org.apache.giraph.block_app.reducers.map

Class BasicMapReduce<K extends org.apache.hadoop.io.WritableComparable,S,R extends org.apache.hadoop.io.Writable>

java.lang.Object

org.apache.giraph.block_app.reducers.map.BasicMapReduce<K,S,R>

Type Parameters:

K - Key type

S - Single value type

R - Reduced value type

All Implemented Interfaces:

ReduceOperation<org.apache.commons.lang3.tuple.Pair<K,S>,Basic2ObjectMap<K,R>>, org.apache.hadoop.io.Writable

public class BasicMapReduce<K extends org.apache.hadoop.io.WritableComparable,S,R extends org.apache.hadoop.io.Writable>
extends Object
implements ReduceOperation<org.apache.commons.lang3.tuple.Pair<K,S>,Basic2ObjectMap<K,R>>

Efficient generic primitive map of values reduce operation. (it is BasicMap Reduce, not to be confused with MapReduce)

Constructor Summary

Constructors

Constructor and Description
BasicMapReduce()
BasicMapReduce(PrimitiveIdTypeOps<K> keyTypeOps, PrimitiveTypeOps<R> typeOps, ReduceOperation<S,R> elementReduceOp) Create ReduceOperation that reduces BasicMaps by reducing individual elements corresponding to the same key.

Method Summary

Modifier and Type	Method and Description
Basic2ObjectMap<K,R>	createInitialValue() Return new reduced value which is neutral to reduce operation.
static <K extends org.apache.hadoop.io.WritableComparable,S,R extends org.apache.hadoop.io.Writable> ReducerMapHandle<K,S,R>	createLocalMapHandles(PrimitiveIdTypeOps<K> keyTypeOps, PrimitiveTypeOps<R> typeOps, ReduceOperation<S,R> elementReduceOp, CreateReducersApi reduceApi) Registers one new local reducer, that will reduce BasicMap, by reducing individual elements corresponding to the same key using elementReduceOp.
static <K extends org.apache.hadoop.io.WritableComparable,S,R extends org.apache.hadoop.io.Writable> ReducerMapHandle<K,S,R>	createMapHandles(PrimitiveIdTypeOps<K> keyTypeOps, PrimitiveTypeOps<R> typeOps, ReduceOperation<S,R> elementReduceOp, CreateReducersApi.CreateReducerFunctionApi createFunction) Registers one new reducer, that will reduce BasicMap, by reducing individual elements corresponding to the same key using elementReduceOp.
void	readFields(DataInput in)
Basic2ObjectMap<K,R>	reduce(Basic2ObjectMap<K,R> curValue, org.apache.commons.lang3.tuple.Pair<K,S> valueToReduce) Add a new value.
Basic2ObjectMap<K,R>	reduceMerge(Basic2ObjectMap<K,R> curValue, Basic2ObjectMap<K,R> valueToReduce) Add partially reduced value to current partially reduced value.
void	write(DataOutput out)

Methods inherited from class java.lang.Object

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

Constructor Detail

BasicMapReduce

public BasicMapReduce()

BasicMapReduce

public BasicMapReduce(PrimitiveIdTypeOps<K> keyTypeOps,
                      PrimitiveTypeOps<R> typeOps,
                      ReduceOperation<S,R> elementReduceOp)

Create ReduceOperation that reduces BasicMaps by reducing individual elements corresponding to the same key.

Parameters:

keyTypeOps - TypeOps of keys

typeOps - TypeOps of individual elements

elementReduceOp - ReduceOperation for individual elements

Method Detail

createLocalMapHandles

public static <K extends org.apache.hadoop.io.WritableComparable,S,R extends org.apache.hadoop.io.Writable> ReducerMapHandle<K,S,R> createLocalMapHandles(PrimitiveIdTypeOps<K> keyTypeOps,
                                                                                                                                                          PrimitiveTypeOps<R> typeOps,
                                                                                                                                                          ReduceOperation<S,R> elementReduceOp,
                                                                                                                                                          CreateReducersApi reduceApi)

Registers one new local reducer, that will reduce BasicMap, by reducing individual elements corresponding to the same key using elementReduceOp. This function will return ReducerMapHandle, by which individual elements can be manipulated separately.

Parameters:

keyTypeOps - TypeOps of keys

typeOps - TypeOps of individual elements

elementReduceOp - ReduceOperation for individual elements

reduceApi - API for creating reducers

Returns:

Created ReducerMapHandle

createMapHandles

public static <K extends org.apache.hadoop.io.WritableComparable,S,R extends org.apache.hadoop.io.Writable> ReducerMapHandle<K,S,R> createMapHandles(PrimitiveIdTypeOps<K> keyTypeOps,
                                                                                                                                                     PrimitiveTypeOps<R> typeOps,
                                                                                                                                                     ReduceOperation<S,R> elementReduceOp,
                                                                                                                                                     CreateReducersApi.CreateReducerFunctionApi createFunction)

Registers one new reducer, that will reduce BasicMap, by reducing individual elements corresponding to the same key using elementReduceOp. This function will return ReducerMapHandle, by which individual elements can be manipulated separately.

Parameters:

keyTypeOps - TypeOps of keys

typeOps - TypeOps of individual elements

elementReduceOp - ReduceOperation for individual elements

createFunction - Function for creating a reducer

Returns:

Created ReducerMapHandle

createInitialValue

public Basic2ObjectMap<K,R> createInitialValue()

Description copied from interface: ReduceOperation

Return new reduced value which is neutral to reduce operation.

Specified by:

createInitialValue in interface ReduceOperation<org.apache.commons.lang3.tuple.Pair<K extends org.apache.hadoop.io.WritableComparable,S>,Basic2ObjectMap<K extends org.apache.hadoop.io.WritableComparable,R extends org.apache.hadoop.io.Writable>>

Returns:

Neutral value

reduce

public Basic2ObjectMap<K,R> reduce(Basic2ObjectMap<K,R> curValue,
                                   org.apache.commons.lang3.tuple.Pair<K,S> valueToReduce)

Description copied from interface: ReduceOperation

Add a new value. Needs to be commutative and associative Commonly, returned value should be same as curValue argument.

Specified by:

reduce in interface ReduceOperation<org.apache.commons.lang3.tuple.Pair<K extends org.apache.hadoop.io.WritableComparable,S>,Basic2ObjectMap<K extends org.apache.hadoop.io.WritableComparable,R extends org.apache.hadoop.io.Writable>>

Parameters:

curValue - Partial value into which to reduce and store the result

valueToReduce - Single value to be reduced

Returns:

reduced value

reduceMerge

public Basic2ObjectMap<K,R> reduceMerge(Basic2ObjectMap<K,R> curValue,
                                        Basic2ObjectMap<K,R> valueToReduce)

Description copied from interface: ReduceOperation

Add partially reduced value to current partially reduced value. Commonly, returned value should be same as curValue argument.

Specified by:

reduceMerge in interface ReduceOperation<org.apache.commons.lang3.tuple.Pair<K extends org.apache.hadoop.io.WritableComparable,S>,Basic2ObjectMap<K extends org.apache.hadoop.io.WritableComparable,R extends org.apache.hadoop.io.Writable>>

Parameters:

curValue - Partial value into which to reduce and store the result

valueToReduce - Partial value to be reduced

Returns:

reduced value

write

public void write(DataOutput out)
           throws IOException

Specified by:

write in interface org.apache.hadoop.io.Writable

Throws:

IOException

readFields

public void readFields(DataInput in)
                throws IOException

Specified by:

readFields in interface org.apache.hadoop.io.Writable

Throws:

IOException