package mil.nga.giat.geowave.accumulo.util;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map.Entry;
import mil.nga.giat.geowave.accumulo.AccumuloOperations;
import mil.nga.giat.geowave.accumulo.Writer;
import org.apache.accumulo.core.client.ScannerBase;
import org.apache.accumulo.core.data.Key;
import org.apache.accumulo.core.data.Mutation;
import org.apache.accumulo.core.data.Value;
import org.apache.commons.lang3.tuple.Pair;
import org.apache.log4j.Logger;
/**
* Unlike the transform iterator, this transform works on the client side deleting to original cell and adding a new cell.
* The transformation is carried out by a {@link Transformer}.
*
*/
public class TransformerWriter
{
private final static Logger LOGGER = Logger.getLogger(TransformerWriter.class);
private final ScannerBase scanner;
private final String tableName;
private final AccumuloOperations accumuloOperations;
private final Transformer transformer;
public TransformerWriter(
final ScannerBase scanner,
final String tableName,
final AccumuloOperations accumuloOperations,
final Transformer transformer ) {
super();
this.scanner = scanner;
this.tableName = tableName;
this.accumuloOperations = accumuloOperations;
this.transformer = transformer;
}
public void transform() {
try {
final Iterator<Entry<Key, Value>> rawIt = scanner.iterator();
Writer writer = accumuloOperations.createWriter(tableName);
writer.write(new Iterable<Mutation>() {
@Override
public Iterator<Mutation> iterator() {
return new Iterator<Mutation>() {
LinkedList<Mutation> pendingOutput = new LinkedList<Mutation>();
@Override
public boolean hasNext() {
return !pendingOutput.isEmpty() || rawIt.hasNext();
}
@Override
public Mutation next() {
if (!pendingOutput.isEmpty()) {
return pendingOutput.removeFirst();
}
else if (rawIt.hasNext()) {
Entry<Key, Value> entry = rawIt.next();
Entry<Key, Value> newEntry = transformer.transform(Pair.of(entry.getKey(),entry.getValue()));
Mutation mutation = new Mutation(
entry.getKey().getRow());
mutation.putDelete(
entry.getKey().getColumnFamily(),
entry.getKey().getColumnQualifier(),
entry.getKey().getColumnVisibilityParsed(),
entry.getKey().getTimestamp());
pendingOutput.add(mutation);
mutation = new Mutation(
newEntry.getKey().getRow());
mutation.put(
newEntry.getKey().getColumnFamily(),
newEntry.getKey().getColumnQualifier(),
newEntry.getKey().getColumnVisibilityParsed(),
newEntry.getValue());
pendingOutput.add(mutation);
}
return pendingOutput.removeFirst();
}
@Override
public void remove() {
}
};
}
});
writer.close();
}
catch (Exception ex) {
LOGGER.error(
"Cannot perform transformation",
ex);
}
}
}