Support brotlicffi alternatively to brotli

Support the brotlicffi implementation as an alternative to brotli.
This is necessary since the current version of brotli (as of 1.1.0)
does not work on PyPy.  This uses the approach of preferring brotlicffi
over brotli in imports, and listing brotli or brotlicffi depending
on the Python implementation in dependencies, as recommended
in brotlicffi documentation:
https://pypi.org/project/brotlicffi/1.1.0.0/#using-brotlicffi-in-projects

aiohttp/compression_utils.py

@@ -4,7 +4,10 @@
 from typing import Optional, cast
 
 try:
-    import brotli
+    try:
+        import brotlicffi as brotli
+    except ImportError:
+        import brotli
 
     HAS_BROTLI = True
 except ImportError:  # pragma: no cover

docs/client_quickstart.rst

@@ -187,7 +187,8 @@ The ``gzip`` and ``deflate`` transfer-encodings are automatically
 decoded for you.
 
 You can enable ``brotli`` transfer-encodings support,
-just install  `Brotli <https://pypi.org/project/Brotli>`_.
+just install `brotlicffi <https://pypi.org/project/brotlicffi/>`_
+or `Brotli <https://pypi.org/project/Brotli/>`_.
 
 JSON Request
 ============

docs/index.rst

@@ -158,7 +158,8 @@ Dependencies
 
      $ pip install aiodns
 
-- *Optional* :term:`Brotli` for brotli (:rfc:`7932`) client compression support.
+- *Optional* :term:`brotlicffi` or  :term:`Brotli` for brotli (:rfc:`7932`)
+  client compression support.
 
   .. code-block:: bash
 

docs/spelling_wordlist.txt

@@ -40,6 +40,7 @@ boolean
 botocore
 brotli
 Brotli
+brotlicffi
 brotlipy
 bugfix
 Bugfixes

setup.cfg

@@ -62,7 +62,8 @@ install_requires =
 speedups =
   # required c-ares (aiodns' backend) will not build on windows
   aiodns >= 1.1; sys_platform=="linux" or sys_platform=="darwin"
-  Brotli
+  Brotli; platform_python_implementation == 'CPython'
+  brotlicffi; platform_python_implementation != 'CPython'
 
 [options.packages.find]
 exclude =

tests/test_http_parser.py

@@ -22,7 +22,10 @@
 )
 
 try:
-    import brotli
+    try:
+        import brotlicffi as brotli
+    except ImportError:
+        import brotli
 except ImportError:
     brotli = None
 

tests/test_web_functional.py

@@ -8,7 +8,6 @@
 from typing import Any, Optional
 from unittest import mock
 
-import brotli
 import pytest
 from multidict import CIMultiDictProxy, MultiDict
 from yarl import URL
@@ -19,6 +18,11 @@
 from aiohttp.test_utils import make_mocked_coro
 from aiohttp.typedefs import Handler
 
+try:
+    import brotlicffi as brotli
+except ImportError:
+    import brotli
+
 try:
     import ssl
 except ImportError: