Overview
Twisted provides a variety of implementations of the twisted.internet.reactor. The specialized
implementations are suited for different purposes and are
designed to integrate better with particular platforms.
The general purpose reactor implementations are:
Platform-specific reactor implementations exist for:
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:
When using applications that runnable using twistd, e.g.
TAPs 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 hasen't already installed one.
Reactor Functionality
| TCP | SSL | UDP | Threading | Processes | Scheduling | Platforms | |
|---|---|---|---|---|---|---|---|
| select() | Y | Y | Y | Y | Y (Unix only) | Y | Unix, Win32 |
| poll() | Y | Y | Y | Y | Y | Y | Unix |
| Win32 | Y | Y | Y | Y | Y | Y | Win32 |
| cfreactor | Y | Y | Y | Y | Y | Y | OS X |
| GTK+ | Y | Y | Y | Y | Y (Unix only) | Y | Unix, Win32 |
| Qt | Y | Y | Y | Y | Y (Unix only) | Y | Unix, Win32 |
| kqueue | Y | Y | Y | Y | Y | Y | FreeBSD |
| C | Y | N | N | Y | Y | Y | Unix |
General Purpose Reactors
Select()-based Reactor
The SelectReactor is the default reactor.
from twisted.internet import reactor
The SelectReactor may be explicitly installed by:
from twisted.internet import default default.install()
Poll()-based Reactor
The PollReactor will work on any platform that provides
poll(). With larger numbers of
connected sockets, it may provide for better performance.
from twisted.internet import pollreactor pollreactor.install()
Platform-Specific Reactors
cReactor for Unix
The cReactor is a high-performance C implementation of the Reactor interfaces. It is currently experimental and under active development.
from twisted.internet import cReactor cReactor.install()
KQueue
The KQueue Reactor allows Twisted to use FreeBSD's kqueue mechanism for
event scheduling. See instructions in the twisted.internet.kqreactor's
docstring for installation notes.
from twisted.internet import kqreactor kqreactor.install()
Win32
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.
from twisted.internet import win32eventreactor win32eventreactor.install()
GUI Integration Reactors
GTK+
Twisted integrates with PyGTK, versions 1.2 and 2.0. Sample applications using GTK+ and Twisted are available in the Twisted CVS.
from twisted.internet import gtkreactor gtkreactor.install()
GUI Integration Reactors
Cocoa
Twisted integrates with PyObjC, version 1.0. Sample applications using Cocoa and Twisted
are available in the examples directory under Cocoa.
from twisted.internet import cfreactor cfreactor.install()
Qt
An example Twisted application that uses Qt can be found in
doc/examples/qtdemo.py.
When installing the reactor, pass a QApplication instance, and if you don't a new one will be created for you.
from qt import QApplication app = QApplication([]) from twisted.internet import qtreactor qtreactor.install(app)
Non-Reactor GUI Integration
Tkinter
The support for Tkinter doesn't use a specialized reactor. Instead, there is some specialized support code:
from Tkinter import * from twisted.internet import tksupport root = Tk() root.withdraw() # 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()".
wxPython
As with Tkinter, the support for integrating Twisted with a wxPython application uses specialized support code rather than a simple reactor.
from wxPython.wx import * from twisted.internet import wxsupport, reactor myWxAppInstance = wxApp(0) wxsupport.install(myWxAppInstance)
However, this has issues when runnin 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:
from twisted.internet import wxreactor wxreactor.install()
Later, once a wxApp instance has
been created, but before reactor.run()
is called:
myWxAppInstance = wxApp(0) reactor.registerWxApp(myWxAppInstance)
An example Twisted application that uses WxWindows can be found
in doc/examples/wxdemo.py.
PyUI
As with Tkinter, the support for integrating Twisted with a PyUI application uses specialized support code rather than a simple reactor.
from twisted.internet import pyuisupport, reactor pyuisupport.install(args=(640, 480), kw={'renderer': 'gl'})
An example Twisted application that uses PyUI can bve found in doc/examples/pyuidemo.py.