[IPython-dev] ipython embedded in twisted, no threads

Brian Granger ellisonbg.net@gmail....
Wed Apr 18 12:48:42 CDT 2007


I am interested in this, but unfortunately am very busy right now.
Another thing to keep in mind.  In a future version of IPython,
IPython _will be_ running in a twisted process, so this type of
intgration will be built in.  But, doing that will require a full
refactoring of IPython - which we are in the process of doing.  Keep
us posted on how this goes?

Brian

On 4/16/07, Stefan Rank <list-ener@strank.info> wrote:
> Hi Jörgen,
>
> on 16.04.2007 20:16 Jörgen Stenarson said the following:
> > Hi Stefan,
> >
> > I'm not sure exactly what you are after (I don't use twisted myself).
>
> I am not an expert either, I am afraid.
>
> > But in pyreadline it is now fairly straightforward to add a new console
> > class (there are currently two: the standard win32 and one for
> > .NET/IronPython) which should implement the lowlevel keyboard and screen
> > output routines. If this is what is needed I would be happy to accept
> > patches and answer questions to help make it happen. We would probably
> > also have to work out a more sofisticated method of choosing low-level
> > console backend than what is used now.
>
> I think what is needed for readline support in twisted is not a new
> backend but an additional frontend/API.
> The 'problem' (read advantage ;-) with twisted is that it needs a
> callback interface that does not block, as it wants to do the polling
> for input events itself.
>
> GNU readline has a callback interface that should be usable for that:
> http://cnswww.cns.cwru.edu/php/chet/readline/readline.html#SEC41
> (for triggering single character reading)
> Would this be possible with pyreadline?
>
> cheers,
> stefan
>
> > Stefan Rank skrev:
> >> Hi,
> >> [apologies if this arrives twice, posting via gmane didn't work - yet.]
> >>
> >> attached is an ugly first attempt at embedding IPython in a twisted
> >> application without using threads.
> >>
> >> twisted.internet.stdio and a LineReceiver implementation are responsible
> >> for getting input events.
> >> I had to subclass the IPython shell and rearrange code to
> >> create a non-blocking callback interface (splitting on the main,
> >> blocking, raw_input call).
> >>
> >> It's far from perfect: readline functionality is missing (no commandline
> >> navigation, history navigation, completion), and sometimes continuation
> >> lines eat the input counter (In[2] ... In[4]).
> >>
> >> Would IPython developers be interested in patches that allow a less ugly
> >> version of such a callback-friendly subclass? ;-)
> >> The basic idea: refactor the main loop (InteractiveShell.interact) to::
> >>
> >>    setup()
> >>    while ...:
> >>        promptforline()
> >>        raw_input
> >>        handleline()
> >>    teardown()
> >>
> >> (I think it might also be interesting for the frontend to the IPython
> >> parallel computing effort, which uses twisted.)
> >>
> >> cheers,
> >> stefan
> >>
> >>
> >> ------------------------------------------------------------------------
> >>
> >> '''Testing a way to embed IPython in a twisted app without using threads.
> >> (seems to work on Py25/WinXP, twisted2.5 patched with #2157, IPython0.8.0)
> >>
> >> twisted.internet.stdio is responsible for getting user input.
> >> An implementation of the LineReceiver protocol passes received lines
> >> to a custom subclass of the IPython shell (main raw_input call removed).
> >>
> >> No readline behaviour is available.
> >> (But IPython still sets up readline and uses it for colour printing.)
> >>
> >> TODO:
> >>     integrate readline functionality: two possibilities
> >>
> >>     1) Change pyreadline so that it can be called back by t.i.stdio for
> >>        all things except waiting for input (i.e. completion, key bindings, ...)
> >>        This would mean no further changes to IPython, which would still
> >>        be using pyreadline directly.
> >>        (or use a GNU readline callback interface: a t.i.stdio-alike would be
> >>        polling/selecting for input, but then call readline to actually consume it.)
> >>     2) Build a readline compatible interface for t.i.stdio
> >>        (only the parts for setting up completeres, key bindings, ...)
> >>        and make the IPython subclass use that instead of pyreadline
> >>
> >> As there is a lot of pasted IPython code including comments, I added
> >> ##### multi-hash comments and
> >> docstrings explaining the rearrangements.
