[Piglit] [Patch v3 1/4] framework/dmesg: Adds a new module for dmesg
Ilia Mirkin
imirkin at alum.mit.edu
Mon Feb 3 16:54:15 PST 2014
On Mon, Feb 3, 2014 at 7:39 PM, Dylan Baker <baker.dylan.c at gmail.com> wrote:
> On Monday, February 03, 2014 06:53:53 PM Ilia Mirkin wrote:
>> On Mon, Feb 3, 2014 at 6:40 PM, Dylan Baker <baker.dylan.c at gmail.com> wrote:
>> > 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
>> >
>> > Signed-off-by: Dylan Baker <baker.dylan.c at gmail.com>
>> > ---
>> >
>> > framework/dmesg.py | 167
>> > +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed,
>> > 167 insertions(+)
>> > create mode 100644 framework/dmesg.py
>> >
>> > diff --git a/framework/dmesg.py b/framework/dmesg.py
>> > new file mode 100644
>> > index 0000000..d270aaa
>> > --- /dev/null
>> > +++ b/framework/dmesg.py
>> > @@ -0,0 +1,167 @@
>> > +# 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()
>> > +
>> > + # 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]
>>
>> > + if not re.match('\[\s*\d+\.\d+\]', self._last_message):
>> So if I do dmesg -c; ./piglit-run bla this will fail, right? (I'm
>> surprised that the string works without the r prefix for raw string,
>> but I double-checked and it does...)
>
> I'll add the r
> And I don't know how I managed to drop the check to ensure that dmesg wasn't
> Falsy, I wrote that code originally.
>
>>
>> > + raise EnvironmentError("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 + try:
>> > + self._new_messages = dmesg[dmesg.index(self._last_message) +
>> > 1:]
>> IMO it'd still be an improvement to search from the end -- the vast
>> majority of the time, when a piglit test does not emit a new message,
>> the _last_message will match up to the last element in dmesg. Instead
>> of checking n items (n = # of lines in dmesg), you'd be only checking
>> 1...
>
> It's the obvious solution, but I can't find a way to do it that doesn't create
> a lot of code bloat with minimal performance gains, or that doesn't produce
> performance regressions. I'm opened to suggestions here, I tried to implement
> your idea in the other thread, but it ended up being over 20 lines before I
> got it working, and it wasn't any faster.
My idea from the other thread was supposed to be slower, but more
correct for cases that didn't have timestamps to make each line unique
:) But you've legislated that situation out.
For this idea, what would happen if you did...
index = 0
for i, line in enumerate(reversed(dmesg)):
if line == self._last_message:
index = len(dmesg) - i
break
self._new_messages = dmesg[index:]
>
>>
>> > + except ValueError:
>> > + self._new_messages = dmesg
>> > +
>> > + # Attempt to store the contents of the last message in the dmesg
>> > + # snapshot for lookup later. If something happens inbetween (say
>> > a user + # calls dmesg -C), then set it to None
>>
>> ... or if dmesg is clean at the start -- it doesn't have to be someone
>> clearing it in the middle of the run.
>
> I'll reword this
>
>>
>> > + try:
>> > + self._last_message = dmesg[-1]
>> > + except IndexError:
>> > + self._last_message = None
>>
>> Completely optional suggestion:
>>
>> self._last_message = dmesg[-1] if dmesg else None
>>
>> (In general I prefer to avoid exceptions since you can end up catching
>> things you didn't mean to. But that's not everyone's style, so feel
>> free to do it whichever way you prefer.)
>
> Yeah, I don't really care either, I'll do it your way
>
>>
>> > +
>> > +
>> > +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
>> > +
>> > +
>> > +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
>> >
>> > _______________________________________________
>> > Piglit mailing list
>> > Piglit at lists.freedesktop.org
>> > http://lists.freedesktop.org/mailman/listinfo/piglit
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