001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.activemq.kaha.impl.data;
018
019import java.io.IOException;
020import java.io.RandomAccessFile;
021import org.apache.activemq.kaha.Marshaller;
022import org.apache.activemq.kaha.StoreLocation;
023import org.apache.activemq.util.DataByteArrayInputStream;
024
025/**
026 * Optimized Store reader
027 * 
028 * 
029 */
030public final class SyncDataFileReader {
031
032    private DataManagerImpl dataManager;
033    private DataByteArrayInputStream dataIn;
034
035    /**
036     * Construct a Store reader
037     * 
038     * @param fileId
039     */
040    SyncDataFileReader(DataManagerImpl fileManager) {
041        this.dataManager = fileManager;
042        this.dataIn = new DataByteArrayInputStream();
043    }
044
045    /*
046     * (non-Javadoc)
047     * 
048     * @see org.apache.activemq.kaha.impl.data.DataFileReader#readDataItemSize(org.apache.activemq.kaha.impl.data.DataItem)
049     */
050    public synchronized byte readDataItemSize(DataItem item) throws IOException {
051        RandomAccessFile file = dataManager.getDataFile(item).getRandomAccessFile();
052        file.seek(item.getOffset()); // jump to the size field
053        byte rc = file.readByte();
054        item.setSize(file.readInt());
055        return rc;
056    }
057
058    /*
059     * (non-Javadoc)
060     * 
061     * @see org.apache.activemq.kaha.impl.data.DataFileReader#readItem(org.apache.activemq.kaha.Marshaller,
062     *      org.apache.activemq.kaha.StoreLocation)
063     */
064    public synchronized Object readItem(Marshaller marshaller, StoreLocation item) throws IOException {
065        RandomAccessFile file = dataManager.getDataFile(item).getRandomAccessFile();
066
067        // TODO: we could reuse the buffer in dataIn if it's big enough to avoid
068        // allocating byte[] arrays on every readItem.
069        byte[] data = new byte[item.getSize()];
070        file.seek(item.getOffset() + DataManagerImpl.ITEM_HEAD_SIZE);
071        file.readFully(data);
072        dataIn.restart(data);
073        return marshaller.readPayload(dataIn);
074    }
075}