IPython/zmq/ipkernel.py

#!/usr/bin/env python
"""A simple interactive kernel that talks to a frontend over 0MQ.

Things to do:

* Implement `set_parent` logic. Right before doing exec, the Kernel should
  call set_parent on all the PUB objects with the message about to be executed.
* Implement random port and security key logic.
* Implement control messages.
* Implement event loop and poll version.
"""

#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

# Standard library imports.
import __builtin__
import sys
import time
import traceback

# System library imports.
import zmq

# Local imports.
from IPython.config.configurable import Configurable
from IPython.utils.traitlets import Instance
from completer import KernelCompleter
from entry_point import base_launch_kernel, make_argument_parser, make_kernel, \
    start_kernel
from iostream import OutStream
from session import Session, Message
from zmqshell import ZMQInteractiveShell

#-----------------------------------------------------------------------------
# Main kernel class
#-----------------------------------------------------------------------------

class Kernel(Configurable):

    #---------------------------------------------------------------------------
    # Kernel interface
    #---------------------------------------------------------------------------

    shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
    session = Instance(Session)
    reply_socket = Instance('zmq.Socket')
    pub_socket = Instance('zmq.Socket')
    req_socket = Instance('zmq.Socket')

    # Maps user-friendly backend names to matplotlib backend identifiers.
    _pylab_map = { 'tk': 'TkAgg',
                   'gtk': 'GTKAgg',
                   'wx': 'WXAgg',
                   'qt': 'Qt4Agg', # qt3 not supported
                   'qt4': 'Qt4Agg',
                   'payload-svg' : \
                       'module://IPython.zmq.pylab.backend_payload_svg' }

    def __init__(self, **kwargs):
        super(Kernel, self).__init__(**kwargs)

        # Initialize the InteractiveShell subclass
        self.shell = ZMQInteractiveShell.instance()
        self.shell.displayhook.session = self.session
        self.shell.displayhook.pub_socket = self.pub_socket

        # Build dict of handlers for message types
        msg_types = [ 'execute_request', 'complete_request', 
                      'object_info_request', 'prompt_request',
                      'history_request' ]
        self.handlers = {}
        for msg_type in msg_types:
            self.handlers[msg_type] = getattr(self, msg_type)

    def activate_pylab(self, backend=None, import_all=True):
        """ Activates pylab in this kernel's namespace.

        Parameters:
        -----------
        backend : str, optional
            A valid backend name.

        import_all : bool, optional
            If true, an 'import *' is done from numpy and pylab.
        """
        # FIXME: This is adapted from IPython.lib.pylabtools.pylab_activate.
        #        Common funtionality should be refactored.

        # We must set the desired backend before importing pylab.
        import matplotlib
        if backend:
            backend_id = self._pylab_map[backend]
            if backend_id.startswith('module://'):
                # Work around bug in matplotlib: matplotlib.use converts the
                # backend_id to lowercase even if a module name is specified!
                matplotlib.rcParams['backend'] = backend_id
            else:
                matplotlib.use(backend_id)

        # Import numpy as np/pyplot as plt are conventions we're trying to
        # somewhat standardize on. Making them available to users by default
        # will greatly help this.
        exec ("import numpy\n"
              "import matplotlib\n"
              "from matplotlib import pylab, mlab, pyplot\n"
              "np = numpy\n"
              "plt = pyplot\n"
              ) in self.shell.user_ns

        if import_all:
            exec("from matplotlib.pylab import *\n"
                 "from numpy import *\n") in self.shell.user_ns

        matplotlib.interactive(True)

    def start(self):
        """ Start the kernel main loop.
        """

        while True:
            ident = self.reply_socket.recv()
            assert self.reply_socket.rcvmore(), "Missing message part."
            msg = self.reply_socket.recv_json()
            omsg = Message(msg)
            print>>sys.__stdout__
            print>>sys.__stdout__, omsg
            handler = self.handlers.get(omsg.msg_type, None)
            if handler is None:
                print >> sys.__stderr__, "UNKNOWN MESSAGE TYPE:", omsg
            else:
                handler(ident, omsg)

