Add is_complete request and reply to messaging infrastructure

IPython/kernel/channels.py

@@ -1,639 +1,644 b''
 """Base classes to manage a Client's interaction with a running kernel"""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 from __future__ import absolute_import
 
 import atexit
 import errno
 from threading import Thread
 import time
 
 import zmq
 # import ZMQError in top-level namespace, to avoid ugly attribute-error messages
 # during garbage collection of threads at exit:
 from zmq import ZMQError
 from zmq.eventloop import ioloop, zmqstream
 
 from IPython.core.release import kernel_protocol_version_info
 
 from .channelsabc import (
     ShellChannelABC, IOPubChannelABC,
     HBChannelABC, StdInChannelABC,
 )
 from IPython.utils.py3compat import string_types, iteritems
 
 #-----------------------------------------------------------------------------
 # Constants and exceptions
 #-----------------------------------------------------------------------------
 
 major_protocol_version = kernel_protocol_version_info[0]
 
 class InvalidPortNumber(Exception):
     pass
 
 #-----------------------------------------------------------------------------
 # Utility functions
 #-----------------------------------------------------------------------------
 
 # some utilities to validate message structure, these might get moved elsewhere
 # if they prove to have more generic utility
 
 def validate_string_list(lst):
     """Validate that the input is a list of strings.
 
     Raises ValueError if not."""
     if not isinstance(lst, list):
         raise ValueError('input %r must be a list' % lst)
     for x in lst:
         if not isinstance(x, string_types):
             raise ValueError('element %r in list must be a string' % x)
 
 
 def validate_string_dict(dct):
     """Validate that the input is a dict with string keys and values.
 
     Raises ValueError if not."""
     for k,v in iteritems(dct):
         if not isinstance(k, string_types):
             raise ValueError('key %r in dict must be a string' % k)
         if not isinstance(v, string_types):
             raise ValueError('value %r in dict must be a string' % v)
 
 
 #-----------------------------------------------------------------------------
 # ZMQ Socket Channel classes
 #-----------------------------------------------------------------------------
 
 class ZMQSocketChannel(Thread):
     """The base class for the channels that use ZMQ sockets."""
     context = None
     session = None
     socket = None
     ioloop = None
     stream = None
     _address = None
     _exiting = False
     proxy_methods = []
 
     def __init__(self, context, session, address):
         """Create a channel.
 
         Parameters
         ----------
         context : :class:`zmq.Context`
             The ZMQ context to use.
         session : :class:`session.Session`
             The session to use.
         address : zmq url
             Standard (ip, port) tuple that the kernel is listening on.
         """
         super(ZMQSocketChannel, self).__init__()
         self.daemon = True
 
         self.context = context
         self.session = session
         if isinstance(address, tuple):
             if address[1] == 0:
                 message = 'The port number for a channel cannot be 0.'
                 raise InvalidPortNumber(message)
             address = "tcp://%s:%i" % address
         self._address = address
         atexit.register(self._notice_exit)
 
     def _notice_exit(self):
         self._exiting = True
 
     def _run_loop(self):
         """Run my loop, ignoring EINTR events in the poller"""
         while True:
             try:
                 self.ioloop.start()
             except ZMQError as e:
                 if e.errno == errno.EINTR:
                     continue
                 else:
                     raise
             except Exception:
                 if self._exiting:
                     break
                 else:
                     raise
             else:
                 break
 
     def stop(self):
         """Stop the channel's event loop and join its thread.
 
         This calls :meth:`~threading.Thread.join` and returns when the thread
         terminates. :class:`RuntimeError` will be raised if
         :meth:`~threading.Thread.start` is called again.
         """
         if self.ioloop is not None:
             self.ioloop.stop()
         self.join()
         self.close()
     
     def close(self):
         if self.ioloop is not None:
             try:
                 self.ioloop.close(all_fds=True)
             except Exception:
                 pass
         if self.socket is not None:
             try:
                 self.socket.close(linger=0)
             except Exception:
                 pass
             self.socket = None
 
     @property
     def address(self):
         """Get the channel's address as a zmq url string.
 
         These URLS have the form: 'tcp://127.0.0.1:5555'.
         """
         return self._address
 
     def _queue_send(self, msg):
         """Queue a message to be sent from the IOLoop's thread.
 
         Parameters
         ----------
         msg : message to send
 
         This is threadsafe, as it uses IOLoop.add_callback to give the loop's
         thread control of the action.
         """
         def thread_send():
             self.session.send(self.stream, msg)
         self.ioloop.add_callback(thread_send)
 
     def _handle_recv(self, msg):
         """Callback for stream.on_recv.
 
         Unpacks message, and calls handlers with it.
         """
         ident,smsg = self.session.feed_identities(msg)
         msg = self.session.unserialize(smsg)
         self.call_handlers(msg)
 
 
 
 class ShellChannel(ZMQSocketChannel):
     """The shell channel for issuing request/replies to the kernel."""
 
     command_queue = None
     # flag for whether execute requests should be allowed to call raw_input:
     allow_stdin = True
     proxy_methods = [
         'execute',
         'complete',
         'inspect',
         'history',
         'kernel_info',
         'shutdown',
+        'is_complete',
     ]
 
     def __init__(self, context, session, address):
         super(ShellChannel, self).__init__(context, session, address)
         self.ioloop = ioloop.IOLoop()
     
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.DEALER)
         self.socket.linger = 1000
         self.socket.setsockopt(zmq.IDENTITY, self.session.bsession)
         self.socket.connect(self.address)
         self.stream = zmqstream.ZMQStream(self.socket, self.ioloop)
         self.stream.on_recv(self._handle_recv)
         self._run_loop()
 
     def call_handlers(self, msg):
         """This method is called in the ioloop thread when a message arrives.
 
         Subclasses should override this method to handle incoming messages.
         It is important to remember that this method is called in the thread
         so that some logic must be done to ensure that the application level
         handlers are called in the application thread.
         """
         raise NotImplementedError('call_handlers must be defined in a subclass.')
 
     def execute(self, code, silent=False, store_history=True,
                 user_expressions=None, allow_stdin=None):
         """Execute code in the kernel.
 
         Parameters
         ----------
         code : str
             A string of Python code.
 
         silent : bool, optional (default False)
             If set, the kernel will execute the code as quietly possible, and
             will force store_history to be False.
 
         store_history : bool, optional (default True)
             If set, the kernel will store command history.  This is forced
             to be False if silent is True.
 
         user_expressions : dict, optional
             A dict mapping names to expressions to be evaluated in the user's
             dict. The expression values are returned as strings formatted using
             :func:`repr`.
 
         allow_stdin : bool, optional (default self.allow_stdin)
             Flag for whether the kernel can send stdin requests to frontends.
 
