lightning-core/src/main/java/org/apache/directmemory/lightning/internal/util/InternalUtil.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.directmemory.lightning.internal.util;

import java.lang.reflect.Constructor;
import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import org.apache.directmemory.lightning.instantiator.ObjectInstantiator;
import org.apache.directmemory.lightning.internal.beans.PropertyAccessorFactory;
import org.apache.directmemory.lightning.logging.Logger;
import org.apache.directmemory.lightning.metadata.PropertyDescriptor;

public final class InternalUtil
{

    public static final Charset CHARSET = Charset.forName( "UTF-8" );

    public static final boolean UNSAFE_AVAILABLE;

    static
    {
        boolean unsafeAvailable = false;
        try
        {
            Class.forName( "sun.misc.Unsafe" );
            unsafeAvailable = true;
        }
        catch ( Exception e )
        {
            // Intentionally left blank
        }

        UNSAFE_AVAILABLE = unsafeAvailable;
    }

    private InternalUtil()
    {
    }

    public static byte[] getChecksum( byte[] data, Logger logger )
    {
        try
        {
            MessageDigest digest = MessageDigest.getInstance( "SHA-1" );
            digest.update( data, 0, data.length );
            return digest.digest();
        }
        catch ( Exception e )
        {
            throw new RuntimeException( "Could not build checksum of data" );
        }
    }

    public static byte[] getChecksum( Collection<PropertyDescriptor> propertyDescriptors, Logger logger )
    {
        final StringBuilder builder = new StringBuilder();

        // Clone and sort list of PropertyDescriptors
        List<PropertyDescriptor> temp = new ArrayList<PropertyDescriptor>( propertyDescriptors );
        Collections.sort( temp );

        for ( PropertyDescriptor propertyDescriptor : temp )
        {
            logger.trace( "Adding property " + propertyDescriptor.getName() + " to checksum" );
            builder.append( propertyDescriptor.getInternalSignature() );
        }

        return getChecksum( builder.toString().getBytes( CHARSET ), logger );
    }

    public static boolean isUnsafeAvailable()
    {
        return UNSAFE_AVAILABLE;
    }

    @SuppressWarnings( "unchecked" )
    public static ObjectInstantiator buildSunUnsafeInstantiator( Class<?> type )
    {
        try
        {
            Class<? extends ObjectInstantiator> clazz =
                (Class<? extends ObjectInstantiator>) ClassUtil.loadClass( "org.apache.directmemory.lightning.internal.instantiator.sun.SunUnsafeAllocateInstanceInstantiator" );

            Constructor<? extends ObjectInstantiator> constructor = clazz.getDeclaredConstructor( Class.class );
            return constructor.newInstance( type );
        }
        catch ( Exception e )
        {
            return null;
        }
    }

    @SuppressWarnings( "unchecked" )
    public static PropertyAccessorFactory buildSunUnsafePropertyAccessor()
    {
        try
        {
            Class<? extends PropertyAccessorFactory> clazz =
                (Class<? extends PropertyAccessorFactory>) ClassUtil.loadClass( "org.apache.directmemory.lightning.internal.beans.SunUnsafePropertyAccessorFactory" );

            Constructor<? extends PropertyAccessorFactory> constructor = clazz.getDeclaredConstructor();
            constructor.setAccessible( true );
            return constructor.newInstance();
        }
        catch ( Exception e )
        {
            return null;
        }
    }
}