deviceaccess/src/main/java/org/apache/felix/das/util/DriverLoader.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.felix.das.util;


import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Dictionary;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.felix.das.DriverAttributes;
import org.apache.felix.das.Log;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleException;
import org.osgi.framework.ServiceReference;
import org.osgi.service.device.Constants;
import org.osgi.service.device.DriverLocator;


/**
 * TODO: add javadoc
 * 
 * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a>
 */
public class DriverLoader
{

    private final BundleContext m_context;

    private final Log m_log;

    public final static String DRIVER_LOCATION_PREFIX = "_DD_";

    /**
     * to keep track of all loaded drivers
     */
    private final List<ServiceReference> m_loadedDrivers;


    public DriverLoader( Log log, BundleContext context )
    {
        m_log = log;
        m_context = context;
        m_loadedDrivers = new ArrayList<ServiceReference>();
    }


    @SuppressWarnings("all")
    public Set<String> findDrivers( Collection<DriverLocator> locators, Dictionary dict )
    {
        final Set<String> list = new HashSet<String>();
        for ( DriverLocator locator : locators )
        {
            list.addAll( findDrivers( locator, dict ) );
        }

        return list;
    }


    @SuppressWarnings("all")
    private List<String> findDrivers( DriverLocator locator, Dictionary dict )
    {
        final List<String> list = new ArrayList<String>();
        try
        {
            String[] ids = locator.findDrivers( dict );
            if ( ids != null )
            {
                list.addAll( Arrays.asList( ids ) );
            }
        }
        catch ( Exception e )
        {
            // ignore, will also frequently happen (?)
            // m_log.error("findDrivers failed for: " + locator, e);
        }

        return list;
    }


    /**
     * load all drivers that belong to the given driver Ids
     * 
     * @param locator
     * @param driverIds
     */
    public List<ServiceReference> loadDrivers( List<DriverLocator> locators, String[] driverIds )
    {
        List<ServiceReference> driverRefs = new ArrayList<ServiceReference>();

        for ( String driverId : driverIds )
        {
            driverRefs.addAll( loadDriver( locators, driverId ) );
        }

        return driverRefs;
    }


    private List<ServiceReference> loadDriver( List<DriverLocator> locators, String driverId )
    {
        List<ServiceReference> driverRefs = new ArrayList<ServiceReference>();

        for ( DriverLocator driverLocator : locators )
        {
            List<ServiceReference> drivers = loadDriver( driverLocator, driverId );
            driverRefs.addAll( drivers );
            if ( drivers.size() > 0 )
            {
                break;
            }
        }

        return driverRefs;
    }


    private List<ServiceReference> loadDriver( DriverLocator locator, String driverId )
    {
        List<ServiceReference> driverRefs = new ArrayList<ServiceReference>();
        try
        {
            InputStream in = locator.loadDriver( driverId );
            // System.out.println(driverId + ", " + locator + " returned: " +
            // in);
            Bundle driverBundle = m_context.installBundle( DRIVER_LOCATION_PREFIX + driverId, in );

            driverBundle.start();

            ServiceReference[] refs = driverBundle.getRegisteredServices();

            driverRefs.addAll( Arrays.asList( refs ) );
            // keep track of them locally
            m_loadedDrivers.addAll( Arrays.asList( refs ) );

        }
        catch ( Throwable t )
        {
            // ignore, this will happen frequently, if there are multiple
            // locators
        }
        return driverRefs;
    }


    public void unload( DriverAttributes finalDriver )
    {

        ServiceReference finalRef = null;
        if ( finalDriver != null )
        {
            finalRef = finalDriver.getReference();
            m_log.debug( "unloading all except: " + finalRef.getProperty( Constants.DRIVER_ID ) );
        }
        for ( ServiceReference ref : m_loadedDrivers )
        {
            if ( !ref.equals( finalRef ) )
            {
                try
                {
                    m_log.debug( "uninstalling: " + ref.getProperty( Constants.DRIVER_ID ) );
                    ref.getBundle().uninstall();
                }
                catch ( BundleException e )
                {
                    m_log.warning( "unable to uninstall: " + ref.getProperty( Constants.DRIVER_ID ) );
                }
            }
        }
    }
}