Coverage Report

Coverage Report - org.apache.giraph.reducers.ReduceOperation

Classes in this File

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package org.apache.giraph.reducers;
 
 import org.apache.hadoop.io.Writable;
 
 /**
  * Reduce operations defining how to reduce single values
  * passed on workers, into partial values on workers, and then
  * into a single global reduced value.
  *
  * Object should be thread safe. Most frequently it should be
  * immutable object, so that functions can execute concurrently.
  * Rarely when object is mutable
  * ({@link org.apache.giraph.master.AggregatorReduceOperation}),
  * i.e. stores reusable object inside, accesses should be synchronized.
  *
  * @param <S> Single value type, objects passed on workers
  * @param <R> Reduced value type
  */
 public interface ReduceOperation<S, R extends Writable> extends Writable {
   /**
    * Return new reduced value which is neutral to reduce operation.
    *
    * @return Neutral value
    */
   R createInitialValue();
   /**
    * Add a new value.
    * Needs to be commutative and associative
    *
    * Commonly, returned value should be same as curValue argument.
    *
    * @param curValue Partial value into which to reduce and store the result
    * @param valueToReduce Single value to be reduced
    * @return reduced value
    */
   R reduce(R curValue, S valueToReduce);
   /**
    * Add partially reduced value to current partially reduced value.
    *
    * Commonly, returned value should be same as curValue argument.
    *
    * @param curValue Partial value into which to reduce and store the result
    * @param valueToReduce Partial value to be reduced
    * @return reduced value
    */
   R reduceMerge(R curValue, R valueToReduce);
 }

1		/*
2		* Licensed to the Apache Software Foundation (ASF) under one
3		* or more contributor license agreements. See the NOTICE file
4		* distributed with this work for additional information
5		* regarding copyright ownership. The ASF licenses this file
6		* to you under the Apache License, Version 2.0 (the
7		* "License"); you may not use this file except in compliance
8		* with the License. You may obtain a copy of the License at
9		*
10		* http://www.apache.org/licenses/LICENSE-2.0
11		*
12		* Unless required by applicable law or agreed to in writing, software
13		* distributed under the License is distributed on an "AS IS" BASIS,
14		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15		* See the License for the specific language governing permissions and
16		* limitations under the License.
17		*/
18		package org.apache.giraph.reducers;
19
20		import org.apache.hadoop.io.Writable;
21
22		/**
23		* Reduce operations defining how to reduce single values
24		* passed on workers, into partial values on workers, and then
25		* into a single global reduced value.
26		*
27		* Object should be thread safe. Most frequently it should be
28		* immutable object, so that functions can execute concurrently.
29		* Rarely when object is mutable
30		* ({@link org.apache.giraph.master.AggregatorReduceOperation}),
31		* i.e. stores reusable object inside, accesses should be synchronized.
32		*
33		* @param <S> Single value type, objects passed on workers
34		* @param <R> Reduced value type
35		*/
36		public interface ReduceOperation<S, R extends Writable> extends Writable {
37		/**
38		* Return new reduced value which is neutral to reduce operation.
39		*
40		* @return Neutral value
41		*/
42		R createInitialValue();
43		/**
44		* Add a new value.
45		* Needs to be commutative and associative
46		*
47		* Commonly, returned value should be same as curValue argument.
48		*
49		* @param curValue Partial value into which to reduce and store the result
50		* @param valueToReduce Single value to be reduced
51		* @return reduced value
52		*/
53		R reduce(R curValue, S valueToReduce);
54		/**
55		* Add partially reduced value to current partially reduced value.
56		*
57		* Commonly, returned value should be same as curValue argument.
58		*
59		* @param curValue Partial value into which to reduce and store the result
60		* @param valueToReduce Partial value to be reduced
61		* @return reduced value
62		*/
63		R reduceMerge(R curValue, R valueToReduce);
64		}