[Piglit] [Patch v4 1/4] framework/dmesg: Adds a new module for dmesg
Dylan Baker
baker.dylan.c at gmail.com
Tue Feb 4 07:50:44 PST 2014
This modules implements two classes and a helper function. The two
classes are both dmesg wrapper classes, one, PosixDmesg is used on posix
systems when requested to actually do checks on dmesg. The second class,
DummyDmesg, is used to reduce code complexity by providing dummy
versions of the methods in PosixDmesg. This means that we don't need
separate code paths for Posix systems wanting to check dmesg, Posix
systems not wanting to check dmesg, and non-posix systems which lack
dmesg.
Beyond reducing complexity this module also gives better isolation,
dmesg is only used in Test.execute(), no where else. Additional classes
don't need to worry about dmesg that way, it's just available.
v2: - Remove unnecessary assert from PosixDmesg.update_result()
- simplify replace helper in PoixDmesg.update_result()
- replace try/except with if check
- Change PosixDmesg.update_dmesg() to work even if dmesg 'wraps'
v3: - Try/Except assignment of PosixDmesg._last_message in update_dmesg()
- Set the dmesg levels the same as the previous implementation
- Change PosixDmesg into LinuxDmesg and enforce that dmesg has
timestamps
v4: - Add check in LinuxDmesg.__init__ to ensure there is something in
dmesg before doing the timestamp check. This should make problems
clearer
- Refactor some code in LinuxDmesg.update_result()
Signed-off-by: Dylan Baker <baker.dylan.c at gmail.com>
---
framework/dmesg.py | 174 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 174 insertions(+)
create mode 100644 framework/dmesg.py
diff --git a/framework/dmesg.py b/framework/dmesg.py
new file mode 100644
index 0000000..eac9606
--- /dev/null
+++ b/framework/dmesg.py
@@ -0,0 +1,174 @@
+# Copyright (c) 2013-2014 Intel Corporation
+#
+# Permission is hereby granted, free of charge, to any person obtaining a
+# copy of this software and associated documentation files (the "Software"),
+# to deal in the Software without restriction, including without limitation
+# the rights to use, copy, modify, merge, publish, distribute, sublicense,
+# and/or sell copies of the Software, and to permit persons to whom the
+# Software is furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice (including the next
+# paragraph) shall be included in all copies or substantial portions of the
+# Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+# IN THE SOFTWARE.
+
+""" Module implementing classes for reading posix dmesg
+
+Currently this module only has the default DummyDmesg, and a LinuxDmesg.
+The method used on Linux requires that timetamps are enabled, and no other
+posix system has timestamps.
+
+On OSX and *BSD one would likely want to implement a system that reads the
+sysloger, since timestamps can be added by the sysloger, and are not inserted
+by dmesg.
+
+"""
+
+import re
+import sys
+import subprocess
+
+__all__ = ['LinuxDmesg', 'DummyDmesg', 'get_dmesg']
+
+
+class LinuxDmesg(object):
+ """ Read dmesg on posix systems
+
+ This reads the dmesg ring buffer, stores the contents of the buffer, and
+ then compares it whenever called, returning the difference between the
+ calls. It requires timestamps to be enabled.
+
+ """
+ DMESG_COMMAND = ['dmesg', '--level', 'emerg,alert,crit,err,warn,notice']
+
+ def __init__(self):
+ """ Create a dmesg instance """
+ self._last_message = None
+ self._new_messages = []
+
+ # Populate self.dmesg initially, otherwise the first test will always
+ # be full of dmesg crud.
+ self.update_dmesg()
+
+ if not self._last_message:
+ # We need to ensure that there is something in dmesg to check
+ # timestamps.
+ raise DmesgError(
+ "Your dmesg ringbuffer is empty, so it's not possible to check "
+ "for timestamp support. Try adding something to dmesg by "
+ "writing /dev/kmsg. ex `echo 'foo' >> /dev/kmsg")
+ if not re.match(r'\[\s*\d+\.\d+\]', self._last_message):
+ # Do an initial check to ensure that dmesg has timestamps, we need
+ # timestamps to work correctly. A proper linux dmesg timestamp
+ # looks like this: [ 0.00000]
+ raise DmesgError(
+ "Your kernel does not seem to support timestamps, which "
+ "are required by the --dmesg option")
+
+ def update_result(self, result):
+ """ Takes a TestResult object and updates it with dmesg statuses
+
+ If dmesg is enabled, and if dmesg has been updated, then replace pass
+ with dmesg-warn and warn and fail with dmesg-fail. If dmesg has not
+ been updated, it will return the original result passed in.
+
+ Arguments:
+ result -- A TestResult instance
+
+ """
+
+ def replace(res):
+ """ helper to replace statuses with the new dmesg status
+
+ Replaces pass with dmesg-warn, and warn and fail with dmesg-fail,
+ otherwise returns the input
+
+ """
+ return {"pass": "dmesg-warn",
+ "warn": "dmesg-fail",
+ "fail": "dmesg-fail"}.get(res, res)
+
+ # Get a new snapshot of dmesg
+ self.update_dmesg()
+
+ # if update_dmesg() found new entries replace the results of the test
+ # and subtests
+ if self._new_messages:
+ result['result'] = replace(result['result'])
+
+ # Replace any subtests
+ if 'subtest' in result:
+ for key, value in result['subtest'].iteritems():
+ result['subtest'][key] = replace(value)
+
+ # Add the dmesg values to the result
+ result['dmesg'] = self._new_messages
+
+ return result
+
+ def update_dmesg(self):
+ """ Call dmesg using subprocess.check_output
+
+ Get the contents of dmesg, then calculate new messages, finally set
+ self.dmesg equal to the just read contents of dmesg.
+
+ """
+ dmesg = subprocess.check_output(self.DMESG_COMMAND).strip().splitlines()
+
+ # Find all new entries, do this by slicing the list of dmesg to only
+ # returns elements after the last element stored. If there are not
+ # matches a value error is raised, that means all of dmesg is new
+ l = 0
+ for index, item in enumerate(reversed(dmesg)):
+ if item == self._last_message:
+ l = len(dmesg) - index # don't include the matched element
+ self._new_messages = dmesg[l:]
+
+ # Attempt to store the last element of dmesg, unless there was no dmesg
+ self._last_message = dmesg[-1] if dmesg else None
+
+
+class DummyDmesg(object):
+ """ An dummy class for dmesg on non unix-like systems
+
+ This implements a dummy version of the LinuxDmesg, and can be used anytime
+ it is not desirable to actually read dmesg, such as non-posix systems, or
+ when the contents of dmesg don't matter.
+
+ """
+ DMESG_COMMAND = []
+
+ def __init__(self):
+ pass
+
+ def update_dmesg(self):
+ """ Dummy version of update_dmesg """
+ pass
+
+ def update_result(self, result):
+ """ Dummy version of update_result """
+ return result
+
+
+class DmesgError(EnvironmentError):
+ pass
+
+
+def get_dmesg(not_dummy=True):
+ """ Return a Dmesg type instance
+
+ Normally this does a system check, and returns the type that proper for
+ your system. However, if Dummy is True then it will always return a
+ DummyDmesg instance.
+
+ """
+ if sys.platform.startswith('linux') and not_dummy:
+ return LinuxDmesg()
+ return DummyDmesg()
--
1.8.5.3
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