# 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.

"""

Sample application that demonstrates how to use the App Engine background

threads.

app.yaml scaling must be set to manual or basic.

"""

# [START background-imp]

from google.appengine.api import background_thread

# [END background-imp]

import webapp2

val = 'Dog'

class MainHandler(webapp2.RequestHandler):

def get(self):

self.response.headers['Content-Type'] = 'text/plain'

self.response.write(str(val))

class SetDogHandler(webapp2.RequestHandler):

""" Resets the global val to 'Dog'"""

def get(self):

global val

val = 'Dog'

self.response.headers['Content-Type'] = 'text/plain'

self.response.write('Done')

class SetCatBackgroundHandler(webapp2.RequestHandler):

""" Demonstrates two ways to start new background threads

"""

def get(self):

"""

Demonstrates using a background thread to change the global

val from 'Dog' to 'Cat'

The auto GET parameter determines whether to start the thread

automatically or manually

"""

auto = self.request.get('auto')

# [START background-start]

# sample function to run in a background thread

def change_val(arg):

global val

val = arg

if auto:

# Start the new thread in one command

background_thread.start_new_background_thread(change_val, ['Cat'])

else:

# create a new thread and start it

t = background_thread.BackgroundThread(

target=change_val, args=['Cat'])

t.start()

# [END background-start]

self.response.headers['Content-Type'] = 'text/plain'

self.response.write('Done')

app = webapp2.WSGIApplication([

('/', MainHandler),

('/dog', SetDogHandler),

('/cat', SetCatBackgroundHandler),

], debug=True)

# [END all]