'generate a hash value for this match
This generates a hash code which might be useful, but without locking
the match object.'

def hash_code(self):

    h = self.wildcards
    for f in ofp_match_data:
        v = getattr(self, f)
        if (type(v) is int):
            h ^= v
        elif (type(v) is long):
            h ^= v
        else:
            h ^= hash(v)
    return int((h & 2147483647))
