Merge lp:~termie/nova/mega_flags into lp:~hudson-openstack/nova/trunk

[termie]

Add some useful features to our flags

* No longer dies if there are unknown flags.
* Allows you to declare that you will use a flag from another file
* Allows you to import new flags at runtime and reparses the original arguments to fill them once they are accessed.

This hopefully gets around the issues described by vish in this thread:

https://lists.launchpad.net/nova/msg00009.html

Add some useful features to our flags

* No longer dies if there are unknown flags.
* Allows you to declare that you will use a flag from another file
* Allows you to import new flags at runtime and reparses the original arguments to fill them once they are accessed.

This hopefully gets around the issues described by vish in this thread:

https://lists.launchpad.net/nova/msg00009.html

[lp:~termie/nova/mega_flags]

199. By termie on 2010-07-29

strip out some useless imports

[Vish Ishaya (vishvananda)]

This stuff all makes me happy. I think I can continue to deal with flags with these changes. If we can create a best-practices for naming of flags, where they should go, and how they fit into conf files, I think I'm content to stick with gflags.

(copying the above comment to the mailing list)

review: Approve

[lp:~termie/nova/mega_flags]

200. By termie on 2010-08-03

add copyright headers

[Joshua McKenty (joshua-mckenty)]

Party wrapper might be an inappropriate name?
Missing copyright block on declare_flags.py.
I find the name of DECLARE confusing, since it's not a declaration, it's an IMPORT.
Can we call it gflags.IMPORT instead?

Would love to see a docstring on the FlagValues class at some point.

lgtm with nits.

review: Needs Fixing

[lp:~termie/nova/mega_flags]

201. By termie on 2010-08-03

updated doc string and wrapper

[Vish Ishaya (vishvananda)]

Termie, any comment on IMPORT vs DECLARE. That was the last thing on josh's list of nits. I'd like to merge this.

[termie (termie)]

Oh, I had already hassled him about it, but I think maybe since he has been traveling he didn't have a chance to click accept yet.

DECLARE is the syntax used in the C version of gflags. It's meaning is that you are declaring that you will be using a given flag. It's syntax varies slightly from that of the C version in that C has everything in the same namespace and is generally all compiled together where as in python the flag may not already be loaded so it will make sure it is. This is also in line with the DECLARE_key_flag syntax.

[Eric Day (eday)]

It sounds like all outstanding concerns are addressed, I'll mark accept for merge later today unless someone objects.

review: Approve

=== modified file 'nova/flags.py'
--- nova/flags.py	2010-07-28 23:11:02 +0000
+++ nova/flags.py	2010-08-03 16:04:46 +0000
@@ -21,16 +21,145 @@
 where they're used.
 """
 
