181 lines
6.6 KiB
Python
181 lines
6.6 KiB
Python
# -*- coding: utf-8 -*-
|
|
|
|
# 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 json
|
|
import logging
|
|
import os
|
|
import sys
|
|
import time
|
|
|
|
logging.basicConfig(level=logging.ERROR)
|
|
|
|
top_dir = os.path.abspath(os.path.join(os.path.dirname(__file__),
|
|
os.pardir,
|
|
os.pardir))
|
|
sys.path.insert(0, top_dir)
|
|
|
|
|
|
from taskflow import engines
|
|
from taskflow.listeners import printing
|
|
from taskflow.openstack.common import uuidutils
|
|
from taskflow.patterns import graph_flow as gf
|
|
from taskflow.patterns import linear_flow as lf
|
|
from taskflow import task
|
|
from taskflow.utils import misc
|
|
|
|
# INTRO: This example walks through a miniature workflow which simulates a
|
|
# the reception of a API request, creation of a database entry, driver
|
|
# activation (which invokes a 'fake' webservice) and final completion.
|
|
#
|
|
# This example also shows how a function/object (in this class the url sending)
|
|
# that occurs during driver activation can update the progress of a task
|
|
# without being aware of the internals of how to do this by associating a
|
|
# callback that the url sending can update as the sending progresses from 0.0%
|
|
# complete to 100% complete.
|
|
|
|
|
|
class DB(object):
|
|
def query(self, sql):
|
|
print("Querying with: %s" % (sql))
|
|
|
|
|
|
class UrlCaller(object):
|
|
def __init__(self):
|
|
self._send_time = 0.5
|
|
self._chunks = 25
|
|
|
|
def send(self, url, data, status_cb=None):
|
|
sleep_time = float(self._send_time) / self._chunks
|
|
for i in range(0, len(data)):
|
|
time.sleep(sleep_time)
|
|
# As we send the data, each chunk we 'fake' send will progress
|
|
# the sending progress that much further to 100%.
|
|
if status_cb:
|
|
status_cb(float(i) / len(data))
|
|
|
|
|
|
# Since engines save the output of tasks to a optional persistent storage
|
|
# backend resources have to be dealt with in a slightly different manner since
|
|
# resources are transient and can *not* be persisted (or serialized). For tasks
|
|
# that require access to a set of resources it is a common pattern to provide
|
|
# a object (in this case this object) on construction of those tasks via the
|
|
# task constructor.
|
|
class ResourceFetcher(object):
|
|
def __init__(self):
|
|
self._db_handle = None
|
|
self._url_handle = None
|
|
|
|
@property
|
|
def db_handle(self):
|
|
if self._db_handle is None:
|
|
self._db_handle = DB()
|
|
return self._db_handle
|
|
|
|
@property
|
|
def url_handle(self):
|
|
if self._url_handle is None:
|
|
self._url_handle = UrlCaller()
|
|
return self._url_handle
|
|
|
|
|
|
class ExtractInputRequest(task.Task):
|
|
def __init__(self, resources):
|
|
super(ExtractInputRequest, self).__init__(provides="parsed_request")
|
|
self._resources = resources
|
|
|
|
def execute(self, request):
|
|
return {
|
|
'user': request.user,
|
|
'user_id': misc.as_int(request.id),
|
|
'request_id': uuidutils.generate_uuid(),
|
|
}
|
|
|
|
|
|
class MakeDBEntry(task.Task):
|
|
def __init__(self, resources):
|
|
super(MakeDBEntry, self).__init__()
|
|
self._resources = resources
|
|
|
|
def execute(self, parsed_request):
|
|
db_handle = self._resources.db_handle
|
|
db_handle.query("INSERT %s INTO mydb" % (parsed_request))
|
|
|
|
def revert(self, result, parsed_request):
|
|
db_handle = self._resources.db_handle
|
|
db_handle.query("DELETE %s FROM mydb IF EXISTS" % (parsed_request))
|
|
|
|
|
|
class ActivateDriver(task.Task):
|
|
def __init__(self, resources):
|
|
super(ActivateDriver, self).__init__(provides='sent_to')
|
|
self._resources = resources
|
|
self._url = "http://blahblah.com"
|
|
|
|
def execute(self, parsed_request):
|
|
print("Sending billing data to %s" % (self._url))
|
|
url_sender = self._resources.url_handle
|
|
# Note that here we attach our update_progress function (which is a
|
|
# function that the engine also 'binds' to) to the progress function
|
|
# that the url sending helper class uses. This allows the task progress
|
|
# to be tied to the url sending progress, which is very useful for
|
|
# downstream systems to be aware of what a task is doing at any time.
|
|
url_sender.send(self._url, json.dumps(parsed_request),
|
|
status_cb=self.update_progress)
|
|
return self._url
|
|
|
|
def update_progress(self, progress, **kwargs):
|
|
# Override the parent method to also print out the status.
|
|
super(ActivateDriver, self).update_progress(progress, **kwargs)
|
|
print("%s is %0.2f%% done" % (self.name, progress * 100))
|
|
|
|
|
|
class DeclareSuccess(task.Task):
|
|
def execute(self, sent_to):
|
|
print("Done!")
|
|
print("All data processed and sent to %s" % (sent_to))
|
|
|
|
|
|
# Resources (db handles and similar) of course can *not* be persisted so we
|
|
# need to make sure that we pass this resource fetcher to the tasks constructor
|
|
# so that the tasks have access to any needed resources (the resources are
|
|
# lazily loaded so that they are only created when they are used).
|
|
resources = ResourceFetcher()
|
|
flow = lf.Flow("initialize-me")
|
|
|
|
# 1. First we extract the api request into a usable format.
|
|
# 2. Then we go ahead and make a database entry for our request.
|
|
flow.add(ExtractInputRequest(resources), MakeDBEntry(resources))
|
|
|
|
# 3. Then we activate our payment method and finally declare success.
|
|
sub_flow = gf.Flow("after-initialize")
|
|
sub_flow.add(ActivateDriver(resources), DeclareSuccess())
|
|
flow.add(sub_flow)
|
|
|
|
# Initially populate the storage with the following request object,
|
|
# prepopulating this allows the tasks that dependent on the 'request' variable
|
|
# to start processing (in this case this is the ExtractInputRequest task).
|
|
store = {
|
|
'request': misc.AttrDict(user="bob", id="1.35"),
|
|
}
|
|
eng = engines.load(flow, engine_conf='serial', store=store)
|
|
|
|
# This context manager automatically adds (and automatically removes) a
|
|
# helpful set of state transition notification printing helper utilities
|
|
# that show you exactly what transitions the engine is going through
|
|
# while running the various billing related tasks.
|
|
with printing.PrintingListener(eng):
|
|
eng.run()
|