qt4reactor.py

# Copyright (c) 2001-2011 Twisted Matrix Laboratories.
# See LICENSE for details.


"""
This module provides support for Twisted to be driven by the Qt mainloop.

In order to use this support, simply do the following::
    |  app = QApplication(sys.argv) # your code to init Qt
    |  import qt4reactor
    |  qt4reactor.install()
    
alternatively:

    |  from twisted.application import reactors
    |  reactors.installReactor('qt4')

Then use twisted.internet APIs as usual.  The other methods here are not
intended to be called directly.

If you don't instantiate a QApplication or QCoreApplication prior to
installing the reactor, a QCoreApplication will be constructed
by the reactor.  QCoreApplication does not require a GUI so trial testing
can occur normally.

Twisted can be initialized after QApplication.exec_() with a call to
reactor.runReturn().  calling reactor.stop() will unhook twisted but
leave your Qt application running

API Stability: stable

Maintainer: U{Glenn H Tarbox, PhD<mailto:glenn@tarbox.org>}

Previous maintainer: U{Itamar Shtull-Trauring<mailto:twisted@itamarst.org>}
Original port to QT4: U{Gabe Rudy<mailto:rudy@goldenhelix.com>}
Subsequent port by therve
"""

import sys
import time
from zope.interface import implements
from twisted.internet.interfaces import IReactorFDSet
from twisted.python import log, runtime
from twisted.internet import posixbase
from twisted.python.runtime import platformType, platform

try:
    from PyQt4.QtCore import QSocketNotifier, QObject, SIGNAL, QTimer, QCoreApplication
    from PyQt4.QtCore import QEventLoop
except ImportError:
    from PySide.QtCore import QSocketNotifier, QObject, SIGNAL, QTimer, QCoreApplication
    from PySide.QtCore import QEventLoop


class TwistedSocketNotifier(QObject):
    """
    Connection between an fd event and reader/writer callbacks.
    """

    def __init__(self, parent, reactor, watcher, socketType):
        QObject.__init__(self, parent)
        self.reactor = reactor
        self.watcher = watcher
        fd = watcher.fileno()
        self.notifier = QSocketNotifier(fd, socketType, parent)
        self.notifier.setEnabled(True)
        if socketType == QSocketNotifier.Read:
            self.fn = self.read
        else:
            self.fn = self.write
        QObject.connect(self.notifier, SIGNAL("activated(int)"), self.fn)


    def shutdown(self):
        self.notifier.setEnabled(False)
        self.disconnect(self.notifier, SIGNAL("activated(int)"), self.fn)
        self.fn = self.watcher = None
        self.notifier.deleteLater()
        self.deleteLater()


    def read(self, fd):
        if not self.watcher:
            return
        w = self.watcher
        # doRead can cause self.shutdown to be called so keep a reference to self.watcher
        def _read():
            #Don't call me again, until the data has been read
            self.notifier.setEnabled(False)
            why = None
            try:
                why = w.doRead()
                inRead = True
            except:
                inRead = False
                log.err()
                why = sys.exc_info()[1]
            if why:
                self.reactor._disconnectSelectable(w, why, inRead)
            elif self.watcher:
                self.notifier.setEnabled(True) # Re enable notification following sucessfull read
            self.reactor._iterate(fromqt=True)
        log.callWithLogger(w, _read)

    def write(self, sock):
        if not self.watcher:
            return
        w = self.watcher
        def _write():
            why = None
            self.notifier.setEnabled(False)
            
            try:
                why = w.doWrite()
            except:
                log.err()
                why = sys.exc_info()[1]
            if why:
                self.reactor._disconnectSelectable(w, why, False)
            elif self.watcher:
                self.notifier.setEnabled(True)
            self.reactor._iterate(fromqt=True)
        log.callWithLogger(w, _write)



class QtReactor(posixbase.PosixReactorBase):
    implements(IReactorFDSet)

    def __init__(self):
        self._reads = {}
        self._writes = {}
        self._notifiers = {}
        self._timer = QTimer()
        self._timer.setSingleShot(True)
        QObject.connect(self._timer, SIGNAL("timeout()"), self.iterate)

        if QCoreApplication.instance() is None:
            # Application Object has not been started yet
            self.qApp=QCoreApplication([])
            self._ownApp=True
        else:
            self.qApp = QCoreApplication.instance()
            self._ownApp=False
        self._blockApp = None
        posixbase.PosixReactorBase.__init__(self)


    def _add(self, xer, primary, type):
        """
        Private method for adding a descriptor from the event loop.

