aiohttpとaiopgを使ってasync web+dbアプリケーション

app.py

# -*- coding:utf-8 -*-
import io
import argparse
import asyncio
import aiopg
import sqlalchemy as sa
import webob
from aiopg.sa import create_engine
from aiohttp.wsgi import WSGIServerHttpProtocol
from webdispatch import URLDispatcher, MethodDispatcher
from jinja2 import Environment, PackageLoader

templates = Environment(loader=PackageLoader(__name__, 'templates'))

engine = None

class Application(URLDispatcher):
    def __init__(self):
        super(Application, self).__init__()
        self.add_url('top', '/', index)

metadata = sa.MetaData()

document_table = sa.Table("documents", metadata,
    sa.Column("id", sa.Integer, primary_key=True),
    sa.Column("name", sa.Unicode(255)),
    sa.Column("contents", sa.UnicodeText),
)


def async_request(environ):
    data = yield from environ['wsgi.input'].read()
    environ['wsgi.input'] = io.BytesIO(data)
    request = webob.Request(environ)
    return request


def render_response(name, values):
    tmpl = templates.get_template(name)
    response = webob.Response(tmpl.render(values))
    return response

@asyncio.coroutine
def get_index(environ, start_response):
    with (yield from engine) as conn:
        documents = yield from conn.execute(document_table.select())
        response = render_response('index.html', {'documents': documents})
        return response(environ, start_response)


@asyncio.coroutine
def post_index(environ, start_response):
    request = yield from async_request(environ)
    with (yield from engine) as conn:
        tx = yield from conn.begin()
        yield from conn.execute(document_table.insert().values(
            name=request.params['name'],
            contents=request.params['contents']))

        documents = yield from conn.execute(document_table.select())
        response = render_response('index.html', {'documents': documents})
        yield from tx.commit()
        return response(environ, start_response)


index = MethodDispatcher()
index.register_app('get', get_index)
index.register_app('post', post_index)

class AppProtocol(WSGIServerHttpProtocol):
    def __init__(self):
        super(AppProtocol, self).__init__(Application())


def main():
    global engine
    parser = argparse.ArgumentParser()
    parser.add_argument('dsn')
    parser.add_argument('host')
    parser.add_argument('port', type=int)
    args = parser.parse_args()

    loop = asyncio.get_event_loop()
    engine = loop.run_until_complete(create_engine(dsn=args.dsn))
    print(engine)
    proto = loop.create_server(AppProtocol, args.host, args.port)
    server = loop.run_until_complete(proto)
    print(server)
    loop.run_forever()

requirements.txt

Jinja2==2.7.2
MarkupSafe==0.23
SQLAlchemy==0.9.4
WebDispatch==1.2
WebOb==1.4
aiohttp==0.7.2
aiopg==0.2.1
psycopg2==2.5.3