Compile the hub operations that use Waiters with Cython

Since we've come this far, might as well keep taking advantage of the
effort...

There are substantial improvements on the micro benchmarks for things
that wait and switch:

| Benchmark           | 27_hub_master2 | 27_hub_cython5               |
|---------------------|----------------|------------------------------|
| multiple wait ready | 1.96 us        | 1.10 us: 1.77x faster (-44%) |
| wait ready          | 1.47 us        | 897 ns: 1.64x faster (-39%)  |
| cancel wait         | 2.93 us        | 1.81 us: 1.61x faster (-38%) |
| switch              | 2.33 us        | 1.94 us: 1.20x faster (-17%) |

| Benchmark           | 36_hub_master2 | 36_hub_cython6 |
|---------------------|----------------|------------------------------|
| multiple wait ready | 1.28 us        | 820 ns: 1.56x faster (-36%)  |
| wait ready          | 939 ns         | 722 ns: 1.30x faster (-23%)  |
| cancel wait         | 1.76 us        | 1.37 us: 1.29x faster (-23%) |
| switch              | 1.60 us        | 1.35 us: 1.18x faster (-16%) |

.gitignore

@@ -16,6 +16,8 @@ src/gevent/event.c
 src/gevent/_hub_local.c
 src/gevent/_waiter.c
 src/gevent/queue.c
+src/gevent/_hub_primitives.c
+src/gevent/_greenlet_primitives.c
 src/gevent/libev/corecext.c
 src/gevent/libev/corecext.h
 src/gevent/libev/_corecffi.c

CHANGES.rst

@@ -51,7 +51,8 @@ Enhancements
 
 - The classes `gevent.event.Event` and `gevent.event.AsyncResult`
   are compiled with Cython for improved performance, as is the
-  ``gevent.queue`` module and ``gevent.hub.Waiter``. Please report any
+  ``gevent.queue`` module and ``gevent.hub.Waiter`` and certain
+  time-sensitive parts of the hub itself. Please report any
   compatibility issues.
 
 Monitoring and Debugging

benchmarks/bench_hub.py

+# -*- coding: utf-8 -*-
+"""
+Benchmarks for hub primitive operations.
+
+"""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import perf
+from perf import perf_counter
+
+import gevent
+from greenlet import greenlet
+from greenlet import getcurrent
+
+
+N = 1000
+
+def bench_switch():
+
+    class Parent(type(gevent.get_hub())):
+        def run(self):
+            parent = self.parent
+            for _ in range(N):
+                parent.switch()
+
+    def child():
+        parent = getcurrent().parent
+        # Back to the hub, which in turn goes
+        # back to the main greenlet
+        for _ in range(N):
+            parent.switch()
+
+    hub = Parent(None, None)
+    child_greenlet = greenlet(child, hub)
+    for _ in range(N):
+        child_greenlet.switch()
+
+def bench_wait_ready():
+
+    class Watcher(object):
+        def start(self, cb, obj):
+            # Immediately switch back to the waiter, mark as ready
+            cb(obj)
+
+        def stop(self):
+            pass
+
+    watcher = Watcher()
+    hub = gevent.get_hub()
+
+    for _ in range(1000):
+        hub.wait(watcher)
+
+def bench_cancel_wait():
+
+    class Watcher(object):
+        active = True
+        callback = object()
+
+        def close(self):
+            pass
+
+    watcher = Watcher()
+    hub = gevent.get_hub()
+    loop = hub.loop
+
+    for _ in range(1000):
+        # Schedule all the callbacks.
+        hub.cancel_wait(watcher, None, True)
+
+    # Run them!
+    for cb in loop._callbacks:
+        if cb.callback:
+            cb.callback(*cb.args)
+            cb.stop() # so the real loop won't do it
+
+    # destroy the loop so we don't keep building these functions
+    # up
+    hub.destroy(True)
+
+def bench_wait_func_ready():
+    from gevent.hub import wait
+    class ToWatch(object):
+        def rawlink(self, cb):
+            cb(self)
+
+    watched_objects = [ToWatch() for _ in range(N)]
+
+    t0 = perf_counter()
+
+    wait(watched_objects)
+
+    return perf_counter() - t0
+
+def main():
+
+    runner = perf.Runner()
+
+    runner.bench_func('multiple wait ready',
+                      bench_wait_func_ready,
+                      inner_loops=N)
+
+    runner.bench_func('wait ready',
+                      bench_wait_ready,
+                      inner_loops=N)
+
+    runner.bench_func('cancel wait',
+                      bench_cancel_wait,
+                      inner_loops=N)
+
+    runner.bench_func('switch',
+                      bench_switch,
+                      inner_loops=N)
+
+if __name__ == '__main__':
+    main()