        It takes care of adding it if  new or modifying it if already added
        for another state (read -> read/write for example).
        """
        if xer not in primary:
            primary[xer] = TwistedSocketNotifier(None, self, xer, type)


    def addReader(self, reader):
        """
        Add a FileDescriptor for notification of data available to read.
        """
        self._add(reader, self._reads, QSocketNotifier.Read)


    def addWriter(self, writer):
        """
        Add a FileDescriptor for notification of data available to write.
        """
        self._add(writer, self._writes, QSocketNotifier.Write)


    def _remove(self, xer, primary):
        """
        Private method for removing a descriptor from the event loop.

        It does the inverse job of _add, and also add a check in case of the fd
        has gone away.
        """
        if xer in primary:
            notifier = primary.pop(xer)
            notifier.shutdown()

        
    def removeReader(self, reader):
        """
        Remove a Selectable for notification of data available to read.
        """
        self._remove(reader, self._reads)


    def removeWriter(self, writer):
        """
        Remove a Selectable for notification of data available to write.
        """
        self._remove(writer, self._writes)


    def removeAll(self):
        """
        Remove all selectables, and return a list of them.
        """
        rv = self._removeAll(self._reads, self._writes)
        return rv


    def getReaders(self):
        return self._reads.keys()


    def getWriters(self):
        return self._writes.keys()


    def callLater(self,howlong, *args, **kargs):
        rval = super(QtReactor,self).callLater(howlong, *args, **kargs)
        self.reactorInvocation()
        return rval


    def reactorInvocation(self):
        self._timer.stop()
        self._timer.setInterval(0)
        self._timer.start()
        

    def _iterate(self, delay=None, fromqt=False):
        """See twisted.internet.interfaces.IReactorCore.iterate.
        """
        self.runUntilCurrent()
        self.doIteration(delay, fromqt)

    iterate = _iterate

    def doIteration(self, delay=None, fromqt=False):
        'This method is called by a Qt timer or by network activity on a file descriptor'
        
        if not self.running and self._blockApp:
            self._blockApp.quit()
        self._timer.stop()
        delay = max(delay, 1)
        if not fromqt:
            self.qApp.processEvents(QEventLoop.AllEvents, delay * 1000)
        if self.timeout() is None:
            timeout = 0.1
        elif self.timeout() == 0:
            timeout = 0
        else:
            timeout = self.timeout()
        self._timer.setInterval(timeout * 1000)
        self._timer.start()


    def runReturn(self, installSignalHandlers=True):
        self.startRunning(installSignalHandlers=installSignalHandlers)
        self.reactorInvocation()


    def run(self, installSignalHandlers=True):
        if self._ownApp:
            self._blockApp = self.qApp
        else:
            self._blockApp = QEventLoop()
        self.runReturn()
        self._blockApp.exec_()


class QtEventReactor(QtReactor):
    def __init__(self, *args, **kwargs):
        self._events = {}
        super(QtEventReactor, self).__init__()

        
    def addEvent(self, event, fd, action):
        """
        Add a new win32 event to the event loop.
        """
        self._events[event] = (fd, action)


    def removeEvent(self, event):
        """
        Remove an event.
        """
        if event in self._events:
            del self._events[event]


    def doEvents(self):
        handles = self._events.keys()
        if len(handles) > 0:
            val = None
            while val != WAIT_TIMEOUT:
                val = MsgWaitForMultipleObjects(handles, 0, 0, QS_ALLINPUT | QS_ALLEVENTS)
                if val >= WAIT_OBJECT_0 and val < WAIT_OBJECT_0 + len(handles):
                    event_id = handles[val - WAIT_OBJECT_0]
                    if event_id in self._events:
                        fd, action = self._events[event_id]
                        log.callWithLogger(fd, self._runAction, action, fd)
                elif val == WAIT_TIMEOUT:
                    pass
                else:
                    #print 'Got an unexpected return of %r' % val
                    return


    def _runAction(self, action, fd):
        try:
            closed = getattr(fd, action)()
        except:
            closed = sys.exc_info()[1]
            log.deferr()

        if closed:
            self._disconnectSelectable(fd, closed, action == 'doRead')

            
    def timeout(self):
        t = super(QtEventReactor, self).timeout()
        return min(t, 0.01)


    def iterate(self, delay=None):
        """See twisted.internet.interfaces.IReactorCore.iterate.
        """
        self.runUntilCurrent()
        self.doEvents()
        self.doIteration(delay)


def posixinstall():
    """
    Install the Qt reactor.
    """
    p = QtReactor()
    from twisted.internet.main import installReactor
    installReactor(p)


def win32install():
    """
    Install the Qt reactor.
    """
    p = QtEventReactor()
    from twisted.internet.main import installReactor
    installReactor(p)


if runtime.platform.getType() == 'win32':
    from win32event import CreateEvent, MsgWaitForMultipleObjects
    from win32event import WAIT_OBJECT_0, WAIT_TIMEOUT, QS_ALLINPUT, QS_ALLEVENTS
    install = win32install
else:
    install = posixinstall


__all__ = ["install"]