> >>
> >> :author: strank
> >> '''
> >>
> >> __docformat__ = "restructuredtext en"
> >>
> >> import sys
> >> import __builtin__
> >>
> >> from twisted.internet import reactor, stdio
> >> from twisted.protocols import basic
> >> from IPython.Shell import IPShellEmbed
> >> from IPython.iplib import InteractiveShell, ultraTB
> >> from IPython.ipmaker import make_IPython
> >>
> >>
> >> def main():
> >>     ###### this is what we want:
> >>     reactor.callWhenRunning(startTwistedStdioShell)
> >>     ###### because this blocks the reactor while IPython is active:
> >>     #reactor.callWhenRunning(startIPShell)
> >>     reactor.run()
> >>
> >>
> >> def startIPShell(args=None):
> >>     '''The non-twisted-friendly way of embedding IPython.'''
> >>     if args is None:
> >>         args = []
> >>     some_recognisable_local = 'WAGAWAGA' # gets exposed in Shell
> >>     ipshell = IPShellEmbed(args,
> >>                            banner='Standard IPython called from twisted (blocking)',
> >>                            exit_msg='Leaving Interpreter, back to program.')
> >>     ipshell('***Called from top level. '
> >>             'Hit Ctrl-D to exit interpreter and continue program.')
> >>     reactor.stop()
> >>
> >>
> >> def startTwistedStdioShell(args=None, local_ns=None):
> >>     '''On Windows, this only works with a patched twisted,
> >>     because twisted.internet.stdio in twisted2.5 is unix only,
> >>     see ticket #2157.
> >>     '''
> >>     if args is None:
> >>         args = []
> >>     ipshell = TwistedIPShellEmbed([],
> >>                                   banner='IPython embedded in a Twisted application',
> >>                                   exit_msg='Leaving Interpreter, back to program.')
> >>     sp = ShellProtocol(ipshell, '***Called from top level. ', local_ns=local_ns)
> >>     #sp.setRawMode()
> >>     stdio.StandardIO(sp)
> >>
> >>
> >> class TwistedIPShellEmbed(IPShellEmbed):
> >>     '''Same as superclass, BUT:
> >>     __init__ is duplicated, with a single difference:
> >>         The actual IP shell_class is set to our own subclass.
> >>     __call__ is split into two methods for setup / teardown.
> >>     '''
> >>
> >>     def __init__(self,argv=None,banner='',exit_msg=None,rc_override=None,
> >>                  user_ns=None):
> >>         """Note that argv here is a string, NOT a list."""
> >>         self.set_banner(banner)
> >>         self.set_exit_msg(exit_msg)
> >>         self.set_dummy_mode(0)
> >>         # sys.displayhook is a global, we need to save the user's original
> >>         # Don't rely on __displayhook__, as the user may have changed that.
> >>         self.sys_displayhook_ori = sys.displayhook
> >>         # save readline completer status
> >>         try:
> >>             #print 'Save completer',sys.ipcompleter  # dbg
> >>             self.sys_ipcompleter_ori = sys.ipcompleter
> >>         except:
> >>             pass # not nested with IPython
> >>         self.IP = make_IPython(argv,rc_override=rc_override,
> >>                                embedded=True,
> >>                                user_ns=user_ns,
> >>                                ###### HERE IS THE DIFFERENCE  -- StefanRank
> >>                                shell_class=TwistedInteractiveShell)
> >>         # copy our own displayhook also
> >>         self.sys_displayhook_embed = sys.displayhook
> >>         # and leave the system's display hook clean
> >>         sys.displayhook = self.sys_displayhook_ori
> >>         # don't use the ipython crash handler so that user exceptions aren't
> >>         # trapped
> >>         sys.excepthook = ultraTB.FormattedTB(color_scheme = self.IP.rc.colors,
> >>                                              mode = self.IP.rc.xmode,
> >>                                              call_pdb = self.IP.rc.pdb)
> >>         self.restore_system_completer()
> >>
> >>     def __call__(self,header='',local_ns=None,global_ns=None,dummy=None):
> >>         # Set global subsystems (display,completions) to our values
> >>         sys.displayhook = self.sys_displayhook_embed
> >>         if self.IP.has_readline:
> >>             self.IP.set_completer()
> >>         if self.banner and header:
> >>             format = '%s\n%s\n'
> >>         else:
> >>             format = '%s%s\n'
> >>         banner =  format % (self.banner,header)
> >>         # Call the embedding code with a stack depth of 1 so it can skip over
> >>         # our call and get the original caller's namespaces.