             Some frontends (e.g. the Notebook) do not support stdin requests.
             If raw_input is called from code executed from such a frontend, a
             StdinNotImplementedError will be raised.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         if user_expressions is None:
             user_expressions = {}
         if allow_stdin is None:
             allow_stdin = self.allow_stdin
 
 
         # Don't waste network traffic if inputs are invalid
         if not isinstance(code, string_types):
             raise ValueError('code %r must be a string' % code)
         validate_string_dict(user_expressions)
 
         # Create class for content/msg creation. Related to, but possibly
         # not in Session.
         content = dict(code=code, silent=silent, store_history=store_history,
                        user_expressions=user_expressions,
                        allow_stdin=allow_stdin,
                        )
         msg = self.session.msg('execute_request', content)
         self._queue_send(msg)
         return msg['header']['msg_id']
 
     def complete(self, code, cursor_pos=None):
         """Tab complete text in the kernel's namespace.
 
         Parameters
         ----------
         code : str
             The context in which completion is requested.
             Can be anything between a variable name and an entire cell.
         cursor_pos : int, optional
             The position of the cursor in the block of code where the completion was requested.
             Default: ``len(code)``
 
         Returns
         -------
         The msg_id of the message sent.
         """
         if cursor_pos is None:
             cursor_pos = len(code)
         content = dict(code=code, cursor_pos=cursor_pos)
         msg = self.session.msg('complete_request', content)
         self._queue_send(msg)
         return msg['header']['msg_id']
 
     def inspect(self, code, cursor_pos=None, detail_level=0):
         """Get metadata information about an object in the kernel's namespace.
 
         It is up to the kernel to determine the appropriate object to inspect.
 
         Parameters
         ----------
         code : str
             The context in which info is requested.
             Can be anything between a variable name and an entire cell.
         cursor_pos : int, optional
             The position of the cursor in the block of code where the info was requested.
             Default: ``len(code)``
         detail_level : int, optional
             The level of detail for the introspection (0-2)
 
         Returns
         -------
         The msg_id of the message sent.
         """
         if cursor_pos is None:
             cursor_pos = len(code)
         content = dict(code=code, cursor_pos=cursor_pos,
             detail_level=detail_level,
         )
         msg = self.session.msg('inspect_request', content)
         self._queue_send(msg)
         return msg['header']['msg_id']
 
     def history(self, raw=True, output=False, hist_access_type='range', **kwargs):
         """Get entries from the kernel's history list.
 
         Parameters
         ----------
         raw : bool
             If True, return the raw input.
         output : bool
             If True, then return the output as well.
         hist_access_type : str
             'range' (fill in session, start and stop params), 'tail' (fill in n)
              or 'search' (fill in pattern param).
 
         session : int
             For a range request, the session from which to get lines. Session
             numbers are positive integers; negative ones count back from the
             current session.
         start : int
             The first line number of a history range.
         stop : int
             The final (excluded) line number of a history range.
 
         n : int
             The number of lines of history to get for a tail request.
 
         pattern : str
             The glob-syntax pattern for a search request.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         content = dict(raw=raw, output=output, hist_access_type=hist_access_type,
                                                                     **kwargs)
         msg = self.session.msg('history_request', content)
         self._queue_send(msg)
         return msg['header']['msg_id']
 
     def kernel_info(self):
         """Request kernel info."""
         msg = self.session.msg('kernel_info_request')
         self._queue_send(msg)
         return msg['header']['msg_id']
     
     def _handle_kernel_info_reply(self, msg):
         """handle kernel info reply
         
         sets protocol adaptation version
         """
         adapt_version = int(msg['content']['protocol_version'].split('.')[0])
         if adapt_version != major_protocol_version:
             self.session.adapt_version = adapt_version
 
     def shutdown(self, restart=False):
         """Request an immediate kernel shutdown.
 
         Upon receipt of the (empty) reply, client code can safely assume that
         the kernel has shut down and it's safe to forcefully terminate it if
         it's still alive.
 
         The kernel will send the reply via a function registered with Python's
         atexit module, ensuring it's truly done as the kernel is done with all
         normal operation.
         """
         # Send quit message to kernel. Once we implement kernel-side setattr,
         # this should probably be done that way, but for now this will do.
         msg = self.session.msg('shutdown_request', {'restart':restart})
         self._queue_send(msg)
         return msg['header']['msg_id']
 
+    def is_complete(self, code):
+        msg = self.session.msg('is_complete_request', {'code': code})
+        self._queue_send(msg)
+        return msg['header']['msg_id']
 
 
 class IOPubChannel(ZMQSocketChannel):
     """The iopub channel which listens for messages that the kernel publishes.
 
     This channel is where all output is published to frontends.
     """
 
     def __init__(self, context, session, address):
         super(IOPubChannel, self).__init__(context, session, address)
         self.ioloop = ioloop.IOLoop()
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.SUB)
         self.socket.linger = 1000
         self.socket.setsockopt(zmq.SUBSCRIBE,b'')
         self.socket.setsockopt(zmq.IDENTITY, self.session.bsession)
         self.socket.connect(self.address)
         self.stream = zmqstream.ZMQStream(self.socket, self.ioloop)
         self.stream.on_recv(self._handle_recv)
         self._run_loop()
 
     def call_handlers(self, msg):
         """This method is called in the ioloop thread when a message arrives.
 
         Subclasses should override this method to handle incoming messages.
         It is important to remember that this method is called in the thread
         so that some logic must be done to ensure that the application leve
         handlers are called in the application thread.
         """
         raise NotImplementedError('call_handlers must be defined in a subclass.')
 
     def flush(self, timeout=1.0):
         """Immediately processes all pending messages on the iopub channel.
 
         Callers should use this method to ensure that :meth:`call_handlers`
         has been called for all messages that have been received on the
         0MQ SUB socket of this channel.
 
         This method is thread safe.
 
