Signals v2

Makefile

@@ -16,7 +16,7 @@ vtest: flake develop
 cov cover coverage:
 	tox
 
-cov-dev: flake develop
+cov-dev: develop
 	@coverage erase
 	@coverage run -m pytest -s tests
 	@mv .coverage .coverage.accel

aiohttp/signals.py

@@ -0,0 +1,71 @@
+import asyncio
+from itertools import count
+
+
+class BaseSignal(list):
+
+    @asyncio.coroutine
+    def _send(self, *args, **kwargs):
+        for receiver in self:
+            res = receiver(*args, **kwargs)
+            if asyncio.iscoroutine(res) or isinstance(res, asyncio.Future):
+                yield from res
+
+    def copy(self):
+        raise NotImplementedError("copy() is forbidden")
+
+    def sort(self):
+        raise NotImplementedError("sort() is forbidden")
+
+
+class Signal(BaseSignal):
+    """Coroutine-based signal implementation.
+
+    To connect a callback to a signal, use any list method.
+
+    Signals are fired using the :meth:`send` coroutine, which takes named
+    arguments.
+    """
+
+    def __init__(self, app):
+        super().__init__()
+        self._app = app
+        klass = self.__class__
+        self._name = klass.__module__ + ':' + klass.__qualname__
+        self._pre = app.on_pre_signal
+        self._post = app.on_post_signal
+
+    @asyncio.coroutine
+    def send(self, *args, **kwargs):
+        """
+        Sends data to all registered receivers.
+        """
+        ordinal = None
+        debug = self._app._debug
+        if debug:
+            ordinal = self._pre.ordinal()
+            yield from self._pre.send(ordinal, self._name, *args, **kwargs)
+        yield from self._send(*args, **kwargs)
+        if debug:
+            yield from self._post.send(ordinal, self._name, *args, **kwargs)
+
+
+class DebugSignal(BaseSignal):
+
+    @asyncio.coroutine
+    def send(self, ordinal, name, *args, **kwargs):
+        yield from self._send(ordinal, name, *args, **kwargs)
+
+
+class PreSignal(DebugSignal):
+
+    def __init__(self):
+        super().__init__()
+        self._counter = count(1)
+
+    def ordinal(self):
+        return next(self._counter)
+
+
+class PostSignal(DebugSignal):
+    pass

aiohttp/web.py

@@ -7,6 +7,7 @@
 from .web_urldispatcher import *  # noqa
 from .web_ws import *  # noqa
 from .protocol import HttpVersion  # noqa
+from .signals import Signal, PreSignal, PostSignal
 
 
 import asyncio
@@ -179,13 +180,14 @@ class Application(dict):
 
     def __init__(self, *, logger=web_logger, loop=None,
                  router=None, handler_factory=RequestHandlerFactory,
-                 middlewares=()):
+                 middlewares=(), debug=False):
         if loop is None:
             loop = asyncio.get_event_loop()
         if router is None:
             router = UrlDispatcher()
         assert isinstance(router, AbstractRouter), router
 
+        self._debug = debug
         self._router = router
         self._handler_factory = handler_factory
         self._finish_callbacks = []
@@ -196,6 +198,26 @@ def __init__(self, *, logger=web_logger, loop=None,
             assert asyncio.iscoroutinefunction(factory), factory
         self._middlewares = list(middlewares)
 
+        self._on_pre_signal = PreSignal()
+        self._on_post_signal = PostSignal()
+        self._on_response_prepare = Signal(self)
+
+    @property
+    def debug(self):
+        return self._debug
+
+    @property
+    def on_response_prepare(self):
+        return self._on_response_prepare
+
+    @property
+    def on_pre_signal(self):
+        return self._on_pre_signal
+
+    @property
+    def on_post_signal(self):
+        return self._on_post_signal
+
     @property
     def router(self):
         return self._router

aiohttp/web_reqrep.py

@@ -646,6 +646,8 @@ def prepare(self, request):
         resp_impl = self._start_pre_check(request)
         if resp_impl is not None:
             return resp_impl
+        yield from request.app.on_response_prepare.send(request=request,
+                                                        response=self)
 
         return self._start(request)
 

docs/api.rst

@@ -49,6 +49,14 @@ aiohttp.protocol module
     :undoc-members:
     :show-inheritance:
 
+aiohttp.signals module
+----------------------
+
+.. automodule:: aiohttp.signals
+    :members:
+    :undoc-members:
+    :show-inheritance:
+
 aiohttp.streams module
 ----------------------
 

docs/web_reference.rst

@@ -560,6 +560,10 @@ StreamResponse
 
          Use :meth:`prepare` instead.
 
+      .. warning:: The method doesn't call
+         :attr:`web.Application.on_response_prepare` signal, use
+         :meth:`prepare` instead.
+
    .. coroutinemethod:: prepare(request)
 
       :param aiohttp.web.Request request: HTTP request object, that the
@@ -568,6 +572,9 @@ StreamResponse
       Send *HTTP header*. You should not change any header data after
       calling this method.
 
+      The coroutine calls :attr:`web.Application.on_response_prepare`
+      signal handlers.
+
       .. versionadded:: 0.18
 
    .. method:: write(data)
@@ -920,6 +927,13 @@ arbitrary properties for later access from
 
       :ref:`event loop<asyncio-event-loop>` used for processing HTTP requests.
 
