Update synchronized decorator

Changes coordination.synchronized decorator to preserve decorated
function signature.

Change-Id: I0ea24312ec32d844e232a443723b4f065f96efcb

cinder/coordination.py

@@ -20,6 +20,7 @@ import random
 import threading
 import uuid
 
+import decorator
 import eventlet
 from eventlet import tpool
 import itertools
@@ -275,13 +276,12 @@ def synchronized(lock_name, blocking=True, coordinator=None):
     Available field names are: decorated function parameters and
     `f_name` as a decorated function name.
     """
-    def wrap(f):
-        @six.wraps(f)
-        def wrapped(*a, **k):
-            call_args = inspect.getcallargs(f, *a, **k)
-            call_args['f_name'] = f.__name__
-            lock = Lock(lock_name, call_args, coordinator)
-            with lock(blocking):
-                return f(*a, **k)
-        return wrapped
-    return wrap
+
+    @decorator.decorator
+    def _synchronized(f, *a, **k):
+        call_args = inspect.getcallargs(f, *a, **k)
+        call_args['f_name'] = f.__name__
+        lock = Lock(lock_name, call_args, coordinator)
+        with lock(blocking):
+            return f(*a, **k)
+    return _synchronized

cinder/tests/unit/test_coordination.py

@@ -13,6 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import inspect
+
 import mock
 import tooz.coordination
 import tooz.locking
@@ -134,3 +136,4 @@ class CoordinationTestCase(test.TestCase):
         bar.__getitem__.return_value = 8
         func(foo, bar)
         get_lock.assert_called_with('lock-func-7-8')
+        self.assertEqual(['foo', 'bar'], inspect.getargspec(func)[0])