stevenzwu commented on code in PR #5348: URL: https://github.com/apache/iceberg/pull/5348#discussion_r938006420
########## api/src/main/java/org/apache/iceberg/metrics/FixedReservoirHistogram.java: ########## @@ -0,0 +1,145 @@ +/* + * 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.iceberg.metrics; + +import java.util.Arrays; +import org.apache.iceberg.relocated.com.google.common.base.Preconditions; + +/** + * A {@link Histogram} implementation that uses a fixed size reservoir like circular buffer. Oldest + * observation is replaced by latest observation. + */ +public class FixedReservoirHistogram implements Histogram { + private final long[] measurements; + private long count; + + public FixedReservoirHistogram(int reservoirSize) { + this.measurements = new long[reservoirSize]; + this.count = 0L; + } + + @Override + public synchronized long count() { + return count; + } + + @Override + public synchronized void update(long value) { + int index = (int) (count % measurements.length); + measurements[index] = value; + count++; + } + + @Override + public Statistics statistics() { + int size = measurements.length; + if (count < (long) measurements.length) { + size = (int) count; + } + + long[] values = new long[size]; + for (int i = 0; i < values.length; ++i) { + synchronized (this) { + values[i] = measurements[i]; + } + } + + return new UniformWeightStatistics(values); + } + + private static class UniformWeightStatistics implements Statistics { + private final long[] values; + + private UniformWeightStatistics(long[] values) { Review Comment: yeah. avoiding multiple loops makes sense. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
