pnowojski commented on a change in pull request #14526: URL: https://github.com/apache/flink/pull/14526#discussion_r551899075
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/metrics/groups/TimeGauge.java ########## @@ -0,0 +1,80 @@ +/* + * 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. + */ + +// ---------------------------------------------------------------------------- +// This class is largely adapted from "com.google.common.base.Preconditions", +// which is part of the "Guava" library. +// +// Because of frequent issues with dependency conflicts, this class was +// added to the Flink code base to reduce dependency on Guava. +// ---------------------------------------------------------------------------- + +package org.apache.flink.runtime.metrics.groups; + +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.flink.metrics.Gauge; +import org.apache.flink.metrics.View; + +/** + * {@link TimeGauge} encapsulate logic of measuring time rates (like idleTime ms/s). In particularly + * it takes care of the case, when single measurement (as defined by {@link #markStart()} and {@link + * #markEnd()}), crosses the boundary of single {@link #update()} interval. Thanks to the {@link + * #markStart()} {@link TimeGauge} can correctly calculate next value in {@link #update()}, even if + * this measurement hasn't not ended ({@link #markEnd()}). + */ +public class TimeGauge implements Gauge<Long>, View { + private long previousCount; + private long currentCount; + private long lastDifference; + private long currentMeasurementStart; + + public synchronized void markStart() { + if (currentMeasurementStart == 0) { + currentMeasurementStart = System.currentTimeMillis(); Review comment: I agree this is a bit error-prone, but I think adding separate `TimerGauge` per each place where we are starting a measurement is probably not the way to go. It could quickly multiply the number of declared fields/gauges in `TaskIOMetricGroup` to facilitate every call place. If this will prove to be a real issue, we could solve this issue for example by bumping a counter in each `markStart()` call. `markEnd` would decrease that counter, and we would measure the time between first `markStart` and last `markEnd` call. But I think that's over engineering at the moment? ---------------------------------------------------------------- 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
