@Override
public void join(Record rec1, Record rec2, Collector<Record> out) throws Exception {
// rec1 has matching start, rec2 matching end
// Therefore, rec2's end node and rec1's start node are identical
// First half of new path will be rec2, second half will be rec1
// Get from-node and to-node of new path
final StringValue fromNode = rec2.getField(0, StringValue.class);
final StringValue toNode = rec1.getField(1, StringValue.class);
// Check whether from-node = to-node to prevent circles!
if (fromNode.equals(toNode)) {
return;
}
// Create new path
outputRecord.setField(0, fromNode);
outputRecord.setField(1, toNode);
// Compute length of new path
length.setValue(
rec1.getField(2, IntValue.class).getValue()
+ rec2.getField(2, IntValue.class).getValue());
outputRecord.setField(2, length);
// compute hop count
int hops =
rec1.getField(3, IntValue.class).getValue()
+ 1
+ rec2.getField(3, IntValue.class).getValue();
hopCnt.setValue(hops);
outputRecord.setField(3, hopCnt);
// Concatenate hops lists and insert matching node
StringBuilder sb = new StringBuilder();
// first path
sb.append(rec2.getField(4, StringValue.class).getValue());
sb.append(" ");
// common node
sb.append(rec1.getField(0, StringValue.class).getValue());
// second path
sb.append(" ");
sb.append(rec1.getField(4, StringValue.class).getValue());
hopList.setValue(sb.toString().trim());
outputRecord.setField(4, hopList);
out.collect(outputRecord);
}
