adamdebreceni commented on code in PR #1400: URL: https://github.com/apache/nifi-minifi-cpp/pull/1400#discussion_r993313911
########## libminifi/include/utils/Averager.h: ########## @@ -0,0 +1,91 @@ +/** + * 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 <vector> +#include <mutex> + +namespace org::apache::nifi::minifi::utils { + +template<typename T> +concept Summable = requires(T x) { x + x; }; // NOLINT(readability/braces) + +template<typename T> +concept DividableByInteger = requires(T x, uint32_t divisor) { x / divisor; }; // NOLINT(readability/braces) + +template<typename ValueType> +requires Summable<ValueType> && DividableByInteger<ValueType> +class Averager { + public: + explicit Averager(uint32_t sample_size) : SAMPLE_SIZE_(sample_size) { + values_.reserve(SAMPLE_SIZE_); + } + + ValueType getAverage() const; + ValueType getLastValue() const; + void addValue(ValueType runtime); + + private: + const uint32_t SAMPLE_SIZE_; + mutable std::mutex average_value_mutex_; + uint32_t next_average_index_ = 0; + std::vector<ValueType> values_; +}; + +template<typename ValueType> +requires Summable<ValueType> && DividableByInteger<ValueType> +ValueType Averager<ValueType>::getAverage() const { + if (values_.empty()) { + return {}; + } + ValueType sum{}; + std::lock_guard<std::mutex> lock(average_value_mutex_); + for (const auto& value : values_) { + sum += value; + } + return sum / values_.size(); +} + +template<typename ValueType> +requires Summable<ValueType> && DividableByInteger<ValueType> +void Averager<ValueType>::addValue(ValueType runtime) { + std::lock_guard<std::mutex> lock(average_value_mutex_); + if (values_.size() < SAMPLE_SIZE_) { + values_.push_back(runtime); + } else { + if (next_average_index_ >= values_.size()) { + next_average_index_ = 0; + } + values_[next_average_index_] = runtime; + ++next_average_index_; + } +} + +template<typename ValueType> +requires Summable<ValueType> && DividableByInteger<ValueType> +ValueType Averager<ValueType>::getLastValue() const { + std::lock_guard<std::mutex> lock(average_value_mutex_); + if (values_.empty()) { + return {}; + } else if (values_.size() < SAMPLE_SIZE_) { + return values_[values_.size() - 1]; + } else { + return values_[next_average_index_ - 1]; Review Comment: wouldn't this cause an ~underflow~ out-of-bounds indexing, if we query `getLastValue` right after we have pushed the last value at the end of the `values_` vector? (`values_.size() == SAMPLE_SIZE_ && next_average_index_ == 0`) -- 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. To unsubscribe, e-mail: issues-unsubscr...@nifi.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
