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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.documentapi.messagebus.protocol;
import com.yahoo.jrt.slobrok.api.Mirror;
import java.util.List;
import java.util.Random;
/**
* Will pick 2 random candidates and select the one with the least pending operations.
*
* @author baldersheim
*/
class AdaptiveLoadBalancer extends LoadBalancer {
private final Random random;
AdaptiveLoadBalancer(String cluster) {
this(cluster, new Random());
}
AdaptiveLoadBalancer(String cluster, Random random) {
super(cluster);
this.random = random;
}
@Override
Node getRecipient(List<Mirror.Entry> choices) {
if (choices.isEmpty()) return null;
Mirror.Entry entry;
NodeMetrics metrics;
if (choices.size() == 1) {
entry = choices.get(0);
metrics = getNodeMetrics(entry);
} else {
int candA = random.nextInt(choices.size());
int candB = random.nextInt(choices.size());
while (candB == candA) {
candB = random.nextInt(choices.size());
}
entry = choices.get(candA);
Mirror.Entry entryB = choices.get(candB);
metrics = getNodeMetrics(entry);
NodeMetrics metricsB = getNodeMetrics(entryB);
if (metrics.pending() > metricsB.pending()) {
entry = entryB;
metrics = metricsB;
}
}
metrics.incSend();
return new Node(entry, metrics);
}
@Override
void received(Node node, boolean busy) {
node.metrics.incReceived();
if (busy) {
node.metrics.incBusy();
}
}
}
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