org.apache.dubbo.rpc.cluster.loadbalance.RoundRobinLoadBalance 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.dubbo.rpc.cluster.loadbalance;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.common.utils.ConcurrentHashMapUtils;
import org.apache.dubbo.rpc.Invocation;
import org.apache.dubbo.rpc.Invoker;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicLong;
/**
* Round robin load balance.
*/
public class RoundRobinLoadBalance extends AbstractLoadBalance {
public static final String NAME = "roundrobin";
private static final int RECYCLE_PERIOD = 60000;
private final ConcurrentMap> methodWeightMap = new ConcurrentHashMap<>();
protected static class WeightedRoundRobin {
private int weight;
private final AtomicLong current = new AtomicLong(0);
private long lastUpdate;
public int getWeight() {
return weight;
}
public void setWeight(int weight) {
this.weight = weight;
current.set(0);
}
public long increaseCurrent() {
return current.addAndGet(weight);
}
public void sel(int total) {
current.addAndGet(-1 * total);
}
public long getLastUpdate() {
return lastUpdate;
}
public void setLastUpdate(long lastUpdate) {
this.lastUpdate = lastUpdate;
}
}
/**
* get invoker addr list cached for specified invocation
*
* for unit test only
*
* @param invokers
* @param invocation
* @return
*/
protected Collection getInvokerAddrList(List> invokers, Invocation invocation) {
String key = invokers.get(0).getUrl().getServiceKey() + "." + invocation.getMethodName();
Map map = methodWeightMap.get(key);
if (map != null) {
return map.keySet();
}
return null;
}
@Override
protected Invoker doSelect(List> invokers, URL url, Invocation invocation) {
String key = invokers.get(0).getUrl().getServiceKey() + "." + invocation.getMethodName();
ConcurrentMap map = ConcurrentHashMapUtils.computeIfAbsent(methodWeightMap, key, k -> new ConcurrentHashMap<>());
int totalWeight = 0;
long maxCurrent = Long.MIN_VALUE;
long now = System.currentTimeMillis();
Invoker selectedInvoker = null;
WeightedRoundRobin selectedWRR = null;
for (Invoker invoker : invokers) {
String identifyString = invoker.getUrl().toIdentityString();
int weight = getWeight(invoker, invocation);
WeightedRoundRobin weightedRoundRobin = ConcurrentHashMapUtils.computeIfAbsent(map, identifyString, k -> {
WeightedRoundRobin wrr = new WeightedRoundRobin();
wrr.setWeight(weight);
return wrr;
});
if (weight != weightedRoundRobin.getWeight()) {
//weight changed
weightedRoundRobin.setWeight(weight);
}
long cur = weightedRoundRobin.increaseCurrent();
weightedRoundRobin.setLastUpdate(now);
if (cur > maxCurrent) {
maxCurrent = cur;
selectedInvoker = invoker;
selectedWRR = weightedRoundRobin;
}
totalWeight += weight;
}
if (invokers.size() != map.size()) {
map.entrySet().removeIf(item -> now - item.getValue().getLastUpdate() > RECYCLE_PERIOD);
}
if (selectedInvoker != null) {
selectedWRR.sel(totalWeight);
return selectedInvoker;
}
// should not happen here
return invokers.get(0);
}
}