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App Engine Task Queue example using pull queues.
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jeffmendoza committed Apr 12, 2016
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8 changes: 8 additions & 0 deletions appengine/taskqueue/pull-counter/README.md
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# App Engine Task Queue Pull Counter

<!-- auto-doc-link -->
These samples are used on the following documentation page:

> https://cloud.google.com/appengine/docs/python/taskqueue/overview-pull
<!-- end-auto-doc-link -->
11 changes: 11 additions & 0 deletions appengine/taskqueue/pull-counter/app.yaml
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runtime: python27
api_version: 1
threadsafe: true

handlers:
- url: /.*
script: main.app

libraries:
- name: jinja2
version: 2.6
15 changes: 15 additions & 0 deletions appengine/taskqueue/pull-counter/counter.html
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<!DOCTYPE html>
<html>
<body>
<form action="/" method="POST">
<label for="key">Key:</label><input type="text" name="key" id="key">
<input type="submit" value="+1">
</form>
<ul>
{% for counter in counters %}
<li>
{{counter.key.id()|e}}: {{counter.count|e}}
</li>
{% endfor %}
</body>
</html>
84 changes: 84 additions & 0 deletions appengine/taskqueue/pull-counter/main.py
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# Copyright 2016 Google 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.

# [START all]
"""A simple counter with App Engine pull queue."""

import logging
import os
import time

from google.appengine.api import taskqueue
from google.appengine.ext import ndb
from google.appengine.runtime import apiproxy_errors
import jinja2
import webapp2


JINJA_ENV = jinja2.Environment(
loader=jinja2.FileSystemLoader(os.path.dirname(__file__)))


class Counter(ndb.Model):
count = ndb.IntegerProperty(indexed=False)


class CounterHandler(webapp2.RequestHandler):
def get(self):
template_values = {'counters': Counter.query()}
counter_template = JINJA_ENV.get_template('counter.html')
self.response.out.write(counter_template.render(template_values))

def post(self):
key = self.request.get('key')
if key:
queue = taskqueue.Queue('pullq')
queue.add(taskqueue.Task(payload='', method='PULL', tag=key))
self.redirect('/')


class CounterWorker(webapp2.RequestHandler):
def get(self):
"""Indefinitely fetch tasks and update the datastore."""
queue = taskqueue.Queue('pullq')
while True:
try:
tasks = queue.lease_tasks_by_tag(3600, 1000, deadline=60)
except (taskqueue.TransientError,
apiproxy_errors.DeadlineExceededError) as e:
logging.exception(e)
time.sleep(1)
continue
if tasks:
key = tasks[0].tag

@ndb.transactional
def update_counter():
counter = Counter.get_or_insert(key, count=0)
counter.count += len(tasks)
counter.put()
try:
update_counter()
except Exception as e:
logging.exception(e)
else:
queue.delete_tasks(tasks)
time.sleep(1)


app = webapp2.WSGIApplication([
('/', CounterHandler),
('/_ah/start', CounterWorker)
], debug=True)
# [END all]
32 changes: 32 additions & 0 deletions appengine/taskqueue/pull-counter/pullcounter_test.py
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# Copyright 2016 Google 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.

from google.appengine.ext import testbed as gaetestbed
import main
import os
import webtest


def test_app(testbed):
key_name = 'foo'

testbed.init_taskqueue_stub(root_path=os.path.dirname(__file__))

app = webtest.TestApp(main.app)
app.post('/', {'key': key_name})

tq_stub = testbed.get_stub(gaetestbed.TASKQUEUE_SERVICE_NAME)
tasks = tq_stub.get_filtered_tasks()
assert len(tasks) == 1
assert tasks[0].name == 'task1'
3 changes: 3 additions & 0 deletions appengine/taskqueue/pull-counter/queue.yaml
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queue:
- name: pullq
mode: pull
15 changes: 15 additions & 0 deletions appengine/taskqueue/pull-counter/worker.yaml
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module: worker
api_version: 1
runtime: python27
instance_class: B1
threadsafe: yes
manual_scaling:
instances: 1

handlers:
- url: /.*
script: main.app

libraries:
- name: jinja2
version: 2.6

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