Better CFFI exception handling due to an issue seen in 3.7b2.

Makefile

@@ -108,7 +108,7 @@ leaktest: test_prelim
 	@${PYTHON} scripts/travis.py fold_end default
 
 bench:
-	${PYTHON} benchmarks/bench_sendall.py --loops 3 --processes 2 --values 2 --warmups 2
+	${PYTHON} benchmarks/bench_sendall.py --loops 3 --processes 2 --values 2 --warmups 2 --quiet
 
 travis_test_linters:
 	make lint
@@ -180,6 +180,7 @@ develop:
 # We need wheel>=0.26 on Python 3.5. See previous revisions.
 	time ${PYTHON} -m pip install -U -r ci-requirements.txt
 	GEVENTSETUP_EV_VERIFY=3 time ${PYTHON} -m pip install -U -e .
+	${PYTHON} -m pip freeze
 	ccache -s
 	@${PYTHON} scripts/travis.py fold_end install
 

ci-requirements.txt

@@ -16,7 +16,7 @@ prospector[with_pyroma] ; python_version < '3.7'
 coverage>=4.0
 coveralls>=1.0
 # See version requirements in setup.py
-cffi ; platform_python_implementation == "CPython"
+cffi >= 1.11.5 ; platform_python_implementation == "CPython"
 futures
 dnspython
 idna

src/gevent/_ffi/loop.py

@@ -208,7 +208,10 @@ class AbstractCallbacks(object):
             watcher.loop.handle_error(None, t, v, tb)
             return 1
         else:
-            raise v
+            # Raising it causes a lot of noise from CFFI
+            print("WARNING: gevent: Unhandled error with no watcher",
+                  file=sys.stderr)
+            traceback.print_exception(t, v, tb)
 
     def python_stop(self, handle):
         if not handle: # pragma: no cover

src/gevent/event.py

@@ -100,8 +100,7 @@ class _AbstractLinkable(object):
         switch = getcurrent().switch
         self.rawlink(switch)
         try:
-            timer = Timeout._start_new_or_dummy(timeout)
-            try:
+            with Timeout._start_new_or_dummy(timeout) as timer:
                 try:
                     result = self.hub.switch()
                     if result is not self: # pragma: no cover
@@ -113,8 +112,6 @@ class _AbstractLinkable(object):
                     # test_set_and_clear and test_timeout in test_threading
                     # rely on the exact return values, not just truthish-ness
                     return False
-            finally:
-                timer.close()
         finally:
             self.unlink(switch)
 

src/gevent/libuv/watcher.py

@@ -725,16 +725,21 @@ class idle(_base.IdleMixin, watcher):
 class check(_base.CheckMixin, watcher):
     pass
 
+
 class OneShotCheck(check):
 
     _watcher_skip_ffi = True
 
+    def __make_cb(self, func):
+        stop = self.stop
+        @functools.wraps(func)
+        def cb(*args, _stop=stop):
+            _stop()
+            return func(*args)
+        return cb
+
     def start(self, callback, *args):
-        @functools.wraps(callback)
-        def _callback(*args):
-            self.stop()
-            return callback(*args)
-        return check.start(self, _callback, *args)
+        return check.start(self, self.__make_cb(callback), *args)
 
 class prepare(_base.PrepareMixin, watcher):
     pass

src/greentest/tests_that_dont_use_resolver.txt

@@ -128,3 +128,7 @@ test___config.py
 test__destroy_default_loop.py
 test__util.py
 test___ident.py
+test__issue639.py
+test__issue_728.py
+test__refcount_core.py
+test__api.py