# taskflow.listeners.logging

# Source code for taskflow.listeners.logging

    #    Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
    #
    #    Licensed under the Apache License, Version 2.0 (the "License"); you may
    #    not use this file except in compliance with the License. You may obtain
    #    a copy of the License at
    #
    #         http://www.apache.org/licenses/LICENSE-2.0
    #
    #    Unless required by applicable law or agreed to in writing, software
    #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
    #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
    #    License for the specific language governing permissions and limitations
    #    under the License.

    import os

    from taskflow import formatters
    from taskflow.listeners import base
    from taskflow import logging
    from taskflow import states
    from taskflow import task
    from taskflow.types import failure
    from taskflow.utils import misc

    LOG = logging.getLogger(__name__)

    class LoggingListener(base.DumpingListener):
        """Listener that logs notifications it receives.

        It listens for task and flow notifications and writes those notifications
        to a provided logger, or logger of its module
        (``taskflow.listeners.logging``) if none is provided (and no class
        attribute is overridden). The log level can also be
        configured, ``logging.DEBUG`` is used by default when none is provided.
        """

        #: Default logger to use if one is not provided on construction.
        _LOGGER = None

        def __init__(self, engine,
                     task_listen_for=base.DEFAULT_LISTEN_FOR,
                     flow_listen_for=base.DEFAULT_LISTEN_FOR,
                     retry_listen_for=base.DEFAULT_LISTEN_FOR,
                     log=None,
                     level=logging.DEBUG):
            super().__init__(
                engine, task_listen_for=task_listen_for,
                flow_listen_for=flow_listen_for, retry_listen_for=retry_listen_for)
            self._logger = misc.pick_first_not_none(log, self._LOGGER, LOG)
            self._level = level

        def _dump(self, message, *args, **kwargs):
            self._logger.log(self._level, message, *args, **kwargs)

    def _make_matcher(task_name):
        """Returns a function that matches a node with task item with same name."""

        def _task_matcher(node):
            item = node.item
            return isinstance(item, task.Task) and item.name == task_name

        return _task_matcher

    class DynamicLoggingListener(base.Listener):
        """Listener that logs notifications it receives.

        It listens for task and flow notifications and writes those notifications
        to a provided logger, or logger of its module
        (``taskflow.listeners.logging``) if none is provided (and no class
        attribute is overridden). The log level can *slightly* be configured
        and ``logging.DEBUG`` or ``logging.WARNING`` (unless overridden via a
        constructor parameter) will be selected automatically based on the
        execution state and results produced.

        The following flow states cause ``logging.WARNING`` (or provided
        level) to be used:

        * ``states.FAILURE``
        * ``states.REVERTED``

        The following task states cause ``logging.WARNING`` (or provided level)
        to be used:

        * ``states.FAILURE``
        * ``states.RETRYING``
        * ``states.REVERTING``
        * ``states.REVERT_FAILURE``

        When a task produces a :py:class:`~taskflow.types.failure.Failure` object
        as its result (typically this happens when a task raises an exception) this
        will **always** switch the logger to use ``logging.WARNING`` (if the
        failure object contains a ``exc_info`` tuple this will also be logged to
        provide a meaningful traceback).
        """

        #: Default logger to use if one is not provided on construction.
        _LOGGER = None

        #: States which are triggered under some type of failure.
        _FAILURE_STATES = (states.FAILURE, states.REVERT_FAILURE)

        def __init__(self, engine,
                     task_listen_for=base.DEFAULT_LISTEN_FOR,
                     flow_listen_for=base.DEFAULT_LISTEN_FOR,
                     retry_listen_for=base.DEFAULT_LISTEN_FOR,
                     log=None, failure_level=logging.WARNING,
                     level=logging.DEBUG, hide_inputs_outputs_of=(),
                     fail_formatter=None,
                     mask_inputs_keys=(),
                     mask_outputs_keys=()):
            super().__init__(
                engine, task_listen_for=task_listen_for,
                flow_listen_for=flow_listen_for, retry_listen_for=retry_listen_for)
            self._failure_level = failure_level
            self._level = level
            self._task_log_levels = {
                states.FAILURE: self._failure_level,
                states.REVERTED: self._failure_level,
                states.RETRYING: self._failure_level,
                states.REVERT_FAILURE: self._failure_level,
            }
            self._flow_log_levels = {
                states.FAILURE: self._failure_level,
                states.REVERTED: self._failure_level,
            }
            self._hide_inputs_outputs_of = frozenset(hide_inputs_outputs_of)
            self._mask_inputs_keys = frozenset(mask_inputs_keys)
            self._mask_outputs_keys = frozenset(mask_outputs_keys)
            self._logger = misc.pick_first_not_none(log, self._LOGGER, LOG)
            if fail_formatter is None:
                self._fail_formatter = formatters.FailureFormatter(
                    self._engine,
                    hide_inputs_outputs_of=self._hide_inputs_outputs_of,
                    mask_inputs_keys=self._mask_inputs_keys,
                    mask_outputs_keys=self._mask_outputs_keys)
            else:
                self._fail_formatter = fail_formatter

        def _flow_receiver(self, state, details):
            """Gets called on flow state changes."""
            level = self._flow_log_levels.get(state, self._level)
            self._logger.log(level, "Flow '%s' (%s) transitioned into state '%s'"
                             " from state '%s'", details['flow_name'],
                             details['flow_uuid'], state, details.get('old_state'))

        def _task_receiver(self, state, details):
            """Gets called on task state changes."""
            task_name = details['task_name']
            task_uuid = details['task_uuid']
            if 'result' in details and state in base.FINISH_STATES:
                # If the task failed, it's useful to show the exception traceback
                # and any other available exception information.
                result = details.get('result')
                if isinstance(result, failure.Failure):
                    exc_info, fail_details = self._fail_formatter.format(
                        result, _make_matcher(task_name))
                    if fail_details:
                        self._logger.log(self._failure_level,
                                         "Task '%s' (%s) transitioned into state"
                                         " '%s' from state '%s'%s%s",
                                         task_name, task_uuid, state,
                                         details['old_state'], os.linesep,
                                         fail_details, exc_info=exc_info)
                    else:
                        self._logger.log(self._failure_level,
                                         "Task '%s' (%s) transitioned into state"
                                         " '%s' from state '%s'", task_name,
                                         task_uuid, state, details['old_state'],
                                         exc_info=exc_info)
                else:
                    # Otherwise, depending on the enabled logging level/state we
                    # will show or hide results that the task may have produced
                    # during execution.
                    level = self._task_log_levels.get(state, self._level)
                    show_result = (self._logger.isEnabledFor(self._level)
                                   or state == states.FAILURE)
                    if show_result and \
                       task_name not in self._hide_inputs_outputs_of:
                        self._logger.log(level, "Task '%s' (%s) transitioned into"
                                         " state '%s' from state '%s' with"
                                         " result '%s'", task_name, task_uuid,
                                         state, details['old_state'], result)
                    else:
                        self._logger.log(level, "Task '%s' (%s) transitioned into"
                                         " state '%s' from state '%s'",
                                         task_name, task_uuid, state,
                                         details['old_state'])
            else:
                # Just a intermediary state, carry on!
                level = self._task_log_levels.get(state, self._level)
                self._logger.log(level, "Task '%s' (%s) transitioned into state"
                                 " '%s' from state '%s'", task_name, task_uuid,
                                 state, details['old_state'])

this page last updated: 2025-09-22 20:23:52

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