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# Copyright (C) 2015 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 functools
import logging
import os
import sys
import time
import traceback
from kazoo import client
top_dir = os.path.abspath(os.path.join(os.path.dirname(__file__),
os.pardir,
os.pardir))
sys.path.insert(0, top_dir)
from taskflow.conductors import backends as conductor_backends
from taskflow import engines
from taskflow.jobs import backends as job_backends
from taskflow import logging as taskflow_logging
from taskflow.patterns import linear_flow as lf
from taskflow.persistence import backends as persistence_backends
from taskflow.persistence import models
from taskflow import task
from oslo_utils import timeutils
from oslo_utils import uuidutils
# Instructions!
#
# 1. Install zookeeper (or change host listed below)
# 2. Download this example, place in file '99_bottles.py'
# 3. Run `python 99_bottles.py p` to place a song request onto the jobboard
# 4. Run `python 99_bottles.py c` a few times (in different shells)
# 5. On demand kill previously listed processes created in (4) and watch
# the work resume on another process (and repeat)
# 6. Keep enough workers alive to eventually finish the song (if desired).
ME = os.getpid()
ZK_HOST = "localhost:2181"
JB_CONF = {
'hosts': ZK_HOST,
'board': 'zookeeper',
'path': '/taskflow/99-bottles-demo',
}
PERSISTENCE_URI = r"sqlite:////tmp/bottles.db"
TAKE_DOWN_DELAY = 1.0
PASS_AROUND_DELAY = 3.0
HOW_MANY_BOTTLES = 99
class TakeABottleDown(task.Task):
def execute(self, bottles_left):
sys.stdout.write('Take one down, ')
sys.stdout.flush()
time.sleep(TAKE_DOWN_DELAY)
return bottles_left - 1
class PassItAround(task.Task):
def execute(self):
sys.stdout.write('pass it around, ')
sys.stdout.flush()
time.sleep(PASS_AROUND_DELAY)
class Conclusion(task.Task):
def execute(self, bottles_left):
sys.stdout.write('%s bottles of beer on the wall...\n' % bottles_left)
sys.stdout.flush()
def make_bottles(count):
# This is the function that will be called to generate the workflow
# and will also be called to regenerate it on resumption so that work
# can continue from where it last left off...
s = lf.Flow("bottle-song")
take_bottle = TakeABottleDown("take-bottle-%s" % count,
inject={'bottles_left': count},
provides='bottles_left')
pass_it = PassItAround("pass-%s-around" % count)
next_bottles = Conclusion("next-bottles-%s" % (count - 1))
s.add(take_bottle, pass_it, next_bottles)
for bottle in reversed(list(range(1, count))):
take_bottle = TakeABottleDown("take-bottle-%s" % bottle,
provides='bottles_left')
pass_it = PassItAround("pass-%s-around" % bottle)
next_bottles = Conclusion("next-bottles-%s" % (bottle - 1))
s.add(take_bottle, pass_it, next_bottles)
return s
def run_conductor(only_run_once=False):
# This continuously runs consumers until its stopped via ctrl-c or other
# kill signal...
event_watches = {}
# This will be triggered by the conductor doing various activities
# with engines, and is quite nice to be able to see the various timing
# segments (which is useful for debugging, or watching, or figuring out
# where to optimize).
def on_conductor_event(cond, event, details):
print("Event '%s' has been received..." % event)
print("Details = %s" % details)
if event.endswith("_start"):
w = timeutils.StopWatch()
w.start()
base_event = event[0:-len("_start")]
event_watches[base_event] = w
if event.endswith("_end"):
base_event = event[0:-len("_end")]
try:
w = event_watches.pop(base_event)
w.stop()
print("It took %0.3f seconds for event '%s' to finish"
% (w.elapsed(), base_event))
except KeyError:
pass
if event == 'running_end' and only_run_once:
cond.stop()
print("Starting conductor with pid: %s" % ME)
my_name = "conductor-%s" % ME
persist_backend = persistence_backends.fetch(PERSISTENCE_URI)
with contextlib.closing(persist_backend):
with contextlib.closing(persist_backend.get_connection()) as conn:
conn.upgrade()
job_backend = job_backends.fetch(my_name, JB_CONF,
persistence=persist_backend)
job_backend.connect()
with contextlib.closing(job_backend):
cond = conductor_backends.fetch('blocking', my_name, job_backend,
persistence=persist_backend)
on_conductor_event = functools.partial(on_conductor_event, cond)
cond.notifier.register(cond.notifier.ANY, on_conductor_event)
# Run forever, and kill -9 or ctrl-c me...
try:
cond.run()
finally:
cond.stop()
cond.wait()
def run_poster():
# This just posts a single job and then ends...
print("Starting poster with pid: %s" % ME)
my_name = "poster-%s" % ME
persist_backend = persistence_backends.fetch(PERSISTENCE_URI)
with contextlib.closing(persist_backend):
with contextlib.closing(persist_backend.get_connection()) as conn:
conn.upgrade()
job_backend = job_backends.fetch(my_name, JB_CONF,
persistence=persist_backend)
job_backend.connect()
with contextlib.closing(job_backend):
# Create information in the persistence backend about the
# unit of work we want to complete and the factory that
# can be called to create the tasks that the work unit needs
# to be done.
lb = models.LogBook("post-from-%s" % my_name)
fd = models.FlowDetail("song-from-%s" % my_name,
uuidutils.generate_uuid())
lb.add(fd)
with contextlib.closing(persist_backend.get_connection()) as conn:
conn.save_logbook(lb)
engines.save_factory_details(fd, make_bottles,
[HOW_MANY_BOTTLES], {},
backend=persist_backend)
# Post, and be done with it!
jb = job_backend.post("song-from-%s" % my_name, book=lb)
print("Posted: %s" % jb)
print("Goodbye...")
def main_local():
# Run locally typically this is activating during unit testing when all
# the examples are made sure to still function correctly...
global TAKE_DOWN_DELAY
global PASS_AROUND_DELAY
global JB_CONF
# Make everything go much faster (so that this finishes quickly).
PASS_AROUND_DELAY = 0.01
TAKE_DOWN_DELAY = 0.01
JB_CONF['path'] = JB_CONF['path'] + "-" + uuidutils.generate_uuid()
run_poster()
run_conductor(only_run_once=True)
def check_for_zookeeper(timeout=1):
sys.stderr.write("Testing for the existence of a zookeeper server...\n")
sys.stderr.write("Please wait....\n")
with contextlib.closing(client.KazooClient()) as test_client:
try:
test_client.start(timeout=timeout)
except test_client.handler.timeout_exception:
sys.stderr.write("Zookeeper is needed for running this example!\n")
traceback.print_exc()
return False
else:
test_client.stop()
return True
def main():
if not check_for_zookeeper():
return
if len(sys.argv) == 1:
main_local()
elif sys.argv[1] in ('p', 'c'):
if sys.argv[-1] == "v":
logging.basicConfig(level=taskflow_logging.TRACE)
else:
logging.basicConfig(level=logging.ERROR)
if sys.argv[1] == 'p':
run_poster()
else:
run_conductor()
else:
sys.stderr.write("%s p|c (v?)\n" % os.path.basename(sys.argv[0]))
if __name__ == '__main__':
main()
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