:LastChangedDate: $LastChangedDate$ :LastChangedRevision: $LastChangedRevision$ :LastChangedBy: $LastChangedBy$ Choosing a Reactor and GUI Toolkit Integration ============================================== Overview -------- Twisted provides a variety of implementations of the :api:`twisted.internet.reactor ` . The specialized implementations are suited for different purposes and are designed to integrate better with particular platforms. The :ref:`epoll()-based reactor ` is Twisted's default on Linux. Other platforms use :ref:`poll() ` , or the most cross-platform reactor, :ref:`select() ` . Platform-specific reactor implementations exist for: - :ref:`Poll for Linux ` - :ref:`Epoll for Linux 2.6 ` - :ref:`WaitForMultipleObjects (WFMO) for Win32 ` - :ref:`Input/Output Completion Port (IOCP) for Win32 ` - :ref:`KQueue for FreeBSD and Mac OS X ` - :ref:`CoreFoundation for Mac OS X ` The remaining custom reactor implementations provide support for integrating with the native event loops of various graphical toolkits. This lets your Twisted application use all of the usual Twisted APIs while still being a graphical application. Twisted currently integrates with the following graphical toolkits: - :ref:`GTK+ 2.0 ` - :ref:`GTK+ 3.0 and GObject Introspection ` - :ref:`Tkinter ` - :ref:`wxPython ` - :ref:`Win32 ` - :ref:`CoreFoundation ` - :ref:`PyUI ` When using applications that are runnable using ``twistd`` , e.g. TACs or plugins, there is no need to choose a reactor explicitly, since this can be chosen using ``twistd`` 's -r option. In all cases, the event loop is started by calling ``reactor.run()`` . In all cases, the event loop should be stopped with ``reactor.stop()`` . **IMPORTANT:** installing a reactor should be the first thing done in the app, since any code that does ``from twisted.internet import reactor`` will automatically install the default reactor if the code hasn't already installed one. Reactor Functionality --------------------- +-----------------------------------------------+--------------+-----+-----+-----+-----------+-----------+------------+-------------+ | \ | Status | TCP | SSL | UDP | Threading | Processes | Scheduling | Platforms | +===============================================+==============+=====+=====+=====+===========+===========+============+=============+ | select() | Stable | Y | Y | Y | Y | Y | Y | Unix, Win32 | +-----------------------------------------------+--------------+-----+-----+-----+-----------+-----------+------------+-------------+ | poll | Stable | Y | Y | Y | Y | Y | Y | Unix | +-----------------------------------------------+--------------+-----+-----+-----+-----------+-----------+------------+-------------+ | WaitForMultipleObjects (WFMO) for Win32 | Experimental | Y | Y | Y | Y | Y | Y | Win32 | +-----------------------------------------------+--------------+-----+-----+-----+-----------+-----------+------------+-------------+ | Input/Output Completion Port (IOCP) for Win32 | Experimental | Y | Y | Y | Y | Y | Y | Win32 | +-----------------------------------------------+--------------+-----+-----+-----+-----------+-----------+------------+-------------+ | CoreFoundation | Unmaintained | Y | Y | Y | Y | Y | Y | Mac OS X | +-----------------------------------------------+--------------+-----+-----+-----+-----------+-----------+------------+-------------+ | epoll | Stable | Y | Y | Y | Y | Y | Y | Linux 2.6 | +-----------------------------------------------+--------------+-----+-----+-----+-----------+-----------+------------+-------------+ | GTK+ | Stable | Y | Y | Y | Y | Y | Y | Unix, Win32 | +-----------------------------------------------+--------------+-----+-----+-----+-----------+-----------+------------+-------------+ | wx | Experimental | Y | Y | Y | Y | Y | Y | Unix, Win32 | +-----------------------------------------------+--------------+-----+-----+-----+-----------+-----------+------------+-------------+ | kqueue | Stable | Y | Y | Y | Y | Y | Y | FreeBSD | +-----------------------------------------------+--------------+-----+-----+-----+-----------+-----------+------------+-------------+ General Purpose Reactors ------------------------ Select()-based Reactor ~~~~~~~~~~~~~~~~~~~~~~ .. _core-howto-choosing-reactor-select: The ``select`` reactor is the default on platforms that don't provide a better alternative that covers all use cases. If the ``select`` reactor is desired, it may be installed via: .. code-block:: python from twisted.internet import selectreactor selectreactor.install() from twisted.internet import reactor Platform-Specific Reactors -------------------------- Poll-based Reactor ~~~~~~~~~~~~~~~~~~ .. _core-howto-choosing-reactor-poll: The PollReactor will work on any platform that provides ``select.poll`` . With larger numbers of connected sockets, it may provide for better performance than the SelectReactor. .. code-block:: python from twisted.internet import pollreactor pollreactor.install() from twisted.internet import reactor KQueue ~~~~~~ .. _core-howto-choosing-reactor-kqueue: The KQueue Reactor allows Twisted to use FreeBSD's kqueue mechanism for event scheduling. See instructions in the :api:`twisted.internet.kqreactor ` 's docstring for installation notes. .. code-block:: python from twisted.internet import kqreactor kqreactor.install() from twisted.internet import reactor WaitForMultipleObjects (WFMO) for Win32 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. _core-howto-choosing-reactor-win32_wfmo: The Win32 reactor is not yet complete and has various limitations and issues that need to be addressed. The reactor supports GUI integration with the win32gui module, so it can be used for native Win32 GUI