Move files out of the namespace package

Move the public API out of oslo.db to oslo_db. Retain the ability to
import from the old namespace package for backwards compatibility for
this release cycle.

Blueprint: drop-namespace-packages

Change-Id: Ie96b482b9fbcb1d85203ad35bb65c1f43e912a44

1 files changed, 81 insertions, 0 deletions

diff --git a/oslo_db/concurrency.py b/oslo_db/concurrency.py
new file mode 100644
index 0000000..2c59623
--- /dev/null
+++ b/oslo_db/concurrency.py
@@ -0,0 +1,81 @@
+# Copyright 2014 Mirantis.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.
+
+import copy
+import logging
+import threading
+
+from oslo.config import cfg
+
+from oslo_db._i18n import _LE
+from oslo_db import api
+
+
+LOG = logging.getLogger(__name__)
+
+tpool_opts = [
+    cfg.BoolOpt('use_tpool',
+                default=False,
+                deprecated_name='dbapi_use_tpool',
+                deprecated_group='DEFAULT',
+                help='Enable the experimental use of thread pooling for '
+                     'all DB API calls'),
+]
+
+
+class TpoolDbapiWrapper(object):
+    """DB API wrapper class.
+
+    This wraps the oslo DB API with an option to be able to use eventlet's
+    thread pooling. Since the CONF variable may not be loaded at the time
+    this class is instantiated, we must look at it on the first DB API call.
+    """
+
+    def __init__(self, conf, backend_mapping):
+        self._db_api = None
+        self._backend_mapping = backend_mapping
+        self._conf = conf
+        self._conf.register_opts(tpool_opts, 'database')
+        self._lock = threading.Lock()
+
+    @property
+    def _api(self):
+        if not self._db_api:
+            with self._lock:
+                if not self._db_api:
+                    db_api = api.DBAPI.from_config(
+                        conf=self._conf, backend_mapping=self._backend_mapping)
+                    if self._conf.database.use_tpool:
+                        try:
+                            from eventlet import tpool
+                        except ImportError:
+                            LOG.exception(_LE("'eventlet' is required for "
+                                              "TpoolDbapiWrapper."))
+                            raise
+                        self._db_api = tpool.Proxy(db_api)
+                    else:
+                        self._db_api = db_api
+        return self._db_api
+
+    def __getattr__(self, key):
+        return getattr(self._api, key)
+
+
+def list_opts():
+    """Returns a list of oslo.config options available in this module.
+
+    :returns: a list of (group_name, opts) tuples
+    """
+    return [('database', copy.deepcopy(tpool_opts))]