client.py

"""Implements a fully blocking kernel client.

Useful for test suites and blocking terminal interfaces.
"""
# Copyright (c) Jupyter Development Team.
# Distributed under the terms of the Modified BSD License.

from functools import partial
from getpass import getpass
from queue import Empty
import sys
import time

import zmq

from time import monotonic
from traitlets import Type
from jupyter_client.channels import HBChannel
from jupyter_client.client import KernelClient
from .channels import ZMQSocketChannel


def reqrep(meth, channel='shell'):
    def wrapped(self, *args, **kwargs):
        reply = kwargs.pop('reply', False)
        timeout = kwargs.pop('timeout', None)
        msg_id = meth(self, *args, **kwargs)
        if not reply:
            return msg_id

        return self._recv_reply(msg_id, timeout=timeout, channel=channel)

    if not meth.__doc__:
        # python -OO removes docstrings,
        # so don't bother building the wrapped docstring
        return wrapped

    basedoc, _ = meth.__doc__.split('Returns\n', 1)
    parts = [basedoc.strip()]
    if 'Parameters' not in basedoc:
        parts.append("""
        Parameters
        ----------
        """)
    parts.append("""
        reply: bool (default: False)
            Whether to wait for and return reply
        timeout: float or None (default: None)
            Timeout to use when waiting for a reply

        Returns
        -------
        msg_id: str
            The msg_id of the request sent, if reply=False (default)
        reply: dict
            The reply message for this request, if reply=True
    """)
    wrapped.__doc__ = '\n'.join(parts)
    return wrapped

class BlockingKernelClient(KernelClient):
    """A KernelClient with blocking APIs

    ``get_[channel]_msg()`` methods wait for and return messages on channels,
    raising :exc:`queue.Empty` if no message arrives within ``timeout`` seconds.
    """

    def wait_for_ready(self, timeout=None):
        """Waits for a response when a client is blocked

        - Sets future time for timeout
        - Blocks on shell channel until a message is received
        - Exit if the kernel has died
        - If client times out before receiving a message from the kernel, send RuntimeError
        - Flush the IOPub channel
        """
        if timeout is None:
            abs_timeout = float('inf')
        else:
            abs_timeout = time.time() + timeout

        from ..manager import KernelManager
        if not isinstance(self.parent, KernelManager):
            # This Client was not created by a KernelManager,
            # so wait for kernel to become responsive to heartbeats
            # before checking for kernel_info reply
            while not self.is_alive():
                if time.time() > abs_timeout:
                    raise RuntimeError("Kernel didn't respond to heartbeats in %d seconds and timed out" % timeout)
                time.sleep(0.2)

        # Wait for kernel info reply on shell channel
        while True:
            try:
                msg = self.shell_channel.get_msg(block=True, timeout=1)
            except Empty:
                pass
            else:
                if msg['msg_type'] == 'kernel_info_reply':
                    self._handle_kernel_info_reply(msg)
                    break

            if not self.is_alive():
                raise RuntimeError('Kernel died before replying to kernel_info')

            # Check if current time is ready check time plus timeout
            if time.time() > abs_timeout:
                raise RuntimeError("Kernel didn't respond in %d seconds" % timeout)

        # Flush IOPub channel
        while True:
            try:
                msg = self.iopub_channel.get_msg(block=True, timeout=0.2)
            except Empty:
                break

    # The classes to use for the various channels
    shell_channel_class = Type(ZMQSocketChannel)
    iopub_channel_class = Type(ZMQSocketChannel)
    stdin_channel_class = Type(ZMQSocketChannel)
    hb_channel_class = Type(HBChannel)
    control_channel_class = Type(ZMQSocketChannel)


    def _recv_reply(self, msg_id, timeout=None, channel='shell'):
        """Receive and return the reply for a given request"""
        if timeout is not None:
            deadline = monotonic() + timeout
        while True:
            if timeout is not None:
                timeout = max(0, deadline - monotonic())
            try:
                if channel == 'control':
                    reply = self.get_control_msg(timeout=timeout)
                else:
                    reply = self.get_shell_msg(timeout=timeout)
            except Empty:
                raise TimeoutError("Timeout waiting for reply")
            if reply['parent_header'].get('msg_id') != msg_id:
                # not my reply, someone may have forgotten to retrieve theirs
                continue
            return reply


    # replies come on the shell channel
    execute = reqrep(KernelClient.execute)
    history = reqrep(KernelClient.history)
    complete = reqrep(KernelClient.complete)
    inspect = reqrep(KernelClient.inspect)
    kernel_info = reqrep(KernelClient.kernel_info)
    comm_info = reqrep(KernelClient.comm_info)

