opendaylight/blueprint/src/main/java/org/opendaylight/controller/blueprint/ext/StaticServiceReferenceRecipe.java

   1 /*
   2  * Copyright (c) 2016 Brocade Communications 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.blueprint.ext;
   9
  10 import com.google.common.base.Preconditions;
  11 import java.util.Collections;
  12 import java.util.function.Consumer;
  13 import org.apache.aries.blueprint.container.AbstractServiceReferenceRecipe;
  14 import org.apache.aries.blueprint.container.SatisfiableRecipe;
  15 import org.apache.aries.blueprint.services.ExtendedBlueprintContainer;
  16 import org.osgi.framework.ServiceReference;
  17 import org.osgi.service.blueprint.container.ComponentDefinitionException;
  18 import org.slf4j.Logger;
  19 import org.slf4j.LoggerFactory;
  20
  21 /**
  22  * A Blueprint bean recipe for a static OSGi service reference, meaning it obtains the service instance once
  23  * and doesn't react to service removal. In addition the returned object is the actual service instance and
  24  * not a proxy.
  25  *
  26  * @author Thomas Pantelis
  27  */
  28 class StaticServiceReferenceRecipe extends AbstractServiceReferenceRecipe {
  29     private static final Logger LOG = LoggerFactory.getLogger(StaticServiceReferenceRecipe.class);
  30
  31     private static final SatisfactionListener NOOP_LISTENER = new SatisfactionListener() {
  32         @Override
  33         public void notifySatisfaction(SatisfiableRecipe satisfiable) {
  34
  35         }
  36     };
  37
  38     private volatile ServiceReference<?> trackedServiceReference;
  39     private volatile Object trackedService;
  40     private Consumer<Object> serviceSatisfiedCallback;
  41
  42     StaticServiceReferenceRecipe(String name, ExtendedBlueprintContainer blueprintContainer,
  43             String interfaceClass) {
  44         super(name, blueprintContainer, new MandatoryServiceReferenceMetadata(name, interfaceClass), null, null,
  45                 Collections.emptyList());
  46     }
  47
  48     void startTracking(Consumer<Object> serviceSatisfiedCallback) {
  49         this.serviceSatisfiedCallback = serviceSatisfiedCallback;
  50         super.start(NOOP_LISTENER);
  51     }
  52
  53     @SuppressWarnings("rawtypes")
  54     @Override
  55     protected void track(ServiceReference reference) {
  56         retrack();
  57     }
  58
  59     @SuppressWarnings("rawtypes")
  60     @Override
  61     protected void untrack(ServiceReference reference) {
  62         LOG.debug("{}: In untrack {}", getName(), reference);
  63
  64         if(trackedServiceReference == reference) {
  65             LOG.debug("{}: Current reference has been untracked", getName(), trackedServiceReference);
  66         }
  67     }
  68
  69     @Override
  70     protected void retrack() {
  71         LOG.debug("{}: In retrack", getName());
  72
  73         if(trackedServiceReference == null) {
  74             trackedServiceReference = getBestServiceReference();
  75
  76             LOG.debug("{}: getBestServiceReference: {}", getName(), trackedServiceReference);
  77
  78             if(trackedServiceReference != null && serviceSatisfiedCallback != null) {
  79                 serviceSatisfiedCallback.accept(internalCreate());
  80             }
  81         }
  82     }
  83
  84     @Override
  85     protected void doStop() {
  86         LOG.debug("{}: In doStop", getName());
  87
  88         if(trackedServiceReference != null && trackedService != null) {
  89             try {
  90                 getBundleContextForServiceLookup().ungetService(trackedServiceReference);
  91             } catch(IllegalStateException e) {
  92                 // In case the service no longer exists, ignore.
  93             }
  94
  95             trackedServiceReference = null;
  96             trackedService = null;
  97         }
  98     }
  99
 100     @Override
 101     protected Object internalCreate() throws ComponentDefinitionException {
 102         ServiceReference<?> localTrackedServiceReference = trackedServiceReference;
 103
 104         LOG.debug("{}: In internalCreate: trackedServiceReference: {}", getName(), localTrackedServiceReference);
 105
 106         // being paranoid - internalCreate should only get called once
 107         if(trackedService != null) {
 108             return trackedService;
 109         }
 110
 111         Preconditions.checkNotNull(localTrackedServiceReference, "trackedServiceReference is null");
 112
 113         trackedService = getServiceSecurely(localTrackedServiceReference);
 114
 115         LOG.debug("{}: Returning service instance: {}", getName(), trackedService);
 116
 117         Preconditions.checkNotNull(trackedService, "getService() returned null for %s", localTrackedServiceReference);
 118
 119         return trackedService;
 120     }
 121 }