org.apache.flink.runtime.metrics.TimerGauge Maven / Gradle / Ivy
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* 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.flink.runtime.metrics;
import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.metrics.Gauge;
import org.apache.flink.metrics.View;
import org.apache.flink.util.clock.Clock;
import org.apache.flink.util.clock.SystemClock;
/**
* {@link TimerGauge} measures how much time is spent in a given state, with entry into that state
* being signaled by {@link #markStart()}. Measuring is stopped by {@link #markEnd()}. This class in
* particularly takes care of the case, when {@link #update()} is called when some measurement
* started but has not yet finished. For example even if next {@link #markEnd()} call is expected to
* happen in a couple of hours, the returned value will account for this ongoing measurement.
*/
public class TimerGauge implements Gauge, View {
private final Clock clock;
private long previousCount;
private long currentCount;
private long currentMeasurementStart;
public TimerGauge() {
this(SystemClock.getInstance());
}
public TimerGauge(Clock clock) {
this.clock = clock;
}
public synchronized void markStart() {
if (currentMeasurementStart == 0) {
currentMeasurementStart = clock.absoluteTimeMillis();
}
}
public synchronized void markEnd() {
if (currentMeasurementStart != 0) {
currentCount += clock.absoluteTimeMillis() - currentMeasurementStart;
currentMeasurementStart = 0;
}
}
@Override
public synchronized void update() {
if (currentMeasurementStart != 0) {
long now = clock.absoluteTimeMillis();
currentCount += now - currentMeasurementStart;
currentMeasurementStart = now;
}
previousCount = Math.max(Math.min(currentCount / UPDATE_INTERVAL_SECONDS, 1000), 0);
currentCount = 0;
}
@Override
public synchronized Long getValue() {
return previousCount;
}
@VisibleForTesting
public synchronized long getCount() {
return currentCount;
}
@VisibleForTesting
public synchronized boolean isMeasuring() {
return currentMeasurementStart != 0;
}
}