com.tangosol.util.aggregator

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

Nested Class Summary

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

Base.LoggingWriter, Base.StackFrame

Field Summary

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

BY_MEMBER, BY_PARTITION, PARALLEL, PRESENT_ONLY, RETAINS_ENTRIES, SERIAL

Constructor Summary

Constructors

Constructor and Description
Count() Default constructor (necessary for the ExternalizableLite interface).

Method Summary

Modifier and Type	Method and 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.
Integer	finalizeResult() Return the final result of the aggregation.
Integer	getPartialResult() Return the partial result of the aggregation.
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.
InvocableMap.StreamingAggregator<K,V,Integer,Integer>	supply() Create a new instance of this aggregator.
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.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, 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, 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, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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

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

Constructor Detail

Count

public Count()

Default constructor (necessary for the ExternalizableLite interface).

Method Detail

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>

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:

<c>true</c> to continue the aggregation, and <c>false</c> 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:

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

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:

<c>true</c> to continue the aggregation, and <c>false</c> 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

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,Integer,Integer>

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

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

NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

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