+import getopt
 import socket
-
-
-from gflags import *
-
-# This keeps pylint from barfing on the imports
-FLAGS = FLAGS
-DEFINE_string = DEFINE_string
-DEFINE_integer = DEFINE_integer
-DEFINE_bool = DEFINE_bool
+import sys
+
+import gflags
+
+
+class FlagValues(gflags.FlagValues):
+    """Extension of gflags.FlagValues that allows undefined and runtime flags.
+
+    Unknown flags will be ignored when parsing the command line, but the
+    command line will be kept so that it can be replayed if new flags are
+    defined after the initial parsing.
+    
+    """
+
+    def __init__(self):
+        gflags.FlagValues.__init__(self)
+        self.__dict__['__dirty'] = []
+        self.__dict__['__was_already_parsed'] = False
+        self.__dict__['__stored_argv'] = []
+
+    def __call__(self, argv):
+        # We're doing some hacky stuff here so that we don't have to copy
+        # out all the code of the original verbatim and then tweak a few lines.
+        # We're hijacking the output of getopt so we can still return the
+        # leftover args at the end
+        sneaky_unparsed_args = {"value": None}
+        original_argv = list(argv)
+        
+        if self.IsGnuGetOpt():
+            orig_getopt = getattr(getopt, 'gnu_getopt')
+            orig_name = 'gnu_getopt'
+        else:
+            orig_getopt = getattr(getopt, 'getopt')
+            orig_name = 'getopt'
+
+        def _sneaky(*args, **kw):
+            optlist, unparsed_args = orig_getopt(*args, **kw)
+            sneaky_unparsed_args['value'] = unparsed_args
+            return optlist, unparsed_args
+
+        try:
+            setattr(getopt, orig_name, _sneaky)
+            args = gflags.FlagValues.__call__(self, argv)
+        except gflags.UnrecognizedFlagError:
+            # Undefined args were found, for now we don't care so just
+            # act like everything went well
+            # (these three lines are copied pretty much verbatim from the end
+            # of the __call__ function we are wrapping)
+            unparsed_args = sneaky_unparsed_args['value']
+            if unparsed_args:
+                if self.IsGnuGetOpt():
+                    args = argv[:1] + unparsed
+                else:
+                    args = argv[:1] + original_argv[-len(unparsed_args):]
+            else:
+                args = argv[:1]
+        finally:
+            setattr(getopt, orig_name, orig_getopt)
+        
+        # Store the arguments for later, we'll need them for new flags
+        # added at runtime
+        self.__dict__['__stored_argv'] = original_argv
+        self.__dict__['__was_already_parsed'] = True
+        self.ClearDirty()
+        return args
+
+    def SetDirty(self, name):
+        """Mark a flag as dirty so that accessing it will case a reparse."""
+        self.__dict__['__dirty'].append(name)
+    
+    def IsDirty(self, name):
+        return name in self.__dict__['__dirty']
+
+    def ClearDirty(self):
+        self.__dict__['__is_dirty'] = []
+
+    def WasAlreadyParsed(self):
+        return self.__dict__['__was_already_parsed']
+
+    def ParseNewFlags(self):
+        if '__stored_argv' not in self.__dict__:
+            return
+        new_flags = FlagValues()
+        for k in self.__dict__['__dirty']:
+            new_flags[k] = gflags.FlagValues.__getitem__(self, k)
+
+        new_flags(self.__dict__['__stored_argv'])
+        for k in self.__dict__['__dirty']:
+            setattr(self, k, getattr(new_flags, k))
+        self.ClearDirty()
+        
+    def __setitem__(self, name, flag):
+        gflags.FlagValues.__setitem__(self, name, flag)
+        if self.WasAlreadyParsed():
+            self.SetDirty(name)
+    
+    def __getitem__(self, name):
+        if self.IsDirty(name):
+            self.ParseNewFlags()
+        return gflags.FlagValues.__getitem__(self, name)
+
+    def __getattr__(self, name):
+        if self.IsDirty(name):
+            self.ParseNewFlags()
+        return gflags.FlagValues.__getattr__(self, name)
+
+
+FLAGS = FlagValues()
+
+
+def _wrapper(func):
+    def _wrapped(*args, **kw):
+        kw.setdefault('flag_values', FLAGS)
+        func(*args, **kw)
+    _wrapped.func_name = func.func_name
+    return _wrapped
+
+
+DEFINE_string = _wrapper(gflags.DEFINE_string)
+DEFINE_integer = _wrapper(gflags.DEFINE_integer)
+DEFINE_bool = _wrapper(gflags.DEFINE_bool)
+DEFINE_boolean = _wrapper(gflags.DEFINE_boolean)
+DEFINE_float = _wrapper(gflags.DEFINE_float)
+DEFINE_enum = _wrapper(gflags.DEFINE_enum)
+DEFINE_list = _wrapper(gflags.DEFINE_list)
+DEFINE_spaceseplist = _wrapper(gflags.DEFINE_spaceseplist)
+DEFINE_multistring = _wrapper(gflags.DEFINE_multistring)
+DEFINE_multi_int = _wrapper(gflags.DEFINE_multi_int)
+
+
+def DECLARE(name, module_string, flag_values=FLAGS):
+    if module_string not in sys.modules:
+        __import__(module_string, globals(), locals())
+    if name not in flag_values:
+        raise gflags.UnrecognizedFlag(
+                "%s not defined by %s" % (name, module_string))
+
 
 # __GLOBAL FLAGS ONLY__
 # Define any app-specific flags in their own files, docs at:
 
=== added file 'nova/tests/declare_flags.py'
--- nova/tests/declare_flags.py	1970-01-01 00:00:00 +0000
+++ nova/tests/declare_flags.py	2010-08-03 16:04:46 +0000
@@ -0,0 +1,23 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+#
+#    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 nova import flags
+
+FLAGS = flags.FLAGS
+
+flags.DEFINE_integer('answer', 42, 'test flag')
 
