d50a889bae
TODO: more thorough testing Change-Id: I5e1878c78d9e14c5c9aff79315170d3ce9ed4a18 Closes-Bug: #1414821
151 lines
5.2 KiB
Python
151 lines
5.2 KiB
Python
# Copyright 2014 - Mirantis, Inc.
|
|
#
|
|
# 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 networkx as nx
|
|
from networkx.algorithms import traversal
|
|
|
|
from mistral.engine1 import commands
|
|
from mistral import exceptions as exc
|
|
from mistral.workflow import base
|
|
from mistral.workflow import data_flow
|
|
from mistral.workflow import states
|
|
|
|
|
|
class ReverseWorkflowHandler(base.WorkflowHandler):
|
|
"""'Reverse workflow' handler.
|
|
|
|
This handler implements the workflow pattern which is based on
|
|
dependencies between tasks, i.e. each task in a workflow graph
|
|
may be dependent on other tasks. To run this type of workflow
|
|
user must specify a task name that serves a target node in the
|
|
graph that the algorithm should come to by resolving all
|
|
dependencies.
|
|
For example, if there's a workflow consisting of two tasks
|
|
'A' and 'B' where 'A' depends on 'B' and if we specify a target
|
|
task name 'A' then the handler first will run task 'B' and then,
|
|
when a dependency of 'A' is resolved, will run task 'A'.
|
|
"""
|
|
|
|
def start_workflow(self, **params):
|
|
task_name = params.get('task_name')
|
|
|
|
task_spec = self.wf_spec.get_tasks().get(task_name)
|
|
|
|
if not task_spec:
|
|
msg = 'Invalid task name [wf_spec=%s, task_name=%s]' % (
|
|
self.wf_spec, task_name)
|
|
raise exc.WorkflowException(msg)
|
|
|
|
task_specs = self._find_tasks_without_dependencies(task_spec)
|
|
|
|
if len(task_specs) > 0:
|
|
self._set_execution_state(states.RUNNING)
|
|
|
|
return [commands.RunTask(t_s) for t_s in task_specs]
|
|
|
|
def get_upstream_tasks(self, task_spec):
|
|
return [self.wf_spec.get_tasks()[t_name]
|
|
for t_name in task_spec.get_requires() or []]
|
|
|
|
def _evaluate_workflow_final_context(self, cause_task_db):
|
|
return data_flow.evaluate_task_outbound_context(cause_task_db)
|
|
|
|
def _find_next_commands(self, task_db):
|
|
"""Finds all tasks with resolved dependencies and return them
|
|
in the form of engine commands.
|
|
|
|
:param task_db: Task DB model causing the operation.
|
|
:return: Tasks with resolved dependencies.
|
|
"""
|
|
|
|
# If cause task is the target task of the workflow then
|
|
# there's no more tasks to start.
|
|
if self.exec_db.start_params['task_name'] == task_db.name:
|
|
return []
|
|
|
|
# We need to analyse the graph and see which tasks are ready to start.
|
|
resolved_task_specs = []
|
|
success_task_names = set()
|
|
|
|
for t in self.exec_db.tasks:
|
|
if t.state == states.SUCCESS:
|
|
success_task_names.add(t.name)
|
|
|
|
for t_spec in self.wf_spec.get_tasks():
|
|
# Skip task if it doesn't have a direct dependency
|
|
# on the cause task.
|
|
if task_db.name not in t_spec.get_requires():
|
|
continue
|
|
|
|
if not (set(t_spec.get_requires()) - success_task_names):
|
|
t_db = self._find_db_task(t_spec.get_name())
|
|
|
|
if not t_db or t_db.state == states.IDLE:
|
|
resolved_task_specs.append(t_spec)
|
|
|
|
return [commands.RunTask(t_s) for t_s in resolved_task_specs]
|
|
|
|
def _find_tasks_without_dependencies(self, task_spec):
|
|
"""Given a target task name finds tasks with no dependencies.
|
|
|
|
:param task_spec: Target task specification in the workflow graph
|
|
that dependencies are unwound from.
|
|
:return: Tasks with no dependencies.
|
|
"""
|
|
tasks_spec = self.wf_spec.get_tasks()
|
|
|
|
graph = self._build_graph(tasks_spec)
|
|
|
|
# Unwind tasks from the target task
|
|
# and filter out tasks with dependencies.
|
|
return [
|
|
t_spec for t_spec in
|
|
traversal.dfs_postorder_nodes(graph.reverse(), task_spec)
|
|
if not t_spec.get_requires()
|
|
]
|
|
|
|
def _build_graph(self, tasks_spec):
|
|
graph = nx.DiGraph()
|
|
|
|
# Add graph nodes.
|
|
for t in tasks_spec:
|
|
graph.add_node(t)
|
|
|
|
# Add graph edges.
|
|
for t_spec in tasks_spec:
|
|
for dep_t_spec in self._get_dependency_tasks(tasks_spec, t_spec):
|
|
graph.add_edge(dep_t_spec, t_spec)
|
|
|
|
return graph
|
|
|
|
def _get_dependency_tasks(self, tasks_spec, task_spec):
|
|
dep_task_names = tasks_spec[task_spec.get_name()].get_requires()
|
|
|
|
if len(dep_task_names) == 0:
|
|
return []
|
|
|
|
dep_t_specs = set()
|
|
|
|
for t_spec in tasks_spec:
|
|
for t_name in dep_task_names:
|
|
if t_name == t_spec.get_name():
|
|
dep_t_specs.add(t_spec)
|
|
|
|
return dep_t_specs
|
|
|
|
def _find_db_task(self, name):
|
|
db_tasks = filter(lambda t: t.name == name, self.exec_db.tasks)
|
|
|
|
return db_tasks[0] if db_tasks else None
|