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# -*- coding: utf-8 -*-
# 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.
import abc
import itertools
from taskflow import deciders
from taskflow.engines.action_engine import compiler
from taskflow.engines.action_engine import traversal
from taskflow import logging
from taskflow import states
LOG = logging.getLogger(__name__)
class Decider(object, metaclass=abc.ABCMeta):
"""Base class for deciders.
Provides interface to be implemented by sub-classes.
Deciders check whether next atom in flow should be executed or not.
"""
@abc.abstractmethod
def tally(self, runtime):
"""Tally edge deciders on whether this decider should allow running.
The returned value is a list of edge deciders that voted
'nay' (do not allow running).
"""
@abc.abstractmethod
def affect(self, runtime, nay_voters):
"""Affects associated atoms due to at least one 'nay' edge decider.
This will alter the associated atom + some set of successor atoms by
setting there state and intention to ``IGNORE`` so that they are
ignored in future runtime activities.
"""
def check_and_affect(self, runtime):
"""Handles :py:func:`~.tally` + :py:func:`~.affect` in right order.
NOTE(harlowja): If there are zero 'nay' edge deciders then it is
assumed this decider should allow running.
Returns boolean of whether this decider allows for running (or not).
"""
nay_voters = self.tally(runtime)
if nay_voters:
self.affect(runtime, nay_voters)
return False
return True
def _affect_all_successors(atom, runtime):
execution_graph = runtime.compilation.execution_graph
successors_iter = traversal.depth_first_iterate(
execution_graph, atom, traversal.Direction.FORWARD)
runtime.reset_atoms(itertools.chain([atom], successors_iter),
state=states.IGNORE, intention=states.IGNORE)
def _affect_successor_tasks_in_same_flow(atom, runtime):
execution_graph = runtime.compilation.execution_graph
successors_iter = traversal.depth_first_iterate(
execution_graph, atom, traversal.Direction.FORWARD,
# Do not go through nested flows but do follow *all* tasks that
# are directly connected in this same flow (thus the reason this is
# called the same flow decider); retries are direct successors
# of flows, so they should also be not traversed through, but
# setting this explicitly ensures that.
through_flows=False, through_retries=False)
runtime.reset_atoms(itertools.chain([atom], successors_iter),
state=states.IGNORE, intention=states.IGNORE)
def _affect_atom(atom, runtime):
runtime.reset_atoms([atom], state=states.IGNORE, intention=states.IGNORE)
def _affect_direct_task_neighbors(atom, runtime):
def _walk_neighbors():
execution_graph = runtime.compilation.execution_graph
for node in execution_graph.successors(atom):
node_data = execution_graph.nodes[node]
if node_data['kind'] == compiler.TASK:
yield node
successors_iter = _walk_neighbors()
runtime.reset_atoms(itertools.chain([atom], successors_iter),
state=states.IGNORE, intention=states.IGNORE)
class IgnoreDecider(Decider):
"""Checks any provided edge-deciders and determines if ok to run."""
_depth_strategies = {
deciders.Depth.ALL: _affect_all_successors,
deciders.Depth.ATOM: _affect_atom,
deciders.Depth.FLOW: _affect_successor_tasks_in_same_flow,
deciders.Depth.NEIGHBORS: _affect_direct_task_neighbors,
}
def __init__(self, atom, edge_deciders):
self._atom = atom
self._edge_deciders = edge_deciders
def tally(self, runtime):
voters = {
'run_it': [],
'do_not_run_it': [],
'ignored': [],
}
history = {}
if self._edge_deciders:
# Gather all atoms (the ones that were not ignored) results so
# that those results can be used by the decider(s) that are
# making a decision as to pass or not pass...
states_intentions = runtime.storage.get_atoms_states(
ed.from_node.name for ed in self._edge_deciders
if ed.kind in compiler.ATOMS)
for atom_name in states_intentions.keys():
atom_state, _atom_intention = states_intentions[atom_name]
if atom_state != states.IGNORE:
history[atom_name] = runtime.storage.get(atom_name)
for ed in self._edge_deciders:
if (ed.kind in compiler.ATOMS and
# It was an ignored atom (not included in history and
# the only way that is possible is via above loop
# skipping it...)
ed.from_node.name not in history):
voters['ignored'].append(ed)
continue
if not ed.decider(history=history):
voters['do_not_run_it'].append(ed)
else:
voters['run_it'].append(ed)
if LOG.isEnabledFor(logging.TRACE):
LOG.trace("Out of %s deciders there were %s 'do no run it'"
" voters, %s 'do run it' voters and %s 'ignored'"
" voters for transition to atom '%s' given history %s",
sum(len(eds) for eds in voters.values()),
list(ed.from_node.name
for ed in voters['do_not_run_it']),
list(ed.from_node.name for ed in voters['run_it']),
list(ed.from_node.name for ed in voters['ignored']),
self._atom.name, history)
return voters['do_not_run_it']
def affect(self, runtime, nay_voters):
# If there were many 'nay' edge deciders that were targeted
# at this atom, then we need to pick the one which has the widest
# impact and respect that one as the decider depth that will
# actually affect things.
widest_depth = deciders.pick_widest(ed.depth for ed in nay_voters)
affector = self._depth_strategies[widest_depth]
return affector(self._atom, runtime)
class NoOpDecider(Decider):
"""No-op decider that says it is always ok to run & has no effect(s)."""
def tally(self, runtime):
"""Always good to go."""
return []
def affect(self, runtime, nay_voters):
"""Does nothing."""
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