Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/absl/app.py: 30%
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1# Copyright 2017 The Abseil Authors.
2#
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
6#
7# http://www.apache.org/licenses/LICENSE-2.0
8#
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"""Generic entry point for Abseil Python applications.
17To use this module, define a ``main`` function with a single ``argv`` argument
18and call ``app.run(main)``. For example::
20 def main(argv):
21 if len(argv) > 1:
22 raise app.UsageError('Too many command-line arguments.')
24 if __name__ == '__main__':
25 app.run(main)
26"""
28import collections
29import errno
30import os
31import pdb
32import sys
33import textwrap
34import traceback
36from absl import command_name
37from absl import flags
38from absl import logging
40try:
41 import faulthandler
42except ImportError:
43 faulthandler = None
45FLAGS = flags.FLAGS
47flags.DEFINE_boolean('run_with_pdb', False, 'Set to true for PDB debug mode')
48flags.DEFINE_boolean('pdb_post_mortem', False,
49 'Set to true to handle uncaught exceptions with PDB '
50 'post mortem.')
51flags.DEFINE_alias('pdb', 'pdb_post_mortem')
52flags.DEFINE_boolean('run_with_profiling', False,
53 'Set to true for profiling the script. '
54 'Execution will be slower, and the output format might '
55 'change over time.')
56flags.DEFINE_string('profile_file', None,
57 'Dump profile information to a file (for python -m '
58 'pstats). Implies --run_with_profiling.')
59flags.DEFINE_boolean('use_cprofile_for_profiling', True,
60 'Use cProfile instead of the profile module for '
61 'profiling. This has no effect unless '
62 '--run_with_profiling is set.')
63flags.DEFINE_boolean('only_check_args', False,
64 'Set to true to validate args and exit.',
65 allow_hide_cpp=True)
68# If main() exits via an abnormal exception, call into these
69# handlers before exiting.
70EXCEPTION_HANDLERS = []
73class Error(Exception):
74 pass
77class UsageError(Error):
78 """Exception raised when the arguments supplied by the user are invalid.
80 Raise this when the arguments supplied are invalid from the point of
81 view of the application. For example when two mutually exclusive
82 flags have been supplied or when there are not enough non-flag
83 arguments. It is distinct from flags.Error which covers the lower
84 level of parsing and validating individual flags.
85 """
87 def __init__(self, message, exitcode=1):
88 super(UsageError, self).__init__(message)
89 self.exitcode = exitcode
92class HelpFlag(flags.BooleanFlag):
93 """Special boolean flag that displays usage and raises SystemExit."""
94 NAME = 'help'
95 SHORT_NAME = '?'
97 def __init__(self):
98 super(HelpFlag, self).__init__(
99 self.NAME, False, 'show this help',
100 short_name=self.SHORT_NAME, allow_hide_cpp=True)
102 def parse(self, arg):
103 if self._parse(arg):
104 usage(shorthelp=True, writeto_stdout=True)
105 # Advertise --helpfull on stdout, since usage() was on stdout.
106 print()
107 print('Try --helpfull to get a list of all flags.')
108 sys.exit(1)
111class HelpshortFlag(HelpFlag):
112 """--helpshort is an alias for --help."""
113 NAME = 'helpshort'
114 SHORT_NAME = None
117class HelpfullFlag(flags.BooleanFlag):
118 """Display help for flags in the main module and all dependent modules."""
120 def __init__(self):
121 super(HelpfullFlag, self).__init__(
122 'helpfull', False, 'show full help', allow_hide_cpp=True)
124 def parse(self, arg):
125 if self._parse(arg):
126 usage(writeto_stdout=True)
127 sys.exit(1)
130class HelpXMLFlag(flags.BooleanFlag):
131 """Similar to HelpfullFlag, but generates output in XML format."""
133 def __init__(self):
134 super(HelpXMLFlag, self).__init__(
135 'helpxml', False, 'like --helpfull, but generates XML output',
136 allow_hide_cpp=True)
138 def parse(self, arg):
139 if self._parse(arg):
140 flags.FLAGS.write_help_in_xml_format(sys.stdout)
141 sys.exit(1)
144def parse_flags_with_usage(args):
145 """Tries to parse the flags, print usage, and exit if unparsable.
147 Args:
148 args: [str], a non-empty list of the command line arguments including
149 program name.
151 Returns:
152 [str], a non-empty list of remaining command line arguments after parsing
153 flags, including program name.
154 """
155 try:
156 return FLAGS(args)
157 except flags.Error as error:
158 message = str(error)
159 if '\n' in message:
160 final_message = 'FATAL Flags parsing error:\n%s\n' % textwrap.indent(
161 message, ' ')
162 else:
163 final_message = 'FATAL Flags parsing error: %s\n' % message
164 sys.stderr.write(final_message)
165 sys.stderr.write('Pass --helpshort or --helpfull to see help on flags.\n')
166 sys.exit(1)
169_define_help_flags_called = False
172def define_help_flags():
173 """Registers help flags. Idempotent."""
174 # Use a global to ensure idempotence.