    #---------------------------------------------------------------------------
    # Kernel request handlers
    #---------------------------------------------------------------------------

    def execute_request(self, ident, parent):
        try:
            code = parent[u'content'][u'code']
        except:
            print>>sys.__stderr__, "Got bad msg: "
            print>>sys.__stderr__, Message(parent)
            return
        pyin_msg = self.session.msg(u'pyin',{u'code':code}, parent=parent)
        self.pub_socket.send_json(pyin_msg)

        try:
            # Replace raw_input. Note that is not sufficient to replace 
            # raw_input in the user namespace.
            raw_input = lambda prompt='': self._raw_input(prompt, ident, parent)
            __builtin__.raw_input = raw_input

            # Set the parent message of the display hook.
            self.shell.displayhook.set_parent(parent)

            self.shell.runlines(code)
        except:
            etype, evalue, tb = sys.exc_info()
            tb = traceback.format_exception(etype, evalue, tb)
            exc_content = {
                u'status' : u'error',
                u'traceback' : tb,
                u'ename' : unicode(etype.__name__),
                u'evalue' : unicode(evalue)
            }
            exc_msg = self.session.msg(u'pyerr', exc_content, parent)
            self.pub_socket.send_json(exc_msg)
            reply_content = exc_content
        else:
            payload = self.shell.payload_manager.read_payload()
            # Be agressive about clearing the payload because we don't want
            # it to sit in memory until the next execute_request comes in.
            self.shell.payload_manager.clear_payload()
            reply_content = { 'status' : 'ok', 'payload' : payload }

        # Compute the prompt information
        prompt_number = self.shell.displayhook.prompt_count
        reply_content['prompt_number'] = prompt_number        
        prompt_string = self.shell.displayhook.prompt1.peek_next_prompt()
        next_prompt = {'prompt_string' : prompt_string,
                       'prompt_number' : prompt_number+1,
                       'input_sep'     : self.shell.displayhook.input_sep}
        reply_content['next_prompt'] = next_prompt

        # Flush output before sending the reply.
        sys.stderr.flush()
        sys.stdout.flush()

        # Send the reply.
        reply_msg = self.session.msg(u'execute_reply', reply_content, parent)
        print>>sys.__stdout__, Message(reply_msg)
        self.reply_socket.send(ident, zmq.SNDMORE)
        self.reply_socket.send_json(reply_msg)
        if reply_msg['content']['status'] == u'error':
            self._abort_queue()

    def complete_request(self, ident, parent):
        matches = {'matches' : self._complete(parent),
                   'status' : 'ok'}
        completion_msg = self.session.send(self.reply_socket, 'complete_reply',
                                           matches, parent, ident)
        print >> sys.__stdout__, completion_msg

    def object_info_request(self, ident, parent):
        context = parent['content']['oname'].split('.')
        object_info = self._object_info(context)
        msg = self.session.send(self.reply_socket, 'object_info_reply',
                                object_info, parent, ident)
        print >> sys.__stdout__, msg

    def prompt_request(self, ident, parent):
        prompt_number = self.shell.displayhook.prompt_count
        prompt_string = self.shell.displayhook.prompt1.peek_next_prompt()
        content = {'prompt_string' : prompt_string,
                   'prompt_number' : prompt_number+1}
        msg = self.session.send(self.reply_socket, 'prompt_reply',
                                content, parent, ident)
        print >> sys.__stdout__, msg

    def history_request(self, ident, parent):
        output = parent['content'].get('output', True)
        index = parent['content'].get('index')
        raw = parent['content'].get('raw', False)
        hist = self.shell.get_history(index=index, raw=raw, output=output)
        content = {'history' : hist}
        msg = self.session.send(self.reply_socket, 'history_reply',
                                content, parent, ident)
        print >> sys.__stdout__, msg
        
