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.ScheduledExecutorService;
  14 import java.util.concurrent.TimeUnit;
  15 import java.util.concurrent.atomic.AtomicBoolean;
  16 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonService;
  17 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonServiceProvider;
  18 import org.opendaylight.mdsal.singleton.common.api.ClusterSingletonServiceRegistration;
  19 import org.opendaylight.mdsal.singleton.common.api.ServiceGroupIdentifier;
  20 import org.slf4j.Logger;
  21 import org.slf4j.LoggerFactory;
  22
  23 public class FlappingSingletonService implements ClusterSingletonService {
  24
  25     private static final Logger LOG = LoggerFactory.getLogger(FlappingSingletonService.class);
  26
  27     private static final ServiceGroupIdentifier SERVICE_GROUP_IDENTIFIER =
  28             ServiceGroupIdentifier.create("flapping-singleton-service");
  29
  30     private static final ScheduledExecutorService EXECUTOR = FinalizableScheduledExecutorService.newSingleThread();
  31
  32     private final ClusterSingletonServiceProvider singletonServiceProvider;
  33     private final AtomicBoolean active = new AtomicBoolean(true);
  34
  35     private volatile long flapCount = 0;
  36     private volatile ClusterSingletonServiceRegistration registration;
  37
  38     public FlappingSingletonService(final ClusterSingletonServiceProvider singletonServiceProvider) {
  39         LOG.debug("Registering flapping-singleton-service.");
  40
  41         this.singletonServiceProvider = singletonServiceProvider;
  42         registration = singletonServiceProvider.registerClusterSingletonService(this);
  43     }
  44
  45     @Override
  46     public void instantiateServiceInstance() {
  47         LOG.debug("Instantiating flapping-singleton-service.");
  48
  49         // TODO direct registration/close seem to trigger a bug in singleton state transitions,
  50         // remove the whole executor shenanigans after it's fixed.
  51         EXECUTOR.submit(() -> {
  52             try {
  53                 registration.close();
  54                 registration = null;
  55             } catch (final Exception e) {
  56                 LOG.warn("There was a problem closing flapping singleton service.", e);
  57                 setInactive();
  58                 flapCount = -flapCount;
  59             }
  60         });
  61     }
  62
  63     @Override
  64     public ListenableFuture<Void> closeServiceInstance() {
  65         LOG.debug("Closing flapping-singleton-service, flapCount: {}", flapCount);
  66
  67         flapCount++;
  68         if (active.get()) {
  69             // TODO direct registration/close seem to trigger a bug in singleton state transitions,
  70             // remove  whole executor shenanigans after it's fixed.
  71             // Needs to be delayed slightly otherwise it's triggered as well.
  72             EXECUTOR.schedule(() -> {
  73                 LOG.debug("Running re-registration");
  74                 try {
  75                     registration = singletonServiceProvider.registerClusterSingletonService(this);
  76                 } catch (final Exception e) {
  77                     LOG.warn("There was a problem re-registering flapping singleton service.", e);
  78                     setInactive();
  79                     flapCount = -flapCount - 1;
  80                 }
  81
  82             }, 200, TimeUnit.MILLISECONDS);
  83         }
  84
  85         return Futures.immediateFuture(null);
  86     }
  87
  88     @Override
  89     public ServiceGroupIdentifier getIdentifier() {
  90         return SERVICE_GROUP_IDENTIFIER;
  91     }
  92
  93     public long setInactive() {
  94         LOG.debug("Setting flapping-singleton-service to inactive, flap-count: {}", flapCount);
  95
  96         active.set(false);
  97         return flapCount;
  98     }
  99 }