         Parameters
         ----------
         timeout : float, optional
             The maximum amount of time to spend flushing, in seconds. The
             default is one second.
         """
         # We do the IOLoop callback process twice to ensure that the IOLoop
         # gets to perform at least one full poll.
         stop_time = time.time() + timeout
         for i in range(2):
             self._flushed = False
             self.ioloop.add_callback(self._flush)
             while not self._flushed and time.time() < stop_time:
                 time.sleep(0.01)
 
     def _flush(self):
         """Callback for :method:`self.flush`."""
         self.stream.flush()
         self._flushed = True
 
 
 class StdInChannel(ZMQSocketChannel):
     """The stdin channel to handle raw_input requests that the kernel makes."""
 
     msg_queue = None
     proxy_methods = ['input']
 
     def __init__(self, context, session, address):
         super(StdInChannel, self).__init__(context, session, address)
         self.ioloop = ioloop.IOLoop()
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.DEALER)
         self.socket.linger = 1000
         self.socket.setsockopt(zmq.IDENTITY, self.session.bsession)
         self.socket.connect(self.address)
         self.stream = zmqstream.ZMQStream(self.socket, self.ioloop)
         self.stream.on_recv(self._handle_recv)
         self._run_loop()
 
     def call_handlers(self, msg):
         """This method is called in the ioloop thread when a message arrives.
 
         Subclasses should override this method to handle incoming messages.
         It is important to remember that this method is called in the thread
         so that some logic must be done to ensure that the application leve
         handlers are called in the application thread.
         """
         raise NotImplementedError('call_handlers must be defined in a subclass.')
 
     def input(self, string):
         """Send a string of raw input to the kernel."""
         content = dict(value=string)
         msg = self.session.msg('input_reply', content)
         self._queue_send(msg)
 
 
 class HBChannel(ZMQSocketChannel):
     """The heartbeat channel which monitors the kernel heartbeat.
 
     Note that the heartbeat channel is paused by default. As long as you start
     this channel, the kernel manager will ensure that it is paused and un-paused
     as appropriate.
     """
 
     time_to_dead = 3.0
     socket = None
     poller = None
     _running = None
     _pause = None
     _beating = None
 
     def __init__(self, context, session, address):
         super(HBChannel, self).__init__(context, session, address)
         self._running = False
         self._pause =True
         self.poller = zmq.Poller()
 
     def _create_socket(self):
         if self.socket is not None:
             # close previous socket, before opening a new one
             self.poller.unregister(self.socket)
             self.socket.close()
         self.socket = self.context.socket(zmq.REQ)
         self.socket.linger = 1000
         self.socket.connect(self.address)
 
         self.poller.register(self.socket, zmq.POLLIN)
 
     def _poll(self, start_time):
         """poll for heartbeat replies until we reach self.time_to_dead.
 
         Ignores interrupts, and returns the result of poll(), which
         will be an empty list if no messages arrived before the timeout,
         or the event tuple if there is a message to receive.
         """
 
         until_dead = self.time_to_dead - (time.time() - start_time)
         # ensure poll at least once
         until_dead = max(until_dead, 1e-3)
         events = []
         while True:
             try:
                 events = self.poller.poll(1000 * until_dead)
             except ZMQError as e:
                 if e.errno == errno.EINTR:
                     # ignore interrupts during heartbeat
                     # this may never actually happen
                     until_dead = self.time_to_dead - (time.time() - start_time)
                     until_dead = max(until_dead, 1e-3)
                     pass
                 else:
                     raise
             except Exception:
                 if self._exiting:
                     break
                 else:
                     raise
             else:
                 break
         return events
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self._create_socket()
         self._running = True
         self._beating = True
 
         while self._running:
             if self._pause:
                 # just sleep, and skip the rest of the loop
                 time.sleep(self.time_to_dead)
                 continue
 
             since_last_heartbeat = 0.0
             # io.rprint('Ping from HB channel') # dbg
             # no need to catch EFSM here, because the previous event was
             # either a recv or connect, which cannot be followed by EFSM
             self.socket.send(b'ping')
             request_time = time.time()
             ready = self._poll(request_time)
             if ready:
                 self._beating = True
                 # the poll above guarantees we have something to recv
                 self.socket.recv()
                 # sleep the remainder of the cycle
                 remainder = self.time_to_dead - (time.time() - request_time)
                 if remainder > 0:
                     time.sleep(remainder)
                 continue
             else:
                 # nothing was received within the time limit, signal heart failure
                 self._beating = False
                 since_last_heartbeat = time.time() - request_time
                 self.call_handlers(since_last_heartbeat)
                 # and close/reopen the socket, because the REQ/REP cycle has been broken
                 self._create_socket()
                 continue
 
     def pause(self):
         """Pause the heartbeat."""
         self._pause = True
 
     def unpause(self):
         """Unpause the heartbeat."""
         self._pause = False
 
     def is_beating(self):
         """Is the heartbeat running and responsive (and not paused)."""
         if self.is_alive() and not self._pause and self._beating:
             return True
         else:
             return False
 
     def stop(self):
         """Stop the channel's event loop and join its thread."""
         self._running = False
         super(HBChannel, self).stop()
 
     def call_handlers(self, since_last_heartbeat):
         """This method is called in the ioloop thread when a message arrives.
 
         Subclasses should override this method to handle incoming messages.
         It is important to remember that this method is called in the thread
         so that some logic must be done to ensure that the application level
         handlers are called in the application thread.
         """
         raise NotImplementedError('call_handlers must be defined in a subclass.')
 
 
 #---------------------------------------------------------------------#-----------------------------------------------------------------------------
 # ABC Registration
 #-----------------------------------------------------------------------------
 
 ShellChannelABC.register(ShellChannel)
 IOPubChannelABC.register(IOPubChannel)
 HBChannelABC.register(HBChannel)
 StdInChannelABC.register(StdInChannel)

IPython/kernel/tests/test_message_spec.py

@@ -1,409 +1,420 b''
 """Test suite for our zeromq-based message specification."""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import re
 from distutils.version import LooseVersion as V
 from subprocess import PIPE
 try:
     from queue import Empty  # Py 3
 except ImportError:
     from Queue import Empty  # Py 2
 
 import nose.tools as nt
 
 from IPython.kernel import KernelManager
 
 from IPython.utils.traitlets import (
     HasTraits, TraitError, Bool, Unicode, Dict, Integer, List, Enum, Any,
 )
 from IPython.utils.py3compat import string_types, iteritems
 
 from .utils import TIMEOUT, start_global_kernel, flush_channels, execute
 
 #-----------------------------------------------------------------------------
 # Globals
 #-----------------------------------------------------------------------------
 KC = None
 
 def setup():
     global KC
     KC = start_global_kernel()
 
 #-----------------------------------------------------------------------------
 # Message Spec References
 #-----------------------------------------------------------------------------
 
 class Reference(HasTraits):
 
     """
     Base class for message spec specification testing.
 
     This class is the core of the message specification test.  The
     idea is that child classes implement trait attributes for each
     message keys, so that message keys can be tested against these
     traits using :meth:`check` method.
 
