path: root/Lib/fontTools/misc/loggingTools.py

""" fontTools.misc.loggingTools.py -- tools for interfacing with the Python
logging package.
"""

from __future__ import print_function, absolute_import
from fontTools.misc.py23 import *
import sys
import logging
import timeit
from functools import wraps
try:
	from collections.abc import Mapping, Callable
except ImportError:  # python < 3.3
	from collections import Mapping, Callable
import warnings

try:
	from logging import PercentStyle
except ImportError:
	PercentStyle = None


# default logging level used by Timer class
TIME_LEVEL = logging.DEBUG

# per-level format strings used by the default formatter
# (the level name is not printed for INFO and DEBUG messages)
DEFAULT_FORMATS = {
	"*": "%(levelname)s: %(message)s",
	"INFO": "%(message)s",
	"DEBUG": "%(message)s",
	}


class LevelFormatter(logging.Formatter):
	""" Formatter class which optionally takes a dict of logging levels to
	format strings, allowing to customise the log records appearance for
	specific levels.
	The '*' key identifies the default format string.

	>>> import sys
	>>> handler = logging.StreamHandler(sys.stdout)
	>>> formatter = LevelFormatter(
	...     fmt={
	...         '*':     '[%(levelname)s] %(message)s',
	...         'DEBUG': '%(name)s [%(levelname)s] %(message)s',
	...         'INFO':  '%(message)s',
	...     })
	>>> handler.setFormatter(formatter)
	>>> log = logging.getLogger('test')
	>>> log.setLevel(logging.DEBUG)
	>>> log.addHandler(handler)
	>>> log.debug('this uses a custom format string')
	test [DEBUG] this uses a custom format string
	>>> log.info('this also uses a custom format string')
	this also uses a custom format string
	>>> log.warning("this one uses the default format string")
	[WARNING] this one uses the default format string
	"""

	def __init__(self, fmt=None, datefmt=None, style="%"):
		if style != '%':
			raise ValueError(
				"only '%' percent style is supported in both python 2 and 3")
		if fmt is None:
			fmt = DEFAULT_FORMATS
		if isinstance(fmt, basestring):
			default_format = fmt
			custom_formats = {}
		elif isinstance(fmt, Mapping):
			custom_formats = dict(fmt)
			default_format = custom_formats.pop("*", None)
		else:
			raise TypeError('fmt must be a str or a dict of str: %r' % fmt)
		super(LevelFormatter, self).__init__(default_format, datefmt)
		self.default_format = self._fmt
		self.custom_formats = {}
		for level, fmt in custom_formats.items():
			level = logging._checkLevel(level)
			self.custom_formats[level] = fmt

	def format(self, record):
		if self.custom_formats:
			fmt = self.custom_formats.get(record.levelno, self.default_format)
			if self._fmt != fmt:
				self._fmt = fmt
				# for python >= 3.2, _style needs to be set if _fmt changes
				if PercentStyle:
					self._style = PercentStyle(fmt)
		return super(LevelFormatter, self).format(record)


def configLogger(**kwargs):
	""" Do basic configuration for the logging system. This is more or less
	the same as logging.basicConfig with some additional options and defaults.

	The default behaviour is to create a StreamHandler which writes to
	sys.stderr, set a formatter using the DEFAULT_FORMATS strings, and add
	the handler to the top-level library logger ("fontTools").

	A number of optional keyword arguments may be specified, which can alter
	the default behaviour.