doc/gevent.hub.rst

@@ -10,6 +10,9 @@
     :members:
     :undoc-members:
 
+    .. automethod:: wait
+    .. automethod:: cancel_wait
+
 .. autoclass:: Waiter
 
 .. autoclass:: LoopExit

setup.py

@@ -119,17 +119,32 @@ WAITER = Extension(name="gevent.__waiter",
                    depends=['src/gevent/__waiter.pxd'],
                    include_dirs=include_dirs)
 
+HUB_PRIMITIVES = Extension(name="gevent.__hub_primitives",
+                           sources=["src/gevent/_hub_primitives.py"],
+                           depends=['src/gevent/__hub_primitives.pxd'],
+                           include_dirs=include_dirs)
+
+GLT_PRIMITIVES = Extension(name="gevent.__greenlet_primitives",
+                           sources=["src/gevent/_greenlet_primitives.py"],
+                           depends=['src/gevent/__greenlet_primitives.pxd'],
+                           include_dirs=include_dirs)
+
+
 
 _to_cythonize = [
+    GLT_PRIMITIVES,
+    HUB_PRIMITIVES,
+    HUB_LOCAL,
+    WAITER,
+    GREENLET,
+
     SEMAPHORE,
     LOCAL,
-    GREENLET,
+
     IDENT,
     IMAP,
     EVENT,
     QUEUE,
-    HUB_LOCAL,
-    WAITER,
 ]
 
 EXT_MODULES = [
@@ -144,6 +159,8 @@ EXT_MODULES = [
     QUEUE,
     HUB_LOCAL,
     WAITER,
+    HUB_PRIMITIVES,
+    GLT_PRIMITIVES,
 ]
 
 LIBEV_CFFI_MODULE = 'src/gevent/libev/_corecffi_build.py:ffi'
@@ -221,6 +238,12 @@ if PYPY:
     EXT_MODULES.remove(WAITER)
     _to_cythonize.remove(WAITER)
 
+    EXT_MODULES.remove(GLT_PRIMITIVES)
+    _to_cythonize.remove(GLT_PRIMITIVES)
+    EXT_MODULES.remove(HUB_PRIMITIVES)
+    _to_cythonize.remove(HUB_PRIMITIVES)
+
+
 for mod in _to_cythonize:
     EXT_MODULES.remove(mod)
     EXT_MODULES.append(cythonize1(mod))

src/gevent/__greenlet_primitives.pxd

+cimport cython
+
+# This file must not cimport anything from gevent.
+
+cdef wref
+
+cdef BlockingSwitchOutError
+
+
+cdef extern from "greenlet/greenlet.h":
+
+    ctypedef class greenlet.greenlet [object PyGreenlet]:
+        pass
+
+    # These are actually macros and so much be included
+    # (defined) in each .pxd, as are the two functions
+    # that call them.
+    greenlet PyGreenlet_GetCurrent()
+    object PyGreenlet_Switch(greenlet self, void* args, void* kwargs)
+    void PyGreenlet_Import()
+
+@cython.final
+cdef inline greenlet getcurrent():
+    return PyGreenlet_GetCurrent()
+
+cdef bint _greenlet_imported
+
+cdef inline void greenlet_init():
+    global _greenlet_imported
+    if not _greenlet_imported:
+        PyGreenlet_Import()
+        _greenlet_imported = True
+
+cdef inline object _greenlet_switch(greenlet self):
+    return PyGreenlet_Switch(self, NULL, NULL)
+
+cdef class TrackedRawGreenlet(greenlet):
+    pass
+
+cdef class SwitchOutGreenletWithLoop(TrackedRawGreenlet):
+    cdef public loop
+
+    cpdef switch(self)
+    cpdef switch_out(self)

