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Elasticsearch subproject :server
/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.watcher;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Setting.Property;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.core.TimeValue;
import org.elasticsearch.threadpool.Scheduler.Cancellable;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.threadpool.ThreadPool.Names;
import java.io.Closeable;
import java.io.IOException;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;
/**
* Generic resource watcher service
*
* Other elasticsearch services can register their resource watchers with this service using {@link #add(ResourceWatcher)}
* method. This service will call {@link org.elasticsearch.watcher.ResourceWatcher#checkAndNotify()} method of all
* registered watcher periodically. The frequency of checks can be specified using {@code resource.reload.interval} setting, which
* defaults to {@code 60s}. The service can be disabled by setting {@code resource.reload.enabled} setting to {@code false}.
*/
public class ResourceWatcherService implements Closeable {
private static final Logger logger = LogManager.getLogger(ResourceWatcherService.class);
public enum Frequency {
/**
* Defaults to 5 seconds
*/
HIGH(TimeValue.timeValueSeconds(5)),
/**
* Defaults to 30 seconds
*/
MEDIUM(TimeValue.timeValueSeconds(30)),
/**
* Defaults to 60 seconds
*/
LOW(TimeValue.timeValueSeconds(60));
final TimeValue interval;
Frequency(TimeValue interval) {
this.interval = interval;
}
}
public static final Setting ENABLED = Setting.boolSetting("resource.reload.enabled", true, Property.NodeScope);
public static final Setting RELOAD_INTERVAL_HIGH = Setting.timeSetting(
"resource.reload.interval.high",
Frequency.HIGH.interval,
Property.NodeScope
);
public static final Setting RELOAD_INTERVAL_MEDIUM = Setting.timeSetting(
"resource.reload.interval.medium",
Setting.timeSetting("resource.reload.interval", Frequency.MEDIUM.interval),
Property.NodeScope
);
public static final Setting RELOAD_INTERVAL_LOW = Setting.timeSetting(
"resource.reload.interval.low",
Frequency.LOW.interval,
Property.NodeScope
);
private final boolean enabled;
final ResourceMonitor lowMonitor;
final ResourceMonitor mediumMonitor;
final ResourceMonitor highMonitor;
private final Cancellable lowFuture;
private final Cancellable mediumFuture;
private final Cancellable highFuture;
public ResourceWatcherService(Settings settings, ThreadPool threadPool) {
this.enabled = ENABLED.get(settings);
TimeValue interval = RELOAD_INTERVAL_LOW.get(settings);
lowMonitor = new ResourceMonitor(interval, Frequency.LOW);
interval = RELOAD_INTERVAL_MEDIUM.get(settings);
mediumMonitor = new ResourceMonitor(interval, Frequency.MEDIUM);
interval = RELOAD_INTERVAL_HIGH.get(settings);
highMonitor = new ResourceMonitor(interval, Frequency.HIGH);
if (enabled) {
lowFuture = threadPool.scheduleWithFixedDelay(lowMonitor, lowMonitor.interval, Names.SAME);
mediumFuture = threadPool.scheduleWithFixedDelay(mediumMonitor, mediumMonitor.interval, Names.SAME);
highFuture = threadPool.scheduleWithFixedDelay(highMonitor, highMonitor.interval, Names.SAME);
} else {
lowFuture = null;
mediumFuture = null;
highFuture = null;
}
}
@Override
public void close() {
if (enabled) {
lowFuture.cancel();
mediumFuture.cancel();
highFuture.cancel();
}
}
/**
* Register new resource watcher that will be checked in default {@link Frequency#MEDIUM MEDIUM} frequency
*/
public WatcherHandle add(W watcher) throws IOException {
return add(watcher, Frequency.MEDIUM);
}
/**
* Register new resource watcher that will be checked in the given frequency
*/
public WatcherHandle add(W watcher, Frequency frequency) throws IOException {
watcher.init();
return switch (frequency) {
case LOW -> lowMonitor.add(watcher);
case MEDIUM -> mediumMonitor.add(watcher);
case HIGH -> highMonitor.add(watcher);
};
}
public void notifyNow(Frequency frequency) {
switch (frequency) {
case LOW -> lowMonitor.run();
case MEDIUM -> mediumMonitor.run();
case HIGH -> highMonitor.run();
default -> throw new IllegalArgumentException("Unknown frequency [" + frequency + "]");
}
}
static class ResourceMonitor implements Runnable {
final TimeValue interval;
final Frequency frequency;
final Set watchers = new CopyOnWriteArraySet<>();
private ResourceMonitor(TimeValue interval, Frequency frequency) {
this.interval = interval;
this.frequency = frequency;
}
private WatcherHandle add(W watcher) {
watchers.add(watcher);
return new WatcherHandle<>(this, watcher);
}
@Override
public synchronized void run() {
for (ResourceWatcher watcher : watchers) {
try {
watcher.checkAndNotify();
} catch (IOException e) {
logger.trace("failed to check resource watcher", e);
}
}
}
}
}