=== added file 'nova/tests/flags_unittest.py'
--- nova/tests/flags_unittest.py	1970-01-01 00:00:00 +0000
+++ nova/tests/flags_unittest.py	2010-08-03 16:04:46 +0000
@@ -0,0 +1,87 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+#
+#    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 nova import exception
+from nova import flags
+from nova import test
+
+
+class FlagsTestCase(test.TrialTestCase):
+    def setUp(self):
+        super(FlagsTestCase, self).setUp()
+        self.FLAGS = flags.FlagValues()
+        self.global_FLAGS = flags.FLAGS
+
+    def test_define(self):
+        self.assert_('string' not in self.FLAGS)
+        self.assert_('int' not in self.FLAGS)
+        self.assert_('false' not in self.FLAGS)
+        self.assert_('true' not in self.FLAGS)
+
+        flags.DEFINE_string('string', 'default', 'desc', flag_values=self.FLAGS)
+        flags.DEFINE_integer('int', 1, 'desc', flag_values=self.FLAGS)
+        flags.DEFINE_bool('false', False, 'desc', flag_values=self.FLAGS)
+        flags.DEFINE_bool('true', True, 'desc', flag_values=self.FLAGS)
+
+        self.assert_(self.FLAGS['string'])
+        self.assert_(self.FLAGS['int'])
+        self.assert_(self.FLAGS['false'])
+        self.assert_(self.FLAGS['true'])
+        self.assertEqual(self.FLAGS.string, 'default')
+        self.assertEqual(self.FLAGS.int, 1)
+        self.assertEqual(self.FLAGS.false, False)
+        self.assertEqual(self.FLAGS.true, True)
+
+        argv = ['flags_test',
+                '--string', 'foo',
+                '--int', '2',
+                '--false',
+                '--notrue']
+
+        self.FLAGS(argv)
+        self.assertEqual(self.FLAGS.string, 'foo')
+        self.assertEqual(self.FLAGS.int, 2)
+        self.assertEqual(self.FLAGS.false, True)
+        self.assertEqual(self.FLAGS.true, False)
+
+    def test_declare(self):
+        self.assert_('answer' not in self.global_FLAGS)
+        flags.DECLARE('answer', 'nova.tests.declare_flags')
+        self.assert_('answer' in self.global_FLAGS)
+        self.assertEqual(self.global_FLAGS.answer, 42)
+
+        # Make sure we don't overwrite anything
+        self.global_FLAGS.answer = 256
+        self.assertEqual(self.global_FLAGS.answer, 256)
+        flags.DECLARE('answer', 'nova.tests.declare_flags')
+        self.assertEqual(self.global_FLAGS.answer, 256)
+
+    def test_runtime_and_unknown_flags(self):
+        self.assert_('runtime_answer' not in self.global_FLAGS)
+
+        argv = ['flags_test', '--runtime_answer=60', 'extra_arg']
+        args = self.global_FLAGS(argv)
+        self.assertEqual(len(args), 2)
+        self.assertEqual(args[1], 'extra_arg')
+
+        self.assert_('runtime_answer' not in self.global_FLAGS)
+
+        import nova.tests.runtime_flags
+
+        self.assert_('runtime_answer' in self.global_FLAGS)
+        self.assertEqual(self.global_FLAGS.runtime_answer, 60)
 
=== added file 'nova/tests/runtime_flags.py'
--- nova/tests/runtime_flags.py	1970-01-01 00:00:00 +0000
+++ nova/tests/runtime_flags.py	2010-08-03 16:04:46 +0000
@@ -0,0 +1,23 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+#
+#    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 nova import flags
+
+FLAGS = flags.FLAGS
+
+flags.DEFINE_integer('runtime_answer', 54, 'test flag')
 
=== modified file 'run_tests.py'
--- run_tests.py	2010-07-27 20:08:22 +0000
+++ run_tests.py	2010-08-03 16:04:46 +0000
@@ -54,6 +54,7 @@
 from nova.tests.api_unittest import *
 from nova.tests.cloud_unittest import *
 from nova.tests.compute_unittest import *
+from nova.tests.flags_unittest import *
 from nova.tests.model_unittest import *
 from nova.tests.network_unittest import *
 from nova.tests.objectstore_unittest import *
 
=== modified file 'run_tests.sh'
--- run_tests.sh	2010-07-28 04:39:58 +0000
+++ run_tests.sh	2010-08-03 16:04:46 +0000
@@ -4,7 +4,7 @@
 with_venv=tools/with_venv.sh
 
 if [ -e ${venv} ]; then
-  ${with_venv} python run_tests.py
+  ${with_venv} python run_tests.py $@
 else  
   echo "You need to install the Nova virtualenv before you can run this."
   echo ""