Initial Django app.

.gitignore

@@ -0,0 +1,2 @@
+*.pyc
+*.sqlite3

README.md

@@ -0,0 +1,80 @@
+Async Task Channels Demo
+========================
+
+The demo goes with the talk [Async Tasks with Django
+Channels](http://albertoconnor.ca/pycon-canada-2016-talk.html) given
+at [PyCon Canada 2016](https://2016.pycon.ca/en/schedule/016-albert-oconnor/)
+
+It is split up into a few different step with tags so you can more
+easily see how it was built up.
+
+step1
+-----
+
+    git clone https://github.com/albertoconnor/asyncdemo.git
+    cd asyncdemo
+    git checkout step1
+
+At this point, the code is for a basic Django 1.10 web app. Get into your
+favorite type of virtual env and then run the following.
+
+    pip install -r requirements.text
+    cd asyncdemo
+    python manage.py migrate
+    python manage.py runserver
+
+Now you should have the hello_view being served at
+http://127.0.0.1:8000/. You can append "?name=yourname" to change the
+name displayed.
+
+Meanwhile, there is a simulated slow network call which writes out the
+hello message to the console and takes between 5 and 30 seconds to
+do it.
+
+step2
+-----
+
+    git checkout step2
+
+This has updated requirements.txt and settings.py and created a
+routes.py which is even to get Django to run with Channels. The view
+remains unchanged, so it will still be slow when you runserver. You can
+see though the output Django produces when you runserver has been
+changed.
+
+step 3
+------
+
+    git checkout step3
+
+A "notify" channel has been declared and the view now uses it. When you
+runserver the website is more responsive, but if you hammer it those
+slow 30 second simulated network calls will gum up the system.
+
+bonusround
+----------
+
+    git checkout bonusround
+
+This changes channels to use redis as the broker of messages. Even to
+runserver you will need to have redis running locally.
+
+When you do you will get the same behavior of step 3. To get around the
+slow down under load we will need to run everything in separate
+processes, in separate terminals.
+
+    daphne asyncdemo.asgi:channel_layer --port 8000
+
+This runs the interface server in it's own process. If you try to
+connect now it will time out because there are no workers running.
+
+You can run workers in as many separate terminals as you like:
+
+    python manage.py runworker
+
+But the key to trying to maintain throughput is to run a worker which
+will never be tied up with a notification task:
+
+    python manage.py runworker --exclude-channels=notify
+
+This worker will ensure that hello_view remains responsive.

asyncdemo/asyncdemo/settings.py

@@ -0,0 +1,121 @@
+"""
+Django settings for asyncdemo project.
+
+Generated by 'django-admin startproject' using Django 1.10.2.
+
+For more information on this file, see
+https://docs.djangoproject.com/en/1.10/topics/settings/
+
+For the full list of settings and their values, see
+https://docs.djangoproject.com/en/1.10/ref/settings/
+"""
+
+import os
+
+# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
+BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+
+
+# Quick-start development settings - unsuitable for production
+# See https://docs.djangoproject.com/en/1.10/howto/deployment/checklist/
+
+# SECURITY WARNING: keep the secret key used in production secret!
+SECRET_KEY = 'ud9(^27w%&0j=1oe1kvp@i*1=y0#6#e!4dz^4sncz#pihs_%kt'
+
+# SECURITY WARNING: don't run with debug turned on in production!
+DEBUG = True
+
+ALLOWED_HOSTS = []
+
+
+# Application definition
+
+INSTALLED_APPS = [
+    'django.contrib.admin',
+    'django.contrib.auth',
+    'django.contrib.contenttypes',
+    'django.contrib.sessions',
+    'django.contrib.messages',
+    'django.contrib.staticfiles',
+    'hello',
+]
+
+MIDDLEWARE = [
+    'django.middleware.security.SecurityMiddleware',
+    'django.contrib.sessions.middleware.SessionMiddleware',
+    'django.middleware.common.CommonMiddleware',
+    'django.middleware.csrf.CsrfViewMiddleware',
+    'django.contrib.auth.middleware.AuthenticationMiddleware',
+    'django.contrib.messages.middleware.MessageMiddleware',
+    'django.middleware.clickjacking.XFrameOptionsMiddleware',
+]
+
+ROOT_URLCONF = 'asyncdemo.urls'
+
+TEMPLATES = [
+    {
+        'BACKEND': 'django.template.backends.django.DjangoTemplates',
+        'DIRS': [],
+        'APP_DIRS': True,
+        'OPTIONS': {
+            'context_processors': [
+                'django.template.context_processors.debug',
+                'django.template.context_processors.request',
+                'django.contrib.auth.context_processors.auth',
+                'django.contrib.messages.context_processors.messages',
+            ],
+        },
+    },
+]
+
+WSGI_APPLICATION = 'asyncdemo.wsgi.application'
+
+
+# Database
+# https://docs.djangoproject.com/en/1.10/ref/settings/#databases
+
+DATABASES = {
+    'default': {
+        'ENGINE': 'django.db.backends.sqlite3',
+        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
+    }
+}
+
+
+# Password validation
+# https://docs.djangoproject.com/en/1.10/ref/settings/#auth-password-validators
+
+AUTH_PASSWORD_VALIDATORS = [
+    {
+        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
+    },
+    {
+        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
+    },
+    {
+        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
+    },
+    {
+        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
+    },
+]
+
+
+# Internationalization
+# https://docs.djangoproject.com/en/1.10/topics/i18n/
+
+LANGUAGE_CODE = 'en-us'
+
+TIME_ZONE = 'UTC'
+
+USE_I18N = True
+
+USE_L10N = True
+
+USE_TZ = True
+
+
+# Static files (CSS, JavaScript, Images)
+# https://docs.djangoproject.com/en/1.10/howto/static-files/
+
+STATIC_URL = '/static/'