     """
 
     def check(self, d):
         """validate a dict against our traits"""
         for key in self.trait_names():
             nt.assert_in(key, d)
             # FIXME: always allow None, probably not a good idea
             if d[key] is None:
                 continue
             try:
                 setattr(self, key, d[key])
             except TraitError as e:
                 assert False, str(e)
 
 
 class Version(Unicode):
     def __init__(self, *args, **kwargs):
         self.min = kwargs.pop('min', None)
         self.max = kwargs.pop('max', None)
         kwargs['default_value'] = self.min
         super(Version, self).__init__(*args, **kwargs)
     
     def validate(self, obj, value):
         if self.min and V(value) < V(self.min):
             raise TraitError("bad version: %s < %s" % (value, self.min))
         if self.max and (V(value) > V(self.max)):
             raise TraitError("bad version: %s > %s" % (value, self.max))
 
 
 class RMessage(Reference):
     msg_id = Unicode()
     msg_type = Unicode()
     header = Dict()
     parent_header = Dict()
     content = Dict()
     
     def check(self, d):
         super(RMessage, self).check(d)
         RHeader().check(self.header)
         if self.parent_header:
             RHeader().check(self.parent_header)
 
 class RHeader(Reference):
     msg_id = Unicode()
     msg_type = Unicode()
     session = Unicode()
     username = Unicode()
     version = Version(min='5.0')
 
 mime_pat = re.compile(r'^[\w\-\+\.]+/[\w\-\+\.]+$')
 
 class MimeBundle(Reference):
     metadata = Dict()
     data = Dict()
     def _data_changed(self, name, old, new):
         for k,v in iteritems(new):
             assert mime_pat.match(k)
             nt.assert_is_instance(v, string_types)
 
 # shell replies
 
 class ExecuteReply(Reference):
     execution_count = Integer()
     status = Enum((u'ok', u'error'))
     
     def check(self, d):
         Reference.check(self, d)
         if d['status'] == 'ok':
             ExecuteReplyOkay().check(d)
         elif d['status'] == 'error':
             ExecuteReplyError().check(d)
 
 
 class ExecuteReplyOkay(Reference):
     payload = List(Dict)
     user_expressions = Dict()
 
 
 class ExecuteReplyError(Reference):
     ename = Unicode()
     evalue = Unicode()
     traceback = List(Unicode)
 
 
 class InspectReply(MimeBundle):
     found = Bool()
 
 
 class ArgSpec(Reference):
     args = List(Unicode)
     varargs = Unicode()
     varkw = Unicode()
     defaults = List()
 
 
 class Status(Reference):
     execution_state = Enum((u'busy', u'idle', u'starting'))
 
 
 class CompleteReply(Reference):
     matches = List(Unicode)
     cursor_start = Integer()
     cursor_end = Integer()
     status = Unicode()
 
 
 class KernelInfoReply(Reference):
     protocol_version = Version(min='5.0')
     implementation = Unicode('ipython')
     implementation_version = Version(min='2.1')
     language_version = Version(min='2.7')
     language = Unicode('python')
     banner = Unicode()
 
 
+class IsCompleteReply(Reference):
+    complete = Bool()
+
+
 # IOPub messages
 
 class ExecuteInput(Reference):
     code = Unicode()
     execution_count = Integer()
 
 
 Error = ExecuteReplyError
 
 
 class Stream(Reference):
     name = Enum((u'stdout', u'stderr'))
     data = Unicode()
 
 
 class DisplayData(MimeBundle):
     pass
 
 
 class ExecuteResult(MimeBundle):
     execution_count = Integer()
 
 
 references = {
     'execute_reply' : ExecuteReply(),
     'inspect_reply' : InspectReply(),
     'status' : Status(),
     'complete_reply' : CompleteReply(),
     'kernel_info_reply': KernelInfoReply(),
+    'is_complete_reply': IsCompleteReply(),
     'execute_input' : ExecuteInput(),
     'execute_result' : ExecuteResult(),
     'error' : Error(),
     'stream' : Stream(),
     'display_data' : DisplayData(),
     'header' : RHeader(),
 }
 """
 Specifications of `content` part of the reply messages.
 """
 
 
 def validate_message(msg, msg_type=None, parent=None):
     """validate a message
     
     This is a generator, and must be iterated through to actually
     trigger each test.
     
     If msg_type and/or parent are given, the msg_type and/or parent msg_id
     are compared with the given values.
     """
     RMessage().check(msg)
     if msg_type:
         nt.assert_equal(msg['msg_type'], msg_type)
     if parent:
         nt.assert_equal(msg['parent_header']['msg_id'], parent)
     content = msg['content']
     ref = references[msg['msg_type']]
     ref.check(content)
 
 
 #-----------------------------------------------------------------------------
 # Tests
 #-----------------------------------------------------------------------------
 
 # Shell channel
 
 def test_execute():
     flush_channels()
     
     msg_id = KC.execute(code='x=1')
     reply = KC.get_shell_msg(timeout=TIMEOUT)
     validate_message(reply, 'execute_reply', msg_id)
 
 
 def test_execute_silent():
     flush_channels()
     msg_id, reply = execute(code='x=1', silent=True)
     
     # flush status=idle
     status = KC.iopub_channel.get_msg(timeout=TIMEOUT)
     validate_message(status, 'status', msg_id)
     nt.assert_equal(status['content']['execution_state'], 'idle')
 
     nt.assert_raises(Empty, KC.iopub_channel.get_msg, timeout=0.1)
     count = reply['execution_count']
     
     msg_id, reply = execute(code='x=2', silent=True)
     
     # flush status=idle
     status = KC.iopub_channel.get_msg(timeout=TIMEOUT)
     validate_message(status, 'status', msg_id)
     nt.assert_equal(status['content']['execution_state'], 'idle')
     
     nt.assert_raises(Empty, KC.iopub_channel.get_msg, timeout=0.1)
     count_2 = reply['execution_count']
     nt.assert_equal(count_2, count)
 
 
 def test_execute_error():
     flush_channels()
     
     msg_id, reply = execute(code='1/0')
     nt.assert_equal(reply['status'], 'error')
     nt.assert_equal(reply['ename'], 'ZeroDivisionError')
     
     error = KC.iopub_channel.get_msg(timeout=TIMEOUT)
     validate_message(error, 'error', msg_id)
 
 
 def test_execute_inc():
     """execute request should increment execution_count"""
     flush_channels()
 
     msg_id, reply = execute(code='x=1')
     count = reply['execution_count']
     
     flush_channels()
     