> >>         ###### STOP HERE, THIS embed_mainloop DOESN'T BLOCK, RETURN THE SHELL --StefanRank
> >>         return self.IP.embed_mainloop(banner,local_ns,global_ns,stack_depth=1)
> >>
> >>     def teardown(self):
> >>         ###### call the code that would have been called at the end of IP.embed_mainloop:
> >>         self.IP.teardown()
> >>         ###### This is the code formerly known as: the end of __call__:
> >>         if self.exit_msg:
> >>             print self.exit_msg
> >>         # Restore global systems (display, completion)
> >>         sys.displayhook = self.sys_displayhook_ori
> >>         self.restore_system_completer()
> >>
> >>
> >> class TwistedInteractiveShell(InteractiveShell):
> >>     '''Subclassing to remove raw_input call and provide a callback interface.
> >>     Copy-pasted and split up code of embed_mainloop, interact, raw_input.
> >>     '''
> >>
> >>     def embed_mainloop(self,header='',local_ns=None,global_ns=None,stack_depth=0):
> >>         # Get locals and globals from caller
> >>         if local_ns is None or global_ns is None:
> >>             call_frame = sys._getframe(stack_depth).f_back
> >>             if local_ns is None:
> >>                 local_ns = call_frame.f_locals
> >>             if global_ns is None:
> >>                 global_ns = call_frame.f_globals
> >>         self.user_global_ns = global_ns
> >>         local_varnames = local_ns.keys()
> >>         self.user_ns.update(local_ns)
> >>         if local_ns is None and global_ns is None:
> >>             self.user_global_ns.update(__main__.__dict__)
> >>         self.set_completer_frame()
> >>         self.add_builtins()
> >>         self.interact(header)
> >>         return self ###### needed for later calls, interact is now non-blocking
> >>
> >>     def teardown(self):
> >>         '''This is the code formerly known as: the end of interact and embed_mainloop.'''
> >>         ##### from interact:
> >>         # We are off again...
> >>         __builtin__.__dict__['__IPYTHON__active'] -= 1
> >>         ##### from embed_mainloop:
> >>         # now, purge out the user namespace from anything we might have added
> >>         # from the caller's local namespace
> >>         ###### local_varnames not accessible any more,
> >>         ###### should probably be saved... (TODO)
> >>         ###delvar = self.user_ns.pop
> >>         ###for var in local_varnames:
> >>         ###    delvar(var,None)
> >>         # and clean builtins we may have overridden
> >>         self.clean_builtins()
> >>
> >>     def interact(self, banner=None):
> >>         ###### HERE IT GETS HAIRY: code copied from self.interact(header)
> >>         if self.exit_now:
> >>             # batch run -> do not interact
> >>             return ###### This does not make any sense now, since we are non-blocking
> >>         cprt = 'Type "copyright", "credits" or "license" for more information.'
> >>         if banner is None:
> >>             self.write("Python %s on %s\n%s\n(%s)\n" %
> >>                        (sys.version, sys.platform, cprt,
> >>                         self.__class__.__name__))
> >>         else:
> >>             self.write(banner)
> >>         more = 0
> >>         # Mark activity in the builtins
> >>         __builtin__.__dict__['__IPYTHON__active'] += 1
> >>         self.promptForLine(more)
> >>         return self
> >>
> >>     def promptForLine(self, more):
> >>         '''New method. To be called before waiting for the next line.'''
> >>         prompt = ''
> >>         ###### THIS NEEDED TO BE UNTANGLED: originally a while loop in self.interact
> >>         # exit_now is set by a call to %Exit or %Quit
> >>         if not self.exit_now:
> >>             if more:
> >>                 prompt = self.hooks.generate_prompt(True)
> >>                 if self.autoindent:
> >>                     self.readline_startup_hook(self.pre_readline)
> >>             else:
> >>                 prompt = self.hooks.generate_prompt(False)
> >>             ####### code from self.raw_input:
> >>             self.set_completer()
> >>             ####### write the prompt here, writing it in the LineReceiver
> >>             ####### with sendLine messes up the colouring
> >>             self.write(prompt)
> >>         ####### raw_input BEGONE!!!