src/gevent/__hub_local.pxd

+from gevent.__greenlet_primitives cimport SwitchOutGreenletWithLoop
+
 cdef _threadlocal
 
 cpdef get_hub_class()
-cpdef get_hub_if_exists()
-cpdef set_hub(hub)
+cpdef SwitchOutGreenletWithLoop get_hub_if_exists()
+cpdef set_hub(SwitchOutGreenletWithLoop hub)
 cpdef get_loop()
 cpdef set_loop(loop)
 
+# We can't cdef this, it won't do varargs.
+# cpdef WaitOperationsGreenlet get_hub(*args, **kwargs)
 
 # XXX: TODO: Move the definition of TrackedRawGreenlet
 # into a file that can be cython compiled so get_hub can
 # return that.
-cpdef get_hub_noargs()
+cpdef SwitchOutGreenletWithLoop get_hub_noargs()

src/gevent/__hub_primitives.pxd

+cimport cython
+
+from gevent.__greenlet_primitives cimport SwitchOutGreenletWithLoop
+from gevent.__hub_local cimport get_hub_noargs as get_hub
+
+from gevent.__waiter cimport Waiter
+from gevent.__waiter cimport MultipleWaiter
+
+cdef InvalidSwitchError
+cdef _waiter
+cdef _greenlet_primitives
+cdef traceback
+
+
+cdef extern from "greenlet/greenlet.h":
+
+    ctypedef class greenlet.greenlet [object PyGreenlet]:
+        pass
+
+    # These are actually macros and so much be included
+    # (defined) in each .pxd, as are the two functions
+    # that call them.
+    greenlet PyGreenlet_GetCurrent()
+    void PyGreenlet_Import()
+
+@cython.final
+cdef inline greenlet getcurrent():
+    return PyGreenlet_GetCurrent()
+
+cdef bint _greenlet_imported
+
+cdef inline void greenlet_init():
+    global _greenlet_imported
+    if not _greenlet_imported:
+        PyGreenlet_Import()
+        _greenlet_imported = True
+
+
+cdef class WaitOperationsGreenlet(SwitchOutGreenletWithLoop):
+
+    cpdef wait(self, watcher)
+    cpdef cancel_wait(self, watcher, error, close_watcher=*)
+    cpdef _cancel_wait(self, watcher, error, close_watcher)
+
+cdef class _WaitIterator:
+    cdef SwitchOutGreenletWithLoop _hub
+    cdef MultipleWaiter _waiter
+    cdef _switch
+    cdef _timeout
+    cdef _objects
+    cdef _timer
+    cdef Py_ssize_t _count
+    cdef bint _begun
+
+
+
+    cdef _cleanup(self)
+
+cpdef iwait(objects, timeout=*, count=*)
+cpdef wait(objects=*, timeout=*, count=*)

src/gevent/__ident.pxd

@@ -20,5 +20,7 @@ cdef class IdentRegistry:
     cdef object _registry
     cdef list _available_idents
 
+    @cython.final
     cpdef object get_ident(self, obj)
+    @cython.final
     cpdef _return_ident(self, ValuedWeakRef ref)

src/gevent/__semaphore.pxd

-# cython: auto_pickle=False
-
+cimport cython
 
 from gevent.__hub_local cimport get_hub_noargs as get_hub
 cdef Timeout

src/gevent/__waiter.pxd

 cimport cython
 
+from gevent.__greenlet_primitives cimport SwitchOutGreenletWithLoop
+from gevent.__hub_local cimport get_hub_noargs as get_hub
+
 cdef sys
 cdef ConcurrentObjectUseError
 
-from gevent.__hub_local cimport get_hub_noargs as get_hub
 
 cdef bint _greenlet_imported
 cdef _NONE
@@ -29,11 +31,17 @@ cdef inline void greenlet_init():
         _greenlet_imported = True
 
 cdef class Waiter:
-    cdef readonly hub
-    cdef readonly greenlet
+    cdef readonly SwitchOutGreenletWithLoop hub
+    cdef readonly greenlet greenlet
     cdef readonly value
     cdef _exception
 