     msg_id, reply = execute(code='x=2')
     count_2 = reply['execution_count']
     nt.assert_equal(count_2, count+1)
 
 
 def test_user_expressions():
     flush_channels()
 
     msg_id, reply = execute(code='x=1', user_expressions=dict(foo='x+1'))
     user_expressions = reply['user_expressions']
     nt.assert_equal(user_expressions, {u'foo': {
         u'status': u'ok',
         u'data': {u'text/plain': u'2'},
         u'metadata': {},
     }})
 
 
 def test_user_expressions_fail():
     flush_channels()
 
     msg_id, reply = execute(code='x=0', user_expressions=dict(foo='nosuchname'))
     user_expressions = reply['user_expressions']
     foo = user_expressions['foo']
     nt.assert_equal(foo['status'], 'error')
     nt.assert_equal(foo['ename'], 'NameError')
 
 
 def test_oinfo():
     flush_channels()
 
     msg_id = KC.inspect('a')
     reply = KC.get_shell_msg(timeout=TIMEOUT)
     validate_message(reply, 'inspect_reply', msg_id)
 
 
 def test_oinfo_found():
     flush_channels()
 
     msg_id, reply = execute(code='a=5')
     
     msg_id = KC.inspect('a')
     reply = KC.get_shell_msg(timeout=TIMEOUT)
     validate_message(reply, 'inspect_reply', msg_id)
     content = reply['content']
     assert content['found']
     text = content['data']['text/plain']
     nt.assert_in('Type:', text)
     nt.assert_in('Docstring:', text)
 
 
 def test_oinfo_detail():
     flush_channels()
 
     msg_id, reply = execute(code='ip=get_ipython()')
     
     msg_id = KC.inspect('ip.object_inspect', cursor_pos=10, detail_level=1)
     reply = KC.get_shell_msg(timeout=TIMEOUT)
     validate_message(reply, 'inspect_reply', msg_id)
     content = reply['content']
     assert content['found']
     text = content['data']['text/plain']
     nt.assert_in('Definition:', text)
     nt.assert_in('Source:', text)
 
 
 def test_oinfo_not_found():
     flush_channels()
 
     msg_id = KC.inspect('dne')
     reply = KC.get_shell_msg(timeout=TIMEOUT)
     validate_message(reply, 'inspect_reply', msg_id)
     content = reply['content']
     nt.assert_false(content['found'])
 
 
 def test_complete():
     flush_channels()
 
     msg_id, reply = execute(code="alpha = albert = 5")
     
     msg_id = KC.complete('al', 2)
     reply = KC.get_shell_msg(timeout=TIMEOUT)
     validate_message(reply, 'complete_reply', msg_id)
     matches = reply['content']['matches']
     for name in ('alpha', 'albert'):
         nt.assert_in(name, matches)
 
 
 def test_kernel_info_request():
     flush_channels()
 
     msg_id = KC.kernel_info()
     reply = KC.get_shell_msg(timeout=TIMEOUT)
     validate_message(reply, 'kernel_info_reply', msg_id)
 
 
 def test_single_payload():
     flush_channels()
     msg_id, reply = execute(code="for i in range(3):\n"+
                                  "   x=range?\n")
     payload = reply['payload']
     next_input_pls = [pl for pl in payload if pl["source"] == "set_next_input"]
     nt.assert_equal(len(next_input_pls), 1)
 
+def test_is_complete():
+    flush_channels()
+    
+    msg_id = KC.is_complete("a = 1")
+    reply = KC.get_shell_msg(timeout=TIMEOUT)
+    validate_message(reply, 'is_complete_reply', msg_id)
 
 # IOPub channel
 
 
 def test_stream():
     flush_channels()
 
     msg_id, reply = execute("print('hi')")
 
     stdout = KC.iopub_channel.get_msg(timeout=TIMEOUT)
     validate_message(stdout, 'stream', msg_id)
     content = stdout['content']
     nt.assert_equal(content['data'], u'hi\n')
 
 
 def test_display_data():
     flush_channels()
 
     msg_id, reply = execute("from IPython.core.display import display; display(1)")
     
     display = KC.iopub_channel.get_msg(timeout=TIMEOUT)
     validate_message(display, 'display_data', parent=msg_id)
     data = display['content']['data']
     nt.assert_equal(data['text/plain'], u'1')
 

IPython/kernel/zmq/kernelbase.py

@@ -1,677 +1,693 b''
 """Base class for a kernel that talks to frontends over 0MQ."""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 from __future__ import print_function
 
 import sys
 import time
 import logging
 import uuid
 
 from datetime import datetime
 from signal import (
         signal, default_int_handler, SIGINT
 )
 
 import zmq
 from zmq.eventloop import ioloop
 from zmq.eventloop.zmqstream import ZMQStream
 
 from IPython.config.configurable import Configurable
 from IPython.core.error import StdinNotImplementedError
 from IPython.core import release
 from IPython.utils import py3compat
 from IPython.utils.py3compat import unicode_type, string_types
 from IPython.utils.jsonutil import json_clean
 from IPython.utils.traitlets import (
     Any, Instance, Float, Dict, List, Set, Integer, Unicode, Bool,
 )
 
 from .session import Session
 
 
 class Kernel(Configurable):
 
     #---------------------------------------------------------------------------
     # Kernel interface
     #---------------------------------------------------------------------------
 
     # attribute to override with a GUI
     eventloop = Any(None)
     def _eventloop_changed(self, name, old, new):
         """schedule call to eventloop from IOLoop"""
         loop = ioloop.IOLoop.instance()
         loop.add_callback(self.enter_eventloop)
 
     session = Instance(Session)
     profile_dir = Instance('IPython.core.profiledir.ProfileDir')
     shell_streams = List()
     control_stream = Instance(ZMQStream)
     iopub_socket = Instance(zmq.Socket)
     stdin_socket = Instance(zmq.Socket)
     log = Instance(logging.Logger)
 
     # identities:
     int_id = Integer(-1)
     ident = Unicode()
 
     def _ident_default(self):
         return unicode_type(uuid.uuid4())
 
     # Private interface
     
     _darwin_app_nap = Bool(True, config=True,
         help="""Whether to use appnope for compatiblity with OS X App Nap.
         