> >>         ####### unfortunately all the exception handling in self.interact is also gone.
> >>         ####### return and wait for a call to useLine
> >>
> >>     def useLine(self, line, continue_prompt=False):
> >>         '''New method. To be called with a new received line.'''
> >>         ####### code from self.raw_input:
> >>         if line.strip():
> >>             if continue_prompt:
> >>                 self.input_hist_raw[-1] += '%s\n' % line
> >>                 if self.has_readline: # and some config option is set?
> >>                     try:
> >>                         histlen = self.readline.get_current_history_length()
> >>                         newhist = self.input_hist_raw[-1].rstrip()
> >>                         self.readline.remove_history_item(histlen-1)
> >>                         self.readline.replace_history_item(histlen-2,newhist)
> >>                     except AttributeError:
> >>                         pass # re{move,place}_history_item are new in 2.4.
> >>             else:
> >>                 self.input_hist_raw.append('%s\n' % line)
> >>         try:
> >>             lineout = self.prefilter(line,continue_prompt)
> >>         except:
> >>             # blanket except, in case a user-defined prefilter crashes, so it
> >>             # can't take all of ipython with it.
> >>             self.showtraceback()
> >>             lineout = ''
> >>         ###### CODE FROM INTERACT AGAIN:
> >>         more = self.push(lineout)
> >>         if (self.SyntaxTB.last_syntax_error and
> >>             self.rc.autoedit_syntax):
> >>             self.edit_syntax_error()
> >>         self.promptForLine(more)
> >>         ###### indicate if we want to quit
> >>         return not self.exit_now
> >>
> >>
> >> class ShellProtocol(basic.LineReceiver):
> >>     delimiter = '\n' # does not work with '\r\n' on Windows...
> >>                      # this might be an issue with the #2157 patches?
> >>
> >>     def __init__(self, ipshell, banner, **kwargs):
> >>         self.ipshell = ipshell
> >>         self.banner = banner
> >>         self.kwargs = kwargs
> >>
> >>     def connectionMade(self):
> >>         #self.sendLine("Yay, type something!")
> >>         # locals here are available in the shell:
> >>         # (but in practice the locals of the ShellProtocol() call site
> >>         # would be more interesting.)
> >>         another_strange_local = 'hubabuba'
> >>         from twisted.internet import reactor
> >>         self.sheller = self.ipshell(self.banner
> >>                 + '\n  quit.....quits via LineReceiver,'
> >>                 + '\n  exit()...quits via IPython,'
> >>                 + '\n  pause....test pausing the LineReceiver',
> >>                 **self.kwargs)
> >>
> >>     def lineReceived(self, line):
> >>         if line == 'quit':
> >>             self.sendLine('OK quitting')
> >>             self.transport.loseConnection()
> >>             return
> >>         if line == 'pause':
> >>             self.sendLine('OK pausing for 2 seconds')
> >>             self.pauseProducing()
> >>             self.clearLineBuffer()
> >>             # still receives keys typed during the pause,
> >>             # no matter how many clearLineBuffer()s, I use.
> >>             # might be a feature of Windows cmd... ?
> >>             def restart():
> >>                 self.clearLineBuffer()
> >>                 self.resumeProducing()
> >>                 self.clearLineBuffer()
> >>             reactor.callLater(2, restart)
> >>             return
> >>         #self.sendLine("Echo: " + line)
> >>         if not self.sheller.useLine(line): # processes line, prints output and next prompt
> >>             self.sendLine("IPython wants to quit")
> >>             self.transport.loseConnection()
> >>         #self.transport.write("Yay, type more!")
> >>
> >>     #def rawDataReceived(self, data):
> >>     #    self.sendLine('RawEcho: ' + str(data))
> >>     #    self.transport.write("Yay, type more!")
> >>
> >>     def connectionLost(self, reason):
> >>         try:
> >>             self.ipshell.teardown()
> >>         except IOError:
> >>             pass # is raised by IPython code when you type quit
> >>         # stop the reactor, only because this is meant to be run in Stdio.
> >>         reactor.stop()
> >>
> >>
> >> if __name__ == '__main__':
> >>     main()
> >>
> >>
> >> ------------------------------------------------------------------------
> >>
> >> _______________________________________________
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> >
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