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