Adds a manual garbage collector script

It's the responsibility of the operator to call the garbage
collector manually. Using crontab or a similar tool is advised.

A more intelligent approach for this will be added in a follow-up
patch.

Change-Id: I9cf22a5c65920be0eaff909c8f090d29ef300d1f

setup.cfg

@@ -35,6 +35,7 @@ console_scripts =
     zaqar-bench = zaqar.bench.conductor:main
     zaqar-server = zaqar.cmd.server:run
     marconi-server = zaqar.cmd.server:run
+    zaqar-gc = zaqar.cmd.gc:run
 
 zaqar.queues.data.storage =
     # NOTE(flaper87): sqlite points to sqla for backwards compatibility

zaqar/cmd/gc.py

@@ -0,0 +1,37 @@
+# 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 oslo.config import cfg
+
+from zaqar.common import cli
+from zaqar.openstack.common import log
+from zaqar.queues import bootstrap
+
+LOG = log.getLogger(__name__)
+
+
+# In this first approach it's the responsibility of the operator
+# to call the garbage collector manually. Using crontab or a similar
+# tool is advised.
+@cli.runnable
+def run():
+    # TODO(kgriffs): For now, we have to use the global config
+    # to pick up common options from openstack.common.log, since
+    # that module uses the global CONF instance exclusively.
+    conf = cfg.CONF
+    conf(project='zaqar', prog='zaqar-gc')
+
+    server = bootstrap.Bootstrap(conf)
+
+    LOG.debug(u'Calling the garbage collector')
+    server.storage.gc()