	logger    Specifies the logger name or a Logger instance to be configured.
	          (it defaults to "fontTools" logger). Unlike basicConfig, this
	          function can be called multiple times to reconfigure a logger.
	          If the logger or any of its children already exists before the
	          call is made, they will be reset before the new configuration
	          is applied.
	filename  Specifies that a FileHandler be created, using the specified
	          filename, rather than a StreamHandler.
	filemode  Specifies the mode to open the file, if filename is specified
	          (if filemode is unspecified, it defaults to 'a').
	format    Use the specified format string for the handler. This argument
	          also accepts a dictionary of format strings keyed by level name,
	          to allow customising the records appearance for specific levels.
	          The special '*' key is for 'any other' level.
	datefmt   Use the specified date/time format.
	level     Set the logger level to the specified level.
	stream    Use the specified stream to initialize the StreamHandler. Note
	          that this argument is incompatible with 'filename' - if both
	          are present, 'stream' is ignored.
	handlers  If specified, this should be an iterable of already created
	          handlers, which will be added to the logger. Any handler
	          in the list which does not have a formatter assigned will be
	          assigned the formatter created in this function.
	filters   If specified, this should be an iterable of already created
	          filters, which will be added to the handler(s), if the latter
	          do(es) not already have filters assigned.
	propagate All loggers have a "propagate" attribute initially set to True,
	          which determines whether to continue searching for handlers up
	          the logging hierarchy. By default, this arguments sets the
	          "propagate" attribute to False.
	"""
	# using kwargs to enforce keyword-only arguments in py2.
	handlers = kwargs.pop("handlers", None)
	if handlers is None:
		if "stream" in kwargs and "filename" in kwargs:
			raise ValueError("'stream' and 'filename' should not be "
							 "specified together")
	else:
		if "stream" in kwargs or "filename" in kwargs:
			raise ValueError("'stream' or 'filename' should not be "
							 "specified together with 'handlers'")
	if handlers is None:
		filename = kwargs.pop("filename", None)
		mode = kwargs.pop("filemode", 'a')
		if filename:
			h = logging.FileHandler(filename, mode)
		else:
			stream = kwargs.pop("stream", None)
			h = logging.StreamHandler(stream)
		handlers = [h]
	# By default, the top-level library logger is configured.
	logger = kwargs.pop("logger", "fontTools")
	if not logger or isinstance(logger, basestring):
		# empty "" or None means the 'root' logger
		logger = logging.getLogger(logger)
	# before (re)configuring, reset named logger and its children (if exist)
	_resetExistingLoggers(parent=logger.name)
	# use DEFAULT_FORMATS if 'format' is None
	fs = kwargs.pop("format", None)
	dfs = kwargs.pop("datefmt", None)
	# XXX: '%' is the only format style supported on both py2 and 3
	style = kwargs.pop("style", '%')
	fmt = LevelFormatter(fs, dfs, style)
	filters = kwargs.pop("filters", [])
	for h in handlers:
		if h.formatter is None:
			h.setFormatter(fmt)
		if not h.filters:
			for f in filters:
				h.addFilter(f)
		logger.addHandler(h)
	if logger.name != "root":
		# stop searching up the hierarchy for handlers
		logger.propagate = kwargs.pop("propagate", False)
	# set a custom severity level
	level = kwargs.pop("level", None)
	if level is not None:
		logger.setLevel(level)
	if kwargs:
		keys = ', '.join(kwargs.keys())
		raise ValueError('Unrecognised argument(s): %s' % keys)


def _resetExistingLoggers(parent="root"):
	""" Reset the logger named 'parent' and all its children to their initial
	state, if they already exist in the current configuration.
	"""
	root = logging.root
	# get sorted list of all existing loggers
	existing = sorted(root.manager.loggerDict.keys())
	if parent == "root":
		# all the existing loggers are children of 'root'
		loggers_to_reset = [parent] + existing
	elif parent not in existing:
		# nothing to do
		return
	elif parent in existing:
		loggers_to_reset = [parent]
		# collect children, starting with the entry after parent name
		i = existing.index(parent) + 1
		prefixed = parent + "."
		pflen = len(prefixed)
		num_existing = len(existing)
		while i < num_existing:
			if existing[i][:pflen] == prefixed:
				loggers_to_reset.append(existing[i])
			i += 1
	for name in loggers_to_reset:
		if name == "root":
			root.setLevel(logging.WARNING)
			for h in root.handlers[:]:
				root.removeHandler(h)
			for f in root.filters[:]:
				root.removeFilters(f)
			root.disabled = False
		else:
			logger = root.manager.loggerDict[name]
			logger.level = logging.NOTSET
			logger.handlers = []
			logger.filters = []
			logger.propagate = True
			logger.disabled = False


class Timer(object):
	""" Keeps track of overall time and split/lap times.

	>>> import time
	>>> timer = Timer()
	>>> time.sleep(0.01)
	>>> print("First lap:", timer.split())
	First lap: ...
	>>> time.sleep(0.02)
	>>> print("Second lap:", timer.split())
	Second lap: ...
	>>> print("Overall time:", timer.time())
	Overall time: ...

	Can be used as a context manager inside with-statements.

	>>> with Timer() as t:
	...     time.sleep(0.01)
	>>> print("%0.3f seconds" % t.elapsed)
	0... seconds

	If initialised with a logger, it can log the elapsed time automatically
	upon exiting the with-statement.

	>>> import logging
	>>> log = logging.getLogger("fontTools")
	>>> configLogger(level="DEBUG", format="%(message)s", stream=sys.stdout)
	>>> with Timer(log, 'do something'):
	...     time.sleep(0.01)
	Took ... to do something

	The same Timer instance, holding a reference to a logger, can be reused
	in multiple with-statements, optionally with different messages or levels.

	>>> timer = Timer(log)
	>>> with timer():
	...     time.sleep(0.01)
	elapsed time: ...s
	>>> with timer('redo it', level=logging.INFO):
	...     time.sleep(0.02)
	Took ... to redo it

	It can also be used as a function decorator to log the time elapsed to run
	the decorated function.

