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