Allow choosing vlog levels to patch and restoring the vlog

Change-Id: I99bd8e5deec3cf92aebe8402c3c7b7d7a670556c

ovsdbapp/backend/ovs_idl/fixtures.py

@@ -0,0 +1,32 @@
+#    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 __future__ import absolute_import
+
+import fixtures
+
+from ovsdbapp.backend.ovs_idl import vlog
+
+
+class OvsdbVlogFixture(fixtures.Fixture):
+    def __init__(self, *args, **kwargs):
+        """Constructor for the OvsdbVlogVixture
+
+        The OvsdbVlogFixture will call vlog.use_python_logger with any args or
+        kwargs passed and call vlog.reset_logger() on cleanup
+        """
+        self.args = args
+        self.kwargs = kwargs
+
+    def _setUp(self):
+        vlog.use_python_logger(*self.args, **self.kwargs)
+        self.addCleanup(vlog.reset_logger)

ovsdbapp/backend/ovs_idl/vlog.py

@@ -12,20 +12,64 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import collections
 import logging
 
 from ovs import vlog
 
-LOG = logging.getLogger(__name__)
+_LOG = logging.getLogger(__name__)
+
+# Map local log LEVELS to local LOG functions
+CRITICAL = _LOG.critical
+ERROR = _LOG.error
+WARN = _LOG.warn
+INFO = _LOG.info
+DEBUG = _LOG.debug
+
+_LOG_MAPPING = collections.OrderedDict((
+    (CRITICAL, vlog.Vlog.emer),
+    (ERROR, vlog.Vlog.err),
+    (WARN, vlog.Vlog.warn),
+    (INFO, vlog.Vlog.info),
+    (DEBUG, vlog.Vlog.dbg),
+))
+ALL_LEVELS = tuple(_LOG_MAPPING.keys())
 
 
-def use_python_logger():
-    """Replace the OVS IDL logger functions with our logger"""
+def _original_vlog_fn(level):
+    """Get the original unpatched OVS vlog function for level"""
+    return _LOG_MAPPING[level]
+
+
+def _current_vlog_fn(level):
+    """Get the currently used OVS vlog function mapped to level"""
+    return getattr(vlog.Vlog, _LOG_MAPPING[level].__name__)
+
+
+def use_python_logger(levels=ALL_LEVELS, max_level=None):
+    """Replace the OVS vlog functions with our logger
+
+    :param: levels: log levels *from this module* e.g. [vlog.WARN]
+    :type: levels: iterable
+    :param: max_level: the maximum level to log
+    :type: max_level: vlog level, CRITICAL, ERROR, WARN, INFO, or DEBUG
+    """
+
+    if max_level:
+        levels = levels[:-levels.index(max_level)]
 
     # NOTE(twilson) Replace functions directly instead of subclassing so that
     # debug messages contain the correct function/filename/line information
-    vlog.Vlog.emer = LOG.critical
-    vlog.Vlog.err = LOG.error
-    vlog.Vlog.warn = LOG.warning
-    vlog.Vlog.info = LOG.info
-    vlog.Vlog.dbg = LOG.debug
+    for log in levels:
+        setattr(vlog.Vlog, _LOG_MAPPING[log].__name__, log)
+
+
+def reset_logger():
+    """Reset the OVS vlog functions to their original values"""
+    for log in ALL_LEVELS:
+        setattr(vlog.Vlog, _LOG_MAPPING[log].__name__, _LOG_MAPPING[log])
+
+
+def is_patched(level):
+    """Test if the vlog level is patched"""
+    return _current_vlog_fn(level) != _original_vlog_fn(level)

ovsdbapp/tests/unit/backend/ovs_idl/test_vlog.py

@@ -0,0 +1,50 @@
+# 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 ovsdbapp.backend.ovs_idl import fixtures
+from ovsdbapp.backend.ovs_idl import vlog
+from ovsdbapp.tests import base
+
+
+class TestOvsdbVlog(base.TestCase):
+    def setUp(self):
+        super(TestOvsdbVlog, self).setUp()
+        self.useFixture(fixtures.OvsdbVlogFixture())
+
+    def test_vlog_patched(self):
+        for log_fn in vlog.ALL_LEVELS:
+            self.assertTrue(vlog.is_patched(log_fn))
+
+    def test_vlog_reset(self):
+        vlog.reset_logger()
+        for log_fn in vlog.ALL_LEVELS:
+            self.assertFalse(vlog.is_patched(log_fn))
+
+    def test_vlog_patch_all_but_debug(self):
+        vlog.reset_logger()
+        removed_level = vlog.DEBUG
+        levels = set(vlog.ALL_LEVELS) - set([removed_level])
+        vlog.use_python_logger(levels)
+        for lvl in levels:
+            self.assertTrue(vlog.is_patched(lvl))
+        self.assertFalse(vlog.is_patched(removed_level))
+
+    def test_vlog_max_level(self):
+        vlog.reset_logger()
+        max_level = vlog.WARN
+        vlog.use_python_logger(max_level=max_level)
+        patched_levels = (vlog.CRITICAL, vlog.ERROR, vlog.WARN)
+        unpatched_levels = (vlog.INFO, vlog.DEBUG)
+        for lvl in patched_levels:
+            self.assertTrue(vlog.is_patched(lvl))
+        for lvl in unpatched_levels:
+            self.assertFalse(vlog.is_patched(lvl))

requirements.txt

@@ -2,5 +2,6 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
+fixtures>=3.0.0 # Apache-2.0/BSD
 ovs>=2.7.0 # Apache-2.0
 pbr!=2.1.0,>=2.0.0 # Apache-2.0