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# Copyright (C) 2015 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.
from taskflow.listeners import base
def _freeze_it(values):
"""Freezes a set of values (handling none/empty nicely)."""
if not values:
return frozenset()
else:
return frozenset(values)
class CaptureListener(base.Listener):
"""A listener that captures transitions and saves them locally.
NOTE(harlowja): this listener is *mainly* useful for testing (where it is
useful to test the appropriate/expected transitions, produced results...
occurred after engine running) but it could have other usages as well.
:ivar values: Captured transitions + details (the result of
the :py:meth:`._format_capture` method) are stored into this
list (a previous list to append to may be provided using the
constructor keyword argument of the same name); by default
this stores tuples of the format ``(kind, state, details)``.
"""
# Constant 'kind' strings used in the default capture formatting (to
# identify what was captured); these are saved into the accumulated
# values as the first index (so that your code may differentiate between
# what was captured).
#: Kind that denotes a 'flow' capture.
FLOW = 'flow'
#: Kind that denotes a 'task' capture.
TASK = 'task'
#: Kind that denotes a 'retry' capture.
RETRY = 'retry'
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,
# Easily override what you want captured and where it
# should save into and what should be skipped...
capture_flow=True, capture_task=True, capture_retry=True,
# Skip capturing *all* tasks, all retries, all flows...
skip_tasks=None, skip_retries=None, skip_flows=None,
# Provide your own list (or previous list) to accumulate
# into...
values=None):
super().__init__(
engine,
task_listen_for=task_listen_for,
flow_listen_for=flow_listen_for,
retry_listen_for=retry_listen_for)
self._capture_flow = capture_flow
self._capture_task = capture_task
self._capture_retry = capture_retry
self._skip_tasks = _freeze_it(skip_tasks)
self._skip_flows = _freeze_it(skip_flows)
self._skip_retries = _freeze_it(skip_retries)
if values is None:
self.values = []
else:
self.values = values
@staticmethod
def _format_capture(kind, state, details):
"""Tweak what is saved according to your desire(s)."""
return (kind, state, details)
def _task_receiver(self, state, details):
if self._capture_task:
if details['task_name'] not in self._skip_tasks:
self.values.append(self._format_capture(self.TASK,
state, details))
def _retry_receiver(self, state, details):
if self._capture_retry:
if details['retry_name'] not in self._skip_retries:
self.values.append(self._format_capture(self.RETRY,
state, details))
def _flow_receiver(self, state, details):
if self._capture_flow:
if details['flow_name'] not in self._skip_flows:
self.values.append(self._format_capture(self.FLOW,
state, details))
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