deb-mistral/mistral/workflow/data_flow.py
Winson Chan 61ec312160 Remove the transaction scope from task executions API
Since the task execution API get_all method is in a transaction block,
if there is a lot of read against the task execution API GET method , it
will lead to unnecessary DB locks that can result in deadlocks and
consequently WF execution failures.

Change-Id: I5a6b7829176178bb6e06768e9d52e94202cf4347
Closes-Bug: #1501433
2015-10-06 17:17:24 +00:00

286 lines
8.4 KiB
Python

# Copyright 2013 - Mirantis, Inc.
# Copyright 2015 - StackStorm, 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 copy
import six
from oslo_config import cfg
from oslo_log import log as logging
from mistral import context as auth_ctx
from mistral.db.v2 import api as db_api
from mistral.db.v2.sqlalchemy import models
from mistral import expressions as expr
from mistral import utils
from mistral.utils import inspect_utils
from mistral.workbook import parser as spec_parser
from mistral.workflow import states
LOG = logging.getLogger(__name__)
CONF = cfg.CONF
def evaluate_upstream_context(upstream_task_execs):
published_vars = {}
ctx = {}
for t_ex in upstream_task_execs:
# TODO(rakhmerov): These two merges look confusing. So it's a
# temporary solution.There's still the bug
# https://bugs.launchpad.net/mistral/+bug/1424461 that needs to be
# fixed using context variable versioning.
published_vars = utils.merge_dicts(
published_vars,
t_ex.published
)
utils.merge_dicts(
ctx,
evaluate_task_outbound_context(t_ex, include_result=False)
)
ctx = utils.merge_dicts(ctx, published_vars)
# TODO(rakhmerov): IMO, this method shouldn't deal with these task ids or
# anything else related to task proxies. Need to refactor.
return utils.merge_dicts(
ctx,
_get_task_identifiers_dict(upstream_task_execs)
)
# TODO(rakhmerov): Think how to gt rid of this method and the whole trick
# with upstream tasks. It doesn't look clear from design standpoint.
def _get_task_identifiers_dict(task_execs):
tasks = {}
for task_ex in task_execs:
tasks[task_ex.id] = task_ex.name
return {"__tasks": tasks}
def _extract_execution_result(ex):
if isinstance(ex, models.WorkflowExecution):
return ex.output
if ex.output:
return ex.output['result']
def invalidate_task_execution_result(task_ex):
for ex in task_ex.executions:
ex.accepted = False
def get_task_execution_result(task_ex):
# Use of task_ex.executions requires a session to lazy load the action
# executions. This get_task_execution_result method is also invoked
# from get_all in the task execution API controller. If there is a lot of
# read against the API, it will lead to a lot of unnecessary DB locks
# which result in possible deadlocks and WF execution failures. Therefore,
# use db_api.get_action_executions here to avoid session-less use cases.
action_execs = db_api.get_action_executions(task_execution_id=task_ex.id)
action_execs.sort(
key=lambda x: x.runtime_context.get('with_items_index')
)
results = [
_extract_execution_result(ex)
for ex in action_execs
if hasattr(ex, 'output') and ex.accepted
]
task_spec = spec_parser.get_task_spec(task_ex.spec)
if task_spec.get_with_items():
return results
return results[0] if len(results) == 1 else results
class TaskResultProxy(object):
def __init__(self, task_id):
self.task_id = task_id
def get(self):
task_ex = db_api.get_task_execution(self.task_id)
return get_task_execution_result(task_ex)
def __str__(self):
return "%s [task_id = '%s']" % (self.__class__.__name__, self.task_id)
def __repr__(self):
return self.__str__()
class ProxyAwareDict(dict):
def __getitem__(self, item):
val = super(ProxyAwareDict, self).__getitem__(item)
if isinstance(val, TaskResultProxy):
return val.get()
return val
def get(self, k, d=None):
try:
return self.__getitem__(k)
except KeyError:
return d
def iteritems(self):
for k, _ in six.iteritems(super(ProxyAwareDict, self)):
yield k, self[k]
def to_builtin_dict(self):
return {k: self[k] for k, _ in self.iteritems()}
def publish_variables(task_ex, task_spec):
if task_ex.state != states.SUCCESS:
return
expr_ctx = extract_task_result_proxies_to_context(task_ex.in_context)
if task_ex.name in expr_ctx:
LOG.warning(
'Shadowing context variable with task name while publishing: %s' %
task_ex.name
)
# Add result of current task to context for variables evaluation.
expr_ctx[task_ex.name] = TaskResultProxy(task_ex.id)
task_ex.published = expr.evaluate_recursively(
task_spec.get_publish(),
expr_ctx
)
def destroy_task_result(task_ex):
for ex in task_ex.executions:
if hasattr(ex, 'output'):
ex.output = {}
def evaluate_task_outbound_context(task_ex, include_result=True):
"""Evaluates task outbound Data Flow context.
This method assumes that complete task output (after publisher etc.)
has already been evaluated.
:param task_ex: DB task.
:param include_result: boolean argument, if True - include the
TaskResultProxy in outbound context under <task_name> key.
:return: Outbound task Data Flow context.
"""
in_context = (copy.deepcopy(dict(task_ex.in_context))
if task_ex.in_context is not None else {})
out_ctx = utils.merge_dicts(in_context, task_ex.published)
# Add task output under key 'taskName'.
if include_result:
task_ex_result = TaskResultProxy(task_ex.id)
out_ctx = utils.merge_dicts(
out_ctx,
{task_ex.name: task_ex_result or None}
)
return ProxyAwareDict(out_ctx)
def evaluate_workflow_output(wf_spec, context):
"""Evaluates workflow output.
:param wf_spec: Workflow specification.
:param context: Final Data Flow context (cause task's outbound context).
"""
# Convert context to ProxyAwareDict for correct output evaluation.
context = ProxyAwareDict(copy.deepcopy(context))
output_dict = wf_spec.get_output()
# Evaluate workflow 'publish' clause using the final workflow context.
output = expr.evaluate_recursively(output_dict, context)
# TODO(rakhmerov): Many don't like that we return the whole context
# TODO(rakhmerov): if 'output' is not explicitly defined.
return ProxyAwareDict(output or context).to_builtin_dict()
def add_openstack_data_to_context(wf_ex):
wf_ex.context = wf_ex.context or {}
if CONF.pecan.auth_enable:
exec_ctx = auth_ctx.ctx()
LOG.debug('Data flow security context: %s' % exec_ctx)
if exec_ctx:
wf_ex.context.update({'openstack': exec_ctx.to_dict()})
def add_execution_to_context(wf_ex):
wf_ex.context = wf_ex.context or {}
wf_ex.context['__execution'] = {
'id': wf_ex.id,
'spec': wf_ex.spec,
'params': wf_ex.params,
'input': wf_ex.input
}
def add_environment_to_context(wf_ex):
wf_ex.context = wf_ex.context or {}
# If env variables are provided, add an evaluated copy into the context.
if 'env' in wf_ex.params:
env = copy.deepcopy(wf_ex.params['env'])
# An env variable can be an expression of other env variables.
wf_ex.context['__env'] = expr.evaluate_recursively(env, {'__env': env})
def add_workflow_variables_to_context(wf_ex, wf_spec):
wf_ex.context = wf_ex.context or {}
return utils.merge_dicts(
wf_ex.context,
expr.evaluate_recursively(wf_spec.get_vars(), wf_ex.context)
)
# TODO(rakhmerov): Think how to get rid of this method. It should not be
# exposed in API.
def extract_task_result_proxies_to_context(ctx):
ctx = ProxyAwareDict(copy.deepcopy(ctx))
for task_ex_id, task_ex_name in six.iteritems(ctx['__tasks']):
ctx[task_ex_name] = TaskResultProxy(task_ex_id)
return ctx
def evaluate_object_fields(obj, context):
fields = inspect_utils.get_public_fields(obj)
evaluated_fields = expr.evaluate_recursively(fields, context)
for k, v in evaluated_fields.items():
setattr(obj, k, v)