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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.container.jdisc.state;
import com.google.inject.Inject;
import com.yahoo.component.AbstractComponent;
import com.yahoo.container.jdisc.config.HealthMonitorConfig;
import com.yahoo.jdisc.Timer;
import com.yahoo.jdisc.application.MetricConsumer;
import com.yahoo.log.LogLevel;
import java.util.Map;
import java.util.TreeSet;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.TimeUnit;
import java.util.logging.Logger;
/**
* A state monitor keeps track of the current health and metrics state of a container.
* It is used by jDisc to hand out metric update API endpoints to workers through {@link #newMetricConsumer},
* and to inspect the current accumulated state of metrics through {@link #snapshot}.
*
* @author <a href="mailto:simon@yahoo-inc.com">Simon Thoresen Hult</a>
*/
public class StateMonitor extends AbstractComponent {
private final static Logger log = Logger.getLogger(StateMonitor.class.getName());
public enum Status {up, down, initializing};
private final CopyOnWriteArrayList<StateMetricConsumer> consumers = new CopyOnWriteArrayList<>();
private final Thread thread;
private final Timer timer;
private final long snapshotIntervalMs;
private volatile long lastSnapshotTimeMs;
private volatile MetricSnapshot snapshot;
private volatile Status status;
private final TreeSet<String> valueNames = new TreeSet<>();
@Inject
public StateMonitor(HealthMonitorConfig config, Timer timer) {
this.timer = timer;
this.snapshotIntervalMs = (long)(config.snapshot_interval() * TimeUnit.SECONDS.toMillis(1));
this.lastSnapshotTimeMs = timer.currentTimeMillis();
this.status = Status.valueOf(config.initialStatus());
thread = new Thread(StateMonitor.this::run, "StateMonitor");
thread.setDaemon(true);
thread.start();
}
/** Returns a metric consumer for jDisc which will write metrics back to this */
public MetricConsumer newMetricConsumer() {
StateMetricConsumer consumer = new StateMetricConsumer();
consumers.add(consumer);
return consumer;
}
public void status(Status status) {
log.log(LogLevel.INFO, "Changing health status code from '" + this.status + "' to '" + status.name() + "'");
this.status = status;
}
public Status status() { return status; }
/** Returns the last snapshot taken of the metrics in this system */
public MetricSnapshot snapshot() {
return snapshot;
}
/** Returns the interval between each metrics snapshot used by this */
public long getSnapshotIntervalMillis() { return snapshotIntervalMs; }
boolean checkTime() {
long now = timer.currentTimeMillis();
if (now < lastSnapshotTimeMs + snapshotIntervalMs) {
return false;
}
snapshot = createSnapshot(lastSnapshotTimeMs, now);
lastSnapshotTimeMs = now;
return true;
}
private void run() {
log.finest("StateMonitor started.");
try {
while (!Thread.interrupted()) {
checkTime();
Thread.sleep((lastSnapshotTimeMs + snapshotIntervalMs) - timer.currentTimeMillis());
}
} catch (InterruptedException e) {
}
log.finest("StateMonitor stopped.");
}
private MetricSnapshot createSnapshot(long fromMillis, long toMillis) {
MetricSnapshot snapshot = new MetricSnapshot(fromMillis, toMillis, TimeUnit.MILLISECONDS);
for (StateMetricConsumer consumer : consumers) {
snapshot.add(consumer.createSnapshot());
}
updateNames(snapshot);
return snapshot;
}
private void updateNames(MetricSnapshot current) {
TreeSet<String> seen = new TreeSet<>();
for (Map.Entry<MetricDimensions, MetricSet> dimensionAndMetric : current) {
for (Map.Entry<String, MetricValue> nameAndMetric : dimensionAndMetric.getValue()) {
seen.add(nameAndMetric.getKey());
}
}
synchronized (valueNames) {
for (String name : valueNames) {
if (!seen.contains(name)) {
current.add((MetricDimensions) StateMetricConsumer.NULL_CONTEXT, name, 0);
}
}
valueNames.addAll(seen);
}
}
@Override
public void deconstruct() {
thread.interrupt();
try {
thread.join(5000);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
if (thread.isAlive()) {
log.warning("StateMonitor failed to terminate within 5 seconds of interrupt signal. Ignoring.");
}
}
}
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