pelican-theme/pelican/log.py

import logging
import os
import sys
from collections import defaultdict
from collections.abc import Mapping

__all__ = [
    'init'
]


class BaseFormatter(logging.Formatter):
    def __init__(self, fmt=None, datefmt=None):
        FORMAT = '%(customlevelname)s %(message)s'
        super().__init__(fmt=FORMAT, datefmt=datefmt)

    def format(self, record):
        customlevel = self._get_levelname(record.levelname)
        record.__dict__['customlevelname'] = customlevel
        # format multiline messages 'nicely' to make it clear they are together
        record.msg = record.msg.replace('\n', '\n  | ')
        if not isinstance(record.args, Mapping):
            record.args = tuple(arg.replace('\n', '\n  | ') if
                                isinstance(arg, str) else
                                arg for arg in record.args)
        return super().format(record)

    def formatException(self, ei):
        ''' prefix traceback info for better representation '''
        s = super().formatException(ei)
        # fancy format traceback
        s = '\n'.join('  | ' + line for line in s.splitlines())
        # separate the traceback from the preceding lines
        s = '  |___\n{}'.format(s)
        return s

    def _get_levelname(self, name):
        ''' NOOP: overridden by subclasses '''
        return name


class ANSIFormatter(BaseFormatter):
    ANSI_CODES = {
        'red': '\033[1;31m',
        'yellow': '\033[1;33m',
        'cyan': '\033[1;36m',
        'white': '\033[1;37m',
        'bgred': '\033[1;41m',
        'bggrey': '\033[1;100m',
        'reset': '\033[0;m'}

    LEVEL_COLORS = {
        'INFO': 'cyan',
        'WARNING': 'yellow',
        'ERROR': 'red',
        'CRITICAL': 'bgred',
        'DEBUG': 'bggrey'}

    def _get_levelname(self, name):
        color = self.ANSI_CODES[self.LEVEL_COLORS.get(name, 'white')]
        if name == 'INFO':
            fmt = '{0}->{2}'
        else:
            fmt = '{0}{1}{2}:'
        return fmt.format(color, name, self.ANSI_CODES['reset'])


class TextFormatter(BaseFormatter):
    """
    Convert a `logging.LogRecord' object into text.
    """

    def _get_levelname(self, name):
        if name == 'INFO':
            return '->'
        else:
            return name + ':'


class LimitFilter(logging.Filter):
    """
    Remove duplicates records, and limit the number of records in the same
    group.

    Groups are specified by the message to use when the number of records in
    the same group hit the limit.
    E.g.: log.warning(('43 is not the answer', 'More erroneous answers'))
    """

    LOGS_DEDUP_MIN_LEVEL = logging.WARNING

    _ignore = set()
    _raised_messages = set()
    _threshold = 5
    _group_count = defaultdict(int)

    def filter(self, record):
        # don't limit log messages for anything above "warning"
        if record.levelno > self.LOGS_DEDUP_MIN_LEVEL:
            return True

        # extract group
        group = record.__dict__.get('limit_msg', None)
        group_args = record.__dict__.get('limit_args', ())

        # ignore record if it was already raised
        message_key = (record.levelno, record.getMessage())
        if message_key in self._raised_messages:
            return False
        else:
            self._raised_messages.add(message_key)

        # ignore LOG_FILTER records by templates or messages
        # when "debug" isn't enabled
        logger_level = logging.getLogger().getEffectiveLevel()
        if logger_level > logging.DEBUG:
            template_key = (record.levelno, record.msg)
            message_key = (record.levelno, record.getMessage())
            if (template_key in self._ignore or message_key in self._ignore):
                return False

        # check if we went over threshold
        if group:
            key = (record.levelno, group)
            self._group_count[key] += 1
            if self._group_count[key] == self._threshold:
                record.msg = group
                record.args = group_args
            elif self._group_count[key] > self._threshold:
                return False
        return True


class LimitLogger(logging.Logger):
    """
    A logger which adds LimitFilter automatically
    """

    limit_filter = LimitFilter()

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.enable_filter()

    def disable_filter(self):
        self.removeFilter(LimitLogger.limit_filter)

    def enable_filter(self):
        self.addFilter(LimitLogger.limit_filter)


class FatalLogger(LimitLogger):
    warnings_fatal = False
    errors_fatal = False

    def warning(self, *args, **kwargs):
        super().warning(*args, **kwargs)
        if FatalLogger.warnings_fatal:
            raise RuntimeError('Warning encountered')

    def error(self, *args, **kwargs):
        super().error(*args, **kwargs)
        if FatalLogger.errors_fatal:
            raise RuntimeError('Error encountered')


logging.setLoggerClass(FatalLogger)


def supports_color():
    """
    Returns True if the running system's terminal supports color,
    and False otherwise.

    from django.core.management.color
    """
    plat = sys.platform
    supported_platform = plat != 'Pocket PC' and \
        (plat != 'win32' or 'ANSICON' in os.environ)

    # isatty is not always implemented, #6223.
    is_a_tty = hasattr(sys.stdout, 'isatty') and sys.stdout.isatty()
    if not supported_platform or not is_a_tty:
        return False
    return True


def get_formatter():
    if supports_color():
        return ANSIFormatter()
    else:
        return TextFormatter()


def init(level=None, fatal='', handler=logging.StreamHandler(), name=None,
         logs_dedup_min_level=None):
    FatalLogger.warnings_fatal = fatal.startswith('warning')
    FatalLogger.errors_fatal = bool(fatal)

    logger = logging.getLogger(name)

    handler.setFormatter(get_formatter())
    logger.addHandler(handler)

    if level:
        logger.setLevel(level)
    if logs_dedup_min_level:
        LimitFilter.LOGS_DEDUP_MIN_LEVEL = logs_dedup_min_level


def log_warnings():
    import warnings
    logging.captureWarnings(True)
    warnings.simplefilter("default", DeprecationWarning)
    init(logging.DEBUG, name='py.warnings')


if __name__ == '__main__':
    init(level=logging.DEBUG)

    root_logger = logging.getLogger()
    root_logger.debug('debug')
    root_logger.info('info')
    root_logger.warning('warning')
    root_logger.error('error')
    root_logger.critical('critical')