Adopt pep517 + try compile with cython

pyproject.toml

@@ -1,3 +1,11 @@
+[build-system]
+    build-backend = "setuptools.build_meta"
+    requires = [
+        "setuptools>=47",
+        "wheel",
+        "cython; python_implementation == 'CPython'", # Skip cython when using pypy
+    ]
+
 [tool.towncrier]
     package = "falcon"
     package_dir = ""

setup.cfg

@@ -1,3 +1,70 @@
+[metadata]
+name = falcon
+version = attr: falcon.__version__
+description = An unladen web framework for building APIs and app backends.
+long_description_content_type = text/x-rst
+url = https://falconframework.org
+author = Kurt Griffiths
+author_email = mail@kgriffs.com
+license = Apache 2.0
+license_file = LICENSE
+classifiers =
+    Development Status :: 5 - Production/Stable
+    Environment :: Web Environment
+    Natural Language :: English
+    Intended Audience :: Developers
+    Intended Audience :: System Administrators
+    License :: OSI Approved :: Apache Software License
+    Operating System :: MacOS :: MacOS X
+    Operating System :: Microsoft :: Windows
+    Operating System :: POSIX
+    Topic :: Internet :: WWW/HTTP :: WSGI
+    Topic :: Software Development :: Libraries :: Application Frameworks
+    Programming Language :: Python
+    Programming Language :: Python :: Implementation :: CPython
+    Programming Language :: Python :: Implementation :: PyPy
+    Programming Language :: Python :: 3
+    Programming Language :: Python :: 3.5
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
+    Programming Language :: Python :: 3.8
+keywords =
+    asgi
+    wsgi
+    web
+    api
+    framework
+    rest
+    http
+    cloud
+project_urls =
+    Documentation=https://falcon.readthedocs.io/en/stable/
+    Issue Tracker=https://github.com/falconry/falcon
+
+[options]
+zip_safe = False
+include_package_data = True
+packages = find:
+python_requires = >=3.5
+install_requires =
+tests_require =
+    testtools
+    requests
+    pyyaml
+    pytest
+    pytest-runner
+
+[options.packages.find]
+exclude =
+    examples
+    tests
+
+[options.entry_points]
+console_scripts =
+    falcon-bench = falcon.cmd.bench:main
+    falcon-inspect-app = falcon.cmd.inspect_app:main
+    falcon-print-routes = falcon.cmd.inspect_app:route_main
+
 [egg_info]
 # TODO replace
 tag_build = dev1

setup.py

@@ -1,20 +1,14 @@
 import glob
-import importlib
 import io
 import os
 from os import path
 import re
 import sys
 
-from setuptools import Extension, find_packages, setup
+from setuptools import Extension, setup
 
 MYDIR = path.abspath(os.path.dirname(__file__))
 
-VERSION = importlib.import_module('falcon.version')
-VERSION = VERSION.__version__
-
-REQUIRES = []
-
 try:
     sys.pypy_version_info
     PYPY = True
@@ -30,7 +24,39 @@
     except ImportError:
         CYTHON = False
 
-if CYTHON:
+
+class BuildFailed(Exception):
+    pass
+
+
+def get_cython_options():
+    # from sqlalchemy setup.py
+    from distutils.errors import CCompilerError, DistutilsExecError, DistutilsPlatformError
+    ext_errors = (CCompilerError, DistutilsExecError, DistutilsPlatformError)
+    if sys.platform == 'win32':
+        # Work around issue https://github.com/pypa/setuptools/issues/1902
+        ext_errors += (IOError, TypeError)
+
+    class ve_build_ext(build_ext):
+        # This class allows Cython building to fail.
+
+        def run(self):
+            try:
+                super().run()
+            except DistutilsPlatformError:
+                raise BuildFailed()
+
+        def build_extension(self, ext):
+            try:
+                super().build_extension(ext)
+            except ext_errors as e:
+                raise BuildFailed() from e
+            except ValueError as e:
+                # this can happen on Windows 64 bit, see Python issue 7511
+                if "'path'" in str(e):
+                    raise BuildFailed() from e
+                raise
+
     def list_modules(dirname, pattern):
         filenames = glob.glob(path.join(dirname, pattern))
 
@@ -92,11 +118,8 @@ def list_modules(dirname, pattern):
     for ext_mod in ext_modules:
         ext_mod.cython_directives = {'language_level': '3'}
 
-    cmdclass = {'build_ext': build_ext}
-
-else:
-    cmdclass = {}
-    ext_modules = []
+    cmdclass = {'build_ext': ve_build_ext}
+    return cmdclass, ext_modules
 
 
 def load_description():
@@ -134,56 +157,47 @@ def load_description():
     return ''.join(description_lines)
 
