bundles/org.eclipse.equinox.region/src/org/eclipse/virgo/kernel/osgi/region/hook/RegionBundleFindHook.java

/*******************************************************************************
 * Copyright (c) 2011 VMware Inc.
 * 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:
 *   VMware Inc. - initial contribution
 *******************************************************************************/

package org.eclipse.virgo.kernel.osgi.region.hook;

import java.util.Collection;
import org.eclipse.virgo.kernel.osgi.region.*;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.hooks.bundle.FindHook;

/**
 * {@link RegionBundleFindHook} manages the visibility of bundles across regions according to the {@link RegionDigraph}.
 * <p />
 * 
 * <strong>Concurrent Semantics</strong><br />
 * Thread safe.
 */
public final class RegionBundleFindHook implements FindHook {

    private final RegionDigraph regionDigraph;

    private final long hookImplID;

    public RegionBundleFindHook(RegionDigraph regionDigraph, long hookImplID) {
        this.regionDigraph = regionDigraph;
        this.hookImplID = hookImplID;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void find(BundleContext context, Collection<Bundle> bundles) {
        long bundleID = context.getBundle().getBundleId();

        if (bundleID == 0 || bundleID == hookImplID) {
            // The system bundle and the hook impl bundle can see all bundles
            return;
        }

        Region finderRegion = getRegion(context);
        if (finderRegion == null) {
            bundles.clear();
            return;
        }

        Visitor visitor = new Visitor(bundles);
        finderRegion.visitSubgraph(visitor);
        Collection<Bundle> allowed = visitor.getAllowed();

        bundles.retainAll(allowed);
    }

    private class Visitor extends RegionDigraphVisitorBase<Bundle> {

        private Visitor(Collection<Bundle> candidates) {
            super(candidates);
        }

        /**
         * {@inheritDoc}
         */
        @Override
        protected boolean contains(Region region, Bundle candidate) {
            return region.contains(candidate);
        }

        /**
         * {@inheritDoc}
         */
        @Override
        protected boolean isAllowed(Bundle candidate, RegionFilter filter) {
            return filter.isAllowed(candidate);
        }

    }

    private Region getRegion(BundleContext context) {
        return this.regionDigraph.getRegion(context.getBundle());
    }
}