JoinReducer/JoinCombiner to allow full outer join about dumbo HOT 2 CLOSED

class OuterJoinReducer(JoinCombiner):
    def __call__(self, key, values):
        self.cleanup()
        if key.isprimary:
            self._key = key.body
            output = self.primary(key.body, values)
            if output:
                for k, v in output:
                    jk = copy(key)
                    jk.body = k
                    yield jk, v
        elif not self.secondary_blocked(key.body):
            for k, v in self.secondary(key.body, values):
                jk = copy(key)
                jk.body = k
                yield jk, v

    def cleanup(self):
        pass

class myJoinReducer(OuterJoinReducer):
    def cleanup(self):
        self.primary_data = "UNKNOWN"

    def primary(self, key, values):
        self.primary_data = values.next()

    def secondary(self, key, values):
        for v in values:
            yield key, ((primary_data, ) + v )