szaszm commented on a change in pull request #732: MINIFICPP-1013 URL: https://github.com/apache/nifi-minifi-cpp/pull/732#discussion_r377584537
########## File path: extensions/sql/data/MaxCollector.h ########## @@ -0,0 +1,172 @@ +/** + * + * 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. + */ + +#pragma once + +#include <string> +#include <unordered_map> +#include <tuple> + +#include "SQLRowSubscriber.h" + +namespace org { +namespace apache { +namespace nifi { +namespace minifi { +namespace sql { + +class MaxCollector: public SQLRowSubscriber { + void beginProcessRow() override {} + + void endProcessRow() override { + if (columnsVerified_) { + return; + } + + if (countColumns_ != mapState_.size()) + throw minifi::Exception(PROCESSOR_EXCEPTION, "MaxCollector: Column(s) '" + maxValueColumnNames_ + "' are not found in the columns of '" + selectQuery_ + "' result."); + + columnsVerified_ = true; + } + + void processColumnName(const std::string& name) override { + if (columnsVerified_) { + return; + } + + if (mapState_.count(name)) { + countColumns_++; + } + } + + void processColumn(const std::string& name, const std::string& value) override { + updateMaxValue(name, '\'' + value + '\''); + } + + void processColumn(const std::string& name, double value) override { + updateMaxValue(name, value); + } + + void processColumn(const std::string& name, int value) override { + updateMaxValue(name, value); + } + + void processColumn(const std::string& name, long long value) override { + updateMaxValue(name, value); + } + + void processColumn(const std::string& name, unsigned long long value) override { + updateMaxValue(name, value); + } + + void processColumn(const std::string& name, const char* value) override {} + + template <typename T> + struct MaxValue { + void updateMaxValue(const std::string& name, const T& value) { + const auto it = mapColumnNameValue_.find(name); + if (it == mapColumnNameValue_.end()) { + mapColumnNameValue_.insert({ name, value }); + } else { + if (value > it->second) { + it->second = value; + } + } + } + + std::unordered_map<std::string, T> mapColumnNameValue_; + }; + + template <typename T, typename Tuple, int Index, bool> + struct TupleIndexByType { + constexpr static int index() { + using tupleElType = typename std::decay<decltype(std::get<Index + 1>(Tuple()))>::type; + + return TupleIndexByType<T, Tuple, Index + 1, std::is_same<tupleElType, MaxValue<T>>::value>::index(); + } + }; + + template <typename T, typename Tuple, int Index> + struct TupleIndexByType<T, Tuple, Index, true> { + constexpr static int index() { + return Index; + } + }; + + template <typename Tuple, int Index> + struct UpdateMapState { + UpdateMapState(const Tuple& tpl, std::unordered_map<std::string, std::string>& mapState) { + for (auto& el : mapState) { + const auto& maxVal = std::get<Index>(tpl); + + const auto it = maxVal.mapColumnNameValue_.find(el.first); + if (it != maxVal.mapColumnNameValue_.end()) { + std::stringstream ss; + ss << it->second; + el.second = ss.str(); + } + } + + UpdateMapState<Tuple, Index - 1>(tpl, mapState); + } + }; + + template <typename Tuple> + struct UpdateMapState<Tuple, -1> { + UpdateMapState(const Tuple&, std::unordered_map<std::string, std::string>&) {} + }; + + template <typename ...Ts> + struct MaxValues : public std::tuple<MaxValue<Ts>...> { + constexpr static size_t size = sizeof...(Ts); + }; + + public: + MaxCollector(const std::string& selectQuery, const std::string& maxValueColumnNames, std::unordered_map<std::string, std::string>& mapState) + :selectQuery_(selectQuery), maxValueColumnNames_(maxValueColumnNames), mapState_(mapState) { + } + + template <typename T> + void updateMaxValue(const std::string& columnName, const T& value) { + if (mapState_.count(columnName)) { + constexpr auto index = TupleIndexByType<T, decltype(maxValues_), -1, false>::index(); + std::get<index>(maxValues_).updateMaxValue(columnName, value); + } + } + + bool updateMapState() { + auto mapState = mapState_; + UpdateMapState<decltype(maxValues_), decltype(maxValues_)::size - 1>(maxValues_, mapState_); + + return mapState != mapState_; Review comment: The fact that we copy the whole map here to see if there were changes while make the code way more verbose to avoid additional lookups/writes in `MaxValue` is contradictory and feels wrong. Can we either optimize properly for performance if it matters or reduce verbosity if it doesn't? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
