ThruNumberAndStringConversion.java

package org.epics.archiverappliance.etl.conversion;

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

import org.epics.archiverappliance.Event;
import org.epics.archiverappliance.EventStream;
import org.epics.archiverappliance.EventStreamDesc;
import org.epics.archiverappliance.config.ArchDBRTypes;
import org.epics.archiverappliance.data.DBRTimeEvent;
import org.epics.archiverappliance.data.SampleValue;
import org.epics.archiverappliance.etl.ConversionException;
import org.epics.archiverappliance.etl.ConversionFunction;
import org.epics.archiverappliance.retrieval.RemotableEventStreamDesc;
import org.epics.archiverappliance.retrieval.channelarchiver.HashMapEvent;

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

/**
 * Generic class for some standard type conversions. 
 * Not all type conversions are supported; some type conversions may be completely (or even worse, incompletely) inaccurate for your use case.
 * Only a few of these have been tested and even those only incompletely.
 * In most cases, you should roll your own conversion function and then apply using the ETLDest interface.
 * 
 * @author mshankar
 *
 */
public class ThruNumberAndStringConversion implements ConversionFunction {
	private ArchDBRTypes destDBRType;
	private Constructor<? extends DBRTimeEvent> serializingConstructor;

	public ThruNumberAndStringConversion(ArchDBRTypes destDBRType) { 
		this.destDBRType = destDBRType;
		this.serializingConstructor = DBR2PBTypeMapping.getPBClassFor(destDBRType).getSerializingConstructor();
	}

	@Override
	public EventStream convertStream(final EventStream srcEventStream) throws IOException {
		return new EventStream() {
			Iterator<Event> theIterator = srcEventStream.iterator();

			@Override
			public void close() throws IOException {
				theIterator = null;
				srcEventStream.close();
			}

			@Override
			public Iterator<Event> iterator() {
				return new Iterator<Event>() {

					@Override
					public boolean hasNext() {
						return theIterator.hasNext();
					}

					@Override
					public Event next() {
						try { 
							DBRTimeEvent event = (DBRTimeEvent) theIterator.next();
							HashMapEvent hashEvent = new HashMapEvent(destDBRType, event);
							hashEvent.setValue(HashMapEvent.VALUE_FIELD_NAME, convert2DestType(event.getSampleValue()));
							DBRTimeEvent retEvent = (DBRTimeEvent) serializingConstructor.newInstance(hashEvent);
							return retEvent;
						} catch(Exception ex) { 
							throw new ConversionException("Exception during conversion of pv " + srcEventStream.getDescription().getPvName(), ex);
						}
					}

					private String convert2DestType(SampleValue sampleValue) {
						switch(destDBRType) {
						case DBR_SCALAR_BYTE:
							return Byte.toString(sampleValue.getValue().byteValue());
						case DBR_SCALAR_DOUBLE:
							return Double.toString(sampleValue.getValue().doubleValue());
						case DBR_SCALAR_ENUM:
							return Short.toString(sampleValue.getValue().shortValue());
						case DBR_SCALAR_FLOAT:
							return Float.toString(sampleValue.getValue().floatValue());
						case DBR_SCALAR_INT:
							return Integer.toString(sampleValue.getValue().intValue());
						case DBR_SCALAR_SHORT:
							return Short.toString(sampleValue.getValue().shortValue());
						case DBR_SCALAR_STRING:
							return sampleValue.getStringValue(0);
						case DBR_V4_GENERIC_BYTES:
							throw new UnsupportedOperationException(); 
						case DBR_WAVEFORM_BYTE:
							throw new UnsupportedOperationException(); 
						case DBR_WAVEFORM_DOUBLE:
							throw new UnsupportedOperationException(); 
						case DBR_WAVEFORM_ENUM:
							throw new UnsupportedOperationException(); 
						case DBR_WAVEFORM_FLOAT:
							throw new UnsupportedOperationException(); 
						case DBR_WAVEFORM_INT:
							throw new UnsupportedOperationException(); 
						case DBR_WAVEFORM_SHORT:
							throw new UnsupportedOperationException(); 
						case DBR_WAVEFORM_STRING:
							throw new UnsupportedOperationException(); 
						default:
							throw new UnsupportedOperationException(); 
						}
					}

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

			@Override
			public EventStreamDesc getDescription() {
				return new RemotableEventStreamDesc(destDBRType,
						srcEventStream.getDescription().getPvName(),
						((RemotableEventStreamDesc)srcEventStream.getDescription()).getYear());
			}
		}; 
	}
}