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Python

"""Base class to manage the interaction with a running kernel"""
# Copyright (c) Jupyter Development Team.
# Distributed under the terms of the Modified BSD License.
import asyncio
import inspect
import sys
import time
import typing as t
from functools import partial
from getpass import getpass
from queue import Empty
import zmq.asyncio
from traitlets import Any
from traitlets import Bool
from traitlets import Instance
from traitlets import Type
from .channelsabc import ChannelABC
from .channelsabc import HBChannelABC
from .clientabc import KernelClientABC
from .connect import ConnectionFileMixin
from .session import Session
from .utils import ensure_async
from jupyter_client.channels import major_protocol_version
# some utilities to validate message structure, these might get moved elsewhere
# if they prove to have more generic utility
def validate_string_dict(dct: t.Dict[str, str]) -> None:
"""Validate that the input is a dict with string keys and values.
Raises ValueError if not."""
for k, v in dct.items():
if not isinstance(k, str):
raise ValueError("key %r in dict must be a string" % k)
if not isinstance(v, str):
raise ValueError("value %r in dict must be a string" % v)
def reqrep(wrapped: t.Callable, meth: t.Callable, channel: str = "shell") -> t.Callable:
wrapped = wrapped(meth, 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 KernelClient(ConnectionFileMixin):
"""Communicates with a single kernel on any host via zmq channels.
There are five channels associated with each kernel:
* shell: for request/reply calls to the kernel.
* iopub: for the kernel to publish results to frontends.
* hb: for monitoring the kernel's heartbeat.
* stdin: for frontends to reply to raw_input calls in the kernel.
* control: for kernel management calls to the kernel.
The messages that can be sent on these channels are exposed as methods of the
client (KernelClient.execute, complete, history, etc.). These methods only
send the message, they don't wait for a reply. To get results, use e.g.
:meth:`get_shell_msg` to fetch messages from the shell channel.
"""
# The PyZMQ Context to use for communication with the kernel.
context = Instance(zmq.asyncio.Context)
_created_context = Bool(False)
def _context_default(self) -> zmq.asyncio.Context:
self._created_context = True
return zmq.asyncio.Context()
# The classes to use for the various channels
shell_channel_class = Type(ChannelABC)
iopub_channel_class = Type(ChannelABC)
stdin_channel_class = Type(ChannelABC)
hb_channel_class = Type(HBChannelABC)
control_channel_class = Type(ChannelABC)
# Protected traits
_shell_channel = Any()
_iopub_channel = Any()
_stdin_channel = Any()
_hb_channel = Any()
_control_channel = Any()
# flag for whether execute requests should be allowed to call raw_input:
allow_stdin: bool = True
def __del__(self):
"""Handle garbage collection. Destroy context if applicable."""
if self._created_context and self.context and not self.context.closed:
if self.channels_running:
if self.log:
self.log.warning("Could not destroy zmq context for %s", self)
else:
if self.log:
self.log.debug("Destroying zmq context for %s", self)
self.context.destroy()
try:
super_del = super().__del__
except AttributeError:
pass
else:
super_del()
# --------------------------------------------------------------------------
# Channel proxy methods
# --------------------------------------------------------------------------
async def _async_get_shell_msg(self, *args: t.Any, **kwargs: t.Any) -> t.Dict[str, t.Any]:
"""Get a message from the shell channel"""
return await self.shell_channel.get_msg(*args, **kwargs)
async def _async_get_iopub_msg(self, *args: t.Any, **kwargs: t.Any) -> t.Dict[str, t.Any]:
"""Get a message from the iopub channel"""
return await self.iopub_channel.get_msg(*args, **kwargs)
async def _async_get_stdin_msg(self, *args: t.Any, **kwargs: t.Any) -> t.Dict[str, t.Any]:
"""Get a message from the stdin channel"""
return await self.stdin_channel.get_msg(*args, **kwargs)
async def _async_get_control_msg(self, *args: t.Any, **kwargs: t.Any) -> t.Dict[str, t.Any]:
"""Get a message from the control channel"""
return await self.control_channel.get_msg(*args, **kwargs)
async def _async_wait_for_ready(self, timeout: t.Optional[float] = None) -> 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:
timeout = float("inf")
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 await ensure_async(self.is_alive()):
if time.time() > abs_timeout:
raise RuntimeError(
"Kernel didn't respond to heartbeats in %d seconds and timed out" % timeout
)
await asyncio.sleep(0.2)
# Wait for kernel info reply on shell channel
while True:
self.kernel_info()
try:
msg = await self.shell_channel.get_msg(timeout=1)
except Empty:
pass
else:
if msg["msg_type"] == "kernel_info_reply":
