Fix libuv multiplex io watchers from polling too much when one event has been...

Fix libuv multiplex io watchers from polling too much when one event has been completely turned off. Fixes #1144.

CHANGES.rst

@@ -38,6 +38,10 @@
 - Hub objects now include the value of their ``name`` attribute in
   their repr.
 
+- Fix libuv io watchers polling for events that only stopped watchers
+  are interested in, reducing CPU usage. Reported in :issue:`1144` by
+  wwqgtxx.
+
 1.3a2 (2018-03-06)
 ==================
 

src/gevent/libuv/watcher.py

@@ -263,6 +263,8 @@ class io(_base.IoMixin, watcher):
             assert self._handle is not None
             self._watcher_start(self._watcher, self._events, self._watcher_callback)
 
+    events = property(_get_events, _set_events)
+
     def _watcher_ffi_start(self):
         _dbg("Starting watcher", self, "with events", self._events)
         self._watcher_start(self._watcher, self._events, self._watcher_callback)
@@ -326,8 +328,12 @@ class io(_base.IoMixin, watcher):
             self.args = args
 
             watcher = self._watcher_ref
-            if watcher is not None and not watcher.active:
+            if watcher is not None:
+                if not watcher.active:
                     watcher._io_start()
+                else:
+                    # Make sure we're in the event mask
+                    watcher._calc_and_update_events()
 
         def stop(self):
             _dbg("Stopping IO multiplex watcher for", self.fd,
@@ -360,6 +366,8 @@ class io(_base.IoMixin, watcher):
                       lambda self, nv: self._watcher_ref._set_fd(nv))
 
     def _io_maybe_stop(self):
+        _dbg("IO maybe stop on behalf of multiplex", self, "fd", self._fd, "events", self._events)
+        self._calc_and_update_events()
         for w in self._multiplex_watchers:
             if w.callback is not None:
                 # There's still a reference to it, and it's started,
@@ -371,11 +379,14 @@ class io(_base.IoMixin, watcher):
 
     def _io_start(self):
         _dbg("IO start on behalf of multiplex", self, "fd", self._fd, "events", self._events)
+        self._calc_and_update_events()
         self.start(self._io_callback, pass_events=True)
 
     def _calc_and_update_events(self):
         events = 0
         for watcher in self._multiplex_watchers:
+            if watcher.callback is not None:
+                # Only ask for events that are active.
                 events |= watcher.events
         self._set_events(events)
 

src/greentest/greentest/__init__.py

@@ -69,6 +69,7 @@ from greentest.skipping import skipOnPyPy
 from greentest.skipping import skipOnPyPyOnCI
 from greentest.skipping import skipOnPyPy3
 from greentest.skipping import skipIf
+from greentest.skipping import skipOnLibev
 from greentest.skipping import skipOnLibuv
 from greentest.skipping import skipOnLibuvOnWin
 from greentest.skipping import skipOnLibuvOnCI

src/greentest/greentest/patched_tests_setup.py

@@ -269,6 +269,15 @@ if LIBUV:
             'test_socket.GeneralModuleTests.test_uknown_socket_family_repr',
         ]
 
+        if RUN_COVERAGE:
+
+            disabled_tests += [
+                # Starting with #1145 this test (actually
+                # TestTLS_FTPClassMixin) becomes sensitive to timings
+                # under coverage.
+                'test_ftplib.TestFTPClass.test_storlines',
+            ]
+
 
     if sys.platform.startswith('linux'):
         disabled_tests += [

src/greentest/greentest/skipping.py

@@ -49,6 +49,7 @@ skipOnLibuvOnCI = _do_not_skip
 skipOnLibuvOnCIOnPyPy = _do_not_skip
 skipOnLibuvOnPyPyOnWin = _do_not_skip
 
+skipOnLibev = _do_not_skip
 
 if sysinfo.WIN:
     skipOnWindows = unittest.skip
@@ -99,3 +100,5 @@ if sysinfo.LIBUV:
         skipOnLibuvOnWin = unittest.skip
         if sysinfo.PYPY:
             skipOnLibuvOnPyPyOnWin = unittest.skip
+else:
+    skipOnLibev = unittest.skip

src/greentest/test__core.py

@@ -71,6 +71,41 @@ class TestWatchers(unittest.TestCase):
             io.start(lambda: None)
             io.close()
 
+    @greentest.skipOnLibev("libuv-specific")
+    @greentest.skipOnWindows("Destroying the loop somehow fails")
+    def test_io_multiplex_events(self):
+        # pylint:disable=no-member
+        import socket
+        sock = socket.socket()
+        fd = sock.fileno()
+
+        read = self.loop.io(fd, core.READ)
+        write = self.loop.io(fd, core.WRITE)
+
+        try:
+            real_watcher = read._watcher_ref
+
+            read.start(lambda: None)
+            self.assertEqual(real_watcher.events, core.READ)
+
+            write.start(lambda: None)
+            self.assertEqual(real_watcher.events, core.READ | core.WRITE)
+
+            write.stop()
+            self.assertEqual(real_watcher.events, core.READ)
+
+            write.start(lambda: None)
+            self.assertEqual(real_watcher.events, core.READ | core.WRITE)
+
+            read.stop()
+            self.assertEqual(real_watcher.events, core.WRITE)
+
+            write.stop()
+            self.assertEqual(real_watcher.events, 0)
+        finally:
+            read.close()
+            write.close()
+            sock.close()
 
     def test_timer_constructor(self):
         with self.assertRaises(ValueError):