	>>> @timer()
	... def test1():
	...    time.sleep(0.01)
	>>> @timer('run test 2', level=logging.INFO)
	... def test2():
	...    time.sleep(0.02)
	>>> test1()
	Took ... to run 'test1'
	>>> test2()
	Took ... to run test 2
	"""

	# timeit.default_timer choses the most accurate clock for each platform
	_time = timeit.default_timer
	default_msg = "elapsed time: %(time).3fs"
	default_format = "Took %(time).3fs to %(msg)s"

	def __init__(self, logger=None, msg=None, level=None, start=None):
		self.reset(start)
		if logger is None:
			for arg in ('msg', 'level'):
				if locals().get(arg) is not None:
					raise ValueError(
						"'%s' can't be specified without a 'logger'" % arg)
		self.logger = logger
		self.level = level if level is not None else TIME_LEVEL
		self.msg = msg

	def reset(self, start=None):
		""" Reset timer to 'start_time' or the current time. """
		if start is None:
			self.start = self._time()
		else:
			self.start = start
		self.last = self.start
		self.elapsed = 0.0

	def time(self):
		""" Return the overall time (in seconds) since the timer started. """
		return self._time() - self.start

	def split(self):
		""" Split and return the lap time (in seconds) in between splits. """
		current = self._time()
		self.elapsed = current - self.last
		self.last = current
		return self.elapsed

	def formatTime(self, msg, time):
		""" Format 'time' value in 'msg' and return formatted string.
		If 'msg' contains a '%(time)' format string, try to use that.
		Otherwise, use the predefined 'default_format'.
		If 'msg' is empty or None, fall back to 'default_msg'.
		"""
		if not msg:
			msg = self.default_msg
		if msg.find("%(time)") < 0:
			msg = self.default_format % {"msg": msg, "time": time}
		else:
			try:
				msg = msg % {"time": time}
			except (KeyError, ValueError):
				pass  # skip if the format string is malformed
		return msg

	def __enter__(self):
		""" Start a new lap """
		self.last = self._time()
		self.elapsed = 0.0
		return self

	def __exit__(self, exc_type, exc_value, traceback):
		""" End the current lap. If timer has a logger, log the time elapsed,
		using the format string in self.msg (or the default one).
		"""
		time = self.split()
		if self.logger is None or exc_type:
			# if there's no logger attached, or if any exception occurred in
			# the with-statement, exit without logging the time
			return
		message = self.formatTime(self.msg, time)
		# Allow log handlers to see the individual parts to facilitate things
		# like a server accumulating aggregate stats.
		msg_parts = { 'msg': self.msg, 'time': time }
		self.logger.log(self.level, message, msg_parts)

	def __call__(self, func_or_msg=None, **kwargs):
		""" If the first argument is a function, return a decorator which runs
		the wrapped function inside Timer's context manager.
		Otherwise, treat the first argument as a 'msg' string and return an updated
		Timer instance, referencing the same logger.
		A 'level' keyword can also be passed to override self.level.
		"""
		if isinstance(func_or_msg, Callable):
			func = func_or_msg
			# use the function name when no explicit 'msg' is provided
			if not self.msg:
				self.msg = "run '%s'" % func.__name__

			@wraps(func)
			def wrapper(*args, **kwds):
				with self:
					return func(*args, **kwds)
			return wrapper
		else:
			msg = func_or_msg or kwargs.get("msg")
			level = kwargs.get("level", self.level)
			return self.__class__(self.logger, msg, level)

	def __float__(self):
		return self.elapsed

	def __int__(self):
		return int(self.elapsed)

	def __str__(self):
		return "%.3f" % self.elapsed


class ChannelsFilter(logging.Filter):
	""" Filter out records emitted from a list of enabled channel names,
	including their children. It works the same as the logging.Filter class,
	but allows to specify multiple channel names.

	>>> import sys
	>>> handler = logging.StreamHandler(sys.stdout)
	>>> handler.setFormatter(logging.Formatter("%(message)s"))
	>>> filter = ChannelsFilter("A.B", "C.D")
	>>> handler.addFilter(filter)
	>>> root = logging.getLogger()
	>>> root.addHandler(handler)
	>>> root.setLevel(level=logging.DEBUG)
	>>> logging.getLogger('A.B').debug('this record passes through')
	this record passes through
	>>> logging.getLogger('A.B.C').debug('records from children also pass')
	records from children also pass
	>>> logging.getLogger('C.D').debug('this one as well')
	this one as well
	>>> logging.getLogger('A.B.').debug('also this one')
	also this one
	>>> logging.getLogger('A.F').debug('but this one does not!')
	>>> logging.getLogger('C.DE').debug('neither this one!')
	"""

	def __init__(self, *names):
		self.names = names
		self.num = len(names)
		self.lenghts = {n: len(n) for n in names}