         Only affects OS X >= 10.9.
         """
     )
 
     # track associations with current request
     _allow_stdin = Bool(False)
     _parent_header = Dict()
     _parent_ident = Any(b'')
     # Time to sleep after flushing the stdout/err buffers in each execute
     # cycle.  While this introduces a hard limit on the minimal latency of the
     # execute cycle, it helps prevent output synchronization problems for
     # clients.
     # Units are in seconds.  The minimum zmq latency on local host is probably
     # ~150 microseconds, set this to 500us for now.  We may need to increase it
     # a little if it's not enough after more interactive testing.
     _execute_sleep = Float(0.0005, config=True)
 
     # Frequency of the kernel's event loop.
     # Units are in seconds, kernel subclasses for GUI toolkits may need to
     # adapt to milliseconds.
     _poll_interval = Float(0.05, config=True)
 
     # If the shutdown was requested over the network, we leave here the
     # necessary reply message so it can be sent by our registered atexit
     # handler.  This ensures that the reply is only sent to clients truly at
     # the end of our shutdown process (which happens after the underlying
     # IPython shell's own shutdown).
     _shutdown_message = None
 
     # This is a dict of port number that the kernel is listening on. It is set
     # by record_ports and used by connect_request.
     _recorded_ports = Dict()
 
     # set of aborted msg_ids
     aborted = Set()
 
     # Track execution count here. For IPython, we override this to use the
     # execution count we store in the shell.
     execution_count = 0
 
 
     def __init__(self, **kwargs):
         super(Kernel, self).__init__(**kwargs)
 
         # Build dict of handlers for message types
         msg_types = [ 'execute_request', 'complete_request',
                       'inspect_request', 'history_request',
                       'kernel_info_request',
                       'connect_request', 'shutdown_request',
-                      'apply_request',
+                      'apply_request', 'is_complete_request',
                     ]
         self.shell_handlers = {}
         for msg_type in msg_types:
             self.shell_handlers[msg_type] = getattr(self, msg_type)
         
         control_msg_types = msg_types + [ 'clear_request', 'abort_request' ]
         self.control_handlers = {}
         for msg_type in control_msg_types:
             self.control_handlers[msg_type] = getattr(self, msg_type)
 
     
     def dispatch_control(self, msg):
         """dispatch control requests"""
         idents,msg = self.session.feed_identities(msg, copy=False)
         try:
             msg = self.session.unserialize(msg, content=True, copy=False)
         except:
             self.log.error("Invalid Control Message", exc_info=True)
             return
 
         self.log.debug("Control received: %s", msg)
         
         # Set the parent message for side effects.
         self.set_parent(idents, msg)
         self._publish_status(u'busy')
         
         header = msg['header']
         msg_type = header['msg_type']
 
         handler = self.control_handlers.get(msg_type, None)
         if handler is None:
             self.log.error("UNKNOWN CONTROL MESSAGE TYPE: %r", msg_type)
         else:
             try:
                 handler(self.control_stream, idents, msg)
             except Exception:
                 self.log.error("Exception in control handler:", exc_info=True)
         
         sys.stdout.flush()
         sys.stderr.flush()
         self._publish_status(u'idle')
     
     def dispatch_shell(self, stream, msg):
         """dispatch shell requests"""
         # flush control requests first
         if self.control_stream:
             self.control_stream.flush()
         
         idents,msg = self.session.feed_identities(msg, copy=False)
         try:
             msg = self.session.unserialize(msg, content=True, copy=False)
         except:
             self.log.error("Invalid Message", exc_info=True)
             return
 
         # Set the parent message for side effects.
         self.set_parent(idents, msg)
         self._publish_status(u'busy')
         
         header = msg['header']
         msg_id = header['msg_id']
         msg_type = msg['header']['msg_type']
         
         # Print some info about this message and leave a '--->' marker, so it's
         # easier to trace visually the message chain when debugging.  Each
         # handler prints its message at the end.
         self.log.debug('\n*** MESSAGE TYPE:%s***', msg_type)
         self.log.debug('   Content: %s\n   --->\n   ', msg['content'])
 
         if msg_id in self.aborted:
             self.aborted.remove(msg_id)
             # is it safe to assume a msg_id will not be resubmitted?
             reply_type = msg_type.split('_')[0] + '_reply'
             status = {'status' : 'aborted'}
             md = {'engine' : self.ident}
             md.update(status)
             self.session.send(stream, reply_type, metadata=md,
                         content=status, parent=msg, ident=idents)
             return
         
         handler = self.shell_handlers.get(msg_type, None)
         if handler is None:
             self.log.error("UNKNOWN MESSAGE TYPE: %r", msg_type)
         else:
             # ensure default_int_handler during handler call
             sig = signal(SIGINT, default_int_handler)
             self.log.debug("%s: %s", msg_type, msg)
             try:
                 handler(stream, idents, msg)
             except Exception:
                 self.log.error("Exception in message handler:", exc_info=True)
             finally:
                 signal(SIGINT, sig)
         
         sys.stdout.flush()
         sys.stderr.flush()
         self._publish_status(u'idle')
     
     def enter_eventloop(self):
         """enter eventloop"""
         self.log.info("entering eventloop %s", self.eventloop)
         for stream in self.shell_streams:
             # flush any pending replies,
             # which may be skipped by entering the eventloop
             stream.flush(zmq.POLLOUT)
         # restore default_int_handler
         signal(SIGINT, default_int_handler)
         while self.eventloop is not None:
             try:
                 self.eventloop(self)
             except KeyboardInterrupt:
                 # Ctrl-C shouldn't crash the kernel
                 self.log.error("KeyboardInterrupt caught in kernel")
                 continue
             else:
                 # eventloop exited cleanly, this means we should stop (right?)
                 self.eventloop = None
                 break
         self.log.info("exiting eventloop")
 
     def start(self):
         """register dispatchers for streams"""
         if self.control_stream:
             self.control_stream.on_recv(self.dispatch_control, copy=False)
 
         def make_dispatcher(stream):
             def dispatcher(msg):
                 return self.dispatch_shell(stream, msg)
             return dispatcher
 
         for s in self.shell_streams:
             s.on_recv(make_dispatcher(s), copy=False)
 
         # publish idle status
         self._publish_status('starting')
     
     def do_one_iteration(self):
         """step eventloop just once"""
         if self.control_stream:
             self.control_stream.flush()
         for stream in self.shell_streams:
             # handle at most one request per iteration
             stream.flush(zmq.POLLIN, 1)
             stream.flush(zmq.POLLOUT)
 
 
     def record_ports(self, ports):
         """Record the ports that this kernel is using.
 