+    cpdef get(self)
+    cpdef clear(self)
+
+    # cpdef of switch leads to parameter errors...
+    #cpdef switch(self, value)
+
 @cython.final
 @cython.internal
 cdef class MultipleWaiter(Waiter):

src/gevent/_event.pxd

 cimport cython
 
+from gevent.__greenlet_primitives cimport SwitchOutGreenletWithLoop
+from gevent.__hub_local cimport get_hub_noargs as get_hub
+
 cdef _None
 cdef reraise
 cdef dump_traceback
 cdef load_traceback
-cdef get_hub
+
 
 cdef InvalidSwitchError
 cdef Timeout
@@ -35,7 +38,7 @@ cdef void _init()
 cdef class _AbstractLinkable:
    cdef _notifier
    cdef set _links
-   cdef readonly hub
+   cdef readonly SwitchOutGreenletWithLoop hub
 
    cpdef rawlink(self, callback)
    cpdef bint ready(self)

src/gevent/_greenlet.pxd

@@ -9,6 +9,8 @@ cdef bint _PYPY
 cdef sys_getframe
 cdef sys_exc_info
 cdef Timeout
+cdef GreenletExit
+cdef InvalidSwitchError
 
 cdef extern from "greenlet/greenlet.h":
 
@@ -141,14 +143,12 @@ cdef _threadlocal
 cdef get_hub_class
 cdef wref
 
-cdef Timeout
 cdef dump_traceback
 cdef load_traceback
 cdef Waiter
 cdef wait
 cdef iwait
 cdef reraise
-cdef InvalidSwitchError
 cpdef GEVENT_CONFIG
 
 

src/gevent/_greenlet_primitives.py

+# -*- coding: utf-8 -*-
+# copyright (c) 2018 gevent. See  LICENSE.
+# cython: auto_pickle=False,embedsignature=True,always_allow_keywords=False
+"""
+A collection of primitives used by the hub, and suitable for
+compilation with Cython because of their frequency of use.
+
+"""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+from weakref import ref as wref
+
+from greenlet import greenlet
+
+from gevent.exceptions import BlockingSwitchOutError
+
+
+# In Cython, we define these as 'cdef inline' functions. The
+# compilation unit cannot have a direct assignment to them (import
+# is assignment) without generating a 'lvalue is not valid target'
+# error.
+locals()['getcurrent'] = __import__('greenlet').getcurrent
+locals()['greenlet_init'] = lambda: None
+locals()['_greenlet_switch'] = greenlet.switch
+
+__all__ = [
+    'TrackedRawGreenlet',
+    'SwitchOutGreenletWithLoop',
+]
+
+class TrackedRawGreenlet(greenlet):
+
+    def __init__(self, function, parent):
+        greenlet.__init__(self, function, parent)
+        # See greenlet.py's Greenlet class. We capture the cheap
+        # parts to maintain the tree structure, but we do not capture
+        # the stack because that's too expensive for 'spawn_raw'.
+
+        current = getcurrent() # pylint:disable=undefined-variable
+        self.spawning_greenlet = wref(current)
+        # See Greenlet for how trees are maintained.
+        try:
+            self.spawn_tree_locals = current.spawn_tree_locals
+        except AttributeError:
+            self.spawn_tree_locals = {}
+            if current.parent:
+                current.spawn_tree_locals = self.spawn_tree_locals
+
+
+class SwitchOutGreenletWithLoop(TrackedRawGreenlet):
+    # Subclasses must define:
+    # - self.loop
+
+    # This class defines loop in its .pxd for Cython. This lets us avoid
+    # circular dependencies with the hub.
+
+    def switch(self):
+        switch_out = getattr(getcurrent(), 'switch_out', None) # pylint:disable=undefined-variable
+        if switch_out is not None:
+            switch_out()
+        return _greenlet_switch(self) # pylint:disable=undefined-variable
+
+    def switch_out(self):
+        raise BlockingSwitchOutError('Impossible to call blocking function in the event loop callback')
+
+def _init():
+    greenlet_init() # pylint:disable=undefined-variable
+
+_init()
+
+from gevent._util import import_c_accel
+import_c_accel(globals(), 'gevent.__greenlet_primitives')

