Ensure ordered set is pickleable

Since the existing set and frozen sets
are pickleable so should this type so
that it functions and matches how the
the existing types work.

Change-Id: I6994b868ecbf0428ab4bc8ab5c2f4486ad53fb49

taskflow/tests/unit/test_types.py

@@ -18,6 +18,7 @@ import time
 
 import networkx as nx
 import six
+from six.moves import cPickle as pickle
 
 from taskflow import exceptions as excp
 from taskflow import test
@@ -498,6 +499,15 @@ class FSMTest(test.TestCase):
 
 class OrderedSetTest(test.TestCase):
 
+    def test_pickleable(self):
+        items = [10, 9, 8, 7]
+        s = sets.OrderedSet(items)
+        self.assertEqual(items, list(s))
+        s_bin = pickle.dumps(s)
+        s2 = pickle.loads(s_bin)
+        self.assertEqual(s, s2)
+        self.assertEqual(items, list(s2))
+
     def test_retain_ordering(self):
         items = [10, 9, 8, 7]
         s = sets.OrderedSet(iter(items))

taskflow/types/sets.py

@@ -66,6 +66,12 @@ class OrderedSet(collections.Set, collections.Hashable):
         for value in six.iterkeys(self._data):
             yield value
 
+    def __setstate__(self, items):
+        self.__init__(iterable=iter(items))
+
+    def __getstate__(self):
+        return tuple(self)
+
     def __repr__(self):
         return "%s(%s)" % (type(self).__name__, list(self))