block.java

lucene2.2.0版本

package org.apache.lucene.store.db;

/**
 * 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.
 */

import java.io.IOException;

import com.sleepycat.db.DatabaseEntry;
import com.sleepycat.db.internal.Db;
import com.sleepycat.db.internal.DbTxn;
import com.sleepycat.db.DatabaseException;

/**
 * @author Andi Vajda
 */

public class Block extends Object {
    protected DatabaseEntry key, data;

    protected Block(File file)
        throws IOException
    {
        byte[] fileKey = file.getKey();

        key = new DatabaseEntry(new byte[fileKey.length + 8]);
        key.setUserBuffer(fileKey.length + 8, true);

        data = new DatabaseEntry(new byte[DbIndexOutput.BLOCK_LEN]);
        data.setUserBuffer(data.getSize(), true);

        System.arraycopy(fileKey, 0, key.getData(), 0, fileKey.length);
        seek(0L);
    }

    protected byte[] getKey()
    {
        return key.getData();
    }

    protected byte[] getData()
    {
        return data.getData();
    }

    protected void seek(long position)
        throws IOException
    {
        byte[] data = key.getData();
        int index = data.length - 8;

        position >>>= DbIndexOutput.BLOCK_SHIFT;

        data[index + 0] = (byte) (0xff & (position >>> 56));
        data[index + 1] = (byte) (0xff & (position >>> 48));
        data[index + 2] = (byte) (0xff & (position >>> 40));
        data[index + 3] = (byte) (0xff & (position >>> 32));
        data[index + 4] = (byte) (0xff & (position >>> 24));
        data[index + 5] = (byte) (0xff & (position >>> 16));
        data[index + 6] = (byte) (0xff & (position >>>  8));
        data[index + 7] = (byte) (0xff & (position >>>  0));
    }

    protected void get(DbDirectory directory)
        throws IOException
    {
        try {
            directory.blocks.get(directory.txn, key, data, directory.flags);
        } catch (DatabaseException e) {
            throw new IOException(e.getMessage());
        }
    }

    protected void put(DbDirectory directory)
        throws IOException
    {
        try {
            directory.blocks.put(directory.txn, key, data, 0);
        } catch (DatabaseException e) {
            throw new IOException(e.getMessage());
        }
    }
}