applications. .. code-block:: python from twisted.internet import win32eventreactor win32eventreactor.install() from twisted.internet import reactor Input/Output Completion Port (IOCP) for Win32 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. _core-howto-choosing-reactor-win32_iocp: Windows provides a fast, scalable event notification system known as IO Completion Ports, or IOCP for short. Twisted includes a reactor based on IOCP which is nearly complete. .. code-block:: python from twisted.internet import iocpreactor iocpreactor.install() from twisted.internet import reactor Epoll-based Reactor ~~~~~~~~~~~~~~~~~~~ .. _core-howto-choosing-reactor-epoll: The EPollReactor will work on any platform that provides ``epoll`` , today only Linux 2.6 and over. The implementation of the epoll reactor currently uses the Level Triggered interface, which is basically like poll() but scales much better. .. code-block:: python from twisted.internet import epollreactor epollreactor.install() from twisted.internet import reactor GUI Integration Reactors ------------------------ GTK+ ~~~~ .. _core-howto-choosing-reactor-gtk: Twisted integrates with `PyGTK `_ version 2.0 using the ``gtk2reactor`` . An example Twisted application that uses GTK+ can be found in ``doc/core/examples/pbgtk2.py`` . GTK-2.0 split the event loop out of the GUI toolkit and into a separate module called "glib" . To run an application using the glib event loop, use the ``glib2reactor`` . This will be slightly faster than ``gtk2reactor`` (and does not require a working X display), but cannot be used to run GUI applications. .. code-block:: python from twisted.internet import gtk2reactor # for gtk-2.0 gtk2reactor.install() from twisted.internet import reactor .. code-block:: python from twisted.internet import glib2reactor # for non-GUI apps glib2reactor.install() from twisted.internet import reactor GTK+ 3.0 and GObject Introspection ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. _core-howto-choosing-reactor-gtk3: Twisted integrates with `GTK+ 3 `_ and GObject through `PyGObject's `_ introspection using the ``gtk3reactor`` and ``gireactor`` reactors. .. code-block:: python from twisted.internet import gtk3reactor gtk3reactor.install() from twisted.internet import reactor .. code-block:: python from twisted.internet import gireactor # for non-GUI apps gireactor.install() from twisted.internet import reactor GLib 3.0 introduces the concept of ``GApplication`` , a class that handles application uniqueness in a cross-platform way and provides its own main loop. Its counterpart ``GtkApplication`` also handles application lifetime with respect to open windows. Twisted supports registering these objects with the event loop, which should be done before running the reactor: .. code-block:: python from twisted.internet import gtk3reactor gtk3reactor.install() from gi.repository import Gtk app = Gtk.Application(...) from twisted import reactor reactor.registerGApplication(app) reactor.run() wxPython ~~~~~~~~ .. _core-howto-choosing-reactor-wxpython: Twisted currently supports two methods of integrating wxPython. Unfortunately, neither method will work on all wxPython platforms (such as GTK2 or Windows). It seems that the only portable way to integrate with wxPython is to run it in a separate thread. One of these methods may be sufficient if your wx app is limited to a single platform. As with :ref:`Tkinter ` , the support for integrating Twisted with a `wxPython `_ application uses specialized support code rather than a simple reactor. .. code-block:: python from wxPython.wx import * from twisted.internet import wxsupport, reactor myWxAppInstance = wxApp(0) wxsupport.install(myWxAppInstance) However, this has issues when running on Windows, so Twisted now comes with alternative wxPython support using a reactor. Using this method is probably better. Initialization is done in two stages. In the first, the reactor is installed: .. code-block:: python from twisted.internet import wxreactor wxreactor.install() from twisted.internet import reactor Later, once a ``wxApp`` instance has been created, but before ``reactor.run()`` is called: .. code-block:: python from twisted.internet import reactor myWxAppInstance = wxApp(0) reactor.registerWxApp(myWxAppInstance) An example Twisted application that uses wxPython can be found in ``doc/core/examples/wxdemo.py`` . CoreFoundation ~~~~~~~~~~~~~~ .. _core-howto-choosing-reactor-cfreactor: Twisted integrates with `PyObjC `_ version 1.0. Sample applications using Cocoa and Twisted are available in the examples directory under ``doc/core/examples/threadedselect/Cocoa`` . .. code-block:: python from twisted.internet import cfreactor cfreactor.install() from twisted.internet import reactor Non-Reactor GUI Integration --------------------------- Tkinter ~~~~~~~ .. _core-howto-choosing-reactor-tkinter: The support for `Tkinter `_ doesn't use a specialized reactor. Instead, there is some specialized support code: .. code-block:: python from Tkinter import * from twisted.internet import tksupport, reactor root = Tk() # Install the Reactor support tksupport.install(root) # at this point build Tk app as usual using the root object, # and start the program with "reactor.run()", and stop it # with "reactor.stop()". PyUI ~~~~ .. _core-howto-choosing-reactor-pyui: As with :ref:`Tkinter ` , the support for integrating Twisted with a `PyUI `_ application uses specialized support code rather than a simple reactor. .. code-block:: python from twisted.internet import pyuisupport, reactor pyuisupport.install(args=(640, 480), kw={'renderer': 'gl'}) An example Twisted application that uses PyUI can be found in ``doc/core/examples/pyuidemo.py`` .