@Override
public void coGroup(Iterator<Record> inputRecords, Iterator<Record> concatRecords, Collector<Record> out) {
// init minimum length and minimum path
Record pathRec = null;
StringValue path = null;
if(inputRecords.hasNext()) {
// path is in input paths
pathRec = inputRecords.next();
} else {
// path must be in concat paths
pathRec = concatRecords.next();
}
// get from node (common for all paths)
StringValue fromNode = pathRec.getField(0, StringValue.class);
// get to node (common for all paths)
StringValue toNode = pathRec.getField(1, StringValue.class);
// get length of path
minLength.setValue(pathRec.getField(2, IntValue.class).getValue());
// store path and hop count
path = new StringValue(pathRec.getField(4, StringValue.class));
shortestPaths.add(path);
hopCnts.put(path, new IntValue(pathRec.getField(3, IntValue.class).getValue()));
// find shortest path of all input paths
while (inputRecords.hasNext()) {
pathRec = inputRecords.next();
IntValue length = pathRec.getField(2, IntValue.class);
if (length.getValue() == minLength.getValue()) {
// path has also minimum length add to list
path = new StringValue(pathRec.getField(4, StringValue.class));
if(shortestPaths.add(path)) {
hopCnts.put(path, new IntValue(pathRec.getField(3, IntValue.class).getValue()));
}
} else if (length.getValue() < minLength.getValue()) {
// path has minimum length
minLength.setValue(length.getValue());
// clear lists
hopCnts.clear();
shortestPaths.clear();
// get path and add path and hop count
path = new StringValue(pathRec.getField(4, StringValue.class));
shortestPaths.add(path);
hopCnts.put(path, new IntValue(pathRec.getField(3, IntValue.class).getValue()));
}
}
// find shortest path of all input and concatenated paths
while (concatRecords.hasNext()) {
pathRec = concatRecords.next();
IntValue length = pathRec.getField(2, IntValue.class);
if (length.getValue() == minLength.getValue()) {
// path has also minimum length add to list
path = new StringValue(pathRec.getField(4, StringValue.class));
if(shortestPaths.add(path)) {
hopCnts.put(path, new IntValue(pathRec.getField(3, IntValue.class).getValue()));
}
} else if (length.getValue() < minLength.getValue()) {
// path has minimum length
minLength.setValue(length.getValue());
// clear lists
hopCnts.clear();
shortestPaths.clear();
// get path and add path and hop count
path = new StringValue(pathRec.getField(4, StringValue.class));
shortestPaths.add(path);
hopCnts.put(path, new IntValue(pathRec.getField(3, IntValue.class).getValue()));
}
}
outputRecord.setField(0, fromNode);
outputRecord.setField(1, toNode);