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ZooDB Java JDO Object Database.
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/*
 * Copyright 2009-2013 Tilmann Zaeschke. All rights reserved.
 * 
 * This file is part of ZooDB.
 * 
 * ZooDB is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * ZooDB is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with ZooDB.  If not, see .
 * 
 * See the README and COPYING files for further information. 
 */
package org.zoodb.jdo.internal.server;


import org.zoodb.jdo.internal.ZooClassDef;
import org.zoodb.jdo.internal.server.DiskIO.DATA_TYPE;
import org.zoodb.jdo.internal.server.index.PagedOidIndex;
import org.zoodb.jdo.internal.server.index.PagedPosIndex;
import org.zoodb.jdo.internal.server.index.PagedUniqueLongLong.LLEntry;
import org.zoodb.jdo.internal.server.index.SchemaIndex;
import org.zoodb.jdo.internal.server.index.SchemaIndex.SchemaIndexEntry;

/**
 * This class serves as a mediator between the serializer and the file access class.
 * Compared to the StorageWrite, the ObjectWriter also provides the following:
 * - Updating the oid- and class-index with new object positions.
 * - Insert the page header (currently containing only the class-oid).
 * 
 * SV stands for 'server'.
 * 
 * @author Tilmann Zaeschke
 */
public class ObjectWriterSV implements ObjectWriter, CallbackPageWrite {

	private final StorageChannelOutput out;
    private final PagedOidIndex oidIndex;
    private SchemaIndexEntry schemaIndexEntry;
    private final SchemaIndex schemaIndex;
    private final ZooClassDef def;
	private PagedPosIndex posIndex = null;
	private int currentPage = -1;
	private long currentOffs = -1;
	private final long headerForWrite;
	
	public ObjectWriterSV(StorageChannel file, PagedOidIndex oidIndex,
            ZooClassDef def, SchemaIndex schemaIndex) {
        this.out = file.getWriter(true);
        this.oidIndex = oidIndex;
        out.setOverflowCallbackWrite(this);
        this.def = def;
        this.headerForWrite = def.getOid();
        this.schemaIndex = schemaIndex;
    }

    @Override
	public void startObject(long oid, int prevSchemaVersion) {
        if (posIndex == null) {
            if (schemaIndexEntry == null) {
                schemaIndexEntry = schemaIndex.getSchema(def); 
            }
            posIndex = schemaIndexEntry.getObjectIndexLatestSchemaVersion();
        }
        PagedPosIndex prevIndex = schemaIndexEntry.getObjectIndexVersion(prevSchemaVersion);
		currentPage = out.getPage();
		currentOffs = out.getOffset();

        //first remove possible previous position
        final LLEntry objPos = oidIndex.findOidGetLong(oid);
        if (objPos != null) {
	        long pos = objPos.getValue(); //long with 32=page + 32=offs
	        //prevPos.getValue() returns > 0, so the loop is performed at least once.
	        do {
	            //remove and report to FSM if applicable
                //TODO
                //In cache, use separate list for evolved objects to be written (Map