175 global _define_help_flags_called
177 if not _define_help_flags_called:
178 flags.DEFINE_flag(HelpFlag())
179 flags.DEFINE_flag(HelpshortFlag()) # alias for --help
180 flags.DEFINE_flag(HelpfullFlag())
181 flags.DEFINE_flag(HelpXMLFlag())
182 _define_help_flags_called = True
185def _register_and_parse_flags_with_usage(
186 argv=None,
187 flags_parser=parse_flags_with_usage,
188):
189 """Registers help flags, parses arguments and shows usage if appropriate.
191 This also calls sys.exit(0) if flag --only_check_args is True.
193 Args:
194 argv: [str], a non-empty list of the command line arguments including
195 program name, sys.argv is used if None.
196 flags_parser: Callable[[List[Text]], Any], the function used to parse flags.
197 The return value of this function is passed to `main` untouched.
198 It must guarantee FLAGS is parsed after this function is called.
200 Returns:
201 The return value of `flags_parser`. When using the default `flags_parser`,
202 it returns the following:
203 [str], a non-empty list of remaining command line arguments after parsing
204 flags, including program name.
206 Raises:
207 Error: Raised when flags_parser is called, but FLAGS is not parsed.
208 SystemError: Raised when it's called more than once.
209 """
210 if _register_and_parse_flags_with_usage.done:
211 raise SystemError('Flag registration can be done only once.')
213 define_help_flags()
215 original_argv = sys.argv if argv is None else argv
216 args_to_main = flags_parser(original_argv)
217 if not FLAGS.is_parsed():
218 raise Error('FLAGS must be parsed after flags_parser is called.')
220 # Exit when told so.
221 if FLAGS.only_check_args:
222 sys.exit(0)
223 # Immediately after flags are parsed, bump verbosity to INFO if the flag has
224 # not been set.
225 if FLAGS['verbosity'].using_default_value:
226 FLAGS.verbosity = 0
227 _register_and_parse_flags_with_usage.done = True
229 return args_to_main
231_register_and_parse_flags_with_usage.done = False
234def _run_main(main, argv):
235 """Calls main, optionally with pdb or profiler."""
236 if FLAGS.run_with_pdb:
237 sys.exit(pdb.runcall(main, argv))
238 elif FLAGS.run_with_profiling or FLAGS.profile_file:
239 # Avoid import overhead since most apps (including performance-sensitive
240 # ones) won't be run with profiling.
241 # pylint: disable=g-import-not-at-top
242 import atexit
243 if FLAGS.use_cprofile_for_profiling:
244 import cProfile as profile
245 else:
246 import profile
247 profiler = profile.Profile()
248 if FLAGS.profile_file:
249 atexit.register(profiler.dump_stats, FLAGS.profile_file)
250 else:
251 atexit.register(profiler.print_stats)
252 sys.exit(profiler.runcall(main, argv))
253 else:
254 sys.exit(main(argv))
257def _call_exception_handlers(exception):
258 """Calls any installed exception handlers."""
259 for handler in EXCEPTION_HANDLERS:
260 try:
261 if handler.wants(exception):
262 handler.handle(exception)
263 except: # pylint: disable=bare-except
264 try:
265 # We don't want to stop for exceptions in the exception handlers but
266 # we shouldn't hide them either.
267 logging.error(traceback.format_exc())
268 except: # pylint: disable=bare-except
269 # In case even the logging statement fails, ignore.
270 pass
273def run(
274 main,
275 argv=None,
276 flags_parser=parse_flags_with_usage,
277):
278 """Begins executing the program.
280 Args:
281 main: The main function to execute. It takes an single argument "argv",
282 which is a list of command line arguments with parsed flags removed.
283 The return value is passed to `sys.exit`, and so for example
284 a return value of 0 or None results in a successful termination, whereas
285 a return value of 1 results in abnormal termination.
286 For more details, see https://docs.python.org/3/library/sys#sys.exit
287 argv: A non-empty list of the command line arguments including program name,
288 sys.argv is used if None.
289 flags_parser: Callable[[List[Text]], Any], the function used to parse flags.
290 The return value of this function is passed to `main` untouched.
291 It must guarantee FLAGS is parsed after this function is called.
292 Should be passed as a keyword-only arg which will become mandatory in a
293 future release.
294 - Parses command line flags with the flag module.
295 - If there are any errors, prints usage().
296 - Calls main() with the remaining arguments.
297 - If main() raises a UsageError, prints usage and the error message.
298 """
299 try:
300 args = _run_init(
301 sys.argv if argv is None else argv,
302 flags_parser,
303 )
304 while _init_callbacks:
305 callback = _init_callbacks.popleft()
306 callback()
307 try:
308 _run_main(main, args)
309 except UsageError as error:
310 usage(shorthelp=True, detailed_error=error, exitcode=error.exitcode)
311 except:
312 exc = sys.exc_info()[1]
313 # Don't try to post-mortem debug successful SystemExits, since those
314 # mean there wasn't actually an error. In particular, the test framework
315 # raises SystemExit(False) even if all tests passed.