+   .. attribute:: on_response_prepare
+
+      A :class:`~aiohttp.signals.Signal` that is fired at the beginning
+      of :meth:`StreamResponse.prepare` with parameters *request* and
+      *response*. It can be used, for example, to add custom headers to each
+      response before sending.
+
    .. method:: make_handler(**kwargs)
 
       Creates HTTP protocol factory for handling requests.

tests/test_signals.py

@@ -0,0 +1,145 @@
+import asyncio
+from unittest import mock
+from aiohttp.multidict import CIMultiDict
+from aiohttp.signals import Signal
+from aiohttp.web import Application
+from aiohttp.web import Request, Response
+from aiohttp.protocol import HttpVersion11
+from aiohttp.protocol import RawRequestMessage
+
+import pytest
+
+
+@pytest.fixture
+def app(loop):
+    return Application(loop=loop)
+
+
+@pytest.fixture
+def debug_app(loop):
+    return Application(loop=loop, debug=True)
+
+
+def make_request(app, method, path, headers=CIMultiDict()):
+    message = RawRequestMessage(method, path, HttpVersion11, headers,
+                                False, False)
+    return request_from_message(message, app)
+
+
+def request_from_message(message, app):
+    payload = mock.Mock()
+    transport = mock.Mock()
+    reader = mock.Mock()
+    writer = mock.Mock()
+    req = Request(app, message, payload,
+                  transport, reader, writer)
+    return req
+
+
+def test_add_response_prepare_signal_handler(loop, app):
+    callback = asyncio.coroutine(lambda request, response: None)
+    app.on_response_prepare.append(callback)
+
+
+def test_add_signal_handler_not_a_callable(loop, app):
+    callback = True
+    app.on_response_prepare.append(callback)
+    with pytest.raises(TypeError):
+        app.on_response_prepare(None, None)
+
+
+def test_function_signal_dispatch(loop, app):
+    signal = Signal(app)
+    kwargs = {'foo': 1, 'bar': 2}
+
+    callback_mock = mock.Mock()
+
+    @asyncio.coroutine
+    def callback(**kwargs):
+        callback_mock(**kwargs)
+
+    signal.append(callback)
+
+    loop.run_until_complete(signal.send(**kwargs))
+    callback_mock.assert_called_once_with(**kwargs)
+
+
+def test_function_signal_dispatch2(loop, app):
+    signal = Signal(app)
+    args = {'a', 'b'}
+    kwargs = {'foo': 1, 'bar': 2}
+
+    callback_mock = mock.Mock()
+
+    @asyncio.coroutine
+    def callback(*args, **kwargs):
+        callback_mock(*args, **kwargs)
+
+    signal.append(callback)
+
+    loop.run_until_complete(signal.send(*args, **kwargs))
+    callback_mock.assert_called_once_with(*args, **kwargs)
+
+
+def test_response_prepare(loop, app):
+    callback = mock.Mock()
+
+    @asyncio.coroutine
+    def cb(*args, **kwargs):
+        callback(*args, **kwargs)
+
+    app.on_response_prepare.append(cb)
+
+    request = make_request(app, 'GET', '/')
+    response = Response(body=b'')
+    loop.run_until_complete(response.prepare(request))
+
+    callback.assert_called_once_with(request=request,
+                                     response=response)
+
+
+def test_non_coroutine(loop, app):
+    signal = Signal(app)
+    kwargs = {'foo': 1, 'bar': 2}
+
+    callback = mock.Mock()
+
+    signal.append(callback)
+
+    loop.run_until_complete(signal.send(**kwargs))
+    callback.assert_called_once_with(**kwargs)
+
+
+def test_copy_forbidden(app):
+    signal = Signal(app)
+    with pytest.raises(NotImplementedError):
+        signal.copy()
+
+
+def test_sort_forbidden(app):
+    l1 = lambda: None
+    l2 = lambda: None
+    l3 = lambda: None
+    signal = Signal(app)
+    signal.extend([l1, l2, l3])
+    with pytest.raises(NotImplementedError):
+        signal.sort()
+    assert signal == [l1, l2, l3]
+
+
+def test_debug_signal(loop, debug_app):
+    assert debug_app.debug, "Should be True"
+    signal = Signal(debug_app)
+
+    callback = mock.Mock()
+    pre = mock.Mock()
+    post = mock.Mock()
+
+    signal.append(callback)
+    debug_app.on_pre_signal.append(pre)
+    debug_app.on_post_signal.append(post)
+
+    loop.run_until_complete(signal.send(1, a=2))
+    callback.assert_called_once_with(1, a=2)
+    pre.assert_called_once_with(1, 'aiohttp.signals:Signal', 1, a=2)
+    post.assert_called_once_with(1, 'aiohttp.signals:Signal', 1, a=2)

tests/test_web_exceptions.py

@@ -6,7 +6,7 @@
 from aiohttp.web import Request
 from aiohttp.protocol import RawRequestMessage, HttpVersion11
 
-from aiohttp import web
+from aiohttp import signals, web
 
 
 class TestHTTPExceptions(unittest.TestCase):
@@ -32,6 +32,8 @@ def append(self, data):
 
     def make_request(self, method='GET', path='/', headers=CIMultiDict()):
         self.app = mock.Mock()
+        self.app._debug = False
+        self.app.on_response_prepare = signals.Signal(self.app)
         message = RawRequestMessage(method, path, HttpVersion11, headers,
                                     False, False)
         req = Request(self.app, message, self.payload,

tests/test_web_request.py

@@ -1,6 +1,7 @@
 import asyncio
 import unittest
 from unittest import mock
+from aiohttp.signals import Signal
 from aiohttp.web import Request
 from aiohttp.multidict import MultiDict, CIMultiDict
 from aiohttp.protocol import HttpVersion
@@ -23,6 +24,8 @@ def make_request(self, method, path, headers=CIMultiDict(), *,
         if version < HttpVersion(1, 1):
             closing = True
         self.app = mock.Mock()
+        self.app._debug = False
+        self.app.on_response_prepare = Signal(self.app)
         message = RawRequestMessage(method, path, version, headers, closing,
                                     False)
         self.payload = mock.Mock()