1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
# -*- coding: utf-8 -*-
# Copyright (C) 2012-2013 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 logging
import os
import sys
import tempfile
import traceback
logging.basicConfig(level=logging.ERROR)
self_dir = os.path.abspath(os.path.dirname(__file__))
top_dir = os.path.abspath(os.path.join(os.path.dirname(__file__),
os.pardir,
os.pardir))
sys.path.insert(0, top_dir)
sys.path.insert(0, self_dir)
from taskflow import engines
from taskflow.patterns import linear_flow as lf
from taskflow.persistence import models
from taskflow import task
import example_utils as eu # noqa
# INTRO: In this example we create two tasks, one that will say hi and one
# that will say bye with optional capability to raise an error while
# executing. During execution if a later task fails, the reverting that will
# occur in the hi task will undo this (in a ~funny~ way).
#
# To also show the effect of task persistence we create a temporary database
# that will track the state transitions of this hi + bye workflow, this
# persistence allows for you to examine what is stored (using a sqlite client)
# as well as shows you what happens during reversion and what happens to
# the database during both of these modes (failing or not failing).
class HiTask(task.Task):
def execute(self):
print("Hi!")
def revert(self, **kwargs):
print("Whooops, said hi too early, take that back!")
class ByeTask(task.Task):
def __init__(self, blowup):
super(ByeTask, self).__init__()
self._blowup = blowup
def execute(self):
if self._blowup:
raise Exception("Fail!")
print("Bye!")
# This generates your flow structure (at this stage nothing is run).
def make_flow(blowup=False):
flow = lf.Flow("hello-world")
flow.add(HiTask(), ByeTask(blowup))
return flow
# Persist the flow and task state here, if the file/dir exists already blow up
# if not don't blow up, this allows a user to see both the modes and to see
# what is stored in each case.
if eu.SQLALCHEMY_AVAILABLE:
persist_path = os.path.join(tempfile.gettempdir(), "persisting.db")
backend_uri = "sqlite:///%s" % (persist_path)
else:
persist_path = os.path.join(tempfile.gettempdir(), "persisting")
backend_uri = "file:///%s" % (persist_path)
if os.path.exists(persist_path):
blowup = False
else:
blowup = True
with eu.get_backend(backend_uri) as backend:
# Make a flow that will blow up if the file didn't exist previously, if it
# did exist, assume we won't blow up (and therefore this shows the undo
# and redo that a flow will go through).
book = models.LogBook("my-test")
flow = make_flow(blowup=blowup)
eu.print_wrapped("Running")
try:
eng = engines.load(flow, engine='serial',
backend=backend, book=book)
eng.run()
if not blowup:
eu.rm_path(persist_path)
except Exception:
# NOTE(harlowja): don't exit with non-zero status code, so that we can
# print the book contents, as well as avoiding exiting also makes the
# unit tests (which also runs these examples) pass.
traceback.print_exc(file=sys.stdout)
eu.print_wrapped("Book contents")
print(book.pformat())
|