         The creator of the Kernel instance must call this methods if they
         want the :meth:`connect_request` method to return the port numbers.
         """
         self._recorded_ports = ports
 
     #---------------------------------------------------------------------------
     # Kernel request handlers
     #---------------------------------------------------------------------------
     
     def _make_metadata(self, other=None):
         """init metadata dict, for execute/apply_reply"""
         new_md = {
             'dependencies_met' : True,
             'engine' : self.ident,
             'started': datetime.now(),
         }
         if other:
             new_md.update(other)
         return new_md
     
     def _publish_execute_input(self, code, parent, execution_count):
         """Publish the code request on the iopub stream."""
 
         self.session.send(self.iopub_socket, u'execute_input',
                             {u'code':code, u'execution_count': execution_count},
                             parent=parent, ident=self._topic('execute_input')
         )
     
     def _publish_status(self, status, parent=None):
         """send status (busy/idle) on IOPub"""
         self.session.send(self.iopub_socket,
                           u'status',
                           {u'execution_state': status},
                           parent=parent or self._parent_header,
                           ident=self._topic('status'),
                           )
     
     def set_parent(self, ident, parent):
         """Set the current parent_header
         
         Side effects (IOPub messages) and replies are associated with
         the request that caused them via the parent_header.
         
         The parent identity is used to route input_request messages
         on the stdin channel.
         """
         self._parent_ident = ident
         self._parent_header = parent
     
     def send_response(self, stream, msg_or_type, content=None, ident=None,
              buffers=None, track=False, header=None, metadata=None):
         """Send a response to the message we're currently processing.
         
         This accepts all the parameters of :meth:`IPython.kernel.zmq.session.Session.send`
         except ``parent``.
         
         This relies on :meth:`set_parent` having been called for the current
         message.
         """
         return self.session.send(stream, msg_or_type, content, self._parent_header,
                                  ident, buffers, track, header, metadata)
     
     def execute_request(self, stream, ident, parent):
         """handle an execute_request"""
         
         try:
             content = parent[u'content']
             code = py3compat.cast_unicode_py2(content[u'code'])
             silent = content[u'silent']
             store_history = content.get(u'store_history', not silent)
             user_expressions = content.get('user_expressions', {})
             allow_stdin = content.get('allow_stdin', False)
         except:
             self.log.error("Got bad msg: ")
             self.log.error("%s", parent)
             return
         
         md = self._make_metadata(parent['metadata'])
         
         # Re-broadcast our input for the benefit of listening clients, and
         # start computing output
         if not silent:
             self.execution_count += 1
             self._publish_execute_input(code, parent, self.execution_count)
         
         reply_content = self.do_execute(code, silent, store_history,
                                         user_expressions, allow_stdin)
 
         # Flush output before sending the reply.
         sys.stdout.flush()
         sys.stderr.flush()
         # FIXME: on rare occasions, the flush doesn't seem to make it to the
         # clients... This seems to mitigate the problem, but we definitely need
         # to better understand what's going on.
         if self._execute_sleep:
             time.sleep(self._execute_sleep)
 
         # Send the reply.
         reply_content = json_clean(reply_content)
         
         md['status'] = reply_content['status']
         if reply_content['status'] == 'error' and \
                         reply_content['ename'] == 'UnmetDependency':
                 md['dependencies_met'] = False
 
         reply_msg = self.session.send(stream, u'execute_reply',
                                       reply_content, parent, metadata=md,
                                       ident=ident)
         
         self.log.debug("%s", reply_msg)
 
         if not silent and reply_msg['content']['status'] == u'error':
             self._abort_queues()
 
     def do_execute(self, code, silent, store_history=True,
                    user_experssions=None, allow_stdin=False):
         """Execute user code. Must be overridden by subclasses.
         """
         raise NotImplementedError
 
     def complete_request(self, stream, ident, parent):
         content = parent['content']
         code = content['code']
         cursor_pos = content['cursor_pos']
         
         matches = self.do_complete(code, cursor_pos)
         matches = json_clean(matches)
         completion_msg = self.session.send(stream, 'complete_reply',
                                            matches, parent, ident)
         self.log.debug("%s", completion_msg)
 
     def do_complete(self, code, cursor_pos):
         """Override in subclasses to find completions.
         """
         return {'matches' : [],
                 'cursor_end' : cursor_pos,
                 'cursor_start' : cursor_pos,
                 'metadata' : {},
                 'status' : 'ok'}
 
     def inspect_request(self, stream, ident, parent):
         content = parent['content']
         
         reply_content = self.do_inspect(content['code'], content['cursor_pos'],
                                         content.get('detail_level', 0))
         # Before we send this object over, we scrub it for JSON usage
         reply_content = json_clean(reply_content)
         msg = self.session.send(stream, 'inspect_reply',
                                 reply_content, parent, ident)
         self.log.debug("%s", msg)
 
     def do_inspect(self, code, cursor_pos, detail_level=0):
         """Override in subclasses to allow introspection.
         """
         return {'status': 'ok', 'data':{}, 'metadata':{}, 'found':False}
 
     def history_request(self, stream, ident, parent):
         content = parent['content']
 
         reply_content = self.do_history(**content)
 
         reply_content = json_clean(reply_content)
         msg = self.session.send(stream, 'history_reply',
                                 reply_content, parent, ident)
         self.log.debug("%s", msg)
 
     def do_history(self, hist_access_type, output, raw, session=None, start=None,
                    stop=None, n=None, pattern=None, unique=False):
         """Override in subclasses to access history.
         """
         return {'history': []}
 
     def connect_request(self, stream, ident, parent):
         if self._recorded_ports is not None:
             content = self._recorded_ports.copy()
         else:
             content = {}
         msg = self.session.send(stream, 'connect_reply',
                                 content, parent, ident)
         self.log.debug("%s", msg)
 
     @property
     def kernel_info(self):
         return {
             'protocol_version': release.kernel_protocol_version,
             'implementation': self.implementation,
             'implementation_version': self.implementation_version,
             'language': self.language,
             'language_version': self.language_version,
             'banner': self.banner,
         }
 
     def kernel_info_request(self, stream, ident, parent):
         msg = self.session.send(stream, 'kernel_info_reply',
                                 self.kernel_info, parent, ident)
         self.log.debug("%s", msg)
 
     def shutdown_request(self, stream, ident, parent):
         content = self.do_shutdown(parent['content']['restart'])
         self.session.send(stream, u'shutdown_reply', content, parent, ident=ident)
         # same content, but different msg_id for broadcasting on IOPub
         self._shutdown_message = self.session.msg(u'shutdown_reply',
                                                   content, parent
         )
 
         self._at_shutdown()
         # call sys.exit after a short delay
         loop = ioloop.IOLoop.instance()
         loop.add_timeout(time.time()+0.1, loop.stop)
 
     def do_shutdown(self, restart):
         """Override in subclasses to do things when the frontend shuts down the
         kernel.
         """
         return {'status': 'ok', 'restart': restart}
+    
+    def is_complete_request(self, stream, ident, parent):
+        content = parent['content']
+        code = content['code']
+        
+        reply_content = self.do_is_complete(code)
+        reply_content = json_clean(reply_content)
+        reply_msg = self.session.send(stream, 'is_complete_reply',
+                                           reply_content, parent, ident)
+        self.log.debug("%s", reply_msg)
+
+    def do_is_complete(self, code):
+        """Override in subclasses to find completions.
+        """
+        return {'complete' : True,
+                }
 
