java/engine/org/apache/derby/impl/sql/catalog/DDColumnDependableFinder.java

/*

   Derby - Class org.apache.derby.impl.sql.catalog.DDColumnDependableFinder

   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.derby.impl.sql.catalog;

import org.apache.derby.catalog.UUID;
import org.apache.derby.catalog.Dependable;
import org.apache.derby.iapi.sql.dictionary.DataDictionary;
import org.apache.derby.iapi.sql.dictionary.TableDescriptor;
import org.apache.derby.iapi.error.StandardException;

import org.apache.derby.iapi.services.io.FormatableHashtable;
import org.apache.derby.iapi.services.io.FormatableBitSet;

import java.io.ObjectOutput;
import java.io.ObjectInput;
import java.io.IOException;

/**
 *	Class for implementation of DependableFinder in the core DataDictionary 
 *	for referenced columns in a table.
 *
 *
 */

public class DDColumnDependableFinder extends DDdependableFinder
{
	////////////////////////////////////////////////////////////////////////
	//
	//  STATE
	//
	////////////////////////////////////////////////////////////////////////

	// write least amount of data to disk, just the byte array, not even
	// a FormatableBitSet
	private byte[] columnBitMap;

    ////////////////////////////////////////////////////////////////////////
    //
    //  CONSTRUCTORS
    //
    ////////////////////////////////////////////////////////////////////////

	/**
	 * Constructor same as in parent.
	 */
	public  DDColumnDependableFinder(int formatId)
	{
		super(formatId);
	}

	/**
	 * Constructor given referenced column bit map byte array as in FormatableBitSet
	 */
    DDColumnDependableFinder(int formatId, byte[] columnBitMap)
	{
		super(formatId);
		this.columnBitMap = columnBitMap;
	}

    ////////////////////////////////////////////////////////////////////////
    //
    //  DDColumnDependable METHODS
    //
    ////////////////////////////////////////////////////////////////////////

	/**
	 * Find a dependable object, which is essentially a table descriptor with
	 * referencedColumnMap field set.
	 *
	 * @param	dd data dictionary
	 * @param	dependableObjectID dependable object ID (table UUID)
	 * @return	a dependable, a table descriptor with referencedColumnMap
	 *			field set
	 */
	Dependable findDependable(DataDictionary dd, UUID dependableObjectID)
		throws StandardException
	{
		TableDescriptor td = dd.getTableDescriptor(dependableObjectID);
		if (td != null)  // see beetle 4444
			td.setReferencedColumnMap(new FormatableBitSet(columnBitMap));
		return td;
	}

    //////////////////////////////////////////////////////////////////
    //
    //  FORMATABLE METHODS
    //
    //////////////////////////////////////////////////////////////////

	/**
	 * Read this object from a stream of stored objects.  Just read the
	 * byte array, besides what the parent does.
	 *
	 * @param in read this.
	 */
	public void readExternal( ObjectInput in )
			throws IOException, ClassNotFoundException
	{
		super.readExternal(in);
		FormatableHashtable fh = (FormatableHashtable)in.readObject();
		columnBitMap = (byte[])fh.get("columnBitMap");
	}

	/**
	 * Write this object to a stream of stored objects.  Just write the
	 * byte array, besides what the parent does.
	 *
	 * @param out write bytes here.
	 */
	public void writeExternal( ObjectOutput out )
			throws IOException
	{
		super.writeExternal(out);
		FormatableHashtable fh = new FormatableHashtable();
		fh.put("columnBitMap", columnBitMap);
		out.writeObject(fh);
	}
}