asyncdemo/asyncdemo/urls.py

@@ -0,0 +1,7 @@
+from django.conf.urls import url
+
+from hello import views
+
+urlpatterns = [
+    url(r'^$', views.hello_view),
+]

asyncdemo/asyncdemo/wsgi.py

@@ -0,0 +1,16 @@
+"""
+WSGI config for asyncdemo project.
+
+It exposes the WSGI callable as a module-level variable named ``application``.
+
+For more information on this file, see
+https://docs.djangoproject.com/en/1.10/howto/deployment/wsgi/
+"""
+
+import os
+
+from django.core.wsgi import get_wsgi_application
+
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "asyncdemo.settings")
+
+application = get_wsgi_application()

asyncdemo/hello/admin.py

@@ -0,0 +1,3 @@
+from django.contrib import admin
+
+# Register your models here.

asyncdemo/hello/apps.py

@@ -0,0 +1,5 @@
+from django.apps import AppConfig
+
+
+class HelloConfig(AppConfig):
+    name = 'hello'

asyncdemo/hello/models.py

@@ -0,0 +1,3 @@
+from django.db import models
+
+# Create your models here.

asyncdemo/hello/templates/hello.html

@@ -0,0 +1,12 @@
+<!doctype html>
+<html>
+<head>
+  <meta charset="utf-8"/>
+  <title>Asyc Demo</title>
+</head>
+
+<body>
+<h1>{{ message }}</h1>
+</body>
+
+</html>

asyncdemo/hello/tests.py

@@ -0,0 +1,3 @@
+from django.test import TestCase
+
+# Create your tests here.

asyncdemo/hello/views.py

@@ -0,0 +1,29 @@
+import time
+from django.shortcuts import render
+
+
+def delay():
+    while True:
+        for i in [5, 5, 5, 30]:  # Simulate unreliability
+            yield i
+
+
+delay_generator = delay()
+
+
+def send_notification(message):
+    time.sleep(next(delay_generator))
+    print(message)  # Simulate sending to slack etc.
+
+
+def hello_view(request, template="hello.html"):
+    name = request.GET.get('name', 'World')
+    message = 'Hello, {}!'.format(name)
+
+    send_notification(message)
+
+    return render(
+        request,
+        template,
+        dict(message=message),
+    )

asyncdemo/manage.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+import os
+import sys
+
+if __name__ == "__main__":
+    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "asyncdemo.settings")
+    try:
+        from django.core.management import execute_from_command_line
+    except ImportError:
+        # The above import may fail for some other reason. Ensure that the
+        # issue is really that Django is missing to avoid masking other
+        # exceptions on Python 2.
+        try:
+            import django
+        except ImportError:
+            raise ImportError(
+                "Couldn't import Django. Are you sure it's installed and "
+                "available on your PYTHONPATH environment variable? Did you "
+                "forget to activate a virtual environment?"
+            )
+        raise
+    execute_from_command_line(sys.argv)