[Piglit] [PATCH 1/6] framework/dmesg: Adds a new module for dmesg

[Dylan Baker]

This class implements a class for reading dmesg, including a dummy class
for running on non-posix systems. It works as a class, and is cleaner
than the current implementation.

Signed-off-by: Dylan Baker <baker.dylan.c at gmail.com>
---
 framework/dmesg.py | 108 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 framework/dmesg.py

diff --git a/framework/dmesg.py b/framework/dmesg.py
new file mode 100644
index 0000000..9a23c14
--- /dev/null
+++ b/framework/dmesg.py
@@ -0,0 +1,108 @@
+# Copyright (c) 2013 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 """
+
+import os
+import subprocess
+from threads import synchronized_self
+
+__all__ = ['Dmesg']
+
+# plain text list of statuses to be considered either a warn or a fail, any
+# statuses not on this list will simply be ignored.
+WARN_STATUSES = []
+FAIL_STATUSES = []
+
+
+class PosixDmesg(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.
+
+    This class is threadsafe, but with the caveat that the test reported dmesg
+    problems might not be the test that generated them. dmesg reporting can
+    only be considered authoratative when running non-concurrently.
+    
+    """
+    def __init__(self):
+        """ Create a dmesg instance """
+        self.dmesg = []
+        self._last_message = ""
+        self._new_messages = []
+        
+        # Populate self.dmesg initially, otherwise the first test will always
+        # be full of dmesg crud.
+        self._call_dmesg()
+        
+    @synchronized_self
+    def update_dmesg(self):
+        """ Call dmesg and look for changes. """
+        self._call_dmesg()
+
+        return self._new_messages
+        
+    def _call_dmesg(self):
+        """ Call dmesg using subproces.check_output 
+        
+        Get the contents of dmesg, then calculate new messages, finally set
+        self.dmesg equal to the just read contents of dmesg.
+        
+        """
+        # Call strip to remove the trailing newline before splitting on the \n.
+        # posix systems *should* use \n for newlines 
+        dmesg = subprocess.check_output( ['dmesg']).strip().split('\n')
+
+        # Calculate new entires in dmesg by returning any strings that are in
+        # the new dmesg list but not in the old one. This circumvents the
+        # ringbuffer issue, since if there are not entries in common all of the
+        # new messages will be returned.
+        self._new_messages = [x for x in dmesg if x not in self.dmesg]
+        self.dmesg = dmesg
+
+
+class DummyDmesg(object):
+    """ An dummy class for dmesg on non unix-like systems
+    
+    This implments only a very small subset of the UnixDmesg class, which
+    allows it to return None anywhere Dmesg is called.
+    
+    The usage of the dmesg class is universally to call ``if dmesg:'', so by
+    returning None the DummyDmesg class will always skip any dmesg handling
+    code.
+    
+    """
+    
+    def __init__(self):
+        pass
+    
+    def update_dmesg(self):
+        return None
+    
+
+# Export the Dmesg class as either PosixDmesg (if on a posix system) or
+# DummyDmesg if not on a posix system
+if os.name == "posix":
+    Dmesg = PosixDmesg
+else:
+    Dmesg = DummyDmesg
-- 
1.8.1.5