1 # The software in this package is distributed under the GNU General
2 # Public License version 2 (with a special exception described below).
4 # A copy of GNU General Public License (GPL) is included in this distribution,
5 # in the file COPYING.GPL.
7 # As a special exception, if other files instantiate templates or use macros
8 # or inline functions from this file, or you compile this file and link it
9 # with other works to produce a work based on this file, this file
10 # does not by itself cause the resulting work to be covered
11 # by the GNU General Public License.
13 # However the source code for this file must still be made available
14 # in accordance with section (3) of the GNU General Public License.
16 # This exception does not invalidate any other reasons why a work based
17 # on this file might be covered by the GNU General Public License.
19 # Copyright (c) 2016-2018 Intra2net AG <info@intra2net.com>
21 """ Helpers for logging; featuring:
23 ShortLevelFormatter: provide a 4-char-sized field "shortlevel" for message
24 urgency (dbug/info/warn/err /crit)
26 I2nLogger: logger that provides a notice(), allows omission for str.format
27 and is quite convenient in general
29 get_logger: factor for creating I2nLoggers
32 * allow milliseconds in dateformat field (see test_short_level_format)
33 * create own basicConfig-like function that uses our classes as default
34 --> started using I2nLogger constructor and get_logger
35 * try to find out module that calls I2nLogger constructor to provide a good
36 default value for name (finding out the current module is a pain in the a..)
38 .. todo:: create unittests from test_* functions at bottom
39 .. todo:: think about how to allow different levels per handler
40 .. todo:: do not limit logs by line numbers but by disc size? Warn when at 50%,
41 75%, 90%, 99% of limit?
45 from logging import DEBUG, INFO, WARNING, ERROR, CRITICAL, NOTSET
46 from math import log10, floor
49 from .type_helpers import isstr
51 #: log level half-way between INFO and WARNING
52 NOTICE = (INFO + WARNING)//2
53 logging.addLevelName(NOTICE, 'NOTICE')
55 #: default formatting string for ShortLevelFormatter
56 DEFAULT_SHORT_LEVEL_FORMAT = '%(asctime)s:%(msecs)03d %(shortlevel)s| %(msg)s'
58 #: default formatting string for date/time in ShortLevelFormatter
59 DEFAULT_SHORT_LEVEL_DATE_FORMAT = '%H:%M:%S'
61 #: mapping from level name to level int for I2nLogger's set_level
62 LEVEL_DICT = dict(notset=NOTSET, debug=DEBUG, info=INFO, notice=NOTICE,
63 warning=WARNING, error=ERROR, critical=CRITICAL)
65 #: min level allowed in I2nLogger
68 #: max level allowed in I2nLogger
71 #: constant for I2nLogger streams argument: stream to stdout
75 class ShortLevelFormatter(logging.Formatter):
77 Formatter for logging handlers that allows use of format field "shortlevel"
79 using this formatter, you can specify in the log message format string the
80 field "shortlevel" which will introduce in your log messages a 4-char field
81 for the log record urgency: "DEBUG" --> "dbug", "INFO" --> "info",
82 "WARNING" --> "warn", "ERROR" --> "err ", "CRITICAL" --> "crit"
84 All other functionality (like other format fields) is inherited from base
87 Most easily used indirectly through :py:class:`I2nLogger`
88 (uses this by default)
90 Explicit usage example::
92 logger = logging.getLogger(__name__)
93 logger.setLevel(logging.DEBUG)
94 handler = logging.StreamHandler()
95 handler.setLevel(logging.DEBUG)
96 formatter = ShortLevelFormatter('%(shortlevel)s| %(msg)s')
97 handler.setFormatter(formatter)
98 logger.addHandler(handler)
100 You can even add new levels::
102 notice = (logging.INFO + logging.WARNING)/2
103 formatter.add_level(notice, 'note')
104 logger.log(notice, 'more important than info but no warning nor error')
106 .. seealso:: testing funcion :py:func:`test_short_level_format`
109 def __init__(self, fmt=DEFAULT_SHORT_LEVEL_FORMAT,
110 datefmt=DEFAULT_SHORT_LEVEL_DATE_FORMAT, *args, **kwargs):
111 """ creates a new ShortLevelFormatter
113 forwards all args to super class Formatter and initializes dict with
114 levelno and short string representations
116 self.parent = super(ShortLevelFormatter, self)
117 self.parent.__init__(fmt=fmt, datefmt=datefmt, *args, **kwargs)
118 self._shortlevel_dict = {DEBUG: 'dbug', INFO: 'info', WARNING: 'warn',
119 ERROR: 'err ', CRITICAL: 'crit',
122 def format(self, record):
123 """ create string representation of given log record """
125 record.shortlevel = self._shortlevel_dict[record.levelno]
127 record.shortlevel = '????'