src/gevent/_hub_primitives.py

+# -*- coding: utf-8 -*-
+# copyright (c) 2018 gevent. See  LICENSE.
+# cython: auto_pickle=False,embedsignature=True,always_allow_keywords=False
+"""
+A collection of primitives used by the hub, and suitable for
+compilation with Cython because of their frequency of use.
+
+
+"""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import traceback
+
+from gevent.exceptions import InvalidSwitchError
+
+from gevent import _greenlet_primitives
+from gevent import _waiter
+from gevent._hub_local import get_hub_noargs as get_hub
+
+# In Cython, we define these as 'cdef inline' functions. The
+# compilation unit cannot have a direct assignment to them (import
+# is assignment) without generating a 'lvalue is not valid target'
+# error.
+locals()['getcurrent'] = __import__('greenlet').getcurrent
+locals()['greenlet_init'] = lambda: None
+locals()['Waiter'] = _waiter.Waiter
+locals()['MultipleWaiter'] = _waiter.MultipleWaiter
+locals()['SwitchOutGreenletWithLoop'] = _greenlet_primitives.SwitchOutGreenletWithLoop
+
+__all__ = [
+    'WaitOperationsGreenlet',
+    'iwait',
+    'wait',
+]
+
+class WaitOperationsGreenlet(SwitchOutGreenletWithLoop): # pylint:disable=undefined-variable
+
+    def wait(self, watcher):
+        """
+        Wait until the *watcher* (which must not be started) is ready.
+
+        The current greenlet will be unscheduled during this time.
+        """
+        waiter = Waiter(self) # pylint:disable=undefined-variable
+        watcher.start(waiter.switch, waiter)
+        try:
+            result = waiter.get()
+            if result is not waiter:
+                raise InvalidSwitchError('Invalid switch into %s: %r (expected %r)' % (
+                    getcurrent(), # pylint:disable=undefined-variable
+                    result, waiter))
+        finally:
+            watcher.stop()
+
+    def cancel_wait(self, watcher, error, close_watcher=False):
+        """
+        Cancel an in-progress call to :meth:`wait` by throwing the given *error*
+        in the waiting greenlet.
+
+        .. versionchanged:: 1.3a1
+           Added the *close_watcher* parameter. If true, the watcher
+           will be closed after the exception is thrown. The watcher should then
+           be discarded. Closing the watcher is important to release native resources.
+        .. versionchanged:: 1.3a2
+           Allow the *watcher* to be ``None``. No action is taken in that case.
+        """
+        if watcher is None:
+            # Presumably already closed.
+            # See https://github.com/gevent/gevent/issues/1089
+            return
+        if watcher.callback is not None:
+            self.loop.run_callback(self._cancel_wait, watcher, error, close_watcher)
+        elif close_watcher:
+            watcher.close()
+
+    def _cancel_wait(self, watcher, error, close_watcher):
+        # We have to check again to see if it was still active by the time
+        # our callback actually runs.
+        active = watcher.active
+        cb = watcher.callback
+        if close_watcher:
+            watcher.close()
+        if active:
+            # The callback should be greenlet.switch(). It may or may not be None.
+            glet = getattr(cb, '__self__', None)
+            if glet is not None:
+                glet.throw(error)
+
+
+class _WaitIterator(object):
+
+    def __init__(self, objects, hub, timeout, count):
+        self._hub = hub
+        self._waiter = MultipleWaiter(hub) # pylint:disable=undefined-variable
+        self._switch = self._waiter.switch
+        self._timeout = timeout
+        self._objects = objects
+
+        self._timer = None
+        self._begun = False
+
+
+        # Even if we're only going to return 1 object,
+        # we must still rawlink() *all* of them, so that no
+        # matter which one finishes first we find it.
+        self._count = len(objects) if count is None else min(count, len(objects))
+
+
+    def __iter__(self):
+        # When we begin iterating, we begin the timer.
+        # XXX: If iteration doesn't actually happen, we
+        # could leave these links around!
+        if not self._begun:
+            self._begun = True
+
+            for obj in self._objects:
+                obj.rawlink(self._switch)
+
+            if self._timeout is not None:
+                self._timer = self._hub.loop.timer(self._timeout, priority=-1)
+                self._timer.start(self._switch, self)
+        return self
+
