taskflow/taskflow/patterns/linear_flow.py
Michael Johnson dc6495cfa1 Update TaskFlow for networkx 2.x
The networkx 2.x series has been out for two years now and supports
python 3.6 and greater[1]. This patch updates TaskFlow to require
a minimum of networkx 2.1. It also updates the code to support
recent deprecation expiration introduced in the 2.4 release.

[1] https://networkx.github.io/documentation/stable/news.html

Change-Id: Ife31d353ba80824ebc63c8b21ee90943badc8da3
2019-10-18 18:11:44 -07:00

80 lines
2.7 KiB
Python

# -*- coding: utf-8 -*-
# Copyright (C) 2012 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 import flow
from taskflow.types import graph as gr
class Flow(flow.Flow):
"""Linear flow pattern.
A linear (potentially nested) flow of *tasks/flows* that can be
applied in order as one unit and rolled back as one unit using
the reverse order that the *tasks/flows* have been applied in.
"""
_no_last_item = object()
"""Sentinel object used to denote no last item has been assigned.
This is used to track no last item being added, since at creation there
is no last item, but since the :meth:`.add` routine can take any object
including none, we have to use a different object to be able to
distinguish the lack of any last item...
"""
def __init__(self, name, retry=None):
super(Flow, self).__init__(name, retry)
self._graph = gr.OrderedDiGraph(name=name)
self._last_item = self._no_last_item
def add(self, *items):
"""Adds a given task/tasks/flow/flows to this flow."""
for item in items:
if not self._graph.has_node(item):
self._graph.add_node(item)
if self._last_item is not self._no_last_item:
self._graph.add_edge(self._last_item, item,
attr_dict={flow.LINK_INVARIANT: True})
self._last_item = item
return self
def __len__(self):
return len(self._graph)
def __iter__(self):
for item in self._graph.nodes:
yield item
@property
def requires(self):
requires = set()
prior_provides = set()
if self._retry is not None:
requires.update(self._retry.requires)
prior_provides.update(self._retry.provides)
for item in self:
requires.update(item.requires - prior_provides)
prior_provides.update(item.provides)
return frozenset(requires)
def iter_nodes(self):
for (n, n_data) in self._graph.nodes(data=True):
yield (n, n_data)
def iter_links(self):
for (u, v, e_data) in self._graph.edges(data=True):
yield (u, v, e_data)