     #---------------------------------------------------------------------------
     # Engine methods
     #---------------------------------------------------------------------------
 
     def apply_request(self, stream, ident, parent):
         try:
             content = parent[u'content']
             bufs = parent[u'buffers']
             msg_id = parent['header']['msg_id']
         except:
             self.log.error("Got bad msg: %s", parent, exc_info=True)
             return
 
         md = self._make_metadata(parent['metadata'])
 
         reply_content, result_buf = self.do_apply(content, bufs, msg_id, md)
 
         # put 'ok'/'error' status in header, for scheduler introspection:
         md['status'] = reply_content['status']
 
         # flush i/o
         sys.stdout.flush()
         sys.stderr.flush()
         
         self.session.send(stream, u'apply_reply', reply_content,
                     parent=parent, ident=ident,buffers=result_buf, metadata=md)
 
     def do_apply(self, content, bufs, msg_id, reply_metadata):
         """Override in subclasses to support the IPython parallel framework.
         """
         raise NotImplementedError
 
     #---------------------------------------------------------------------------
     # Control messages
     #---------------------------------------------------------------------------
 
     def abort_request(self, stream, ident, parent):
         """abort a specifig msg by id"""
         msg_ids = parent['content'].get('msg_ids', None)
         if isinstance(msg_ids, string_types):
             msg_ids = [msg_ids]
         if not msg_ids:
             self.abort_queues()
         for mid in msg_ids:
             self.aborted.add(str(mid))
 
         content = dict(status='ok')
         reply_msg = self.session.send(stream, 'abort_reply', content=content,
                 parent=parent, ident=ident)
         self.log.debug("%s", reply_msg)
 
     def clear_request(self, stream, idents, parent):
         """Clear our namespace."""
         content = self.do_clear()
         self.session.send(stream, 'clear_reply', ident=idents, parent=parent,
                 content = content)
 
     def do_clear(self):
         """Override in subclasses to clear the namespace
         
         This is only required for IPython.parallel.
         """
         raise NotImplementedError
 
     #---------------------------------------------------------------------------
     # Protected interface
     #---------------------------------------------------------------------------
 
     def _topic(self, topic):
         """prefixed topic for IOPub messages"""
         if self.int_id >= 0:
             base = "engine.%i" % self.int_id
         else:
             base = "kernel.%s" % self.ident
         
         return py3compat.cast_bytes("%s.%s" % (base, topic))
     
     def _abort_queues(self):
         for stream in self.shell_streams:
             if stream:
                 self._abort_queue(stream)
 
     def _abort_queue(self, stream):
         poller = zmq.Poller()
         poller.register(stream.socket, zmq.POLLIN)
         while True:
             idents,msg = self.session.recv(stream, zmq.NOBLOCK, content=True)
             if msg is None:
                 return
 
             self.log.info("Aborting:")
             self.log.info("%s", msg)
             msg_type = msg['header']['msg_type']
             reply_type = msg_type.split('_')[0] + '_reply'
 
             status = {'status' : 'aborted'}
             md = {'engine' : self.ident}
             md.update(status)
             reply_msg = self.session.send(stream, reply_type, metadata=md,
                         content=status, parent=msg, ident=idents)
             self.log.debug("%s", reply_msg)
             # We need to wait a bit for requests to come in. This can probably
             # be set shorter for true asynchronous clients.
             poller.poll(50)
 
 
     def _no_raw_input(self):
         """Raise StdinNotImplentedError if active frontend doesn't support
         stdin."""
         raise StdinNotImplementedError("raw_input was called, but this "
                                        "frontend does not support stdin.") 
     
     def getpass(self, prompt=''):
         """Forward getpass to frontends
         
         Raises
         ------
         StdinNotImplentedError if active frontend doesn't support stdin.
         """
         if not self._allow_stdin:
             raise StdinNotImplementedError(
                 "getpass was called, but this frontend does not support input requests."
             )
         return self._input_request(prompt,
             self._parent_ident,
             self._parent_header,
             password=True,
         )
     
     def raw_input(self, prompt=''):
         """Forward raw_input to frontends
         
         Raises
         ------
         StdinNotImplentedError if active frontend doesn't support stdin.
         """
         if not self._allow_stdin:
             raise StdinNotImplementedError(
                 "raw_input was called, but this frontend does not support input requests."
             )
         return self._input_request(prompt,
             self._parent_ident,
             self._parent_header,
             password=False,
         )
     
     def _input_request(self, prompt, ident, parent, password=False):
         # Flush output before making the request.
         sys.stderr.flush()
         sys.stdout.flush()
         # flush the stdin socket, to purge stale replies
         while True:
             try:
                 self.stdin_socket.recv_multipart(zmq.NOBLOCK)
             except zmq.ZMQError as e:
                 if e.errno == zmq.EAGAIN:
                     break
                 else:
                     raise
         
         # Send the input request.
         content = json_clean(dict(prompt=prompt, password=password))
         self.session.send(self.stdin_socket, u'input_request', content, parent,
                           ident=ident)
 
         # Await a response.
         while True:
             try:
                 ident, reply = self.session.recv(self.stdin_socket, 0)
             except Exception:
                 self.log.warn("Invalid Message:", exc_info=True)
             except KeyboardInterrupt:
                 # re-raise KeyboardInterrupt, to truncate traceback
                 raise KeyboardInterrupt
             else:
                 break
         try:
             value = py3compat.unicode_to_str(reply['content']['value'])
         except:
             self.log.error("Bad input_reply: %s", parent)
             value = ''
         if value == '\x04':
             # EOF
             raise EOFError
         return value
 
     def _at_shutdown(self):
         """Actions taken at shutdown by the kernel, called by python's atexit.
         """
         # io.rprint("Kernel at_shutdown") # dbg
         if self._shutdown_message is not None:
             self.session.send(self.iopub_socket, self._shutdown_message, ident=self._topic('shutdown'))
             self.log.debug("%s", self._shutdown_message)
         [ s.flush(zmq.POLLOUT) for s in self.shell_streams ]