org.apache.activemq.artemis.core.server.balancing.policies.LeastConnectionsPolicy Maven / Gradle / Ivy
/**
* 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.activemq.artemis.core.server.balancing.policies;
import org.apache.activemq.artemis.core.server.balancing.targets.Target;
import org.apache.activemq.artemis.core.server.balancing.targets.TargetProbe;
import org.jboss.logging.Logger;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.NavigableMap;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;
public class LeastConnectionsPolicy extends RoundRobinPolicy {
private static final Logger logger = Logger.getLogger(LeastConnectionsPolicy.class);
public static final String NAME = "LEAST_CONNECTIONS";
public static final String UPDATE_CONNECTION_COUNT_PROBE_NAME = "UPDATE_CONNECTION_COUNT_PROBE";
public static final String CONNECTION_COUNT_THRESHOLD = "CONNECTION_COUNT_THRESHOLD";
private final Map connectionCountCache = new ConcurrentHashMap<>();
private int connectionCountThreshold = 0;
private final TargetProbe targetProbe = new TargetProbe(UPDATE_CONNECTION_COUNT_PROBE_NAME) {
@Override
public boolean check(Target target) {
try {
Integer connectionCount = target.getAttribute("broker", "ConnectionCount", Integer.class, 3000);
if (connectionCount < connectionCountThreshold) {
if (logger.isDebugEnabled()) {
logger.debug("Updating the connection count to 0/" + connectionCount + " for the target " + target);
}
connectionCount = 0;
} else if (logger.isDebugEnabled()) {
logger.debug("Updating the connection count to 0/" + connectionCount + " for the target " + target);
}
connectionCountCache.put(target, connectionCount);
return true;
} catch (Exception e) {
logger.warn("Error on updating the connectionCount for the target " + target, e);
return false;
}
}
};
@Override
public TargetProbe getTargetProbe() {
return targetProbe;
}
public LeastConnectionsPolicy() {
super(NAME);
}
@Override
public void init(Map properties) {
super.init(properties);
if (properties != null) {
if (properties.containsKey(CONNECTION_COUNT_THRESHOLD)) {
connectionCountThreshold = Integer.valueOf(properties.get(CONNECTION_COUNT_THRESHOLD));
}
}
}
@Override
public Target selectTarget(List targets, String key) {
if (targets.size() > 1) {
NavigableMap> sortedTargets = new TreeMap<>();
for (Target target : targets) {
Integer connectionCount = connectionCountCache.get(target);
if (connectionCount == null) {
connectionCount = Integer.MAX_VALUE;
}
List leastTargets = sortedTargets.get(connectionCount);
if (leastTargets == null) {
leastTargets = new ArrayList<>();
sortedTargets.put(connectionCount, leastTargets);
}
leastTargets.add(target);
}
if (logger.isDebugEnabled()) {
logger.debug("LeastConnectionsPolicy.sortedTargets: " + sortedTargets);
}
List selectedTargets = sortedTargets.firstEntry().getValue();
if (selectedTargets.size() > 1) {
return super.selectTarget(selectedTargets, key);
} else {
return selectedTargets.get(0);
}
} else if (targets.size() > 0) {
return targets.get(0);
}
return null;
}
}