_FDWaker in general does not need the reactor

So don't give it one.

The "foreign event loop" reactors do need a reactor so preserve theirs.

src/twisted/internet/_glibbase.py

@@ -56,6 +56,10 @@ class GlibWaker(_UnixWaker):
     Run scheduled events after waking up.
     """
 
+    def __init__(self, reactor):
+        super().__init__()
+        self.reactor = reactor
+
     def doRead(self) -> None:
         super().doRead()
         self.reactor._simulate()
@@ -106,7 +110,8 @@ class GlibReactorBase(posixbase.PosixReactorBase, posixbase._PollLikeMixin):
 
     # Install a waker that knows it needs to call C{_simulate} in order to run
     # callbacks queued from a thread:
-    _wakerFactory = GlibWaker
+    def _wakerFactory(self) -> GlibWaker:
+        return GlibWaker(self)
 
     def __init__(self, glib_module: Any, gtk_module: Any, useGtk: bool = False) -> None:
         self._simtag = None

src/twisted/internet/_signals.py

@@ -181,9 +181,8 @@ class _FDWaker(log.Logger):
     i = None
     o = None
 
-    def __init__(self, reactor):
+    def __init__(self):
         """Initialize."""
-        self.reactor = reactor
         self.i, self.o = os.pipe()
         fdesc.setNonBlocking(self.i)
         fdesc._setCloseOnExec(self.i)
@@ -244,22 +243,19 @@ class _SIGCHLDWaker(_FDWaker):
     received.
     """
 
-    def __init__(self, reactor):
-        _FDWaker.__init__(self, reactor)
-
-    def install(self):
+    def install(self) -> None:
         """
         Install the handler necessary to make this waker active.
         """
         installHandler(self.o)
 
-    def uninstall(self):
+    def uninstall(self) -> None:
         """
         Remove the handler which makes this waker active.
         """
         installHandler(-1)
 
-    def doRead(self):
+    def doRead(self) -> None:
         """
         Having woken up the reactor in response to receipt of
         C{SIGCHLD}, reap the process which exited.

src/twisted/internet/cfreactor.py

@@ -74,6 +74,10 @@ class _WakerPlus(_UnixWaker):
     do.
     """
 
+    def __init__(self, reactor):
+        super().__init__()
+        self.reactor = reactor
+
     def doRead(self):
         """
         Wake up the loop and force C{runUntilCurrent} to run immediately in the
@@ -136,15 +140,8 @@ def __init__(self, runLoop=None, runner=None):
         self._cfrunloop = runLoop
         PosixReactorBase.__init__(self)
 
-    def installWaker(self):
-        """
-        Override C{installWaker} in order to use L{_WakerPlus}; otherwise this
-        should be exactly the same as the parent implementation.
-        """
-        if not self.waker:
-            self.waker = _WakerPlus(self)
-            self._internalReaders.add(self.waker)
-            self.addReader(self.waker)
+    def _wakerFactory(self) -> _WakerPlus:
+        return _WakerPlus(self)
 
     def _socketCallback(
         self, cfSocket, callbackType, ignoredAddress, ignoredData, context

src/twisted/internet/posixbase.py

@@ -30,7 +30,7 @@
 from twisted.internet.main import CONNECTION_DONE, CONNECTION_LOST
 from twisted.python import failure, log
 from twisted.python.runtime import platform, platformType
-from ._signals import _SIGCHLDWaker, _Waker
+from ._signals import _IWaker, _SIGCHLDWaker, _Waker
 
 # Exceptions that doSelect might return frequently
 _NO_FILENO = error.ConnectionFdescWentAway("Handler has no fileno method")
@@ -118,7 +118,8 @@ class PosixReactorBase(_DisconnectSelectableMixin, ReactorBase):
 
     # Callable that creates a waker, overrideable so that subclasses can
     # substitute their own implementation:
-    _wakerFactory = _Waker
+    def _wakerFactory(self) -> _IWaker:
+        return _Waker()
 
     def installWaker(self):
         """
@@ -128,7 +129,7 @@ def installWaker(self):
         the reactor. On Windows we use a pair of sockets.
         """
         if not self.waker:
-            self.waker = self._wakerFactory(self)
+            self.waker = self._wakerFactory()
             self._internalReaders.add(self.waker)
             self.addReader(self.waker)
 
@@ -142,7 +143,7 @@ def _handleSignals(self):
         super()._handleSignals()
         if platformType == "posix" and processEnabled:
             if not self._childWaker:
-                self._childWaker = _SIGCHLDWaker(self)
+                self._childWaker = _SIGCHLDWaker()
                 self._internalReaders.add(self._childWaker)
                 self.addReader(self._childWaker)
             self._childWaker.install()

src/twisted/internet/test/test_posixbase.py

@@ -331,7 +331,7 @@ def test_noWakerConstructionWarnings(self):
         """
         No warnings are generated when constructing the waker.
         """
-        waker = _Waker(reactor=None)
+        waker = _Waker()
 
         warnings = self.flushWarnings()
         self.assertEqual(len(warnings), 0, warnings)