 
-setup(
-    name='falcon',
-    version=VERSION,
-    description='An unladen web framework for building APIs and app backends.',
-    long_description=load_description(),
-    long_description_content_type='text/x-rst',
-    classifiers=[
-        'Development Status :: 5 - Production/Stable',
-        'Environment :: Web Environment',
-        'Natural Language :: English',
-        'Intended Audience :: Developers',
-        'Intended Audience :: System Administrators',
-        'License :: OSI Approved :: Apache Software License',
-        'Operating System :: MacOS :: MacOS X',
-        'Operating System :: Microsoft :: Windows',
-        'Operating System :: POSIX',
-        'Operating System :: POSIX :: Linux',
-        'Topic :: Internet :: WWW/HTTP',
-        'Topic :: Internet :: WWW/HTTP :: WSGI',
-        # 'Topic :: Internet :: WWW/HTTP :: ASGI',
-        'Topic :: Software Development :: Libraries :: Application Frameworks',
-        'Programming Language :: Python',
-        'Programming Language :: Python :: Implementation :: CPython',
-        'Programming Language :: Python :: Implementation :: PyPy',
-        'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.5',
-        'Programming Language :: Python :: 3.6',
-        'Programming Language :: Python :: 3.7',
-        'Programming Language :: Python :: 3.8',
-        'Programming Language :: Python :: 3.9',
-        'Programming Language :: Cython',
-    ],
-    keywords='wsgi web api framework rest http cloud',
-    author='Kurt Griffiths',
-    author_email='mail@kgriffs.com',
-    url='https://falconframework.org',
-    license='Apache 2.0',
-    packages=find_packages(exclude=['examples', 'tests']),
-    include_package_data=True,
-    zip_safe=False,
-    python_requires='>=3.5',
-    install_requires=REQUIRES,
-    cmdclass=cmdclass,
-    ext_modules=ext_modules,
-    tests_require=['testtools', 'requests', 'pyyaml', 'pytest', 'pytest-runner'],
-    entry_points={
-        'console_scripts': [
-            'falcon-bench = falcon.cmd.bench:main',
-            'falcon-inspect-app = falcon.cmd.inspect_app:main',
-            'falcon-print-routes = falcon.cmd.inspect_app:route_main',
-        ]
-    }
-)
+def run_setup(CYTHON):
+    if CYTHON:
+        cmdclass, ext_modules = get_cython_options()
+    else:
+        cmdclass, ext_modules = {}, []
+
+    setup(
+        long_description=load_description(),
+        cmdclass=cmdclass,
+        ext_modules=ext_modules,
+    )
+
+
+def status_msgs(*msgs):
+    print('*' * 75, *msgs, '*' * 75, sep='\n')
+
+
+if not CYTHON:
+    run_setup(False)
+    if not PYPY:
+        status_msgs('Cython compilation not supported in this environment')
+elif os.environ.get('DISABLE_FALCON_CYTHON'):
+    run_setup(False)
+    status_msgs(
+        'DISABLE_FALCON_CYTHON is set, skipping cython compilation.',
+        'Pure-Python build succeeded.',
+    )
+else:
+    try:
+        run_setup(True)
+    except BuildFailed as exc:
+        status_msgs(
+            exc.__cause__,
+            'Cython compilation could not be completed, speedups are not enabled.',
+            'Failure information, if any, is above.',
+            'Retrying the build without the C extension now.'
+        )
+
+        run_setup(False)
+
+        status_msgs(
+            'Cython compilation could not be completed, speedups are not enabled.',
+            'Pure-Python build succeeded.'
+        )

tox.ini

@@ -28,6 +28,7 @@ envlist = py38,
 setenv =
     PIP_CONFIG_FILE={toxinidir}/pip.conf
     PYTHONASYNCIODEBUG=1
+    DISABLE_FALCON_CYTHON=Y
 deps = -r{toxinidir}/requirements/tests
 commands = {toxinidir}/tools/clean.sh {toxinidir}/falcon
            pytest tests []
@@ -132,10 +133,10 @@ commands = {toxinidir}/tools/clean.sh {toxinidir}/falcon
 
 [with-cython]
 deps = -r{toxinidir}/requirements/tests
-       cython
 setenv =
     PIP_CONFIG_FILE={toxinidir}/pip.conf
     FALCON_CYTHON=Y
+    DISABLE_FALCON_CYTHON=
     FALCON_ASGI_WRAP_NON_COROUTINES=Y
     FALCON_TESTING_SESSION=Y
     PYTHONASYNCIODEBUG=1
@@ -183,6 +184,7 @@ commands = {[with-cython]commands}
 
 [testenv:wsgi_servers]
 install_command = {[with-cython]install_command}
+setenv = {[with-cython]setenv}
 deps = {[with-cython]deps}
        gunicorn
        meinheld
@@ -449,6 +451,7 @@ setenv =
     PYTHONNOUSERSITE=1
     FALCON_ASGI_WRAP_NON_COROUTINES=Y
     FALCON_TESTING_SESSION=Y
+    DISABLE_FALCON_CYTHON=Y
 commands =
     pip uninstall --yes falcon
     pip install --find-links {toxinidir}/dist --no-index --ignore-installed falcon