Using python retrying module

Change-Id: I863e064b0802d38038d83fdcf943fd82af5f4422
Signed-off-by: Roey Chen <roeyc@vmware.com>

requirements.txt

@@ -6,6 +6,7 @@ pbr>=0.6,!=0.7,<1.0
 eventlet>=0.15.2
 httplib2>=0.7.5
 netaddr>=0.7.12
+retrying>=1.2.3,!=1.3.0 # Apache-2.0
 SQLAlchemy>=0.9.7,<=0.9.99
 six>=1.7.0
 stevedore>=1.1.0  # Apache-2.0

vmware_nsx/neutron/plugins/vmware/vshield/vcns.py

@@ -14,11 +14,9 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import functools
-import time
-
 from oslo.config import cfg
 from oslo.serialization import jsonutils
+import retrying
 import xml.etree.ElementTree as et
 
 from neutron.openstack.common import log as logging
@@ -60,22 +58,12 @@ DHCP_SERVICE = "dhcp/config"
 DHCP_BINDING_RESOURCE = "bindings"
 
 
-def retry_upon_exception(exception, delay=0.5, max_delay=2):
-    def retry_decorator(f):
-        @functools.wraps(f)
-        def retry_wrapper(*args, **kwargs):
-            retries = max(cfg.CONF.nsxv.retries, 1)
-            for attempt in range(1, retries + 1):
-                try:
-                    return f(*args, **kwargs)
-                except exception as e:
-                    if attempt == retries:
-                        LOG.info("NSXv: API called failed")
-                        raise e
-                    tts = (2 ** (attempt - 1)) * delay
-                    time.sleep(min(tts, max_delay))
-        return retry_wrapper
-    return retry_decorator
+def retry_upon_exception(exc, delay=500, max_delay=2000,
+                         max_attempts=cfg.CONF.nsxv.retries):
+    return retrying.retry(retry_on_exception=lambda e: isinstance(e, exc),
+                          wait_exponential_multiplier=delay,
+                          wait_exponential_max=max_delay,
+                          stop_max_attempt_number=max_attempts)
 
 
 class Vcns(object):

vmware_nsx/neutron/tests/unit/vmware/test_nsx_misc.py

@@ -0,0 +1,53 @@
+# Copyright (c) 2014 VMware.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from neutron.tests import base
+
+from vmware_nsx.neutron.plugins.vmware.vshield.common import exceptions
+from vmware_nsx.neutron.plugins.vmware.vshield import vcns
+
+
+def raise_until_attempt(attempt, exception):
+    def raises_until():
+        if raises_until.current_attempt < attempt:
+            raises_until.current_attempt += 1
+            raise exception
+        else:
+            return raises_until.current_attempt
+    raises_until.current_attempt = 1
+    return raises_until
+
+
+class TestMisc(base.BaseTestCase):
+    def test_retry_on_exception_one_attempt(self):
+        success_on_first_attempt = raise_until_attempt(
+            1, exceptions.RequestBad(uri='', response=''))
+        should_return_one = vcns.retry_upon_exception(
+            exceptions.RequestBad, max_attempts=1)(success_on_first_attempt)
+        self.assertEqual(1, should_return_one())
+
+    def test_retry_on_exception_five_attempts(self):
+        success_on_fifth_attempt = raise_until_attempt(
+            5, exceptions.RequestBad(uri='', response=''))
+        should_return_five = vcns.retry_upon_exception(
+            exceptions.RequestBad, max_attempts=10)(success_on_fifth_attempt)
+        self.assertEqual(5, should_return_five())
+
+    def test_retry_on_exception_exceed_attempts(self):
+        success_on_fifth_attempt = raise_until_attempt(
+            5, exceptions.RequestBad(uri='', response=''))
+        should_raise = vcns.retry_upon_exception(
+            exceptions.RequestBad, max_attempts=4)(success_on_fifth_attempt)
+        self.assertRaises(exceptions.RequestBad, should_raise)