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# -*- coding: utf-8 -*-
# Copyright (C) 2014 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 functools
from taskflow.engines.action_engine import compiler
from taskflow import exceptions as exc
from taskflow import states
from taskflow.types import tree
from taskflow.utils import misc
def _cached_get(cache, cache_key, atom_name, fetch_func, *args, **kwargs):
"""Tries to get a previously saved value or fetches it and caches it."""
value, value_found = None, False
value, value_found = cache[cache_key][atom_name]
except KeyError:
value = fetch_func(*args, **kwargs)
value_found = True
except (exc.StorageFailure, exc.NotFound):
cache[cache_key][atom_name] = value, value_found
return value, value_found
def _fetch_predecessor_tree(graph, atom):
"""Creates a tree of predecessors, rooted at given atom."""
root = tree.Node(atom)
stack = [(root, atom)]
while stack:
parent, node = stack.pop()
for pred_node in graph.predecessors(node):
pred_node_data = graph.nodes[pred_node]
if pred_node_data['kind'] == compiler.FLOW_END:
# Jump over and/or don't show flow end nodes...
for pred_pred_node in graph.predecessors(pred_node):
stack.append((parent, pred_pred_node))
child = tree.Node(pred_node, **pred_node_data)
# And go further backwards...
stack.append((child, pred_node))
return root
class FailureFormatter(object):
"""Formats a failure and connects it to associated atoms & engine."""
states.EXECUTE: (_fetch_predecessor_tree, 'predecessors'),
def __init__(self, engine, hide_inputs_outputs_of=()):
self._hide_inputs_outputs_of = hide_inputs_outputs_of
self._engine = engine
def _format_node(self, storage, cache, node):
"""Formats a single tree node into a string version."""
if node.metadata['kind'] == compiler.FLOW:
flow = node.item
flow_name = flow.name
return "Flow '%s'" % (flow_name)
elif node.metadata['kind'] in compiler.ATOMS:
atom = node.item
atom_name = atom.name
atom_attrs = {}
intention, intention_found = _cached_get(
cache, 'intentions', atom_name, storage.get_atom_intention,
if intention_found:
atom_attrs['intention'] = intention
state, state_found = _cached_get(cache, 'states', atom_name,
if state_found:
atom_attrs['state'] = state
if atom_name not in self._hide_inputs_outputs_of:
# When the cache does not exist for this atom this
# will be called with the rest of these arguments
# used to populate the cache.
fetch_mapped_args = functools.partial(
storage.fetch_mapped_args, atom.rebind,
atom_name=atom_name, optional_args=atom.optional)
requires, requires_found = _cached_get(cache, 'requires',
if requires_found:
atom_attrs['requires'] = requires
provides, provides_found = _cached_get(
cache, 'provides', atom_name,
storage.get_execute_result, atom_name)
if provides_found:
atom_attrs['provides'] = provides
if atom_attrs:
return "Atom '%s' %s" % (atom_name, atom_attrs)
return "Atom '%s'" % (atom_name)
raise TypeError("Unable to format node, unknown node"
" kind '%s' encountered" % node.metadata['kind'])
def format(self, fail, atom_matcher):
"""Returns a (exc_info, details) tuple about the failure.
The ``exc_info`` tuple should be a standard three element
(exctype, value, traceback) tuple that will be used for further
logging. A non-empty string is typically returned for ``details``; it
should contain any string info about the failure (with any specific
details the ``exc_info`` may not have/contain).
buff = misc.StringIO()
storage = self._engine.storage
compilation = self._engine.compilation
if fail.exc_info is None:
# Remote failures will not have a 'exc_info' tuple, so just use
# the captured traceback that was captured by the creator when it
# failed...
if storage is None or compilation is None:
# Somehow we got called before prepared and/or compiled; ok
# that's weird, skip doing the rest...
return (fail.exc_info, buff.getvalue())
hierarchy = compilation.hierarchy
graph = compilation.execution_graph
atom_node = hierarchy.find_first_match(atom_matcher)
atom = None
atom_intention = None
if atom_node is not None:
atom = atom_node.item
atom_intention = storage.get_atom_intention(atom.name)
if atom is not None and atom_intention in self._BUILDERS:
# Cache as much as we can, since the path of various atoms
# may cause the same atom to be seen repeatedly depending on
# the graph structure...
cache = {
'intentions': {},
'provides': {},
'requires': {},
'states': {},
builder, kind = self._BUILDERS[atom_intention]
rooted_tree = builder(graph, atom)
child_count = rooted_tree.child_count(only_direct=False)
buff.write_nl('%s %s (most recent first):' % (child_count, kind))
formatter = functools.partial(self._format_node, storage, cache)
direct_child_count = rooted_tree.child_count(only_direct=True)
for i, child in enumerate(rooted_tree, 1):
if i == direct_child_count:
starting_prefix=" "))
starting_prefix=" "))
return (fail.exc_info, buff.getvalue())