# Checking that IOPub is connected. If it is not connected, start over.
try:
await self.iopub_channel.get_msg(timeout=0.2)
except Empty:
pass
else:
self._handle_kernel_info_reply(msg)
break
if not await ensure_async(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 = await self.iopub_channel.get_msg(timeout=0.2)
except Empty:
break
async def _async_recv_reply(
self, msg_id: str, timeout: t.Optional[float] = None, channel: str = "shell"
) -> t.Dict[str, t.Any]:
"""Receive and return the reply for a given request"""
if timeout is not None:
deadline = time.monotonic() + timeout
while True:
if timeout is not None:
timeout = max(0, deadline - time.monotonic())
try:
if channel == "control":
reply = await self._async_get_control_msg(timeout=timeout)
else:
reply = await self._async_get_shell_msg(timeout=timeout)
except Empty as e:
raise TimeoutError("Timeout waiting for reply") from e
if reply["parent_header"].get("msg_id") != msg_id:
# not my reply, someone may have forgotten to retrieve theirs
continue
return reply
async def _stdin_hook_default(self, msg: t.Dict[str, t.Any]) -> None:
"""Handle an input request"""
content = msg["content"]
if content.get("password", False):
prompt = getpass
else:
prompt = input # type: ignore
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 (await self.stdin_channel.msg_ready() or await self.shell_channel.msg_ready()):
self.input(raw_data)
def _output_hook_default(self, msg: t.Dict[str, t.Any]) -> None:
"""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: Session,
socket: zmq.sugar.socket.Socket,
parent_header: t.Any,
msg: t.Dict[str, t.Any],
) -> None:
"""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)
# --------------------------------------------------------------------------
# Channel management methods
# --------------------------------------------------------------------------
def start_channels(
self,
shell: bool = True,
iopub: bool = True,
stdin: bool = True,
hb: bool = True,
control: bool = True,
) -> None:
"""Starts the channels for this kernel.
This will create the channels if they do not exist and then start
them (their activity runs in a thread). If port numbers of 0 are
being used (random ports) then you must first call
:meth:`start_kernel`. If the channels have been stopped and you
call this, :class:`RuntimeError` will be raised.
"""
if iopub:
self.iopub_channel.start()
if shell:
self.shell_channel.start()
if stdin:
self.stdin_channel.start()
self.allow_stdin = True
else:
self.allow_stdin = False
if hb:
self.hb_channel.start()
if control:
self.control_channel.start()
def stop_channels(self) -> None:
"""Stops all the running channels for this kernel.
This stops their event loops and joins their threads.
"""
if self.shell_channel.is_alive():
self.shell_channel.stop()
if self.iopub_channel.is_alive():
self.iopub_channel.stop()
if self.stdin_channel.is_alive():
self.stdin_channel.stop()
if self.hb_channel.is_alive():
self.hb_channel.stop()
if self.control_channel.is_alive():
self.control_channel.stop()
@property
def channels_running(self) -> bool:
"""Are any of the channels created and running?"""
return (
(self._shell_channel and self.shell_channel.is_alive())
or (self._iopub_channel and self.iopub_channel.is_alive())
or (self._stdin_channel and self.stdin_channel.is_alive())
or (self._hb_channel and self.hb_channel.is_alive())
or (self._control_channel and self.control_channel.is_alive())
)
ioloop = None # Overridden in subclasses that use pyzmq event loop
@property
def shell_channel(self) -> t.Any:
"""Get the shell channel object for this kernel."""
if self._shell_channel is None:
url = self._make_url("shell")
self.log.debug("connecting shell channel to %s", url)
socket = self.connect_shell(identity=self.session.bsession)
self._shell_channel = self.shell_channel_class(socket, self.session, self.ioloop)
return self._shell_channel
@property
def iopub_channel(self) -> t.Any:
"""Get the iopub channel object for this kernel."""
if self._iopub_channel is None:
url = self._make_url("iopub")
self.log.debug("connecting iopub channel to %s", url)
socket = self.connect_iopub()
self._iopub_channel = self.iopub_channel_class(socket, self.session, self.ioloop)
return self._iopub_channel
@property
def stdin_channel(self) -> t.Any:
"""Get the stdin channel object for this kernel."""
if self._stdin_channel is None:
url = self._make_url("stdin")
self.log.debug("connecting stdin channel to %s", url)
socket = self.connect_stdin(identity=self.session.bsession)
self._stdin_channel = self.stdin_channel_class(socket, self.session, self.ioloop)
return self._stdin_channel
@property
def hb_channel(self) -> t.Any:
"""Get the hb channel object for this kernel."""
if self._hb_channel is None:
url = self._make_url("hb")
self.log.debug("connecting heartbeat channel to %s", url)
self._hb_channel = self.hb_channel_class(self.context, self.session, url)
return self._hb_channel
@property
def control_channel(self) -> t.Any:
"""Get the control channel object for this kernel."""