129 return self.parent.format(record)
131 def add_level(self, levelno, shortlevel_str):
132 """ add a new message urgency level
134 :param int levelno: numeric urgency level
135 :param str shortlevel_str: string representation of message urgency;
136 should be of length 4
140 self._shortlevel_dict[levelno] = shortlevel_str
143 #: memory for all I2nLogger instances in current session to avoid overwrite
144 #: used in :py:func:`get_logger` and :py:class:`I2nLogger` constructor
148 def get_logger(name, *args, **kwargs):
149 """ factory for :py:class:`I2nLogger`: create new or return existing object
151 all args as in :py:class:`I2nLogger` constructor; args will be ignored if
152 logger with given name exists already!
155 if name in _i2n_loggers:
156 return _i2n_loggers[name] # ignore all args
158 return I2nLogger(name, *args, **kwargs)
162 """ a more convenient logger
165 * can be used without ".format()" as follows::
167 logger.info('the result is {0}', result) # more convenient than...
168 logger.info('the result is {0}'.format(result)) # ... the original
170 * Has a :py:meth:`Logger.notice` function
171 * Has by default as only handler a :py:class:`logging.StreamHandler` to
172 stdout with a :py:class:`ShortLevelFormatter`
173 * Simplifies setting of logger's logging level using
174 :py:meth:`Logger.set_level`. The level is kept in sync between logger and
175 handlers and can be queried using :py:meth:`get_level`
176 (does not work accross logger hierarchies!)
177 * can specify name and level and [date]fmt all in constructor
178 * can limit the number of lines this logger will produce to prevent filling
179 hard drive with log file
180 (assumes one line per call to log/debug/info/notice/...,
181 only counts calls with priority above this logger's level)
182 * provides shorter method names: dbg, note, warn, err
184 ..note:: Creating multiple instances with the same name is not allowed and
185 will result in an error. Use :py:func:`get_logger` instead of this
186 constructor to avoid such situtations
188 ..note:: Do not change or use the underlying logger or functionality here
189 (in particular, get_level) is no longer reliable!
192 def __init__(self, name, level=INFO, fmt=DEFAULT_SHORT_LEVEL_FORMAT,
193 datefmt=DEFAULT_SHORT_LEVEL_DATE_FORMAT,
194 streams=STDOUT, files=None, handlers=None):
195 """ creates a I2nLogger; forwards args to logging.getLogger
198 :param str name: name of this logger, best practice is module name
199 :param int level: best use one of the constants DEBUG, INFO NOTICE,
201 :param str fmt: format of log messages, see
202 :py:class:`ShortLevelFormatter` for more help
203 :param str datefmt: format of date added to log messages, see
204 :py:class:`ShortLevelFormatter` for more help
205 :param streams: list/tuple of or a single stream to log to, default is
207 :type streams: (:py:class:`io.IOBase`) or [:py:class:`io.IOBase`) or
209 :param files: list/tuple or single file name to log to
210 :type files: None or (str) or [str]
211 :param handlers: other handlers to customize and use with this logger
212 :type handlers: None or [:py:class:`logging.Handler`] or
213 (:py:class:`logging.Handler`)
214 :raise: ValueError if an I2nLogger with the same name exists already
217 # check if an instance with the same name has been created earlier
218 # to prevent conflicts
220 if name in _i2n_loggers:
221 raise ValueError("An I2nLogger with that exact name ('{0}') exists"
222 " already -- use get_logger instead!"
