From 247ada2d94e519411bc0c07dc5e54c8190f04f07 Mon Sep 17 00:00:00 2001
From: sridevik <koushiksridevi8@gmail.com>
Date: Mon, 26 Aug 2013 05:23:34 -0500
Subject: [PATCH] Introduced DB pooling for non blocking DB calls

The DbApi module is wrapped with the tpool wrapper if the configuration is
enabled. use_tpool is disabled (False) by default

Related to bp mysql-thread-pool

Change-Id: Ie7274ac855549b96c581c3eb0bcf79f3c74be0ed
---
 glance/db/__init__.py                     | 28 ++++++++++-
 glance/tests/functional/db/test_db_api.py | 60 +++++++++++++++++++++++
 test-requirements.txt                     |  1 +
 3 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 glance/tests/functional/db/test_db_api.py

diff --git a/glance/db/__init__.py b/glance/db/__init__.py
index 2ab16fdf10..73f5dfa135 100644
--- a/glance/db/__init__.py
+++ b/glance/db/__init__.py
@@ -17,6 +17,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import functools
 from oslo.config import cfg
 
 from glance.common import crypt
@@ -25,13 +26,20 @@ import glance.domain
 import glance.domain.proxy
 from glance.openstack.common import importutils
 
+db_opt = cfg.BoolOpt('use_tpool',
+                     default=False,
+                     help='Enable the use of thread pooling for '
+                     'all DB API calls')
 
 CONF = cfg.CONF
 CONF.import_opt('metadata_encryption_key', 'glance.common.config')
+CONF.register_opt(db_opt)
 
 
 def get_api():
-    return importutils.import_module(CONF.data_api)
+    if not CONF.use_tpool:
+        return importutils.import_module(CONF.data_api)
+    return ThreadPoolWrapper(CONF.data_api)
 
 
 # attributes common to all models
@@ -260,3 +268,21 @@ class ImageMemberRepo(object):
         image_member = self._format_image_member_from_db(
                                                     db_api_image_member[0])
         return image_member
+
+
+class ThreadPoolWrapper(object):
+
+    def __init__(self, wrapped):
+        self.wrapped = importutils.import_module(wrapped)
+
+    def __getattr__(self, key):
+        original = getattr(self.wrapped, key)
+        if not callable(original):
+            return original
+
+        @functools.wraps(original)
+        def wrapper(*args, **kwargs):
+            from eventlet import tpool
+            output = tpool.execute(original, *args, **kwargs)
+            return output
+        return wrapper
diff --git a/glance/tests/functional/db/test_db_api.py b/glance/tests/functional/db/test_db_api.py
new file mode 100644
index 0000000000..76ae0e5bfc
--- /dev/null
+++ b/glance/tests/functional/db/test_db_api.py
@@ -0,0 +1,60 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2013 OpenStack LLC.
+# 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.
+
+from mock import Mock
+from oslo.config import cfg
+import testtools
+
+from glance import db as db_api
+from glance.openstack.common import importutils
+
+CONF = cfg.CONF
+CONF.import_opt('use_tpool', 'glance.db')
+CONF.import_opt('data_api', 'glance.db')
+
+
+class DbApiTest(testtools.TestCase):
+    def test_get_dbapi_when_db_pool_is_enabled(self):
+        CONF.set_override('use_tpool', True)
+        dbapi = db_api.get_api()
+        self.assertTrue(isinstance(dbapi, db_api.ThreadPoolWrapper))
+
+    def test_get_dbapi_when_db_pool_is_disabled(self):
+        CONF.set_override('use_tpool', False)
+        dbapi = db_api.get_api()
+        self.assertFalse(isinstance(dbapi, db_api.ThreadPoolWrapper))
+        self.assertEqual(importutils.import_module(CONF.data_api), dbapi)
+
+
+def method_for_test_1(*args, **kwargs):
+    return args, kwargs
+
+
+class ThreadPoolWrapper(testtools.TestCase):
+    def test_thread_pool(self):
+        module = importutils.import_module('glance.tests.functional.db.'
+                                           'test_db_api')
+        CONF.set_override('use_tpool', True)
+        CONF.set_override('data_api', 'glance.tests.functional.db.'
+                          'test_db_api')
+        dbapi = db_api.get_api()
+
+        from eventlet import tpool
+        tpool.execute = Mock()
+
+        dbapi.method_for_test_1(1, 2, kwarg='arg')
+        tpool.execute.assert_called_with(method_for_test_1, 1, 2, kwarg='arg')
diff --git a/test-requirements.txt b/test-requirements.txt
index 84ec717045..22731691fd 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -14,6 +14,7 @@ mox>=0.5.3
 nose
 nose-exclude
 openstack.nose_plugin>=0.7
+mock>=1.0
 nosehtmloutput>=0.0.3
 sphinx>=1.1.2
 requests>=1.1