opendaylight/config/config-manager/src/main/java/org/opendaylight/controller/config/manager/impl/osgi/ExtensibleBundleTracker.java

   1 /*
   2  * Copyright (c) 2013 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 package org.opendaylight.controller.config.manager.impl.osgi;
   9
  10 import com.google.common.util.concurrent.ThreadFactoryBuilder;
  11 import java.util.concurrent.Callable;
  12 import java.util.concurrent.ExecutionException;
  13 import java.util.concurrent.ExecutorService;
  14 import java.util.concurrent.Executors;
  15 import java.util.concurrent.Future;
  16 import java.util.concurrent.ThreadFactory;
  17 import org.osgi.framework.Bundle;
  18 import org.osgi.framework.BundleContext;
  19 import org.osgi.framework.BundleEvent;
  20 import org.osgi.util.tracker.BundleTracker;
  21 import org.osgi.util.tracker.BundleTrackerCustomizer;
  22 import org.slf4j.Logger;
  23 import org.slf4j.LoggerFactory;
  24
  25
  26 /**
  27  *
  28  * Extensible bundle tracker. Takes several BundleTrackerCustomizers and
  29  * propagates bundle events to all of them.
  30  *
  31  * Primary customizer may return tracking object,
  32  * which will be passed to it during invocation of
  33  * {@link BundleTrackerCustomizer#removedBundle(Bundle, BundleEvent, Future)}
  34  *
  35  *
  36  * This extender modifies behaviour to not leak platform thread
  37  * in {@link BundleTrackerCustomizer#addingBundle(Bundle, BundleEvent)}
  38  * but deliver this event from its own single threaded executor.
  39  *
  40  * If bundle is removed before event for adding bundle was executed,
  41  * that event is cancelled. If addingBundle event is currently in progress
  42  * or was already executed, platform thread is block untill addingBundle
  43  * finishes so bundle could be removed correctly in platform thread.
  44  *
  45  *
  46  * Method {@link BundleTrackerCustomizer#removedBundle(Bundle, BundleEvent, Object)}
  47  * is never invoked on registered trackers.
  48  *
  49  * @param <T>
  50  */
  51 public final class ExtensibleBundleTracker<T> extends BundleTracker<Future<T>> {
  52
  53     private static final ThreadFactory THREAD_FACTORY = new ThreadFactoryBuilder()
  54         .setNameFormat("config-bundle-tracker-%d")
  55         .build();
  56     private final ExecutorService eventExecutor;
  57     private final BundleTrackerCustomizer<T> primaryTracker;
  58     private final BundleTrackerCustomizer<?>[] additionalTrackers;
  59
  60     private static final Logger LOG = LoggerFactory.getLogger(ExtensibleBundleTracker.class);
  61
  62     public ExtensibleBundleTracker(final BundleContext context, final BundleTrackerCustomizer<T> primaryBundleTrackerCustomizer,
  63                                    final BundleTrackerCustomizer<?>... additionalBundleTrackerCustomizers) {
  64         this(context, Bundle.ACTIVE, primaryBundleTrackerCustomizer, additionalBundleTrackerCustomizers);
  65     }
  66
  67     public ExtensibleBundleTracker(final BundleContext context, final int bundleState,
  68                                    final BundleTrackerCustomizer<T> primaryBundleTrackerCustomizer,
  69                                    final BundleTrackerCustomizer<?>... additionalBundleTrackerCustomizers) {
  70         super(context, bundleState, null);
  71         this.primaryTracker = primaryBundleTrackerCustomizer;
  72         this.additionalTrackers = additionalBundleTrackerCustomizers;
  73         eventExecutor = Executors.newSingleThreadExecutor(THREAD_FACTORY);
  74         LOG.trace("Registered as extender with context {} and bundle state {}", context, bundleState);
  75     }
  76
  77     @Override
  78     public Future<T> addingBundle(final Bundle bundle, final BundleEvent event) {
  79         LOG.trace("Submiting AddingBundle for bundle {} and event {} to be processed asynchronously",bundle,event);
  80         Future<T> future = eventExecutor.submit(new Callable<T>() {
  81             @Override
  82             public T call() throws Exception {
  83                 try {
  84                     T primaryTrackerRetVal = primaryTracker.addingBundle(bundle, event);
  85
  86                     forEachAdditionalBundle(new BundleStrategy() {
  87                         @Override
  88                         public void execute(final BundleTrackerCustomizer<?> tracker) {
  89                             tracker.addingBundle(bundle, event);
  90                         }
  91                     });
  92                     LOG.trace("AddingBundle for {} and event {} finished successfully",bundle,event);
  93                     return primaryTrackerRetVal;
  94                 } catch (Exception e) {
  95                     LOG.error("Failed to add bundle {}",e);
  96                     throw e;
  97                 }
  98             }
  99         });
 100         return future;
 101     }
 102
 103     @Override
 104     public void modifiedBundle(final Bundle bundle, final BundleEvent event, final Future<T> object) {
 105         // Intentionally NOOP
 106
 107     }
 108
 109     @Override
 110     public void removedBundle(final Bundle bundle, final BundleEvent event, final Future<T> object) {
 111         if(!object.isDone() && object.cancel(false)) {
 112             // We canceled adding event before it was processed
 113             // so it is safe to return
 114             LOG.trace("Adding Bundle event for {} was cancelled. No additional work required.",bundle);
 115             return;
 116         }
 117         try {
 118             LOG.trace("Invoking removedBundle event for {}",bundle);
 119             primaryTracker.removedBundle(bundle, event, object.get());
 120             forEachAdditionalBundle(new BundleStrategy() {
 121                 @Override
 122                 public void execute(final BundleTrackerCustomizer<?> tracker) {
 123                     tracker.removedBundle(bundle, event, null);
 124                 }
 125             });
 126             LOG.trace("Removed bundle event for {} finished successfully.",bundle);
 127         } catch (InterruptedException | ExecutionException e) {
 128             LOG.error("Addition of bundle failed, ", e);
 129         }
 130     }
 131
 132     private void forEachAdditionalBundle(final BundleStrategy lambda) {
 133         for (BundleTrackerCustomizer<?> trac : additionalTrackers) {
 134             lambda.execute(trac);
 135         }
 136     }
 137
 138     private static interface BundleStrategy {
 139         void execute(BundleTrackerCustomizer<?> tracker);
 140     }
 141
 142 }