225 self._log = logging.getLogger(name)
226 if isinstance(level, str):
227 level = LEVEL_DICT[level]
228 self._level = min(MAX_LEVEL, max(MIN_LEVEL, level))
229 self._log.setLevel(self._level)
231 # remove handlers (sometimes there are mutliple by default)
232 for handler in self._log.handlers:
233 self._log.removeHandler(handler)
235 # create new handlers and formatter
238 elif not isinstance(streams, (list, tuple)):
239 streams = (streams, )
240 for stream in streams:
241 formatter = ShortLevelFormatter(fmt=fmt, datefmt=datefmt)
242 formatter.add_level(NOTICE, 'note')
243 new_handler = logging.StreamHandler(stream)
244 new_handler.setFormatter(formatter)
245 new_handler.setLevel(self._level)
246 self._log.addHandler(new_handler)
250 elif not isinstance(files, (list, tuple)):
252 for file_name in files:
253 formatter = ShortLevelFormatter(fmt=fmt, datefmt=datefmt)
254 formatter.add_level(NOTICE, 'note')
255 new_handler = logging.FileHandler(file_name)
256 new_handler.setFormatter(formatter)
257 new_handler.setLevel(self._level)
258 self._log.addHandler(new_handler)
262 elif not isinstance(handlers, (list, tuple)):
263 handlers = (handlers, )
264 for handler in handlers:
265 formatter = ShortLevelFormatter(fmt=fmt, datefmt=datefmt)
266 formatter.add_level(NOTICE, 'note')
267 handler.setFormatter(formatter)
268 handler.setLevel(self._level)
269 self._log.addHandler(handler)
271 # remember that this logger is a I2nLogger
272 _i2n_loggers[name] = self
274 def dbg(self, message, *args, **kwargs):
275 self._log_no_test(DEBUG, message, *args, **kwargs)
277 def debug(self, message, *args, **kwargs):
278 self._log_no_test(DEBUG, message, *args, **kwargs)
280 def info(self, message, *args, **kwargs):
281 self._log_no_test(INFO, message, *args, **kwargs)
283 def note(self, message, *args, **kwargs):
284 self._log_no_test(NOTICE, message, *args, **kwargs)
286 def notice(self, message, *args, **kwargs):
287 self._log_no_test(NOTICE, message, *args, **kwargs)
289 def warn(self, message, *args, **kwargs):
290 self._log_no_test(WARNING, message, *args, **kwargs)
292 def warning(self, message, *args, **kwargs):
293 self._log_no_test(WARNING, message, *args, **kwargs)
295 def err(self, message, *args, **kwargs):
296 self._log_no_test(ERROR, message, *args, **kwargs)
298 def error(self, message, *args, **kwargs):
299 self._log_no_test(ERROR, message, *args, **kwargs)
301 def exception(self, message, *args, **kwargs):
302 if 'exc_info' in kwargs:
303 self._log_no_test(ERROR, message, *args, **kwargs)
305 self._log_no_test(ERROR, message, *args, exc_info=True, **kwargs)
307 def critical(self, message, *args, **kwargs):
308 self._log_no_test(CRITICAL, message, *args, **kwargs)
310 def log(self, level, message, *args, **kwargs):
311 if isinstance(level, str):
312 level = LEVEL_DICT[level.lower()]
313 if level >= self._level:
315 message_formatted = message.format(*args)
316 except (KeyError, IndexError):
317 message_formatted = '[LOG ARGS!] ' + message
318 self._log.log(level, message_formatted, **kwargs)
320 def _log_no_test(self, level, message, *args, **kwargs):
321 """ same as log() but without the isinstance test for internal use"""
322 if level >= self._level:
324 message_formatted = message.format(*args)
325 except (KeyError, IndexError):
326 message_formatted = '[LOG ARGS!] ' + message
327 self._log.log(level, message_formatted, **kwargs)
329 def log_count_if_interesting(self, count, level=INFO, counter_name=None):
330 """ Log value of a counter in gradually coarser intervals
332 see :py:func:`is_interesting_count` for definition of "interesting"
334 if is_interesting_count(count):
336 self.log(level, '{0} counter is at {1}', counter_name, count)
338 self.log(level, 'Counter is at {0}', count)
341 """ return int level of this logger """
344 def get_level_str(self):
345 """ returns :py:func:`logging.getLevelName` on :py:meth:`get_level` """
346 return logging.getLevelName(self._level)
348 def set_level(self, new_level):
349 """ set level given an int or a str
351 :arg new_level: int or str (str is converted to lower case)
352 :raises: KeyError if new_level is a string that is not in
353 :py:data:`LEVEL_DICT`
356 self._level = LEVEL_DICT[new_level.lower()]
358 self._level = min(MAX_LEVEL, max(MIN_LEVEL, new_level))
359 self._log.setLevel(self._level)
360 for handler in self._log.handlers:
361 handler.setLevel(self._level)
364 def n_digits(number):
365 """ returns the number of digits a number has in decimal format
367 :returns: 1 for 1...9, 2 for 10...99, 3 for 100...999, ...