	def filter(self, record):
		if self.num == 0:
			return True
		for name in self.names:
			nlen = self.lenghts[name]
			if name == record.name:
				return True
			elif (record.name.find(name, 0, nlen) == 0
					and record.name[nlen] == "."):
				return True
		return False


class CapturingLogHandler(logging.Handler):
	def __init__(self, logger, level):
		super(CapturingLogHandler, self).__init__(level=level)
		self.records = []
		if isinstance(logger, basestring):
			self.logger = logging.getLogger(logger)
		else:
			self.logger = logger

	def __enter__(self):
		self.original_disabled = self.logger.disabled
		self.original_level = self.logger.level
		self.original_propagate = self.logger.propagate

		self.logger.addHandler(self)
		self.logger.setLevel(self.level)
		self.logger.disabled = False
		self.logger.propagate = False

		return self

	def __exit__(self, type, value, traceback):
		self.logger.removeHandler(self)
		self.logger.setLevel(self.original_level)
		self.logger.disabled = self.original_disabled
		self.logger.propagate = self.original_propagate

		return self

	def emit(self, record):
		self.records.append(record)

	def assertRegex(self, regexp, msg=None):
		import re
		pattern = re.compile(regexp)
		for r in self.records:
			if pattern.search(r.getMessage()):
				return True
		if msg is None:
			msg = "Pattern '%s' not found in logger records" % regexp
		assert 0, msg


class LogMixin(object):
	""" Mixin class that adds logging functionality to another class.
	You can define a new class that subclasses from LogMixin as well as
	other base classes through multiple inheritance.
	All instances of that class will have a 'log' property that returns
	a logging.Logger named after their respective <module>.<class>.
	For example:

	>>> class BaseClass(object):
	...     pass
	>>> class MyClass(LogMixin, BaseClass):
	...     pass
	>>> a = MyClass()
	>>> isinstance(a.log, logging.Logger)
	True
	>>> print(a.log.name)
	fontTools.misc.loggingTools.MyClass
	>>> class AnotherClass(MyClass):
	...     pass
	>>> b = AnotherClass()
	>>> isinstance(b.log, logging.Logger)
	True
	>>> print(b.log.name)
	fontTools.misc.loggingTools.AnotherClass
	"""

	@property
	def log(self):
		if not hasattr(self, "_log"):
			name = ".".join(
				(self.__class__.__module__, self.__class__.__name__)
			)
			self._log = logging.getLogger(name)
		return self._log


def deprecateArgument(name, msg, category=UserWarning):
	""" Raise a warning about deprecated function argument 'name'. """
	warnings.warn(
		"%r is deprecated; %s" % (name, msg), category=category, stacklevel=3)


def deprecateFunction(msg, category=UserWarning):
	""" Decorator to raise a warning when a deprecated function is called. """
	def decorator(func):
		@wraps(func)
		def wrapper(*args, **kwargs):
			warnings.warn(
				"%r is deprecated; %s" % (func.__name__, msg),
				category=category, stacklevel=2)
			return func(*args, **kwargs)
		return wrapper
	return decorator


class LastResortLogger(logging.Logger):
	""" Adds support for 'lastResort' handler introduced in Python 3.2.
	It allows to print messages to sys.stderr even when no explicit handler
	was configured.
	To enable it, you can do:

		import logging
		logging.lastResort = StderrHandler(logging.WARNING)
		logging.setLoggerClass(LastResortLogger)
	"""

	def callHandlers(self, record):
		# this is the same as Python 3.5's logging.Logger.callHandlers
		c = self
		found = 0
		while c:
			for hdlr in c.handlers:
				found = found + 1
				if record.levelno >= hdlr.level:
					hdlr.handle(record)
			if not c.propagate:
				c = None  # break out
			else:
				c = c.parent
		if found == 0:
			if logging.lastResort:
				if record.levelno >= logging.lastResort.level:
					logging.lastResort.handle(record)
			elif (
				logging.raiseExceptions
				and not self.manager.emittedNoHandlerWarning
			):
				sys.stderr.write(
					"No handlers could be found for logger"
					' "%s"\n' % self.name
				)
				self.manager.emittedNoHandlerWarning = True


class StderrHandler(logging.StreamHandler):
	""" This class is like a StreamHandler using sys.stderr, but always uses
	whateve sys.stderr is currently set to rather than the value of
	sys.stderr at handler construction time.
	"""

	def __init__(self, level=logging.NOTSET):
		"""
		Initialize the handler.
		"""
		logging.Handler.__init__(self, level)

	@property
	def stream(self):
		# the try/execept avoids failures during interpreter shutdown, when
		# globals are set to None
		try:
			return sys.stderr
		except AttributeError:
			return __import__("sys").stderr


if __name__ == "__main__":
	import doctest
	sys.exit(doctest.testmod(optionflags=doctest.ELLIPSIS).failed)