opendaylight/md-sal/samples/clustering-test-app/provider/src/main/java/org/opendaylight/controller/clustering/it/provider/impl/FlappingSingletonService.java

   1 /*
   2  * Copyright (c) 2017 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.clustering.it.provider.impl;
  10
  11 import com.google.common.util.concurrent.Futures;
  12 import com.google.common.util.concurrent.ListenableFuture;
  13 import java.util.concurrent.atomic.AtomicBoolean;
  14 import java.util.concurrent.atomic.AtomicLong;
  15 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonService;
  16 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonServiceProvider;
  17 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonServiceRegistration;
  18 import org.opendaylight.mdsal.singleton.common.api.ServiceGroupIdentifier;
  19 import org.slf4j.Logger;
  20 import org.slf4j.LoggerFactory;
  21
  22 public class FlappingSingletonService implements ClusterSingletonService {
  23
  24     private static final Logger LOG = LoggerFactory.getLogger(FlappingSingletonService.class);
  25
  26     private static final ServiceGroupIdentifier SERVICE_GROUP_IDENTIFIER =
  27             ServiceGroupIdentifier.create("flapping-singleton-service");
  28
  29     private final ClusterSingletonServiceProvider singletonServiceProvider;
  30     private final AtomicBoolean active = new AtomicBoolean(true);
  31
  32     private final AtomicLong flapCount = new AtomicLong();
  33     private volatile ClusterSingletonServiceRegistration registration;
  34
  35     public FlappingSingletonService(final ClusterSingletonServiceProvider singletonServiceProvider) {
  36         LOG.debug("Registering flapping-singleton-service.");
  37
  38         this.singletonServiceProvider = singletonServiceProvider;
  39         registration = singletonServiceProvider.registerClusterSingletonService(this);
  40     }
  41
  42     @Override
  43     @SuppressWarnings("checkstyle:IllegalCatch")
  44     public void instantiateServiceInstance() {
  45         LOG.debug("Instantiating flapping-singleton-service.");
  46         try {
  47             registration.close();
  48             registration = null;
  49         } catch (Exception e) {
  50             LOG.warn("There was a problem closing flapping singleton service.", e);
  51             setInactive();
  52
  53             final long count = flapCount.get();
  54             flapCount.compareAndSet(count, -count);
  55         }
  56     }
  57
  58     @Override
  59     @SuppressWarnings("checkstyle:IllegalCatch")
  60     public ListenableFuture<Void> closeServiceInstance() {
  61         LOG.debug("Closing flapping-singleton-service, flapCount: {}", flapCount);
  62
  63         flapCount.incrementAndGet();
  64         if (active.get()) {
  65             LOG.debug("Running re-registration");
  66             try {
  67                 registration = singletonServiceProvider.registerClusterSingletonService(this);
  68             } catch (RuntimeException e) {
  69                 LOG.warn("There was a problem re-registering flapping singleton service.", e);
  70                 setInactive();
  71
  72                 final long count = flapCount.get();
  73                 flapCount.compareAndSet(count, -count - 1);
  74             }
  75         }
  76
  77         return Futures.immediateFuture(null);
  78     }
  79
  80     @Override
  81     public ServiceGroupIdentifier getIdentifier() {
  82         return SERVICE_GROUP_IDENTIFIER;
  83     }
  84
  85     public long setInactive() {
  86         LOG.debug("Setting flapping-singleton-service to inactive, flap-count: {}", flapCount);
  87
  88         active.set(false);
  89         return flapCount.get();
  90     }
  91 }