mehakmeet commented on a change in pull request #2069: URL: https://github.com/apache/hadoop/pull/2069#discussion_r466190899
########## File path: hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/statistics/impl/DynamicIOStatisticsBuilder.java ########## @@ -0,0 +1,248 @@ +/* + * 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.hadoop.fs.statistics.impl; + +import java.util.concurrent.atomic.AtomicInteger; +import java.util.concurrent.atomic.AtomicLong; +import java.util.function.Function; +import java.util.function.ToLongFunction; + +import org.apache.hadoop.fs.statistics.IOStatistics; +import org.apache.hadoop.fs.statistics.MeanStatistic; +import org.apache.hadoop.metrics2.lib.MutableCounterLong; + +import static com.google.common.base.Preconditions.checkState; + +/** + * Builder of Dynamic IO Statistics which serve up up longs. + * Instantiate through + * {@link IOStatisticsBinding#dynamicIOStatistics()}. + */ +public class DynamicIOStatisticsBuilder { + + /** + * the instance being built up. Will be null after the (single) + * call to {@link #build()}. + */ + private DynamicIOStatistics instance = new DynamicIOStatistics(); + + /** + * Build the IOStatistics instance. + * @return an instance. + * @throws IllegalStateException if the builder has already been built. + */ + public IOStatistics build() { + final DynamicIOStatistics stats = activeInstance(); + // stop the builder from working any more. + instance = null; + return stats; + } + + + /** + * Get the statistics instance. + * @return the instance to build/return + * @throws IllegalStateException if the builder has already been built. + */ + private DynamicIOStatistics activeInstance() { + checkState(instance != null, "Already built"); + return instance; + } + + /** + * Add a new evaluator to the counter statistics. + * @param key key of this statistic + * @param eval evaluator for the statistic + * @return the builder. + */ + public DynamicIOStatisticsBuilder withLongFunctionCounter(String key, + ToLongFunction<String> eval) { + activeInstance().addCounterFunction(key, eval::applyAsLong); + return this; + } + + /** + * Add a counter statistic to dynamically return the + * latest value of the source. + * @param key key of this statistic + * @param source atomic long counter + * @return the builder. + */ + public DynamicIOStatisticsBuilder withAtomicLongCounter(String key, + AtomicLong source) { + withLongFunctionCounter(key, s -> source.get()); + return this; + } + + /** + * Add a counter statistic to dynamically return the + * latest value of the source. + * @param key key of this statistic + * @param source atomic int counter + * @return the builder. + */ + public DynamicIOStatisticsBuilder withAtomicIntegerCounter(String key, + AtomicInteger source) { + withLongFunctionCounter(key, s -> source.get()); + return this; + } + + /** + * Build a dynamic counter statistic from a + * {@link MutableCounterLong}. + * @param key key of this statistic + * @param source mutable long counter + * @return the builder. + */ + public DynamicIOStatisticsBuilder withMutableCounter(String key, + MutableCounterLong source) { + withLongFunctionCounter(key, s -> source.value()); + return this; + } + + /** + * Add a new evaluator to the gauge statistics. + * @param key key of this statistic + * @param eval evaluator for the statistic + * @return the builder. + */ + public DynamicIOStatisticsBuilder withLongFunctionGauge(String key, + ToLongFunction<String> eval) { + activeInstance().addGaugeFunction(key, eval::applyAsLong); + return this; + } + + /** + * Add a gauge statistic to dynamically return the + * latest value of the source. + * @param key key of this statistic + * @param source atomic long gauge + * @return the builder. + */ + public DynamicIOStatisticsBuilder withAtomicLongGauge(String key, + AtomicLong source) { + withLongFunctionGauge(key, s -> source.get()); + return this; + } + + /** + * Add a gauge statistic to dynamically return the + * latest value of the source. + * @param key key of this statistic + * @param source atomic int gauge + * @return the builder. + */ + public DynamicIOStatisticsBuilder withAtomicIntegerGauge(String key, + AtomicInteger source) { + withLongFunctionGauge(key, s -> source.get()); + return this; + } + + /** + * Add a new evaluator to the minumum statistics. + * @param key key of this statistic + * @param eval evaluator for the statistic + * @return the builder. + */ + public DynamicIOStatisticsBuilder withLongFunctionMinumum(String key, Review comment: can be made private and, typo in method name and comment: minumum -> minimum. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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