00001 /* 00002 * Copyright (c) 2000, 2020, Oracle and/or its affiliates. 00003 * 00004 * Licensed under the Universal Permissive License v 1.0 as shown at 00005 * http://oss.oracle.com/licenses/upl. 00006 */ 00007 #ifndef COH_REDUCER_AGGREGATOR_HPP 00008 #define COH_REDUCER_AGGREGATOR_HPP 00009 00010 #include "coherence/lang.ns" 00011 00012 #include "coherence/util/aggregator/AbstractAggregator.hpp" 00013 #include "coherence/util/ValueExtractor.hpp" 00014 00015 COH_OPEN_NAMESPACE3(coherence,util,aggregator) 00016 00017 00018 /** 00019 * The ReducerAggregator is used to implement functionality similar to 00020 * <tt>CacheMap::getAll(Collection)</tt> API. Instead of returning the complete 00021 * set of values, it will return a portion of value attributes based on the 00022 * provided <tt>ValueExtractor</tt>. 00023 * 00024 * This aggregator could be used in combination with 00025 * <tt>coherence.util.extractor.MultiExtractor</tt> allowing one to collect 00026 * tuples that are a subset of the attributes of each object stored in the cache. 00027 * 00028 * @author par 04.25.13 00029 */ 00030 class COH_EXPORT ReducerAggregator 00031 : public class_spec<ReducerAggregator, 00032 extends<AbstractAggregator> > 00033 { 00034 friend class factory<ReducerAggregator>; 00035 00036 00037 // ----- constructors --------------------------------------------------- 00038 00039 protected: 00040 /** 00041 * Default constructor. 00042 */ 00043 ReducerAggregator(); 00044 00045 /** 00046 * Construct a ReducerAggregator based on the specified extractor. 00047 * 00048 * @param vExtractor the extractor that is used to extract the portion 00049 * of the cached value 00050 */ 00051 ReducerAggregator(ValueExtractor::View vExtractor); 00052 00053 /** 00054 * Construct a ReducerAggregator based on the specified method name. 00055 * 00056 * @param vsMethod the name of the method that is used to extract the 00057 * portion of the cached value 00058 */ 00059 ReducerAggregator(String::View vsMethod); 00060 00061 private: 00062 /** 00063 * Blocked copy constructor. 00064 */ 00065 ReducerAggregator(const ReducerAggregator&); 00066 00067 00068 // ----- AbstractAggregator methods ------------------------------------- 00069 00070 protected: 00071 /** 00072 * {@inheritDoc} 00073 */ 00074 virtual void init(bool fFinal); 00075 00076 /** 00077 * {@inheritDoc} 00078 */ 00079 virtual void process(Object::View vO, bool fFinal); 00080 00081 /** 00082 * {@inheritDoc} 00083 */ 00084 virtual Object::Holder finalizeResult(bool fFinal); 00085 00086 00087 // ----- internal helpers ----------------------------------------------- 00088 00089 protected: 00090 /** 00091 * Return a map that can be used to store reduced values, creating it if 00092 * one has not already been created. 00093 * 00094 * @return a set that can be used to store distinct values 00095 */ 00096 virtual Map::Handle ensureMap(); 00097 00098 00099 // ----- data members --------------------------------------------------- 00100 00101 private: 00102 /** 00103 * The resulting map of reduced values. 00104 */ 00105 MemberHandle<Map> m_hMap; 00106 }; 00107 00108 COH_CLOSE_NAMESPACE3 00109 00110 #endif //COH_REDUCER_AGGREGATOR_HPP