if self._control_channel is None:
url = self._make_url("control")
self.log.debug("connecting control channel to %s", url)
socket = self.connect_control(identity=self.session.bsession)
self._control_channel = self.control_channel_class(socket, self.session, self.ioloop)
return self._control_channel
async def _async_is_alive(self) -> bool:
"""Is the kernel process still running?"""
from .manager import KernelManager
if isinstance(self.parent, KernelManager):
# This KernelClient was created by a KernelManager,
# we can ask the parent KernelManager:
return await ensure_async(self.parent.is_alive())
if self._hb_channel is not None:
# We don't have access to the KernelManager,
# so we use the heartbeat.
return self._hb_channel.is_beating()
# no heartbeat and not local, we can't tell if it's running,
# so naively return True
return True
async def _async_execute_interactive(
self,
code: str,
silent: bool = False,
store_history: bool = True,
user_expressions: t.Optional[t.Dict[str, t.Any]] = None,
allow_stdin: t.Optional[bool] = None,
stop_on_error: bool = True,
timeout: t.Optional[float] = None,
output_hook: t.Optional[t.Callable] = None,
stdin_hook: t.Optional[t.Callable] = None,
) -> t.Dict[str, t.Any]:
"""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 or awaitable 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 # type: ignore
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 = time.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 - time.monotonic())
timeout_ms = int(1000 * timeout)
events = dict(poller.poll(timeout_ms))
if not events:
raise TimeoutError("Timeout waiting for output")
if stdin_socket in events:
req = await self.stdin_channel.get_msg(timeout=0)
res = stdin_hook(req)
if inspect.isawaitable(res):
await res
continue
if iopub_socket not in events:
continue
msg = await 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 - time.monotonic())
return await self._async_recv_reply(msg_id, timeout=timeout)
# Methods to send specific messages on channels
def execute(
self,
code: str,
silent: bool = False,
store_history: bool = True,
user_expressions: t.Optional[t.Dict[str, t.Any]] = None,
allow_stdin: t.Optional[bool] = None,
stop_on_error: bool = True,
) -> str:
"""Execute code in the kernel.
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.
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, str):
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,
stop_on_error=stop_on_error,
)
msg = self.session.msg("execute_request", content)
self.shell_channel.send(msg)
return msg["header"]["msg_id"]
def complete(self, code: str, cursor_pos: t.Optional[int] = None) -> str:
"""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.shell_channel.send(msg)
return msg["header"]["msg_id"]
def inspect(self, code: str, cursor_pos: t.Optional[int] = None, detail_level: int = 0) -> str:
"""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.shell_channel.send(msg)
return msg["header"]["msg_id"]
def history(
self,
raw: bool = True,
output: bool = False,
hist_access_type: str = "range",
**kwargs: t.Any,
) -> str:
"""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 ID of the message sent.
"""
if hist_access_type == "range":
kwargs.setdefault("session", 0)
kwargs.setdefault("start", 0)
content = dict(raw=raw, output=output, hist_access_type=hist_access_type, **kwargs)
msg = self.session.msg("history_request", content)
self.shell_channel.send(msg)
return msg["header"]["msg_id"]
def kernel_info(self) -> str:
"""Request kernel info
Returns
-------
The msg_id of the message sent
"""
msg = self.session.msg("kernel_info_request")
self.shell_channel.send(msg)
return msg["header"]["msg_id"]
def comm_info(self, target_name: t.Optional[str] = None) -> str:
"""Request comm info
Returns
-------
The msg_id of the message sent
"""
if target_name is None:
content = {}
else:
content = dict(target_name=target_name)
msg = self.session.msg("comm_info_request", content)
self.shell_channel.send(msg)
return msg["header"]["msg_id"]
def _handle_kernel_info_reply(self, msg: t.Dict[str, t.Any]) -> None:
"""handle kernel info reply
sets protocol adaptation version. This might
be run from a separate thread.
"""
adapt_version = int(msg["content"]["protocol_version"].split(".")[0])
if adapt_version != major_protocol_version:
self.session.adapt_version = adapt_version
def is_complete(self, code: str) -> str:
"""Ask the kernel whether some code is complete and ready to execute."""
msg = self.session.msg("is_complete_request", {"code": code})
self.shell_channel.send(msg)
return msg["header"]["msg_id"]
def input(self, string: str) -> None:
"""Send a string of raw input to the kernel.
This should only be called in response to the kernel sending an
``input_request`` message on the stdin channel.
"""
content = dict(value=string)
msg = self.session.msg("input_reply", content)
self.stdin_channel.send(msg)
def shutdown(self, restart: bool = False) -> str:
"""Request an immediate kernel shutdown on the control channel.
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.
Returns
-------
The msg_id of the message sent
"""
# 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.control_channel.send(msg)
return msg["header"]["msg_id"]
KernelClientABC.register(KernelClient)