ptolemy.actor.ptalon.lib

Class MapReduceAlgorithm

java.lang.Object

java.lang.Thread

ptolemy.actor.ptalon.lib.MapReduceAlgorithm

All Implemented Interfaces:

java.lang.Runnable

Direct Known Subclasses:

ReverseLink, WordCount

public abstract class MapReduceAlgorithm
extends java.lang.Thread

The MapReduce Algorithm.

See MapReduce: Simplified Data Processing on Large Clusters

Since:

Ptolemy II 6.1

Version:

$Id$

Author:

Adam Cataldo

Pt.AcceptedRating:

Red (cxh)

Pt.ProposedRating:

Red (cxh)

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

Fields

Modifier and Type	Field and Description
java.lang.String	reduceKey The key for the reduce algorithm, which should be set externally.
java.util.List<java.lang.String>	reduceOutput The list generated by the reduce algorithm, which should be read externally.
java.util.concurrent.BlockingQueue<java.lang.String>	reduceValues The values for the reduce algorithm, which should be set externally.

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
MapReduceAlgorithm()

Method Summary

Modifier and Type	Method and Description
protected boolean	isQueueEmpty() Return true if no more elements will be added to the list.
boolean	isReduceFinished() Return true if the reduce is finished.
abstract java.util.List<KeyValuePair>	map(java.lang.String key, java.lang.String value) Subclasses should implement their map method here.
abstract java.util.List<java.lang.String>	reduce(java.lang.String key, java.util.concurrent.BlockingQueue<java.lang.String> values) Subclasses should implement their reduce method here, calling the take method of the BlockingQueue to get the next value, and checking the parameter noMoreInputs to test if no more values can be put on the queue.
void	run() This is used to call the reduce algorithm.
void	setNoMoreInputs() Set this true when no more inputs values will be given to the reduce method queue.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

reduceKey

public java.lang.String reduceKey

The key for the reduce algorithm, which should be set externally.

reduceValues

public java.util.concurrent.BlockingQueue<java.lang.String> reduceValues

The values for the reduce algorithm, which should be set externally.

reduceOutput

public java.util.List<java.lang.String> reduceOutput

The list generated by the reduce algorithm, which should be read externally.

Constructor Detail

MapReduceAlgorithm

public MapReduceAlgorithm()

Method Detail

isReduceFinished

public boolean isReduceFinished()
                         throws IllegalActionException

Return true if the reduce is finished.

Returns:

Return true if the reduce is finished.

Throws:

IllegalActionException - If there was a thread error.

map

public abstract java.util.List<KeyValuePair> map(java.lang.String key,
                                                 java.lang.String value)

Subclasses should implement their map method here.

Parameters:

key - The key passed to the map method.

value - The value passed to the map method.

Returns:

The list of key value pairs for the given input.

reduce

public abstract java.util.List<java.lang.String> reduce(java.lang.String key,
                                                        java.util.concurrent.BlockingQueue<java.lang.String> values)
                                                 throws java.lang.InterruptedException

Subclasses should implement their reduce method here, calling the take method of the BlockingQueue to get the next value, and checking the parameter noMoreInputs to test if no more values can be put on the queue. The last value put on the queue may be the empty string. If this is the case, just discard it.

Parameters:

key - The key to reduce over.

values - The queue of values in reduction.

Returns:

The reduced list of values

Throws:

java.lang.InterruptedException - If thrown while reducing.

run

public void run()

This is used to call the reduce algorithm.

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

setNoMoreInputs

public void setNoMoreInputs()

Set this true when no more inputs values will be given to the reduce method queue.

isQueueEmpty

protected boolean isQueueEmpty()

Return true if no more elements will be added to the list.

Returns:

true if no more elements will be added to the list.