316 if isinstance(exc, SystemExit) and not exc.code:
317 raise
319 # Check the tty so that we don't hang waiting for input in an
320 # non-interactive scenario.
321 if FLAGS.pdb_post_mortem and sys.stdout.isatty():
322 traceback.print_exc()
323 print()
324 print(' *** Entering post-mortem debugging ***')
325 print()
326 pdb.post_mortem()
327 raise
328 except Exception as e:
329 _call_exception_handlers(e)
330 raise
332# Callbacks which have been deferred until after _run_init has been called.
333_init_callbacks = collections.deque()
336def call_after_init(callback):
337 """Calls the given callback only once ABSL has finished initialization.
339 If ABSL has already finished initialization when ``call_after_init`` is
340 called then the callback is executed immediately, otherwise `callback` is
341 stored to be executed after ``app.run`` has finished initializing (aka. just
342 before the main function is called).
344 If called after ``app.run``, this is equivalent to calling ``callback()`` in
345 the caller thread. If called before ``app.run``, callbacks are run
346 sequentially (in an undefined order) in the same thread as ``app.run``.
348 Args:
349 callback: a callable to be called once ABSL has finished initialization.
350 This may be immediate if initialization has already finished. It
351 takes no arguments and returns nothing.
352 """
353 if _run_init.done:
354 callback()
355 else:
356 _init_callbacks.append(callback)
359def _run_init(
360 argv,
361 flags_parser,
362):
363 """Does one-time initialization and re-parses flags on rerun."""
364 if _run_init.done:
365 return flags_parser(argv)
366 command_name.make_process_name_useful()
367 # Set up absl logging handler.
368 logging.use_absl_handler()
369 args = _register_and_parse_flags_with_usage(
370 argv=argv,
371 flags_parser=flags_parser,
372 )
373 if faulthandler:
374 try:
375 faulthandler.enable()
376 except Exception: # pylint: disable=broad-except
377 # Some tests verify stderr output very closely, so don't print anything.
378 # Disabled faulthandler is a low-impact error.
379 pass
380 _run_init.done = True
381 return args
384_run_init.done = False
387def usage(shorthelp=False, writeto_stdout=False, detailed_error=None,
388 exitcode=None):
389 """Writes __main__'s docstring to stderr with some help text.
391 Args:
392 shorthelp: bool, if True, prints only flags from the main module,
393 rather than all flags.
394 writeto_stdout: bool, if True, writes help message to stdout,
395 rather than to stderr.
396 detailed_error: str, additional detail about why usage info was presented.
397 exitcode: optional integer, if set, exits with this status code after
398 writing help.
399 """
400 if writeto_stdout:
401 stdfile = sys.stdout
402 else:
403 stdfile = sys.stderr
405 doc = sys.modules['__main__'].__doc__
406 if not doc:
407 doc = '\nUSAGE: %s [flags]\n' % sys.argv[0]
408 doc = flags.text_wrap(doc, indent=' ', firstline_indent='')
409 else:
410 # Replace all '%s' with sys.argv[0], and all '%%' with '%'.
411 num_specifiers = doc.count('%') - 2 * doc.count('%%')
412 try:
413 doc %= (sys.argv[0],) * num_specifiers
414 except (OverflowError, TypeError, ValueError):
415 # Just display the docstring as-is.
416 pass
417 if shorthelp:
418 flag_str = FLAGS.main_module_help()
419 else:
420 flag_str = FLAGS.get_help()
421 try:
422 stdfile.write(doc)
423 if flag_str:
424 stdfile.write('\nflags:\n')
425 stdfile.write(flag_str)
426 stdfile.write('\n')
427 if detailed_error is not None:
428 stdfile.write('\n%s\n' % detailed_error)
429 except IOError as e:
430 # We avoid printing a huge backtrace if we get EPIPE, because
431 # "foo.par --help | less" is a frequent use case.
432 if e.errno != errno.EPIPE:
433 raise
434 if exitcode is not None:
435 sys.exit(exitcode)
438class ExceptionHandler(object):
439 """Base exception handler from which other may inherit."""
441 def wants(self, exc):
442 """Returns whether this handler wants to handle the exception or not.
444 This base class returns True for all exceptions by default. Override in
445 subclass if it wants to be more selective.
447 Args:
448 exc: Exception, the current exception.
449 """
450 del exc # Unused.
451 return True
453 def handle(self, exc):
454 """Do something with the current exception.
456 Args:
457 exc: Exception, the current exception
459 This method must be overridden.
460 """
461 raise NotImplementedError()
464def install_exception_handler(handler):
465 """Installs an exception handler.
467 Args:
468 handler: ExceptionHandler, the exception handler to install.
470 Raises:
471 TypeError: Raised when the handler was not of the correct type.
473 All installed exception handlers will be called if main() exits via
474 an abnormal exception, i.e. not one of SystemExit, KeyboardInterrupt,
475 FlagsError or UsageError.
476 """
477 if not isinstance(handler, ExceptionHandler):
478 raise TypeError('handler of type %s does not inherit from ExceptionHandler'
479 % type(handler))
480 EXCEPTION_HANDLERS.append(handler)