRetainsEntries, isSerial, isStateCheckpointable

Field Details

m_map

protected transient Map<K,E> m_map

The resulting map of reduced values.

Constructor Details

ReducerAggregator

public ReducerAggregator()

Default constructor (necessary for the ExternalizableLite interface).

ReducerAggregator

public ReducerAggregator(String sMethod)

Construct a ReducerAggregator based on the specified method name.

Parameters:

sMethod - the name of the method that is used to extract the portion of the cached value

ReducerAggregator

public ReducerAggregator(ValueExtractor<? super T, ? extends E> extractor)

Construct a ReducerAggregator based on the specified extractor.

Parameters:

extractor - the extractor that is used to extract the portion of the cached value

Method Details

supply

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

Description copied from interface: InvocableMap.StreamingAggregator

Create a new instance of this aggregator.

Specified by:

supply in interface InvocableMap.StreamingAggregator<K,V,T,E>

Overrides:

supply in class AbstractAggregator<K,V,T,E,Map<K,E>>

Returns:

a StreamAggregator

characteristics

public int characteristics()

Description copied from interface: InvocableMap.StreamingAggregator

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

By 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).

Returns:

a bit mask representing the set of characteristics of this aggregator

See Also:

• InvocableMap.StreamingAggregator.ALLOW_INCONSISTENCIES
• InvocableMap.StreamingAggregator.BY_MEMBER
• InvocableMap.StreamingAggregator.BY_PARTITION
• InvocableMap.StreamingAggregator.CONTINUOUS
• InvocableMap.StreamingAggregator.STATE_CHECKPOINTABLE
• InvocableMap.StreamingAggregator.PARALLEL
• InvocableMap.StreamingAggregator.PRESENT_ONLY
• InvocableMap.StreamingAggregator.RETAINS_ENTRIES
• InvocableMap.StreamingAggregator.SERIAL

snapshotState

public Object snapshotState()

Description copied from interface: InvocableMap.StreamingAggregator

Return a detached, serializer-compatible snapshot of the state required to continue incremental maintenance.

This method is used only when InvocableMap.StreamingAggregator.STATE_CHECKPOINTABLE is advertised. The default implementation does not support state checkpointing.

Returns:

a detached maintenance-state snapshot

restoreState

public void restoreState(Object oState)

Description copied from interface: InvocableMap.StreamingAggregator

Restore a maintenance-state snapshot into this empty supplied instance.

This method is used only when InvocableMap.StreamingAggregator.STATE_CHECKPOINTABLE is advertised. The default implementation does not support state checkpointing.

Parameters:

oState - the snapshot returned by InvocableMap.StreamingAggregator.snapshotState()

init

protected void init(boolean fFinal)

Initialize the aggregation result.

Specified by:

init in class AbstractAggregator<K,V,T,E,Map<K,E>>

Parameters:

fFinal - true is passed if the aggregation process that is being initialized must produce a final aggregation result; this will only be false if a parallel approach is being used and the initial (partial) aggregation process is being initialized

processEntry

public void processEntry(InvocableMap.Entry<? extends K, ? extends V> entry)

Incorporate one aggregatable entry into the result.

Overrides:

processEntry in class AbstractAggregator<K,V,T,E,Map<K,E>>

Parameters:

entry - the entry to incorporate into the aggregation result

retract

public InvocableMap.StreamingAggregator.RetractionResult retract(InvocableMap.Entry<? extends K, ? extends V> entry)

Description copied from interface: InvocableMap.StreamingAggregator

Retract the contribution of a single entry from the aggregation result.

When the supplied entry is a MapTrigger.Entry, an implementation should retract the entry's original value. Otherwise, it should retract the value represented by the supplied entry.

The default implementation cannot retract an entry and requires the caller to rebuild the aggregation result.

Specified by:

retract in interface InvocableMap.StreamingAggregator<K,V,T,E>

Overrides:

retract in class AbstractAggregator<K,V,T,E,Map<K,E>>

Parameters:

entry - the entry to retract

Returns:

the state of the aggregation result after the retraction

update

public InvocableMap.StreamingAggregator.RetractionResult update(InvocableMap.Entry<? extends K, ? extends V> entry)

Description copied from interface: InvocableMap.StreamingAggregator

Replace the contribution of an entry that was present before and remains present after a map update.

The supplied entry is expected to be a MapTrigger.Entry exposing both its original and current values. The default implementation retracts the original contribution, accumulates the current contribution, and therefore preserves the semantics of an update for aggregators that do not provide a specialized implementation.

Specified by:

update in interface InvocableMap.StreamingAggregator<K,V,T,E>

Overrides:

update in class AbstractAggregator<K,V,T,E,Map<K,E>>

Parameters:

entry - the updated entry

Returns:

the state of the aggregation result after the update

process

protected void process(Object o,
 boolean fFinal)

Incorporate one aggregatable value into the result.

If the fFinal parameter is true, the given object is a partial result (returned by an individual parallel aggregator) that should be incorporated into the final result; otherwise, the object is a value extracted from an InvocableMap.Entry.

Specified by:

process in class AbstractAggregator<K,V,T,E,Map<K,E>>

Parameters:

o - the value to incorporate into the aggregated result

fFinal - true to indicate that the given object is a partial result returned by a parallel aggregator

finalizeResult

protected Map<K,E> finalizeResult(boolean fFinal)

Obtain the result of the aggregation.

If the fFinal parameter is true, the returned object must be the final result of the aggregation; otherwise, the returned object will be treated as a partial result that should be incorporated into the final result.

Specified by:

finalizeResult in class AbstractAggregator<K,V,T,E,Map<K,E>>

Parameters:

fFinal - true to indicate that the final result of the aggregation process should be returned; this will only be false if a parallel approach is being used

Returns:

the result of the aggregation process

ensureMap

protected Map<K,E> ensureMap()

Return a map that can be used to store reduced values, creating it if one has not already been created.

Returns:

a set that can be used to store distinct values