Prevent wild assignment in DEBUG mode only (#2860)

For sake of performance

aiohttp/client.py

@@ -25,8 +25,8 @@
 from .connector import *  # noqa
 from .connector import TCPConnector
 from .cookiejar import CookieJar
-from .helpers import (PY_36, CeilTimeout, TimeoutHandle, proxies_from_env,
-                      sentinel, strip_auth_from_url)
+from .helpers import (DEBUG, PY_36, CeilTimeout, TimeoutHandle,
+                      proxies_from_env, sentinel, strip_auth_from_url)
 from .http import WS_KEY, WebSocketReader, WebSocketWriter
 from .http_websocket import WSHandshakeError, ws_ext_gen, ws_ext_parse
 from .streams import FlowControlDataQueue
@@ -149,13 +149,14 @@ def __init_subclass__(cls):
                       DeprecationWarning,
                       stacklevel=2)
 
-    def __setattr__(self, name, val):
-        if name not in self.ATTRS:
-            warnings.warn("Setting custom ClientSession.{} attribute "
-                          "is discouraged".format(name),
-                          DeprecationWarning,
-                          stacklevel=2)
-        super().__setattr__(name, val)
+    if DEBUG:
+        def __setattr__(self, name, val):
+            if name not in self.ATTRS:
+                warnings.warn("Setting custom ClientSession.{} attribute "
+                              "is discouraged".format(name),
+                              DeprecationWarning,
+                              stacklevel=2)
+            super().__setattr__(name, val)
 
     def __del__(self, _warnings=warnings):
         if not self.closed:

aiohttp/helpers.py

@@ -43,6 +43,13 @@
 sentinel = object()
 NO_EXTENSIONS = bool(os.environ.get('AIOHTTP_NO_EXTENSIONS'))
 
+# N.B. sys.flags.dev_mode is available on Python 3.7+, use getattr
+# for compatibility with older versions
+DEBUG = (getattr(sys.flags, 'dev_mode', False) or
+         (not sys.flags.ignore_environment and
+          bool(os.environ.get('PYTHONASYNCIODEBUG'))))
+
+
 CHAR = set(chr(i) for i in range(0, 128))
 CTL = set(chr(i) for i in range(0, 32)) | {chr(127), }
 SEPARATORS = {'(', ')', '<', '>', '@', ',', ';', ':', '\\', '"', '/', '[', ']',
@@ -52,6 +59,8 @@
 
 coroutines = asyncio.coroutines
 old_debug = coroutines._DEBUG
+
+# prevent "coroutine noop was never awaited" warning.
 coroutines._DEBUG = False
 
 

aiohttp/web_app.py

@@ -6,7 +6,7 @@
 from . import hdrs
 from .abc import AbstractAccessLogger, AbstractMatchInfo, AbstractRouter
 from .frozenlist import FrozenList
-from .helpers import AccessLogger
+from .helpers import DEBUG, AccessLogger
 from .log import web_logger
 from .signals import Signal
 from .web_middlewares import _fix_request_current_app
@@ -71,13 +71,14 @@ def __init_subclass__(cls):
                       DeprecationWarning,
                       stacklevel=2)
 
-    def __setattr__(self, name, val):
-        if name not in self.ATTRS:
-            warnings.warn("Setting custom web.Application.{} attribute "
-                          "is discouraged".format(name),
-                          DeprecationWarning,
-                          stacklevel=2)
-        super().__setattr__(name, val)
+    if DEBUG:
+        def __setattr__(self, name, val):
+            if name not in self.ATTRS:
+                warnings.warn("Setting custom web.Application.{} attribute "
+                              "is discouraged".format(name),
+                              DeprecationWarning,
+                              stacklevel=2)
+            super().__setattr__(name, val)
 
     # MutableMapping API
 

aiohttp/web_request.py

@@ -19,7 +19,7 @@
 from yarl import URL
 
 from . import hdrs, multipart
-from .helpers import HeadersMixin, reify, sentinel
+from .helpers import DEBUG, HeadersMixin, reify, sentinel
 from .streams import EmptyStreamReader
 from .web_exceptions import HTTPRequestEntityTooLarge
 
@@ -632,14 +632,15 @@ def __init__(self, *args, **kwargs):
         # or information about traversal lookup
         self._match_info = None  # initialized after route resolving
 
-    def __setattr__(self, name, val):
-        if name not in self.ATTRS:
-            warnings.warn("Setting custom {}.{} attribute "
-                          "is discouraged".format(self.__class__.__name__,
-                                                  name),
-                          DeprecationWarning,
-                          stacklevel=2)
-        super().__setattr__(name, val)
+    if DEBUG:
+        def __setattr__(self, name, val):
+            if name not in self.ATTRS:
+                warnings.warn("Setting custom {}.{} attribute "
+                              "is discouraged".format(self.__class__.__name__,
+                                                      name),
+                              DeprecationWarning,
+                              stacklevel=2)
+            super().__setattr__(name, val)
 
     def clone(self, *, method=sentinel, rel_url=sentinel,
               headers=sentinel, scheme=sentinel, host=sentinel,

tests/test_client_session.py

@@ -16,7 +16,7 @@
 from aiohttp.client import ClientSession
 from aiohttp.client_reqrep import ClientRequest
 from aiohttp.connector import BaseConnector, TCPConnector
-from aiohttp.helpers import PY_36
+from aiohttp.helpers import DEBUG, PY_36
 
 
 @pytest.fixture
@@ -640,6 +640,8 @@ class A(ClientSession):
             pass
 
 
+@pytest.mark.skipif(not DEBUG,
+                    reason="The check is applied in DEBUG mode only")
 def test_client_session_custom_attr(loop):
     session = ClientSession(loop=loop)
     with pytest.warns(DeprecationWarning):

tests/test_web_app.py

@@ -6,7 +6,7 @@
 
 from aiohttp import log, web
 from aiohttp.abc import AbstractAccessLogger, AbstractRouter
-from aiohttp.helpers import PY_36
+from aiohttp.helpers import DEBUG, PY_36
 from aiohttp.test_utils import make_mocked_coro
 
 
@@ -256,6 +256,8 @@ class A(web.Application):
             pass
 
 
+@pytest.mark.skipif(not DEBUG,
+                    reason="The check is applied in DEBUG mode only")
 def test_app_custom_attr():
     app = web.Application()
     with pytest.warns(DeprecationWarning):

tests/test_web_request.py

@@ -7,6 +7,7 @@
 from yarl import URL
 
 from aiohttp import HttpVersion
+from aiohttp.helpers import DEBUG
 from aiohttp.streams import StreamReader
 from aiohttp.test_utils import make_mocked_request
 from aiohttp.web import HTTPRequestEntityTooLarge
@@ -601,6 +602,8 @@ def test_clone_remote():
     assert req2.remote == '11.11.11.11'
 
 
+@pytest.mark.skipif(not DEBUG,
+                    reason="The check is applied in DEBUG mode only")
 def test_request_custom_attr():
     req = make_mocked_request('GET', '/')
     with pytest.warns(DeprecationWarning):