Implement paginate query use marker in nova-api

1.add limit and marker param to db.instance_get_all_by_filters()
2.set the filter use marker
3.execute limit before sqlarchmy get_all()
4.add testcase 'test_db_api.test_instance_get_all_by_filters_paginate'
5.related testcase:
    test_get_servers_with_marker()
    test_get_servers_with_limit_and_marker()
  in nova/tests/api/openstack/compute/test_servers.py
    test_instance_get_all_by_filters_paginate()
  in nova/tests/test_db_api.py
6.add InvalidSortkey exception

Implement bp:efficient-limiting.

Change-Id: Iea3eeb7b51194b6017d624506aafc6469d7338e4

2 files changed, 17 insertions, 12 deletions

diff --git a/nova/api/openstack/common.py b/nova/api/openstack/common.py
index b1e31b0c7..ccc70cd1f 100644
--- a/nova/api/openstack/common.py
+++ b/nova/api/openstack/common.py
@@ -185,13 +185,20 @@ def limited(items, request, max_limit=FLAGS.osapi_max_limit):
     return items[offset:range_end]
 
 
-def limited_by_marker(items, request, max_limit=FLAGS.osapi_max_limit):
-    """Return a slice of items according to the requested marker and limit."""
+def get_limit_and_marker(request, max_limit=FLAGS.osapi_max_limit):
+    """get limited parameter from request"""
     params = get_pagination_params(request)
-
     limit = params.get('limit', max_limit)
+    limit = min(max_limit, limit)
     marker = params.get('marker')
 
+    return limit, marker
+
+
+def limited_by_marker(items, request, max_limit=FLAGS.osapi_max_limit):
+    """Return a slice of items according to the requested marker and limit."""
+    limit, marker = get_limit_and_marker(request, max_limit)
+
     limit = min(max_limit, limit)
     start_index = 0
     if marker:
diff --git a/nova/api/openstack/compute/servers.py b/nova/api/openstack/compute/servers.py
index 229c3b5aa..9f462c565 100644
--- a/nova/api/openstack/compute/servers.py
+++ b/nova/api/openstack/compute/servers.py
@@ -446,16 +446,17 @@ class Controller(wsgi.Controller):
             else:
                 search_opts['user_id'] = context.user_id
 
+        limit, marker = common.get_limit_and_marker(req)
         instance_list = self.compute_api.get_all(context,
-                                                 search_opts=search_opts)
+                                                 search_opts=search_opts,
+                                                 limit=limit, marker=marker)
 
-        limited_list = self._limit_items(instance_list, req)
         if is_detail:
-            self._add_instance_faults(context, limited_list)
-            response = self._view_builder.detail(req, limited_list)
+            self._add_instance_faults(context, instance_list)
+            response = self._view_builder.detail(req, instance_list)
         else:
-            response = self._view_builder.index(req, limited_list)
-        req.cache_db_instances(limited_list)
+            response = self._view_builder.index(req, instance_list)
+        req.cache_db_instances(instance_list)
         return response
 
     def _get_server(self, context, req, instance_uuid):
@@ -1021,9 +1022,6 @@ class Controller(wsgi.Controller):
         self.compute_api.set_admin_password(context, server, password)
         return webob.Response(status_int=202)
 
-    def _limit_items(self, items, req):
-        return common.limited_by_marker(items, req)
-
     def _validate_metadata(self, metadata):
         """Ensure that we can work with the metadata given."""
         try: