Files
deb-python-taskflow/taskflow/storage.py
skudriashev aea1f401eb Doc strings and comments clean-up
* Added missing period for doc strings
* Correct syntax errors
* Remove H402 from flake8 ignore list

Change-Id: Ia8592bf99378e3658d6cca2ceb148bf9eb0b5de8
2014-01-26 23:08:39 +02:00

428 lines
15 KiB
Python

# -*- coding: utf-8 -*-
# vim: tabstop=4 shiftwidth=4 softtabstop=4
# 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 contextlib
import logging
import six
from taskflow import exceptions
from taskflow.openstack.common import uuidutils
from taskflow.persistence import logbook
from taskflow import states
from taskflow.utils import misc
from taskflow.utils import threading_utils as tu
LOG = logging.getLogger(__name__)
STATES_WITH_RESULTS = (states.SUCCESS, states.REVERTING, states.FAILURE)
class Storage(object):
"""Interface between engines and logbook.
This class provides a simple interface to save tasks of a given flow and
associated activity and results to persistence layer (logbook,
task_details, flow_details) for use by engines, making it easier to
interact with the underlying storage & backend mechanism.
"""
injector_name = '_TaskFlow_INJECTOR'
def __init__(self, flow_detail, backend=None):
self._result_mappings = {}
self._reverse_mapping = {}
self._backend = backend
self._flowdetail = flow_detail
# NOTE(imelnikov): failure serialization looses information,
# so we cache failures here, in task name -> misc.Failure mapping.
self._failures = {}
self._reload_failures()
self._task_name_to_uuid = dict((td.name, td.uuid)
for td in self._flowdetail)
try:
injector_td = self._taskdetail_by_name(self.injector_name)
except exceptions.NotFound:
pass
else:
names = six.iterkeys(injector_td.results)
self._set_result_mapping(injector_td.name,
dict((name, name) for name in names))
def _with_connection(self, functor, *args, **kwargs):
# NOTE(harlowja): Activate the given function with a backend
# connection, if a backend is provided in the first place, otherwise
# don't call the function.
if self._backend is None:
return
with contextlib.closing(self._backend.get_connection()) as conn:
functor(conn, *args, **kwargs)
def ensure_task(self, task_name, task_version=None, result_mapping=None):
"""Ensure that there is taskdetail that correspond the task.
If task does not exist, adds a record for it. Added task will have
PENDING state. Sets result mapping for the task from result_mapping
argument.
Returns uuid for the task details corresponding to the task with
given name.
"""
try:
task_id = self._task_name_to_uuid[task_name]
except KeyError:
task_id = uuidutils.generate_uuid()
self._add_task(task_id, task_name, task_version)
self._set_result_mapping(task_name, result_mapping)
return task_id
def _add_task(self, uuid, task_name, task_version=None):
"""Add the task to storage.
Task becomes known to storage by that name and uuid.
Task state is set to PENDING.
"""
# TODO(imelnikov): check that task with same uuid or
# task name does not exist.
td = logbook.TaskDetail(name=task_name, uuid=uuid)
td.state = states.PENDING
td.version = task_version
self._flowdetail.add(td)
def save_both(conn):
"""Saves the flow and the task detail with the same connection."""
self._save_flow_detail(conn)
self._save_task_detail(conn, task_detail=td)
self._with_connection(save_both)
self._task_name_to_uuid[task_name] = uuid
@property
def flow_name(self):
return self._flowdetail.name
@property
def flow_uuid(self):
return self._flowdetail.uuid
def _save_flow_detail(self, conn):
# NOTE(harlowja): we need to update our contained flow detail if
# the result of the update actually added more (aka another process
# added item to the flow detail).
self._flowdetail.update(conn.update_flow_details(self._flowdetail))
def _taskdetail_by_name(self, task_name):
try:
td = self._flowdetail.find(self._task_name_to_uuid[task_name])
except KeyError:
td = None
if td is None:
raise exceptions.NotFound("Unknown task name: %s" % task_name)
return td
def _save_task_detail(self, conn, task_detail):
# NOTE(harlowja): we need to update our contained task detail if
# the result of the update actually added more (aka another process
# is also modifying the task detail).
task_detail.update(conn.update_task_details(task_detail))
def get_task_uuid(self, task_name):
"""Get task uuid by given name."""
td = self._taskdetail_by_name(task_name)
return td.uuid
def set_task_state(self, task_name, state):
"""Set task state."""
td = self._taskdetail_by_name(task_name)
td.state = state
self._with_connection(self._save_task_detail, task_detail=td)
def get_task_state(self, task_name):
"""Get state of task with given name."""
return self._taskdetail_by_name(task_name).state
def get_tasks_states(self, task_names):
return dict((name, self.get_task_state(name))
for name in task_names)
def update_task_metadata(self, task_name, update_with):
if not update_with:
return
# NOTE(harlowja): this is a read and then write, not in 1 transaction
# so it is entirely possible that we could write over another writes
# metadata update. Maybe add some merging logic later?
td = self._taskdetail_by_name(task_name)
if not td.meta:
td.meta = {}
td.meta.update(update_with)
self._with_connection(self._save_task_detail, task_detail=td)
def set_task_progress(self, task_name, progress, details=None):
"""Set task progress.
:param task_name: task name
:param progress: task progress
:param details: task specific progress information
"""
metadata_update = {
'progress': progress,
}
if details is not None:
# NOTE(imelnikov): as we can update progress without
# updating details (e.g. automatically from engine)
# we save progress value with details, too.
if details:
metadata_update['progress_details'] = {
'at_progress': progress,
'details': details,
}
else:
metadata_update['progress_details'] = None
self.update_task_metadata(task_name, metadata_update)
def get_task_progress(self, task_name):
"""Get progress of task with given name.
:param task_name: task name
:returns: current task progress value
"""
meta = self._taskdetail_by_name(task_name).meta
if not meta:
return 0.0
return meta.get('progress', 0.0)
def get_task_progress_details(self, task_name):
"""Get progress details of task with given name.
:param task_name: task name
:returns: None if progress_details not defined, else progress_details
dict
"""
meta = self._taskdetail_by_name(task_name).meta
if not meta:
return None
return meta.get('progress_details')
def _check_all_results_provided(self, task_name, data):
"""Warn if task did not provide some of results.
This may happen if task returns shorter tuple or list or dict
without all needed keys. It may also happen if task returns
result of wrong type.
"""
result_mapping = self._result_mappings.get(task_name, None)
if result_mapping is None:
return
for name, index in six.iteritems(result_mapping):
try:
misc.item_from(data, index, name=name)
except exceptions.NotFound:
LOG.warning("Task %s did not supply result "
"with index %r (name %s)",
task_name, index, name)
def save(self, task_name, data, state=states.SUCCESS):
"""Put result for task with id 'uuid' to storage."""
td = self._taskdetail_by_name(task_name)
td.state = state
if state == states.FAILURE and isinstance(data, misc.Failure):
td.results = None
td.failure = data
self._failures[td.name] = data
else:
td.results = data
td.failure = None
self._check_all_results_provided(td.name, data)
self._with_connection(self._save_task_detail, task_detail=td)
def _cache_failure(self, name, fail):
"""Ensure that cache has matching failure for task with this name.
We leave cached version if it matches as it may contain more
information. Returns cached failure.
"""
cached = self._failures.get(name)
if fail.matches(cached):
return cached
self._failures[name] = fail
return fail
def _reload_failures(self):
"""Refresh failures cache."""
for td in self._flowdetail:
if td.failure is not None:
self._cache_failure(td.name, td.failure)
def get(self, task_name):
"""Get result for task with name 'task_name' to storage."""
td = self._taskdetail_by_name(task_name)
if td.failure is not None:
return self._cache_failure(td.name, td.failure)
if td.state not in STATES_WITH_RESULTS:
raise exceptions.NotFound(
"Result for task %s is not known" % task_name)
return td.results
def get_failures(self):
"""Get list of failures that happened with this flow.
No order guaranteed.
"""
return self._failures.copy()
def has_failures(self):
"""Returns True if there are failed tasks in the storage."""
return bool(self._failures)
def _reset_task(self, td, state):
if td.name == self.injector_name:
return False
if td.state == state:
return False
td.results = None
td.failure = None
td.state = state
self._failures.pop(td.name, None)
return True
def reset(self, task_name, state=states.PENDING):
"""Remove result for task with id 'uuid' from storage."""
td = self._taskdetail_by_name(task_name)
if self._reset_task(td, state):
self._with_connection(self._save_task_detail, task_detail=td)
def reset_tasks(self):
"""Reset all tasks to PENDING state, removing results.
Returns list of (name, uuid) tuples for all tasks that were reset.
"""
result = []
def do_reset_all(connection):
for td in self._flowdetail:
if self._reset_task(td, states.PENDING):
self._save_task_detail(connection, td)
result.append((td.name, td.uuid))
self._with_connection(do_reset_all)
return result
def inject(self, pairs):
"""Add values into storage.
This method should be used to put flow parameters (requirements that
are not satisfied by any task in the flow) into storage.
"""
try:
injector_td = self._taskdetail_by_name(self.injector_name)
except exceptions.NotFound:
injector_uuid = uuidutils.generate_uuid()
self._add_task(injector_uuid, self.injector_name)
results = dict(pairs)
else:
results = injector_td.results.copy()
results.update(pairs)
self.save(self.injector_name, results)
names = six.iterkeys(results)
self._set_result_mapping(self.injector_name,
dict((name, name) for name in names))
def _set_result_mapping(self, task_name, mapping):
"""Set mapping for naming task results.
The result saved with given name would be accessible by names
defined in mapping. Mapping is a dict name => index. If index
is None, the whole result will have this name; else, only
part of it, result[index].
"""
if not mapping:
return
self._result_mappings[task_name] = mapping
for name, index in six.iteritems(mapping):
entries = self._reverse_mapping.setdefault(name, [])
# NOTE(imelnikov): We support setting same result mapping for
# the same task twice (e.g when we are injecting 'a' and then
# injecting 'a' again), so we should not log warning below in
# that case and we should have only one item for each pair
# (task_name, index) in entries. It should be put to the end of
# entries list because order matters on fetching.
try:
entries.remove((task_name, index))
except ValueError:
pass
entries.append((task_name, index))
if len(entries) > 1:
LOG.warning("Multiple provider mappings being created for %r",
name)
def fetch(self, name):
"""Fetch named task result."""
try:
indexes = self._reverse_mapping[name]
except KeyError:
raise exceptions.NotFound("Name %r is not mapped" % name)
# Return the first one that is found.
for task_name, index in reversed(indexes):
try:
result = self.get(task_name)
return misc.item_from(result, index, name=name)
except exceptions.NotFound:
pass
raise exceptions.NotFound("Unable to find result %r" % name)
def fetch_all(self):
"""Fetch all named task results known so far.
Should be used for debugging and testing purposes mostly.
"""
result = {}
for name in self._reverse_mapping:
try:
result[name] = self.fetch(name)
except exceptions.NotFound:
pass
return result
def fetch_mapped_args(self, args_mapping):
"""Fetch arguments for the task using arguments mapping."""
return dict((key, self.fetch(name))
for key, name in six.iteritems(args_mapping))
def set_flow_state(self, state):
"""Set flowdetails state and save it."""
self._flowdetail.state = state
self._with_connection(self._save_flow_detail)
def get_flow_state(self):
"""Set state from flowdetails."""
state = self._flowdetail.state
if state is None:
state = states.PENDING
return state
@six.add_metaclass(tu.ThreadSafeMeta)
class ThreadSafeStorage(Storage):
pass