Remove circular import to fix config generation

Patch https://review.openstack.org/278354 created a circular import when
added an "import cinder.db" line to cinder/api/common.py since
cinder/db/api.py imports cinder.api.common back, which breaks genconfig.

Change-Id: Ic60866822e74687101a3885f6000f89d901bb17a
Closes-Bug: #1556889

cinder/api/common.py

@@ -25,7 +25,7 @@ import webob
 
 from cinder.api.openstack import wsgi
 from cinder.api import xmlutil
-import cinder.db
+from cinder.common import constants
 from cinder import exception
 from cinder.i18n import _
 import cinder.policy
@@ -139,7 +139,7 @@ def _get_marker_param(params):
 def _get_offset_param(params):
     """Extract offset id from request's dictionary (defaults to 0) or fail."""
     offset = params.pop('offset', 0)
-    return utils.validate_integer(offset, 'offset', 0, cinder.db.MAX_INT)
+    return utils.validate_integer(offset, 'offset', 0, constants.DB_MAX_INT)
 
 
 def limited(items, request, max_limit=None):

cinder/common/constants.py

@@ -0,0 +1,18 @@
+# Copyright 2016 Red Hat, Inc.
+# All Rights Reserved.
+#
+#    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.
+
+
+# The maximum value a signed INT type may have
+DB_MAX_INT = 0x7FFFFFFF

cinder/db/api.py

@@ -41,6 +41,7 @@ from oslo_db import concurrency as db_concurrency
 from oslo_db import options as db_options
 
 from cinder.api import common
+from cinder.common import constants
 from cinder.i18n import _
 
 db_opts = [
@@ -69,7 +70,7 @@ _BACKEND_MAPPING = {'sqlalchemy': 'cinder.db.sqlalchemy.api'}
 IMPL = db_concurrency.TpoolDbapiWrapper(CONF, _BACKEND_MAPPING)
 
 # The maximum value a signed INT type may have
-MAX_INT = 0x7FFFFFFF
+MAX_INT = constants.DB_MAX_INT
 
 
 ###################