Package org.eclipse.osgi.framework.internal.core

Source Code of org.eclipse.osgi.framework.internal.core.CoreResolverHookFactory$CoreResolverHook

/*******************************************************************************
* Copyright (c) 2010, 2011 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
*     IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.osgi.framework.internal.core;

import java.util.*;
import org.eclipse.osgi.framework.debug.Debug;
import org.eclipse.osgi.internal.serviceregistry.*;
import org.eclipse.osgi.service.resolver.ResolverHookException;
import org.eclipse.osgi.util.NLS;
import org.osgi.framework.*;
import org.osgi.framework.hooks.resolver.ResolverHook;
import org.osgi.framework.hooks.resolver.ResolverHookFactory;
import org.osgi.framework.wiring.*;

/**
* This class encapsulates the delegation to ResolverHooks that are registered with the service
* registry.  This way the resolver implementation only has to call out to a single hook
* which does all the necessary service registry lookups.
*
* This class is not thread safe and expects external synchronization.
*
*/
public class CoreResolverHookFactory implements ResolverHookFactory {
  // need a tuple to hold the service reference and hook object
  // do not use a map for performance reasons; no need to hash based on a key.
  static class HookReference {
    public HookReference(ServiceReferenceImpl<ResolverHookFactory> reference, ResolverHook hook) {
      this.reference = reference;
      this.hook = hook;
    }

    final ServiceReferenceImpl<ResolverHookFactory> reference;
    final ResolverHook hook;
  }

  private final BundleContextImpl context;
  private final ServiceRegistry registry;

  public CoreResolverHookFactory(BundleContextImpl context, ServiceRegistry registry) {
    this.context = context;
    this.registry = registry;
  }

  void handleHookException(Throwable t, Object hook, String method, Bundle hookBundle, List<HookReference> hookRefs, boolean causeFailure) {
    if (Debug.DEBUG_HOOKS) {
      Debug.println(hook.getClass().getName() + "." + method + "() exception:"); //$NON-NLS-1$ //$NON-NLS-2$
      if (t != null)
        Debug.printStackTrace(t);
    }
    String message = NLS.bind(Msg.SERVICE_FACTORY_EXCEPTION, hook.getClass().getName(), method);
    if (causeFailure) {
      releaseHooks(hookRefs);
      throw new ResolverHookException(message, t);
    }
    BundleException be = new BundleException(message, BundleException.REJECTED_BY_HOOK, t);
    context.framework.publishFrameworkEvent(FrameworkEvent.ERROR, hookBundle, be);
  }

  private ServiceReferenceImpl<ResolverHookFactory>[] getHookReferences() {
    try {
      @SuppressWarnings("unchecked")
      ServiceReferenceImpl<ResolverHookFactory>[] result = (ServiceReferenceImpl<ResolverHookFactory>[]) registry.getServiceReferences(context, ResolverHookFactory.class.getName(), null, false, false);
      return result;
    } catch (InvalidSyntaxException e) {
      // cannot happen; no filter
      return null;
    }
  }

  public ResolverHook begin(Collection<BundleRevision> triggers) {
    if (Debug.DEBUG_HOOKS) {
      Debug.println("ResolverHook.begin"); //$NON-NLS-1$
    }
    ServiceReferenceImpl<ResolverHookFactory>[] refs = getHookReferences();
    @SuppressWarnings("unchecked")
    List<HookReference> hookRefs = refs == null ? Collections.EMPTY_LIST : new ArrayList<CoreResolverHookFactory.HookReference>(refs.length);
    if (refs != null)
      for (ServiceReferenceImpl<ResolverHookFactory> hookRef : refs) {
        ResolverHookFactory factory = context.getService(hookRef);
        if (factory != null) {
          try {
            ResolverHook hook = factory.begin(triggers);
            if (hook != null)
              hookRefs.add(new HookReference(hookRef, hook));
          } catch (Throwable t) {
            handleHookException(t, factory, "begin", hookRef.getBundle(), hookRefs, true); //$NON-NLS-1$
          }
        }
      }
    return new CoreResolverHook(hookRefs);
  }

  void releaseHooks(List<HookReference> hookRefs) {
    for (HookReference hookRef : hookRefs)
      context.ungetService(hookRef.reference);
    hookRefs.clear();
  }

  class CoreResolverHook implements ResolverHook {
    private final List<HookReference> hooks;