368 0 for 0 (and everything else beween -1 and 1)
369 1 for -1...-9, 2 for -10...-99, ...
374 return floor(log10(abs(number)))+1
376 def is_interesting_count(counter):
377 """ return True if counter has reached an "interesting" value
379 For the counter to be "interesting" becomes ever harder. At first it is
380 easy (returns True for 1,2,3,6,10), then becomes harder (True only for
381 10,20,30,60,100) and harder (True for 100,200,300,600,1000) and this scheme
382 continues on a logartihmic scale.
384 An example that will print lots in the beginning and then less and less::
387 while not end_reached():
389 if is_interesting_count(counter):
390 log('reached iteration {0}'.format(counter))
393 Or implicitly using I2nLogger::log_count_if_interesting(counter)
395 :returns: True for a few values of counter, False most of the time
398 return float(counter) / 10.**(n_digits(counter)-1.) in (1., 2., 3., 6.)
400 def test_short_level_format():
401 """ quick test of :py:class:`ShortLevelFormatter` """
403 logger = logging.getLogger('logtest')
404 logger.setLevel(DEBUG)
405 handler = logging.StreamHandler()
406 handler.setLevel(DEBUG)
407 formatter = ShortLevelFormatter(
408 '%(asctime)s:%(msecs)03d %(shortlevel)s| %(msg)s'
409 ' [regular levelname=%(levelname)s]',
411 handler.setFormatter(formatter)
412 logger.addHandler(handler)
415 logger.debug('debug message')
416 logger.info('info message')
417 logger.warn('warn message')
418 logger.error('error message')
419 logger.critical('critical message')
420 logger.log(15, 'unknown level')
421 logger.log(NOTSET, 'level not set')
424 notice = (logging.INFO + logging.WARNING)/2
425 formatter.add_level(notice, 'note')
426 logger.log(notice, 'more important than info but no warning nor error')
428 # try if exception formatting still works:
430 logger.info('this is what an exception looks like:')
431 impossible_result = 1/0
432 logger.critical('just divided 1/0! The result is {0}'
433 .format(impossible_result))
434 except ZeroDivisionError:
435 logger.exception('1/0 still does not work!', exc_info=True)
438 logger.info('done testing')
440 def test_get_logger():
441 log = get_logger('logger_test')
442 log2 = get_logger('logger_test')
446 def test_line_counter():
447 log = get_logger('logger_test', max_lines=10)
448 for idx in range(20):
450 log.debug('should not show nor count')
451 print('calling log for idx {0}'.format(idx))
452 log.info('logging with idx {0}', idx)
453 log.log_count_if_interesting(idx)
456 def test_error_in_formatting():
457 log = get_logger('logger_test')
458 log.warn('forgot to add argument {} and {1} and {cnf} to format string')
459 log.warn('wrong number {} of arguments {}', 1)
461 if __name__ == '__main__':
462 #test_short_level_format()
465 test_error_in_formatting()