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@minrk @takluyver @willingc
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"""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 __future__ import print_function
from functools import partial
from getpass import getpass
try:
from queue import Empty # Python 3
except ImportError:
from Queue import Empty # Python 2
import sys
import time
import zmq
from traitlets import Type
from jupyter_client.channels import HBChannel
from jupyter_client.client import KernelClient
from .channels import ZMQSocketChannel
try:
monotonic = time.monotonic
except AttributeError:
# py2
monotonic = time.time # close enough
try:
TimeoutError
except NameError:
# py2
TimeoutError = RuntimeError
def reqrep(meth):
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)
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)
def _recv_reply(self, msg_id, timeout=None):
"""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:
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
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)
shutdown = reqrep(KernelClient.shutdown)
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)
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