    CoreResolverHook(List<HookReference> hooks) {
      this.hooks = hooks;
    }

    public void filterResolvable(Collection<BundleRevision> candidates) {
      if (Debug.DEBUG_HOOKS) {
        Debug.println("ResolverHook.filterResolvable(" + candidates + ")"); //$NON-NLS-1$ //$NON-NLS-2$
      }
      if (hooks.isEmpty())
        return;
      candidates = new ShrinkableCollection<BundleRevision>(candidates);
      for (Iterator<HookReference> iHooks = hooks.iterator(); iHooks.hasNext();) {
        HookReference hookRef = iHooks.next();
        if (hookRef.reference.getBundle() == null) {
          handleHookException(null, hookRef.hook, "filterResolvable", hookRef.reference.getBundle(), hooks, true); //$NON-NLS-1$
        } else {
          try {
            hookRef.hook.filterResolvable(candidates);
          } catch (Throwable t) {
            handleHookException(t, hookRef.hook, "filterResolvable", hookRef.reference.getBundle(), hooks, true); //$NON-NLS-1$
          }
        }
      }
    }

    public void filterSingletonCollisions(BundleCapability singleton, Collection<BundleCapability> collisionCandidates) {
      if (Debug.DEBUG_HOOKS) {
        Debug.println("ResolverHook.filterSingletonCollisions(" + singleton + ", " + collisionCandidates + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
      }
      if (hooks.isEmpty())
        return;
      collisionCandidates = new ShrinkableCollection<BundleCapability>(collisionCandidates);
      for (Iterator<HookReference> iHooks = hooks.iterator(); iHooks.hasNext();) {
        HookReference hookRef = iHooks.next();
        if (hookRef.reference.getBundle() == null) {
          handleHookException(null, hookRef.hook, "filterSingletonCollisions", hookRef.reference.getBundle(), hooks, true); //$NON-NLS-1$
        } else {
          try {
            hookRef.hook.filterSingletonCollisions(singleton, collisionCandidates);
          } catch (Throwable t) {
            handleHookException(t, hookRef.hook, "filterSingletonCollisions", hookRef.reference.getBundle(), hooks, true); //$NON-NLS-1$
          }
        }
      }
    }

    public void filterMatches(BundleRequirement requirement, Collection<BundleCapability> candidates) {
      if (Debug.DEBUG_HOOKS) {
        Debug.println("ResolverHook.filterMatches(" + requirement + ", " + candidates + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
      }
      if (hooks.isEmpty())
        return;
      candidates = new ShrinkableCollection<BundleCapability>(candidates);
      for (Iterator<HookReference> iHooks = hooks.iterator(); iHooks.hasNext();) {
        HookReference hookRef = iHooks.next();
        if (hookRef.reference.getBundle() == null) {
          handleHookException(null, hookRef.hook, "filterMatches", hookRef.reference.getBundle(), hooks, true); //$NON-NLS-1$
        } else {
          try {
            hookRef.hook.filterMatches(requirement, candidates);
          } catch (Throwable t) {
            handleHookException(t, hookRef.hook, "filterMatches", hookRef.reference.getBundle(), hooks, true); //$NON-NLS-1$
          }
        }
      }
    }

    public void end() {
      if (Debug.DEBUG_HOOKS) {
        Debug.println("ResolverHook.end"); //$NON-NLS-1$
      }
      if (hooks.isEmpty())
        return;
      for (Iterator<HookReference> iHooks = hooks.iterator(); iHooks.hasNext();) {
        HookReference hookRef = iHooks.next();
        // We do not remove unregistered services here because we are going to remove of of them at the end
        if (hookRef.reference.getBundle() != null) {
          try {
            hookRef.hook.end();
          } catch (Throwable t) {
            handleHookException(t, hookRef.hook, "end", hookRef.reference.getBundle(), hooks, false); //$NON-NLS-1$
          }

        }
      }
      releaseHooks(hooks);
    }
  }
}
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