1 # Copyright 2015 Intel Corporation.
3 # Licensed under the Apache License, Version 2.0 (the "License");
4 # you may not use this file except in compliance with the License.
5 # You may obtain a copy of the License at
7 # http://www.apache.org/licenses/LICENSE-2.0
9 # Unless required by applicable law or agreed to in writing, software
10 # distributed under the License is distributed on an "AS IS" BASIS,
11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 # See the License for the specific language governing permissions and
13 # limitations under the License.
15 """Loader servant module used by Loader.
17 Module is inteded to be private to serve only Loader itself, nevertheless
18 some methods are exposed outside and can be used by any other clients:
19 - load_modules(self, path, interface)
20 - load_module(self, path, interface, class_name)
21 Those method are stateless static members.
31 class LoaderServant(object):
32 """Class implements basic dynamic import operations.
38 def __init__(self, path, class_name, interface):
39 """LoaderServant constructor
41 Intializes all data needed for import operations.
44 path: path to directory which contains implementations derived from
46 class_name: Class name which will be returned in get_class
47 method, if such definition exists in directory
49 interface: interface type. Every object which doesn't
50 implement this particular interface will be
53 self._class_name = class_name
55 self._interface = interface
58 """Returns class type based on parameters passed in __init__.
60 :return: Type of the found class.
61 None if class hasn't been found
64 return self.load_module(path=self._path,
65 interface=self._interface,
66 class_name=self._class_name)
68 def get_classes(self):
69 """Returns all classes in path derived from interface
71 :return: Dictionary with following data:
72 - key: String representing class name,
75 return self.load_modules(path=self._path,
76 interface=self._interface)
78 def get_classes_printable(self):
79 """Returns all classes derived from _interface found in path
81 :return: String - list of classes in printable format.
84 out = self.load_modules(path=self._path,
85 interface=self._interface)
88 for (name, mod) in list(out.items()):
89 desc = (mod.__doc__ or 'No description').strip().split('\n')[0]
90 results.append((name, desc))
93 'Classes derived from: ' + self._interface.__name__ + '\n======\n']
95 for (name, desc) in results:
96 output.append('* %-18s%s' % ('%s:' % name, desc))
102 return '\n'.join(output)
105 def load_module(path, interface, class_name):
106 """Imports everything from given path and returns class type
108 This is based on following conditions:
109 - Class is derived from interface,
110 - Class type name matches class_name.
112 :return: Type of the found class.
113 None if class hasn't been found
116 results = LoaderServant.load_modules(
117 path=path, interface=interface)
119 if class_name in results:
121 "Class found: " + class_name + ".")
122 return results.get(class_name)
127 def load_modules(path, interface):
128 """Returns dictionary of class name/class type found in path
130 This is based on following conditions:
131 - classes found under path are derived from interface.
132 - class is not interface itself.
134 :return: Dictionary with following data:
135 - key: String representing class name,
140 for _, mod in LoaderServant._load_all_modules(path):
141 # find all system metric loggers defined in the module
142 gens = dict((k, v) for (k, v) in list(mod.__dict__.items())
143 if type(v) == type and
144 issubclass(v, interface) and k != interface.__name__)
146 for (genname, gen) in list(gens.items()):
147 result[genname] = gen
151 def _load_all_modules(path):
152 """Load all modules from ``path`` directory.
154 This is based on the design used by OFTest:
155 https://github.com/floodlight/oftest/blob/master/oft
157 :param path: Path to a folder of modules.
159 :return: List of modules in a folder.
163 for root, _, filenames in os.walk(path):
164 # Iterate over each python file
165 for filename in fnmatch.filter(filenames, '[!.]*.py'):
166 modname = os.path.splitext(os.path.basename(filename))[0]
169 if modname in sys.modules:
170 mod = sys.modules[modname]
172 mod = imp.load_module(
173 modname, *imp.find_module(modname, [root]))
175 logging.error('Could not import file ' + filename)
178 mods.append((modname, mod))