bdbstore/src/main/java/org/apache/qpid/server/store/berkeleydb/tuple/MessageMetaDataBinding.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.qpid.server.store.berkeleydb.tuple;

import com.sleepycat.bind.EntryBinding;
import com.sleepycat.je.DatabaseEntry;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.qpid.bytebuffer.QpidByteBuffer;
import org.apache.qpid.server.plugin.MessageMetaDataType;
import org.apache.qpid.server.store.MessageMetaDataTypeRegistry;
import org.apache.qpid.server.store.StorableMessageMetaData;

/**
 * Handles the mapping to and from message meta data
 */
public class MessageMetaDataBinding implements EntryBinding<StorableMessageMetaData>
{
    private static final Logger LOGGER = LoggerFactory.getLogger(MessageMetaDataBinding.class);

    private static final MessageMetaDataBinding INSTANCE = new MessageMetaDataBinding();

    public static MessageMetaDataBinding getInstance()
    {
        return INSTANCE;
    }

    /** private constructor forces getInstance instead */
    private MessageMetaDataBinding() { }

    @Override
    public StorableMessageMetaData entryToObject(DatabaseEntry entry)
    {
        QpidByteBuffer buf;
        if (entry.getSize() > QpidByteBuffer.getPooledBufferSize())
        {
            buf = QpidByteBuffer.wrap(entry.getData(), entry.getOffset(), entry.getSize());
        }
        else
        {
            buf = QpidByteBuffer.allocateDirect(entry.getSize());
            buf.put(entry.getData(), entry.getOffset(), entry.getSize());
            buf.flip();
        }
        final int bodySize = buf.getInt() ^ 0x80000000;
        final int metaDataType = buf.get() & 0xff;
        QpidByteBuffer slice = buf.slice();
        slice.limit(bodySize-1);
        MessageMetaDataType type = MessageMetaDataTypeRegistry.fromOrdinal(metaDataType);
        final StorableMessageMetaData metaData = type.createMetaData(slice);
        slice.dispose();
        buf.dispose();
        return metaData;
    }

    @Override
    public void objectToEntry(StorableMessageMetaData metaData, DatabaseEntry entry)
    {
        final int bodySize = 1 + metaData.getStorableSize();
        byte[] underlying = new byte[4+bodySize];
        underlying[4] = (byte) metaData.getType().ordinal();
        QpidByteBuffer buf = QpidByteBuffer.wrap(underlying);
        buf.putInt(bodySize ^ 0x80000000);
        buf.position(5);
        buf = buf.slice();

        metaData.writeToBuffer(buf);
        entry.setData(underlying);
    }
}