to_primitive imposes what seems to be an arbitary data structure

depth of 3, but there is at least on case in Nova (Security
group Rules) which requires a depth beyond this.

https://bugs.launchpad.net/nova/+bug/1118608

Specifically security_group_rule_get_by_security_group
returns a set of rules which have the structure:

rule -> grantee_group -> Instance -> Instance_type

Rather than just bumping the depth limit, which might break some
other user of to_primitive we make it a specific parameter that
defaults to the current value but can be over-ridden when
required and log a warning when the depth is exceeded

Change-Id: I1eaebd484e20cb2eae09a693289709973de9943c

2 files changed, 36 insertions, 3 deletions

diff --git a/openstack/common/jsonutils.py b/openstack/common/jsonutils.py
index b7f6bcd..1ea7755 100644
--- a/openstack/common/jsonutils.py
+++ b/openstack/common/jsonutils.py
@@ -38,13 +38,17 @@ import functools
 import inspect
 import itertools
 import json
+import logging
 import xmlrpclib
 
+from openstack.common.gettextutils import _
 from openstack.common import timeutils
 
+LOG = logging.getLogger(__name__)
+
 
 def to_primitive(value, convert_instances=False, convert_datetime=True,
-                 level=0):
+                 level=0, max_depth=3):
     """Convert a complex object into primitives.
 
     Handy for JSON serialization. We can optionally handle instances,
@@ -80,7 +84,9 @@ def to_primitive(value, convert_instances=False, convert_datetime=True,
     if getattr(value, '__module__', None) == 'mox':
         return 'mock'
 
-    if level > 3:
+    if level > max_depth:
+        LOG.error(_('Max serialization depth exceeded on object: %d %s'),
+                  level, value)
         return '?'
 
     # The try block may not be necessary after the class check above,
@@ -89,7 +95,8 @@ def to_primitive(value, convert_instances=False, convert_datetime=True,
         recursive = functools.partial(to_primitive,
                                       convert_instances=convert_instances,
                                       convert_datetime=convert_datetime,
-                                      level=level)
+                                      level=level,
+                                      max_depth=max_depth)
         # It's not clear why xmlrpclib created their own DateTime type, but
         # for our purposes, make it a datetime type which is explicitly
         # handled
diff --git a/tests/unit/test_jsonutils.py b/tests/unit/test_jsonutils.py
index 87ac367..276ae97 100644
--- a/tests/unit/test_jsonutils.py
+++ b/tests/unit/test_jsonutils.py
@@ -143,3 +143,29 @@ class ToPrimitiveTestCase(utils.BaseTestCase):
         self.assertTrue(ret[0].startswith(u"<module 'datetime' from "))
         self.assertTrue(ret[1].startswith('<function foo at 0x'))
         self.assertEquals(ret[2], '<built-in function dir>')
+
+    def test_depth(self):
+        class LevelsGenerator(object):
+            def __init__(self, levels):
+                self._levels = levels
+
+            def iteritems(self):
+                if self._levels == 0:
+                    return iter([])
+                else:
+                    return iter([(0, LevelsGenerator(self._levels - 1))])
+
+        l4_obj = LevelsGenerator(4)
+
+        json_l2 = {0: {0: '?'}}
+        json_l3 = {0: {0: {0: '?'}}}
+        json_l4 = {0: {0: {0: {0: '?'}}}}
+
+        ret = jsonutils.to_primitive(l4_obj, max_depth=2)
+        self.assertEquals(ret, json_l2)
+
+        ret = jsonutils.to_primitive(l4_obj, max_depth=3)
+        self.assertEquals(ret, json_l3)
+
+        ret = jsonutils.to_primitive(l4_obj, max_depth=4)
+        self.assertEquals(ret, json_l4)