+    def __next__(self):
+        if self._count == 0:
+            # Exhausted
+            self._cleanup()
+            raise StopIteration()
+
+        self._count -= 1
+        try:
+            item = self._waiter.get()
+            self._waiter.clear()
+            if item is self:
+                # Timer expired, no more
+                self._cleanup()
+                raise StopIteration()
+            return item
+        except:
+            self._cleanup()
+            raise
+
+    next = __next__
+
+    def _cleanup(self):
+        if self._timer is not None:
+            self._timer.close()
+            self._timer = None
+
+        objs = self._objects
+        self._objects = ()
+        for aobj in objs:
+            unlink = getattr(aobj, 'unlink', None)
+            if unlink is not None:
+                try:
+                    unlink(self._switch)
+                except: # pylint:disable=bare-except
+                    traceback.print_exc()
+
+
+def iwait(objects, timeout=None, count=None):
+    """
+    Iteratively yield *objects* as they are ready, until all (or *count*) are ready
+    or *timeout* expired.
+
+    :param objects: A sequence (supporting :func:`len`) containing objects
+        implementing the wait protocol (rawlink() and unlink()).
+    :keyword int count: If not `None`, then a number specifying the maximum number
+        of objects to wait for. If ``None`` (the default), all objects
+        are waited for.
+    :keyword float timeout: If given, specifies a maximum number of seconds
+        to wait. If the timeout expires before the desired waited-for objects
+        are available, then this method returns immediately.
+
+    .. seealso:: :func:`wait`
+
+    .. versionchanged:: 1.1a1
+       Add the *count* parameter.
+    .. versionchanged:: 1.1a2
+       No longer raise :exc:`LoopExit` if our caller switches greenlets
+       in between items yielded by this function.
+    """
+    # QQQ would be nice to support iterable here that can be generated slowly (why?)
+    hub = get_hub()
+    if objects is None:
+        return [hub.join(timeout=timeout)]
+    return _WaitIterator(objects, hub, timeout, count)
+
+
+def wait(objects=None, timeout=None, count=None):
+    """
+    Wait for ``objects`` to become ready or for event loop to finish.
+
+    If ``objects`` is provided, it must be a list containing objects
+    implementing the wait protocol (rawlink() and unlink() methods):
+
+    - :class:`gevent.Greenlet` instance
+    - :class:`gevent.event.Event` instance
+    - :class:`gevent.lock.Semaphore` instance
+    - :class:`gevent.subprocess.Popen` instance
+
+    If ``objects`` is ``None`` (the default), ``wait()`` blocks until
+    the current event loop has nothing to do (or until ``timeout`` passes):
+
+    - all greenlets have finished
+    - all servers were stopped
+    - all event loop watchers were stopped.
+
+    If ``count`` is ``None`` (the default), wait for all ``objects``
+    to become ready.
+
+    If ``count`` is a number, wait for (up to) ``count`` objects to become
+    ready. (For example, if count is ``1`` then the function exits
+    when any object in the list is ready).
+
+    If ``timeout`` is provided, it specifies the maximum number of
+    seconds ``wait()`` will block.
+
+    Returns the list of ready objects, in the order in which they were
+    ready.
+
+    .. seealso:: :func:`iwait`
+    """
+    if objects is None:
+        hub = get_hub()
+        return hub.join(timeout=timeout) # pylint:disable=
+    return list(iwait(objects, timeout, count))
+
+
+
+def _init():
+    greenlet_init() # pylint:disable=undefined-variable
+
+_init()
+
+from gevent._util import import_c_accel
+import_c_accel(globals(), 'gevent.__hub_primitives')

src/gevent/_ident.py

@@ -70,7 +70,11 @@ class IdentRegistry(object):
     def _return_ident(self, vref):
         # By the time this is called, self._registry has been
         # updated
-        heappush(self._available_idents, vref.value)
+        if heappush is not None:
+            # Under some circumstances we can get called
+            # when the interpreter is shutting down, and globals
+            # aren't available any more.
+            heappush(self._available_idents, vref.value)
 
     def __len__(self):
         return len(self._registry)

src/gevent/_waiter.py

@@ -99,8 +99,14 @@ class Waiter(object):
         if self._exception is not _NONE:
             return self._exception
 
