hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/tuples/SimpleTupleWriter.java

/*
 * Copyright 2009-2010 by The Regents of the University of California
 * Licensed 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 from
 * 
 *     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 edu.uci.ics.hyracks.storage.am.common.tuples;

import java.nio.ByteBuffer;

import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexTupleReference;
import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexTupleWriter;

public class SimpleTupleWriter implements ITreeIndexTupleWriter {

	@Override
	public int bytesRequired(ITupleReference tuple) {
		int bytes = getNullFlagsBytes(tuple) + getFieldSlotsBytes(tuple);
		for (int i = 0; i < tuple.getFieldCount(); i++) {
			bytes += tuple.getFieldLength(i);
		}
		return bytes;
	}

	@Override
	public int bytesRequired(ITupleReference tuple, int startField,
			int numFields) {
		int bytes = getNullFlagsBytes(tuple, startField, numFields)
				+ getFieldSlotsBytes(tuple, startField, numFields);
		for (int i = startField; i < startField + numFields; i++) {
			bytes += tuple.getFieldLength(i);
		}
		return bytes;
	}

	@Override
	public ITreeIndexTupleReference createTupleReference() {
		return new SimpleTupleReference();
	}

	@Override
	public int writeTuple(ITupleReference tuple, ByteBuffer targetBuf,
			int targetOff) {
		int runner = targetOff;
		int nullFlagsBytes = getNullFlagsBytes(tuple);
		int fieldSlotsBytes = getFieldSlotsBytes(tuple);
		for (int i = 0; i < nullFlagsBytes; i++) {
			targetBuf.put(runner++, (byte) 0);
		}
		runner += fieldSlotsBytes;

		int fieldEndOff = 0;
		for (int i = 0; i < tuple.getFieldCount(); i++) {
			System.arraycopy(tuple.getFieldData(i), tuple.getFieldStart(i),
					targetBuf.array(), runner, tuple.getFieldLength(i));
			fieldEndOff += tuple.getFieldLength(i);
			runner += tuple.getFieldLength(i);
			targetBuf.putShort(targetOff + nullFlagsBytes + i * 2,
					(short) fieldEndOff);
		}

		return runner - targetOff;
	}

	@Override
	public int writeTupleFields(ITupleReference tuple, int startField,
			int numFields, ByteBuffer targetBuf, int targetOff) {
		int runner = targetOff;
		int nullFlagsBytes = getNullFlagsBytes(tuple, startField, numFields);
		for (int i = 0; i < nullFlagsBytes; i++) {
			targetBuf.put(runner++, (byte) 0);
		}
		runner += getFieldSlotsBytes(tuple, startField, numFields);

		int fieldEndOff = 0;
		int fieldCounter = 0;
		for (int i = startField; i < startField + numFields; i++) {
			System.arraycopy(tuple.getFieldData(i), tuple.getFieldStart(i),
					targetBuf.array(), runner, tuple.getFieldLength(i));
			fieldEndOff += tuple.getFieldLength(i);
			runner += tuple.getFieldLength(i);
			targetBuf.putShort(targetOff + nullFlagsBytes + fieldCounter * 2,
					(short) fieldEndOff);
			fieldCounter++;
		}

		return runner - targetOff;
	}

	protected int getNullFlagsBytes(ITupleReference tuple) {
		return (int) Math.ceil((double) tuple.getFieldCount() / 8.0);
	}

	protected int getFieldSlotsBytes(ITupleReference tuple) {
		return tuple.getFieldCount() * 2;
	}

	protected int getNullFlagsBytes(ITupleReference tuple, int startField,
			int numFields) {
		return (int) Math.ceil((double) numFields / 8.0);
	}

	protected int getFieldSlotsBytes(ITupleReference tuple, int startField,
			int numFields) {
		return numFields * 2;
	}
}