MultiFilePBEventStreamIterator.java

/*******************************************************************************
 * Copyright (c) 2011 The Board of Trustees of the Leland Stanford Junior University
 * as Operator of the SLAC National Accelerator Laboratory.
 * Copyright (c) 2011 Brookhaven National Laboratory.
 * EPICS archiver appliance is distributed subject to a Software License Agreement found
 * in file LICENSE that is included with this distribution.
 *******************************************************************************/
package edu.stanford.slac.archiverappliance.PlainPB;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.util.Iterator;

import org.apache.log4j.Logger;
import org.epics.archiverappliance.ByteArray;
import org.epics.archiverappliance.Event;
import org.epics.archiverappliance.config.ArchDBRTypes;
import org.epics.archiverappliance.data.DBRTimeEvent;

import edu.stanford.slac.archiverappliance.PB.data.DBR2PBTypeMapping;
import edu.stanford.slac.archiverappliance.PB.utils.LineByteStream;

/**
 * The iterator for MultiFilePBEventStream's
 * All we do is go thru the streams in sequence and then return the events one after the other.
 * @author mshankar
 *
 */
public class MultiFilePBEventStreamIterator implements Iterator<Event> {
	private static Logger logger = Logger.getLogger(MultiFilePBEventStreamIterator.class.getName());
	private short year = 0;
	private ArchDBRTypes type;
	private DBR2PBTypeMapping mapping;
	private Constructor<? extends DBRTimeEvent> unmarshallingConstructor;
	private LineByteStreamCreator istreams[];
	private int currentStreamIndex = 0;
	private LineByteStream currentLis;
	private byte[] nextLine = null;

	public MultiFilePBEventStreamIterator(LineByteStreamCreator istreams[], String pvName, short year, ArchDBRTypes type) throws IOException {
		this.istreams = istreams;
		this.type = type;
		this.year = year;
		mapping = DBR2PBTypeMapping.getPBClassFor(this.type);
		unmarshallingConstructor = mapping.getUnmarshallingFromByteArrayConstructor();
		currentLis = istreams[currentStreamIndex].getLineByteStream();
	}

	
	@Override
	public boolean hasNext() {
		try {
			nextLine = currentLis.readLine();
			if(nextLine != null) return true;
			while(true) {
				currentStreamIndex++;
				if(currentStreamIndex >= istreams.length) {
					logger.debug("All lis's are finished");
					return false;
				} else {
					if(currentLis != null) currentLis.safeClose();
					currentLis = istreams[currentStreamIndex].getLineByteStream();
					logger.debug("Switching to next lis " + currentLis.getAbsolutePath());
				}
				nextLine = currentLis.readLine();
				if(nextLine != null) return true;
			}
		} catch(Exception ex) {
			logger.error("Exception creating event object", ex);
		}
		return false;
	}


	@Override
	public Event next() {
		try {
			return (Event) unmarshallingConstructor.newInstance(year, new ByteArray(nextLine));
		} catch (Exception ex) {
			logger.error("Exception creating event object", ex);
			return null;
		}
	}


	@Override
	public void remove() {
		throw new UnsupportedOperationException();
	}

	public void close() {
	}

}