Implement blocking channels without Python threads

IPython/kernel/blocking/channels.py

@@ -2,16 +2,12 b''
 
 Useful for test suites and blocking terminal interfaces.
 """
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2013 The IPython Development Team
-#
-#  Distributed under the terms of the BSD License.  The full license is in
-#  the file COPYING.txt, distributed as part of this software.
-#-----------------------------------------------------------------------------
 
-#-----------------------------------------------------------------------------
-# Imports
-#-----------------------------------------------------------------------------
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+import atexit
+import zmq
 
 try:
     from queue import Queue, Empty  # Py 3
@@ -19,29 +15,87 b' except ImportError:'
     from Queue import Queue, Empty  # Py 2
 
 from IPython.kernel.channels import IOPubChannel, HBChannel, \
-    ShellChannel, StdInChannel
+    ShellChannel, StdInChannel, InvalidPortNumber, major_protocol_version
+from IPython.utils.py3compat import string_types, iteritems
+
+# 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)
 
-#-----------------------------------------------------------------------------
-# Blocking kernel manager
-#-----------------------------------------------------------------------------
 
+class ZMQSocketChannel(object):
+    """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 = []
 
-class BlockingChannelMixin(object):
+    def __init__(self, context, session, address):
+        """Create a channel.
 
-    def __init__(self, *args, **kwds):
-        super(BlockingChannelMixin, self).__init__(*args, **kwds)
-        self._in_queue = Queue()
+        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
 
-    def call_handlers(self, msg):
-        self._in_queue.put(msg)
+        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
+
+    def _recv(self, **kwargs):
+        msg = self.socket.recv_multipart(**kwargs)
+        ident,smsg = self.session.feed_identities(msg)
+        return self.session.deserialize(smsg)
 
     def get_msg(self, block=True, timeout=None):
         """ Gets a message if there is one that is ready. """
-        if timeout is None:
-            # Queue.get(timeout=None) has stupid uninteruptible
-            # behavior, so wait for a week instead
-            timeout = 604800
-        return self._in_queue.get(block, timeout)
+        if block:
+            if timeout is not None:
+                timeout *= 1000  # seconds to ms
+            ready = self.socket.poll(timeout)
+        else:
+            ready = self.socket.poll(timeout=0)
+
+        if ready:
+            return self._recv()
+        else:
+            raise Empty
 
     def get_msgs(self):
         """ Get all messages that are currently ready. """
@@ -55,22 +109,274 b' class BlockingChannelMixin(object):'
 
     def msg_ready(self):
         """ Is there a message that has been received? """
-        return not self._in_queue.empty()
+        return bool(self.socket.poll(timeout=0))
+
+    def close(self):
+        if self.socket is not None:
+            try:
+                self.socket.close(linger=0)
+            except Exception:
+                pass
+            self.socket = None
+    stop =  close
+
+    def is_alive(self):
+        return (self.socket is not 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):
+        """Pass a message to the ZMQ socket to send
+        """
+        self.session.send(self.socket, msg)
+
+
+class BlockingShellChannel(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 start(self):
+        self.socket = self.context.socket(zmq.DEALER)
+        self.socket.linger = 1000
+        self.socket.setsockopt(zmq.IDENTITY, self.session.bsession)
+        self.socket.connect(self.address)
+
+    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
 
-class BlockingIOPubChannel(BlockingChannelMixin, IOPubChannel):
-    pass
 
+        # 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)
 
-class BlockingShellChannel(BlockingChannelMixin, ShellChannel):
-    def call_handlers(self, msg):
+        # 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']
+
+    def _recv(self, **kwargs):
+        # Listen for kernel_info_reply message to do protocol adaptation
+        msg = ZMQSocketChannel._recv(self, **kwargs)
         if msg['msg_type'] == 'kernel_info_reply':
             self._handle_kernel_info_reply(msg)
-        return super(BlockingShellChannel, self).call_handlers(msg)
+        return msg
+
+
+class BlockingIOPubChannel(ZMQSocketChannel):
+    """The iopub channel which listens for messages that the kernel publishes.
+
+    This channel is where all output is published to frontends.
+    """
+    def start(self):
+        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)
+
+
+class BlockingStdInChannel(ZMQSocketChannel):
+    """The stdin channel to handle raw_input requests that the kernel makes."""
+    msg_queue = None
+    proxy_methods = ['input']
 
+    def start(self):
+        self.socket = self.context.socket(zmq.DEALER)
+        self.socket.linger = 1000
+        self.socket.setsockopt(zmq.IDENTITY, self.session.bsession)
+        self.socket.connect(self.address)
 
-class BlockingStdInChannel(BlockingChannelMixin, StdInChannel):
-    pass
+    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 BlockingHBChannel(HBChannel):

IPython/kernel/inprocess/blocking.py

@@ -9,14 +9,15 b' Useful for test suites and blocking terminal interfaces.'
 #  the file COPYING.txt, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
-#-----------------------------------------------------------------------------
-# Imports
-#-----------------------------------------------------------------------------
+try:
+    from queue import Queue, Empty  # Py 3
+except ImportError:
+    from Queue import Queue, Empty  # Py 2
 
 # IPython imports
 from IPython.utils.io import raw_print
 from IPython.utils.traitlets import Type
-from IPython.kernel.blocking.channels import BlockingChannelMixin
+#from IPython.kernel.blocking.channels import BlockingChannelMixin
 
 # Local imports
 from .channels import (
@@ -26,9 +27,36 b' from .channels import ('
 )
 from .client import InProcessKernelClient
 
-#-----------------------------------------------------------------------------
-# Blocking kernel manager
-#-----------------------------------------------------------------------------
+class BlockingChannelMixin(object):
+
+    def __init__(self, *args, **kwds):
+        super(BlockingChannelMixin, self).__init__(*args, **kwds)
+        self._in_queue = Queue()
+
+    def call_handlers(self, msg):
+        self._in_queue.put(msg)
+
+    def get_msg(self, block=True, timeout=None):
+        """ Gets a message if there is one that is ready. """
+        if timeout is None:
+            # Queue.get(timeout=None) has stupid uninteruptible
+            # behavior, so wait for a week instead
+            timeout = 604800
+        return self._in_queue.get(block, timeout)
+
+    def get_msgs(self):
+        """ Get all messages that are currently ready. """
+        msgs = []
+        while True:
+            try:
+                msgs.append(self.get_msg(block=False))
+            except Empty:
+                break
+        return msgs
+
+    def msg_ready(self):
+        """ Is there a message that has been received? """
+        return not self._in_queue.empty()
 
 class BlockingInProcessShellChannel(BlockingChannelMixin, InProcessShellChannel):
     pass