Class Count<K,V>

java.lang.Object

com.tangosol.util.Base

com.tangosol.util.aggregator.Count<K,V>

All Implemented Interfaces:

ExternalizableLite, PortableObject, InvocableMap.EntryAggregator<K,V,Integer>, InvocableMap.StreamingAggregator<K,V,Integer,Integer>, Serializable

public class Count<K,V>
extends Base
implements InvocableMap.StreamingAggregator<K,V,Integer,Integer>, ExternalizableLite, PortableObject

Calculates a number of values in an entry set.

Since:

Coherence 3.1

Author:

gg 2005.09.05

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class Base

Base.LoggingWriter

Nested classes/interfaces inherited from interface InvocableMap.StreamingAggregator

InvocableMap.StreamingAggregator.RetractionResult

Field Summary

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
Count()	Default constructor (necessary for the ExternalizableLite interface).

Method Summary

Modifier and Type	Method	Description
boolean	accumulate(InvocableMap.Entry<? extends K, ? extends V> entry)	Accumulate one entry into the result.
boolean	accumulate(Streamer<? extends InvocableMap.Entry<? extends K, ? extends V>> streamer)	Accumulate multiple entries into the result.
int	characteristics()	A bit mask representing the set of characteristics of this aggregator.
boolean	combine(Integer partialResult)	Merge another partial result into the result.
boolean	equals(Object o)
Integer	finalizeResult()	Return the final result of the aggregation.
Integer	getPartialResult()	Return the partial result of the aggregation.
int	hashCode()
void	readExternal(PofReader in)	Restore the contents of a user type instance by reading its state using the specified PofReader object.
void	readExternal(DataInput in)	Restore the contents of this object by loading the object's state from the passed DataInput object.
void	restoreState(Object state)	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,Integer,Integer>	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.
void	writeExternal(PofWriter out)	Save the contents of a POF user type instance by writing its state using the specified PofWriter object.
void	writeExternal(DataOutput out)	Save the contents of this object by storing the object's state into the passed DataOutput object.

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, toString, wait, wait, wait

Methods inherited from interface InvocableMap.StreamingAggregator

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

Constructor Details

Count

public Count()

Default constructor (necessary for the ExternalizableLite interface).

Method Details

supply

public InvocableMap.StreamingAggregator<K,V,Integer,Integer> supply()

Description copied from interface: InvocableMap.StreamingAggregator

Create a new instance of this aggregator.

Specified by:

supply in interface InvocableMap.StreamingAggregator<K,V,Integer,Integer>

Returns:

a StreamAggregator

accumulate

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

Description copied from interface: InvocableMap.StreamingAggregator

Accumulate multiple entries into the result.

Important note: The default implementation of this method provides necessary logic for aggregation short-circuiting and should rarely (if ever) be overridden by the custom aggregator implementation.

Specified by:

accumulate in interface InvocableMap.StreamingAggregator<K,V,Integer,Integer>

Parameters:

streamer - a Streamer that can be used to iterate over entries to add

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

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,Integer,Integer>

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

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,Integer,Integer>

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,Integer,Integer>

Parameters:

entry - the updated entry

Returns:

the state of the aggregation result after the update

combine

public boolean combine(Integer partialResult)

Description copied from interface: InvocableMap.StreamingAggregator

Merge another partial result into the result.

Specified by:

combine in interface InvocableMap.StreamingAggregator<K,V,Integer,Integer>

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 Integer getPartialResult()

Description copied from interface: InvocableMap.StreamingAggregator

Return the partial result of the aggregation.

Specified by:

getPartialResult in interface InvocableMap.StreamingAggregator<K,V,Integer,Integer>

Returns:

the partial result of the aggregation

finalizeResult

public Integer finalizeResult()

Description copied from interface: InvocableMap.StreamingAggregator

Return the final result of the aggregation.

Specified by:

finalizeResult in interface InvocableMap.StreamingAggregator<K,V,Integer,Integer>

Returns:

the final result of the aggregation

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.

Specified by:

snapshotState in interface InvocableMap.StreamingAggregator<K,V,Integer,Integer>

Returns:

a detached maintenance-state snapshot

restoreState

public void restoreState(Object state)

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.

Specified by:

restoreState in interface InvocableMap.StreamingAggregator<K,V,Integer,Integer>

Parameters:

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

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).

Specified by:

characteristics in interface InvocableMap.StreamingAggregator<K,V,Integer,Integer>

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

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

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