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.Executors;
  14 import java.util.concurrent.ScheduledExecutorService;
  15 import java.util.concurrent.TimeUnit;
  16 import java.util.concurrent.atomic.AtomicBoolean;
  17 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonService;
  18 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonServiceProvider;
  19 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonServiceRegistration;
  20 import org.opendaylight.mdsal.singleton.common.api.ServiceGroupIdentifier;
  21 import org.slf4j.Logger;
  22 import org.slf4j.LoggerFactory;
  23
  24 public class FlappingSingletonService implements ClusterSingletonService {
  25
  26     private static final Logger LOG = LoggerFactory.getLogger(FlappingSingletonService.class);
  27
  28     private static final ServiceGroupIdentifier SERVICE_GROUP_IDENTIFIER =
  29             ServiceGroupIdentifier.create("flapping-singleton-service");
  30
  31     private final ClusterSingletonServiceProvider singletonServiceProvider;
  32
  33     private volatile long flapCount = 0;
  34     private AtomicBoolean active = new AtomicBoolean(true);
  35
  36     private volatile ClusterSingletonServiceRegistration registration;
  37
  38     private static ScheduledExecutorService EXECUTOR = Executors.newSingleThreadScheduledExecutor();
  39
  40     public FlappingSingletonService(final ClusterSingletonServiceProvider singletonServiceProvider) {
  41         LOG.debug("Registering flapping-singleton-service.");
  42
  43         this.singletonServiceProvider = singletonServiceProvider;
  44         registration = singletonServiceProvider.registerClusterSingletonService(this);
  45     }
  46
  47     @Override
  48     public void instantiateServiceInstance() {
  49         LOG.debug("Instantiating flapping-singleton-service.");
  50
  51         // TODO direct registration/close seem to trigger a bug in singleton state transitions,
  52         // remove the whole executor shenanigans after it's fixed.
  53         EXECUTOR.submit(() -> {
  54             try {
  55                 registration.close();
  56                 registration = null;
  57             } catch (final Exception e) {
  58                 LOG.warn("There was a problem closing flapping singleton service.", e);
  59                 flapCount = -flapCount;
  60             }
  61         });
  62     }
  63
  64     @Override
  65     public ListenableFuture<Void> closeServiceInstance() {
  66         LOG.debug("Closing flapping-singleton-service, flapCount: {}", flapCount);
  67
  68         flapCount++;
  69         if (active.get()) {
  70             // TODO direct registration/close seem to trigger a bug in singleton state transitions,
  71             // remove  whole executor shenanigans after it's fixed.
  72             // Needs to be delayed slightly otherwise it's triggered as well.
  73             EXECUTOR.schedule(() -> {
  74                 LOG.debug("Running registration");
  75                 registration =
  76                         singletonServiceProvider.registerClusterSingletonService(this);
  77
  78             }, 200, TimeUnit.MILLISECONDS);
  79         }
  80
  81         return Futures.immediateFuture(null);
  82     }
  83
  84     @Override
  85     public ServiceGroupIdentifier getIdentifier() {
  86         return SERVICE_GROUP_IDENTIFIER;
  87     }
  88
  89     public long setInactive() {
  90         LOG.debug("Setting flapping-singleton-service to inactive, flap-count: {}", flapCount);
  91
  92         active.set(false);
  93         return flapCount;
  94     }
  95 }