    #---------------------------------------------------------------------------
    # Protected interface
    #---------------------------------------------------------------------------

    def _abort_queue(self):
        while True:
            try:
                ident = self.reply_socket.recv(zmq.NOBLOCK)
            except zmq.ZMQError, e:
                if e.errno == zmq.EAGAIN:
                    break
            else:
                assert self.reply_socket.rcvmore(), "Unexpected missing message part."
                msg = self.reply_socket.recv_json()
            print>>sys.__stdout__, "Aborting:"
            print>>sys.__stdout__, Message(msg)
            msg_type = msg['msg_type']
            reply_type = msg_type.split('_')[0] + '_reply'
            reply_msg = self.session.msg(reply_type, {'status' : 'aborted'}, msg)
            print>>sys.__stdout__, Message(reply_msg)
            self.reply_socket.send(ident,zmq.SNDMORE)
            self.reply_socket.send_json(reply_msg)
            # We need to wait a bit for requests to come in. This can probably
            # be set shorter for true asynchronous clients.
            time.sleep(0.1)

    def _raw_input(self, prompt, ident, parent):
        # Flush output before making the request.
        sys.stderr.flush()
        sys.stdout.flush()

        # Send the input request.
        content = dict(prompt=prompt)
        msg = self.session.msg(u'input_request', content, parent)
        self.req_socket.send_json(msg)

        # Await a response.
        reply = self.req_socket.recv_json()
        try:
            value = reply['content']['value']
        except:
            print>>sys.__stderr__, "Got bad raw_input reply: "
            print>>sys.__stderr__, Message(parent)
            value = ''
        return value
    
    def _complete(self, msg):
        return self.shell.complete(msg.content.line)

    def _object_info(self, context):
        symbol, leftover = self._symbol_from_context(context)
        if symbol is not None and not leftover:
            doc = getattr(symbol, '__doc__', '')
        else:
            doc = ''
        object_info = dict(docstring = doc)
        return object_info

    def _symbol_from_context(self, context):
        if not context:
            return None, context

        base_symbol_string = context[0]
        symbol = self.shell.user_ns.get(base_symbol_string, None)
        if symbol is None:
            symbol = __builtin__.__dict__.get(base_symbol_string, None)
        if symbol is None:
            return None, context

        context = context[1:]
        for i, name in enumerate(context):
            new_symbol = getattr(symbol, name, None)
            if new_symbol is None:
                return symbol, context[i:]
            else:
                symbol = new_symbol

        return symbol, []

#-----------------------------------------------------------------------------
# Kernel main and launch functions
#-----------------------------------------------------------------------------

def launch_kernel(xrep_port=0, pub_port=0, req_port=0, independent=False,
                  pylab=False):
    """ Launches a localhost kernel, binding to the specified ports.

    Parameters
    ----------
    xrep_port : int, optional
        The port to use for XREP channel.

    pub_port : int, optional
        The port to use for the SUB channel.

    req_port : int, optional
        The port to use for the REQ (raw input) channel.

    independent : bool, optional (default False) 
        If set, the kernel process is guaranteed to survive if this process
        dies. If not set, an effort is made to ensure that the kernel is killed
        when this process dies. Note that in this case it is still good practice
        to kill kernels manually before exiting.

    pylab : bool or string, optional (default False)
        If not False, the kernel will be launched with pylab enabled. If a
        string is passed, matplotlib will use the specified backend. Otherwise,
        matplotlib's default backend will be used.

    Returns
    -------
    A tuple of form:
        (kernel_process, xrep_port, pub_port, req_port)
    where kernel_process is a Popen object and the ports are integers.
    """
    extra_arguments = []
    if pylab:
        extra_arguments.append('--pylab')
        if isinstance(pylab, basestring):
            extra_arguments.append(pylab)
    return base_launch_kernel('from IPython.zmq.ipkernel import main; main()',
                              xrep_port, pub_port, req_port, independent, 
                              extra_arguments)

def main():
    """ The IPython kernel main entry point.
    """
    parser = make_argument_parser()
    parser.add_argument('--pylab', type=str, metavar='GUI', nargs='?', 
                        const='auto', help = \
"Pre-load matplotlib and numpy for interactive use. If GUI is not \
given, the GUI backend is matplotlib's, otherwise use one of: \
['tk', 'gtk', 'qt', 'wx', 'payload-svg'].")
    namespace = parser.parse_args()

    kernel = make_kernel(namespace, Kernel, OutStream)
    if namespace.pylab:
        if namespace.pylab == 'auto':
            kernel.activate_pylab()
        else:
            kernel.activate_pylab(namespace.pylab)
    
    start_kernel(namespace, kernel)

if __name__ == '__main__':
    main()