OuterJoinState.java

package storm.cookbook.tfidf.functions;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;

import storm.trident.tuple.TridentTuple;
import backtype.storm.tuple.Values;

public class OuterJoinState {

	// 2 columns, based on streamId. Each column contains the tuples from the
	// given stream
	private HashMap<Integer, List<Object[]>> bothSides = new HashMap<Integer, List<Object[]>>();

	public void addValues(int streamId, TridentTuple input) {
		if (!bothSides.keySet().contains(streamId)) {
			if (bothSides.keySet().size() >= 2)
				throw new IllegalArgumentException("Outer join can only be performed between 2 streams");
			bothSides.put(streamId, new ArrayList<Object[]>());
		}
		bothSides.get(streamId).add(input.toArray());
	}

	// the shorter side is the LHS
	private int getLHS() {
		int len = Integer.MAX_VALUE;
		int index = 0;
		for (int id : bothSides.keySet()) {
			if (bothSides.get(id).size() < len) {
				len = bothSides.get(id).size();
				index = id;
			}
		}
		return index;
	}

	private int getRhs(int lhs) {
		for (int test : bothSides.keySet()) {
			if (test != lhs)
				return test;
		}
		throw new IllegalArgumentException("Can't find RHS!");
	}

	public List<Values> join() {
		List<Values> ret = new ArrayList<Values>();
		try {
			int lhsId = getLHS();
			int rhsId = getRhs(lhsId);
			for (Object[] lhs : bothSides.get(lhsId)) {
				for (Object[] rhs : bothSides.get(rhsId)) {
					Values vals = new Values(lhs);
					vals.addAll(Arrays.asList(rhs));
					ret.add(vals);
				}
			}
		} catch (Exception e) {
		}
		return ret;
	}

}