1011df951e
In addition to iteration over its children (atoms or subflows) each pattern now provides iter_links() method that iterates over dependency links. This allows engines to treat all patterns in the same way instead knowing what structure each pattern expresses. Change-Id: I52cb5b0b501eefc8eb56a9ef5303aeb318013e11
183 lines
7.0 KiB
Python
183 lines
7.0 KiB
Python
# -*- coding: utf-8 -*-
|
|
|
|
# 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 logging
|
|
import threading
|
|
|
|
import networkx as nx
|
|
|
|
from taskflow import exceptions
|
|
from taskflow import flow
|
|
from taskflow import retry
|
|
from taskflow import task
|
|
from taskflow.utils import graph_utils as gu
|
|
from taskflow.utils import lock_utils as lu
|
|
from taskflow.utils import misc
|
|
|
|
|
|
LOG = logging.getLogger(__name__)
|
|
|
|
# Use the 'flatten' attribute as the need to add an edge here, which is useful
|
|
# for doing later analysis of the edges (to determine why the edges were
|
|
# created).
|
|
FLATTEN_EDGE_DATA = {
|
|
'flatten': True,
|
|
}
|
|
|
|
|
|
class Flattener(object):
|
|
def __init__(self, root, freeze=True):
|
|
self._root = root
|
|
self._graph = None
|
|
self._history = set()
|
|
self._freeze = bool(freeze)
|
|
self._lock = threading.Lock()
|
|
self._edge_data = FLATTEN_EDGE_DATA.copy()
|
|
|
|
def _add_new_edges(self, graph, nodes_from, nodes_to, edge_attrs=None):
|
|
"""Adds new edges from nodes to other nodes in the specified graph,
|
|
with the following edge attributes (defaulting to the class provided
|
|
edge_data if None), if the edge does not already exist.
|
|
"""
|
|
if edge_attrs is None:
|
|
edge_attrs = self._edge_data
|
|
else:
|
|
edge_attrs = edge_attrs.copy()
|
|
edge_attrs.update(self._edge_data)
|
|
for u in nodes_from:
|
|
for v in nodes_to:
|
|
if not graph.has_edge(u, v):
|
|
# NOTE(harlowja): give each edge its own attr copy so that
|
|
# if it's later modified that the same copy isn't modified.
|
|
graph.add_edge(u, v, attr_dict=edge_attrs.copy())
|
|
|
|
def _flatten(self, item):
|
|
functor = self._find_flattener(item)
|
|
if not functor:
|
|
raise TypeError("Unknown type requested to flatten: %s (%s)"
|
|
% (item, type(item)))
|
|
self._pre_item_flatten(item)
|
|
graph = functor(item)
|
|
self._post_item_flatten(item, graph)
|
|
return graph
|
|
|
|
def _find_flattener(self, item):
|
|
"""Locates the flattening function to use to flatten the given item."""
|
|
if isinstance(item, flow.Flow):
|
|
return self._flatten_flow
|
|
elif isinstance(item, task.BaseTask):
|
|
return self._flatten_task
|
|
elif isinstance(item, retry.Retry):
|
|
raise TypeError("Retry controller %s (%s) is used not as a flow "
|
|
"parameter" % (item, type(item)))
|
|
else:
|
|
return None
|
|
|
|
def _connect_retry(self, retry, graph):
|
|
graph.add_node(retry)
|
|
# All graph nodes that has not predecessors should be depended on its
|
|
# retry
|
|
for n in gu.get_no_predecessors(graph):
|
|
if n != retry:
|
|
# modified that the same copy isn't modified.
|
|
graph.add_edge(retry, n, FLATTEN_EDGE_DATA.copy())
|
|
|
|
# Add link to retry for each node of subgraph that hasn't
|
|
# a parent retry
|
|
for n in graph.nodes_iter():
|
|
if n != retry and 'retry' not in graph.node[n]:
|
|
graph.add_node(n, {'retry': retry})
|
|
|
|
def _flatten_task(self, task):
|
|
"""Flattens a individual task."""
|
|
graph = nx.DiGraph(name=task.name)
|
|
graph.add_node(task)
|
|
return graph
|
|
|
|
def _flatten_flow(self, flow):
|
|
"""Flattens a graph flow."""
|
|
graph = nx.DiGraph(name=flow.name)
|
|
# Flatten all nodes into a single subgraph per node.
|
|
subgraph_map = {}
|
|
for item in flow:
|
|
subgraph = self._flatten(item)
|
|
subgraph_map[item] = subgraph
|
|
graph = gu.merge_graphs([graph, subgraph])
|
|
# Reconnect all node edges to there corresponding subgraphs.
|
|
for (u, v, u_v_attrs) in flow.iter_links():
|
|
# Connect the ones with no predecessors in v to the ones with no
|
|
# successors in u (thus maintaining the edge dependency).
|
|
self._add_new_edges(graph,
|
|
list(gu.get_no_successors(subgraph_map[u])),
|
|
list(gu.get_no_predecessors(subgraph_map[v])),
|
|
edge_attrs=u_v_attrs)
|
|
if flow.retry is not None:
|
|
self._connect_retry(flow.retry, graph)
|
|
return graph
|
|
|
|
def _pre_item_flatten(self, item):
|
|
"""Called before a item is flattened; any pre-flattening actions."""
|
|
if id(item) in self._history:
|
|
raise ValueError("Already flattened item: %s (%s), recursive"
|
|
" flattening not supported" % (item, id(item)))
|
|
LOG.debug("Starting to flatten '%s'", item)
|
|
self._history.add(id(item))
|
|
|
|
def _post_item_flatten(self, item, graph):
|
|
"""Called before a item is flattened; any post-flattening actions."""
|
|
LOG.debug("Finished flattening '%s'", item)
|
|
# NOTE(harlowja): this one can be expensive to calculate (especially
|
|
# the cycle detection), so only do it if we know debugging is enabled
|
|
# and not under all cases.
|
|
if LOG.isEnabledFor(logging.DEBUG):
|
|
LOG.debug("Translated '%s' into a graph:", item)
|
|
for line in gu.pformat(graph).splitlines():
|
|
# Indent it so that it's slightly offset from the above line.
|
|
LOG.debug(" %s", line)
|
|
|
|
def _pre_flatten(self):
|
|
"""Called before the flattening of the item starts."""
|
|
self._history.clear()
|
|
|
|
def _post_flatten(self, graph):
|
|
"""Called after the flattening of the item finishes successfully."""
|
|
dup_names = misc.get_duplicate_keys(graph.nodes_iter(),
|
|
key=lambda node: node.name)
|
|
if dup_names:
|
|
dup_names = ', '.join(sorted(dup_names))
|
|
raise exceptions.InvariantViolation("Tasks with duplicate names "
|
|
"found: %s" % (dup_names))
|
|
self._history.clear()
|
|
|
|
@lu.locked
|
|
def flatten(self):
|
|
"""Flattens a item (a task or flow) into a single execution graph."""
|
|
if self._graph is not None:
|
|
return self._graph
|
|
self._pre_flatten()
|
|
graph = self._flatten(self._root)
|
|
self._post_flatten(graph)
|
|
if self._freeze:
|
|
self._graph = nx.freeze(graph)
|
|
else:
|
|
self._graph = graph
|
|
return self._graph
|
|
|
|
|
|
def flatten(item, freeze=True):
|
|
"""Flattens a item (a task or flow) into a single execution graph."""
|
|
return Flattener(item, freeze=freeze).flatten()
|