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 package org.opendaylight.controller.clustering.it.provider.impl;
   9
  10 import com.google.common.util.concurrent.Futures;
  11 import com.google.common.util.concurrent.ListenableFuture;
  12 import java.util.concurrent.atomic.AtomicBoolean;
  13 import java.util.concurrent.atomic.AtomicLong;
  14 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonService;
  15 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonServiceProvider;
  16 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonServiceRegistration;
  17 import org.opendaylight.mdsal.singleton.common.api.ServiceGroupIdentifier;
  18 import org.slf4j.Logger;
  19 import org.slf4j.LoggerFactory;
  20
  21 public final class FlappingSingletonService implements ClusterSingletonService {
  22     private static final Logger LOG = LoggerFactory.getLogger(FlappingSingletonService.class);
  23     private static final ServiceGroupIdentifier SERVICE_GROUP_IDENTIFIER =
  24             ServiceGroupIdentifier.create("flapping-singleton-service");
  25
  26     private final ClusterSingletonServiceProvider singletonServiceProvider;
  27     private final AtomicBoolean active = new AtomicBoolean(true);
  28
  29     private final AtomicLong flapCount = new AtomicLong();
  30     private volatile ClusterSingletonServiceRegistration registration;
  31
  32     public FlappingSingletonService(final ClusterSingletonServiceProvider singletonServiceProvider) {
  33         LOG.debug("Registering flapping-singleton-service.");
  34
  35         this.singletonServiceProvider = singletonServiceProvider;
  36         registration = singletonServiceProvider.registerClusterSingletonService(this);
  37     }
  38
  39     @Override
  40     @SuppressWarnings("checkstyle:IllegalCatch")
  41     public void instantiateServiceInstance() {
  42         LOG.debug("Instantiating flapping-singleton-service.");
  43         try {
  44             registration.close();
  45             registration = null;
  46         } catch (Exception e) {
  47             LOG.warn("There was a problem closing flapping singleton service.", e);
  48             setInactive();
  49
  50             final long count = flapCount.get();
  51             flapCount.compareAndSet(count, -count);
  52         }
  53     }
  54
  55     @Override
  56     @SuppressWarnings("checkstyle:IllegalCatch")
  57     public ListenableFuture<Void> closeServiceInstance() {
  58         LOG.debug("Closing flapping-singleton-service, flapCount: {}", flapCount);
  59
  60         flapCount.incrementAndGet();
  61         if (active.get()) {
  62             LOG.debug("Running re-registration");
  63             try {
  64                 registration = singletonServiceProvider.registerClusterSingletonService(this);
  65             } catch (RuntimeException e) {
  66                 LOG.warn("There was a problem re-registering flapping singleton service.", e);
  67                 setInactive();
  68
  69                 final long count = flapCount.get();
  70                 flapCount.compareAndSet(count, -count - 1);
  71             }
  72         }
  73
  74         return Futures.immediateFuture(null);
  75     }
  76
  77     @Override
  78     public ServiceGroupIdentifier getIdentifier() {
  79         return SERVICE_GROUP_IDENTIFIER;
  80     }
  81
  82     public long setInactive() {
  83         LOG.debug("Setting flapping-singleton-service to inactive, flap-count: {}", flapCount);
  84
  85         active.set(false);
  86         return flapCount.get();
  87     }
  88 }