opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/entityownership/selectionstrategy/LeastLoadedCandidateSelectionStrategy.java

   1 /*
   2  * Copyright (c) 2015 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   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
   7  */
   8
   9 package org.opendaylight.controller.cluster.datastore.entityownership.selectionstrategy;
  10
  11 import java.util.Collection;
  12 import java.util.Map;
  13
  14 /**
  15  * The LeastLoadedCandidateSelectionStrategy assigns ownership for an entity to the candidate which owns the least
  16  * number of entities.
  17  */
  18 public class LeastLoadedCandidateSelectionStrategy extends AbstractEntityOwnerSelectionStrategy {
  19     protected LeastLoadedCandidateSelectionStrategy(long selectionDelayInMillis) {
  20         super(selectionDelayInMillis);
  21     }
  22
  23     @Override
  24     public String newOwner(Collection<String> viableCandidates, Map<String, Long> statistics) {
  25         String leastLoadedCandidate = null;
  26         long leastLoadedCount = Long.MAX_VALUE;
  27
  28         for(String candidateName : viableCandidates){
  29             Long val = statistics.get(candidateName);
  30             if(val != null && val < leastLoadedCount){
  31                 leastLoadedCount = val;
  32                 leastLoadedCandidate = candidateName;
  33             }
  34         }
  35
  36         if(leastLoadedCandidate == null){
  37             return viableCandidates.iterator().next();
  38         }
  39         return leastLoadedCandidate;
  40     }
  41 }