    # replies come on the control channel
    shutdown = reqrep(KernelClient.shutdown, channel='control')


    def _stdin_hook_default(self, msg):
        """Handle an input request"""
        content = msg['content']
        if content.get('password', False):
            prompt = getpass
        elif sys.version_info < (3,):
            prompt = raw_input
        else:
            prompt = input

        try:
            raw_data = prompt(content["prompt"])
        except EOFError:
            # turn EOFError into EOF character
            raw_data = '\x04'
        except KeyboardInterrupt:
            sys.stdout.write('\n')
            return

        # only send stdin reply if there *was not* another request
        # or execution finished while we were reading.
        if not (self.stdin_channel.msg_ready() or self.shell_channel.msg_ready()):
            self.input(raw_data)

    def _output_hook_default(self, msg):
        """Default hook for redisplaying plain-text output"""
        msg_type = msg['header']['msg_type']
        content = msg['content']
        if msg_type == 'stream':
            stream = getattr(sys, content['name'])
            stream.write(content['text'])
        elif msg_type in ('display_data', 'execute_result'):
            sys.stdout.write(content['data'].get('text/plain', ''))
        elif msg_type == 'error':
            print('\n'.join(content['traceback']), file=sys.stderr)

    def _output_hook_kernel(self, session, socket, parent_header, msg):
        """Output hook when running inside an IPython kernel

        adds rich output support.
        """
        msg_type = msg['header']['msg_type']
        if msg_type in ('display_data', 'execute_result', 'error'):
            session.send(socket, msg_type, msg['content'], parent=parent_header)
        else:
            self._output_hook_default(msg)

    def execute_interactive(self, code, silent=False, store_history=True,
                 user_expressions=None, allow_stdin=None, stop_on_error=True,
                 timeout=None, output_hook=None, stdin_hook=None,
                ):
        """Execute code in the kernel interactively

        Output will be redisplayed, and stdin prompts will be relayed as well.
        If an IPython kernel is detected, rich output will be displayed.

        You can pass a custom output_hook callable that will be called
        with every IOPub message that is produced instead of the default redisplay.

        .. versionadded:: 5.0

        Parameters
        ----------
        code : str
            A string of code in the kernel's language.

        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.

        stop_on_error: bool, optional (default True)
            Flag whether to abort the execution queue, if an exception is encountered.

        timeout: float or None (default: None)
            Timeout to use when waiting for a reply

        output_hook: callable(msg)
            Function to be called with output messages.
            If not specified, output will be redisplayed.

        stdin_hook: callable(msg)
            Function to be called with stdin_request messages.
            If not specified, input/getpass will be called.

        Returns
        -------
        reply: dict
            The reply message for this request
        """
        if not self.iopub_channel.is_alive():
            raise RuntimeError("IOPub channel must be running to receive output")
        if allow_stdin is None:
            allow_stdin = self.allow_stdin
        if allow_stdin and not self.stdin_channel.is_alive():
            raise RuntimeError("stdin channel must be running to allow input")
        msg_id = self.execute(code,
                              silent=silent,
                              store_history=store_history,
                              user_expressions=user_expressions,
                              allow_stdin=allow_stdin,
                              stop_on_error=stop_on_error,
        )
        if stdin_hook is None:
            stdin_hook = self._stdin_hook_default
        if output_hook is None:
            # detect IPython kernel
            if 'IPython' in sys.modules:
                from IPython import get_ipython
                ip = get_ipython()
                in_kernel = getattr(ip, 'kernel', False)
                if in_kernel:
                    output_hook = partial(
                        self._output_hook_kernel,
                        ip.display_pub.session,
                        ip.display_pub.pub_socket,
                        ip.display_pub.parent_header,
                    )
        if output_hook is None:
            # default: redisplay plain-text outputs
            output_hook = self._output_hook_default

        # set deadline based on timeout
        if timeout is not None:
            deadline = monotonic() + timeout
        else:
            timeout_ms = None

        poller = zmq.Poller()
        iopub_socket = self.iopub_channel.socket
        poller.register(iopub_socket, zmq.POLLIN)
        if allow_stdin:
            stdin_socket = self.stdin_channel.socket
            poller.register(stdin_socket, zmq.POLLIN)
        else:
            stdin_socket = None

        # wait for output and redisplay it
        while True:
            if timeout is not None:
                timeout = max(0, deadline - monotonic())
                timeout_ms = 1e3 * timeout
            events = dict(poller.poll(timeout_ms))
            if not events:
                raise TimeoutError("Timeout waiting for output")
            if stdin_socket in events:
                req = self.stdin_channel.get_msg(timeout=0)
                stdin_hook(req)
                continue
            if iopub_socket not in events:
                continue

            msg = self.iopub_channel.get_msg(timeout=0)

            if msg['parent_header'].get('msg_id') != msg_id:
                # not from my request
                continue
            output_hook(msg)

            # stop on idle
            if msg['header']['msg_type'] == 'status' and \
            msg['content']['execution_state'] == 'idle':
                break

        # output is done, get the reply
        if timeout is not None:
            timeout = max(0, deadline - monotonic())
        return self._recv_reply(msg_id, timeout=timeout)