-    def switch(self, value=None):
-        """Switch to the greenlet if one's available. Otherwise store the value."""
+    def switch(self, value):
+        """
+        Switch to the greenlet if one's available. Otherwise store the
+        *value*.
+
+        .. versionchanged:: 1.3b1
+           The *value* is no longer optional.
+        """
         greenlet = self.greenlet
         if greenlet is None:
             self.value = value
@@ -178,7 +184,7 @@ class MultipleWaiter(Waiter):
         # here can be impractical (see https://github.com/gevent/gevent/issues/652)
         self._values = list()
 
-    def switch(self, value): # pylint:disable=signature-differs
+    def switch(self, value):
         self._values.append(value)
         Waiter.switch(self, True)
 

src/gevent/event.py

@@ -9,9 +9,9 @@ from gevent._util import _NONE
 from gevent._compat import reraise
 from gevent._tblib import dump_traceback, load_traceback
 
-from gevent.hub import _get_hub_noargs as get_hub
+from gevent._hub_local import get_hub_noargs as get_hub
 
-from gevent.hub import InvalidSwitchError
+from gevent.exceptions import InvalidSwitchError
 from gevent.timeout import Timeout
 
 
@@ -23,8 +23,6 @@ __all__ = [
 locals()['getcurrent'] = __import__('greenlet').getcurrent
 locals()['greenlet_init'] = lambda: None
 
-import cython
-
 
 class _AbstractLinkable(object):
     # Encapsulates the standard parts of the linking and notifying protocol

src/gevent/greenlet.py

@@ -7,16 +7,18 @@ from sys import _getframe as sys_getframe
 from sys import exc_info as sys_exc_info
 from weakref import ref as wref
 
-
+# XXX: How to get cython to let us rename this as RawGreenlet
+# like we prefer?
 from greenlet import greenlet
+from greenlet import GreenletExit
 
 from gevent._compat import reraise
 from gevent._compat import PYPY as _PYPY
 from gevent._tblib import dump_traceback
 from gevent._tblib import load_traceback
 
-from gevent.hub import GreenletExit
-from gevent.hub import InvalidSwitchError
+from gevent.exceptions import InvalidSwitchError
+
 from gevent.hub import iwait
 from gevent.hub import wait
 
@@ -875,7 +877,7 @@ def _kill(glet, exception, waiter):
         # XXX do we need this here?
         glet.parent.handle_error(glet, *sys_exc_info())
     if waiter is not None:
-        waiter.switch()
+        waiter.switch(None)
 
 
 def joinall(greenlets, timeout=None, raise_error=False, count=None):

src/greentest/test__greenlet.py

@@ -208,8 +208,8 @@ class TestReturn_link(LinksTestCase):
         self.assertFalse(p)
 
 
-        self.assertIsInstance(event.get(), greenlet.GreenletExit)
-        self.assertIsInstance(queue.get().get(), greenlet.GreenletExit)
+        self.assertIsInstance(event.get(), gevent.GreenletExit)
+        self.assertIsInstance(queue.get().get(), gevent.GreenletExit)
 
         sleep(DELAY)
         self.assertFalse(callback_flag)

src/greentest/test__hub.py

@@ -95,7 +95,7 @@ class TestWaiterGet(greentest.timing.AbstractGenericWaitTestCase):
 
     def wait(self, timeout):
         with get_hub().loop.timer(timeout) as evt:
-            evt.start(self.waiter.switch)
+            evt.start(self.waiter.switch, None)
             return self.waiter.get()