2 * Copyright (c) 2015 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.controller.cluster.entityownership.selectionstrategy;
10 import static com.google.common.base.Preconditions.checkArgument;
11 import static java.util.Objects.requireNonNullElse;
13 import com.google.common.annotations.VisibleForTesting;
14 import com.google.common.base.Strings;
15 import java.util.Collection;
16 import java.util.HashMap;
20 * The LeastLoadedCandidateSelectionStrategy assigns ownership for an entity to the candidate which owns the least
23 public class LeastLoadedCandidateSelectionStrategy extends AbstractEntityOwnerSelectionStrategy {
24 private final Map<String, Long> localStatistics = new HashMap<>();
26 protected LeastLoadedCandidateSelectionStrategy(final long selectionDelayInMillis,
27 final Map<String, Long> initialStatistics) {
28 super(selectionDelayInMillis, initialStatistics);
30 localStatistics.putAll(initialStatistics);
34 public String newOwner(final String currentOwner, final Collection<String> viableCandidates) {
35 checkArgument(viableCandidates.size() > 0);
36 String leastLoadedCandidate = null;
37 long leastLoadedCount = Long.MAX_VALUE;
39 if (!Strings.isNullOrEmpty(currentOwner)) {
40 long localVal = requireNonNullElse(localStatistics.get(currentOwner), 0L);
41 localStatistics.put(currentOwner, localVal - 1);
44 for (String candidateName : viableCandidates) {
45 long val = requireNonNullElse(localStatistics.get(candidateName), 0L);
46 if (val < leastLoadedCount) {
47 leastLoadedCount = val;
48 leastLoadedCandidate = candidateName;
52 if (leastLoadedCandidate == null) {
53 leastLoadedCandidate = viableCandidates.iterator().next();
56 localStatistics.put(leastLoadedCandidate, leastLoadedCount + 1);
57 return leastLoadedCandidate;
61 Map<String, Long> getLocalStatistics() {
62 return localStatistics;