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 java.util.concurrent.atomic.AtomicLong;
  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 static final ScheduledExecutorService EXECUTOR = FinalizableScheduledExecutorService.newSingleThread();
  32
  33     private final ClusterSingletonServiceProvider singletonServiceProvider;
  34     private final AtomicBoolean active = new AtomicBoolean(true);
  35
  36     private final AtomicLong flapCount = new AtomicLong();
  37     private volatile ClusterSingletonServiceRegistration registration;
  38
  39     public FlappingSingletonService(final ClusterSingletonServiceProvider singletonServiceProvider) {
  40         LOG.debug("Registering flapping-singleton-service.");
  41
  42         this.singletonServiceProvider = singletonServiceProvider;
  43         registration = singletonServiceProvider.registerClusterSingletonService(this);
  44     }
  45
  46     @Override
  47     @SuppressWarnings("checkstyle:IllegalCatch")
  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 (Exception e) {
  58                 LOG.warn("There was a problem closing flapping singleton service.", e);
  59                 setInactive();
  60
  61                 final long count = flapCount.get();
  62                 flapCount.compareAndSet(count, -count);
  63             }
  64         });
  65     }
  66
  67     @Override
  68     @SuppressWarnings("checkstyle:IllegalCatch")
  69     public ListenableFuture<Void> closeServiceInstance() {
  70         LOG.debug("Closing flapping-singleton-service, flapCount: {}", flapCount);
  71
  72         flapCount.incrementAndGet();
  73         if (active.get()) {
  74             // TODO direct registration/close seem to trigger a bug in singleton state transitions,
  75             // remove  whole executor shenanigans after it's fixed.
  76             // Needs to be delayed slightly otherwise it's triggered as well.
  77             EXECUTOR.schedule(() -> {
  78                 LOG.debug("Running re-registration");
  79                 try {
  80                     registration = singletonServiceProvider.registerClusterSingletonService(this);
  81                 } catch (RuntimeException e) {
  82                     LOG.warn("There was a problem re-registering flapping singleton service.", e);
  83                     setInactive();
  84
  85                     final long count = flapCount.get();
  86                     flapCount.compareAndSet(count, -count - 1);
  87                 }
  88
  89             }, 200, TimeUnit.MILLISECONDS);
  90         }
  91
  92         return Futures.immediateFuture(null);
  93     }
  94
  95     @Override
  96     public ServiceGroupIdentifier getIdentifier() {
  97         return SERVICE_GROUP_IDENTIFIER;
  98     }
  99
 100     public long setInactive() {
 101         LOG.debug("Setting flapping-singleton-service to inactive, flap-count: {}", flapCount);
 102
 103         active.set(false);
 104         return flapCount.get();
 105     }
 106 }