framework/backends/__init__.py

   1 # coding=utf-8
   2 # Copyright (c) 2014-2016, 2019 Intel Corporation
   3
   4 # Permission is hereby granted, free of charge, to any person obtaining a copy
   5 # of this software and associated documentation files (the "Software"), to deal
   6 # in the Software without restriction, including without limitation the rights
   7 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   8 # copies of the Software, and to permit persons to whom the Software is
   9 # furnished to do so, subject to the following conditions:
  10
  11 # The above copyright notice and this permission notice shall be included in
  12 # all copies or substantial portions of the Software.
  13
  14 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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  20 # SOFTWARE.
  21
  22 """Provides a module like interface for backends.
  23
  24 This package provides an abstract interface for working with backends, which
  25 implement various functions as provided in the Registry class, and then provide
  26 a Registry instance as REGISTRY, which maps individual objects to objects that
  27 piglit expects to use. This module then provides a thin abstraction layer so
  28 that piglit is never aware of what backend it's using, it just asks for an
  29 object and receives one.
  30
  31 Most consumers will want to import framework.backends and work directly with
  32 the helper functions here. For some more detailed uses (test cases especially)
  33 the modules themselves may be used.
  34
  35 When this module is loaded it will search through framework/backends for python
  36 modules (those ending in .py), and attempt to import them. Then it will look
  37 for an attribute REGISTRY in those modules, and if it as a
  38 framework.register.Registry instance, it will add the name of that module (sans
  39 .py) as a key, and the instance as a value to the BACKENDS dictionary. Each of
  40 the helper functions in this module uses that dictionary to find the function
  41 that a user actually wants.
  42
  43 """
  44
  45 import os
  46 import importlib
  47
  48 from .register import Registry
  49 from .compression import COMPRESSION_SUFFIXES
  50
  51 __all__ = [
  52     'BACKENDS',
  53     'BackendError',
  54     'BackendNotImplementedError',
  55     'get_backend',
  56     'load',
  57     'set_meta',
  58     'write',
  59 ]
  60
  61
  62 class BackendError(Exception):
  63     pass
  64
  65
  66 class BackendNotImplementedError(NotImplementedError):
  67     pass
  68
  69
  70 def _register():
  71     """Register backends.
  72
  73     Walk through the list of backends and register them to a name in a
  74     dictionary, so that they can be referenced from helper functions.
  75
  76     """
  77     registry = {}
  78
  79     for module in os.listdir(os.path.dirname(os.path.abspath(__file__))):
  80         module, extension = os.path.splitext(module)
  81         if extension == '.py':
  82             mod = importlib.import_module('framework.backends.{}'.format(module))
  83             if hasattr(mod, 'REGISTRY') and isinstance(mod.REGISTRY, Registry):
  84                 registry[module] = mod.REGISTRY
  85
  86     return registry
  87
  88
  89 BACKENDS = _register()
  90
  91
  92 def get_backend(backend):
  93     """Returns a BackendInstance based on the string passed.
  94
  95     If the backend isn't a known module, then a BackendError will be raised, it
  96     is the responsibility of the caller to handle this error.
  97
  98     If the backend module exists, but there is not active implementation then a
  99     BackendNotImplementedError will be raised, it is also the responsibility of
 100     the caller to handle this error.
 101
 102     """
 103     try:
 104         inst = BACKENDS[backend].backend
 105     except KeyError:
 106         raise BackendError('Unknown backend: {}'.format(backend))
 107
 108     if inst is None:
 109         raise BackendNotImplementedError(
 110             'Backend for {} is not implemented'.format(backend))
 111
 112     return inst
 113
 114
 115 def get_extension(file_path):
 116     """Get the extension name to use when searching for a loader.
 117
 118     This function correctly handles compression suffixes, as long as they are
 119     valid.
 120
 121     """
 122     def _extension(file_path):
 123         """Helper function to get the extension string."""
 124         compression = 'none'
 125         name, extension = os.path.splitext(file_path)
 126
 127         # If we hit a compressed suffix, get an additional suffix to test
 128         # with.
 129         # i.e: Use .json.gz rather that .gz
 130         if extension in COMPRESSION_SUFFIXES:
 131             compression = extension[1:]  # Drop the leading '.'
 132             # Remove any trailing '.', this fixes a bug where the filename
 133             # is 'foo.json..xz, or similar
 134             extension = os.path.splitext(name.rstrip('.'))[1]
 135
 136         return extension, compression
 137
 138     if not os.path.isdir(file_path):
 139         return _extension(file_path)
 140     else:
 141         for file_ in os.listdir(file_path):
 142             if file_.startswith('result') and not file_.endswith('.old'):
 143                 return _extension(file_)
 144
 145     tests = os.path.join(file_path, 'tests')
 146     if os.path.exists(tests):
 147         return _extension(os.listdir(tests)[0])
 148     else:
 149         # At this point we have failed to find any sort of backend, just
 150         # except and die
 151         raise BackendError("No backend found for any file in {}".format(
 152             file_path))
 153
 154
 155 def load(file_path):
 156     """Wrapper for loading runs.
 157
 158     This function will attempt to determine how to load the file (based on file
 159     extension), and then pass the file path into the appropriate loader, and
 160     then return the TestrunResult instance.
 161
 162     """
 163
 164     extension, compression = get_extension(file_path)
 165
 166     for backend in BACKENDS.values():
 167         if extension in backend.extensions:
 168             loader = backend.load
 169
 170             if loader is None:
 171                 raise BackendNotImplementedError(
 172                     'Loader for {} is not implemented'.format(extension))
 173
 174             return loader(file_path, compression)
 175
 176     raise BackendError(
 177         'No module supports file extension "{}"'.format(extension))
 178
 179
 180 def write(results, file_path):
 181     """Wrapper for writing runs.
 182
 183     This function will attempt to determine how to write a TestrunResult
 184     instance into the file (based on file extension), passing the TestrunResult
 185     instance into the appropriate writer.
 186
 187     Returns whether the backend will attempt to use compression when writing
 188     the results file or not.
 189     """
 190
 191     extension, _ = get_extension(file_path)
 192
 193     for backend in BACKENDS.values():
 194         if extension in backend.extensions:
 195             writer = backend.write
 196
 197             if writer is None:
 198                 raise BackendNotImplementedError(
 199                     'Writer for {} is not implemented'.format(extension))
 200
 201             return writer(results, file_path)
 202
 203     raise BackendError(
 204         'No module supports file extension "{}"'.format(extension))
 205
 206
 207 def set_meta(backend, result):
 208     """Wrapper around meta that gets the right meta function."""
 209     try:
 210         BACKENDS[backend].meta(result)
 211     except KeyError:
 212         raise BackendError('No backend {}'.format(backend))
 213     except TypeError as e:
 214         # Since we initialize non-implemented backends as None, and None isn't
 215         # callable then we'll get a TypeError, and we're looking for NoneType
 216         # in the message. If we get that we really want a
 217         # BackendNotImplementedError
 218         if str(e) == "'NoneType' object is not callable":
 219             raise BackendNotImplementedError(
 220                 'meta function for {} not implemented.'.format(backend))
 221         else:
 222             # Otherwise re-raise the error
 223             raise