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285 lines
8.3 KiB
Python
285 lines
8.3 KiB
Python
"""Default classes for Comm and CommManager, for usage in IPython.
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"""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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import uuid
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import logging
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import comm
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from traitlets.utils.importstring import import_item
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logger = logging.getLogger('Comm')
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class BaseComm:
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"""Class for communicating between a Frontend and a Kernel
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Must be subclassed with a publish_msg method implementation which
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sends comm messages through the iopub channel.
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"""
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def __init__(
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self,
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target_name="comm",
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data=None,
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metadata=None,
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buffers=None,
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comm_id=None,
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primary=True,
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target_module=None,
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topic=None,
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_open_data=None,
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_close_data=None,
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**kwargs,
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):
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super(BaseComm, self).__init__(**kwargs)
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self.comm_id = comm_id if comm_id else uuid.uuid4().hex
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self.primary = primary
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self.target_name = target_name
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self.target_module = target_module
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self.topic = topic if topic else ("comm-%s" % self.comm_id).encode("ascii")
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self._open_data = _open_data if _open_data else {}
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self._close_data = _close_data if _close_data else {}
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self._msg_callback = None
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self._close_callback = None
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self._closed = True
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if self.primary:
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# I am primary, open my peer.
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self.open(data=data, metadata=metadata, buffers=buffers)
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else:
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self._closed = False
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def publish_msg(self, msg_type, data=None, metadata=None, buffers=None, **keys):
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raise NotImplementedError("publish_msg Comm method is not implemented")
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def __del__(self):
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"""trigger close on gc"""
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self.close(deleting=True)
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# publishing messages
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def open(self, data=None, metadata=None, buffers=None):
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"""Open the frontend-side version of this comm"""
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if data is None:
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data = self._open_data
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comm_manager = comm.get_comm_manager()
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if comm_manager is None:
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raise RuntimeError("Comms cannot be opened without a comm_manager.")
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comm_manager.register_comm(self)
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try:
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self.publish_msg(
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"comm_open",
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data=data,
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metadata=metadata,
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buffers=buffers,
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target_name=self.target_name,
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target_module=self.target_module,
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)
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self._closed = False
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except Exception:
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comm_manager.unregister_comm(self)
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raise
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def close(self, data=None, metadata=None, buffers=None, deleting=False):
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"""Close the frontend-side version of this comm"""
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if self._closed:
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# only close once
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return
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self._closed = True
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if data is None:
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data = self._close_data
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self.publish_msg(
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"comm_close",
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data=data,
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metadata=metadata,
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buffers=buffers,
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)
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if not deleting:
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# If deleting, the comm can't be registered
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comm.get_comm_manager().unregister_comm(self)
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def send(self, data=None, metadata=None, buffers=None):
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"""Send a message to the frontend-side version of this comm"""
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self.publish_msg(
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"comm_msg",
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data=data,
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metadata=metadata,
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buffers=buffers,
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)
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# registering callbacks
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def on_close(self, callback):
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"""Register a callback for comm_close
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Will be called with the `data` of the close message.
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Call `on_close(None)` to disable an existing callback.
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"""
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self._close_callback = callback
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def on_msg(self, callback):
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"""Register a callback for comm_msg
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Will be called with the `data` of any comm_msg messages.
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Call `on_msg(None)` to disable an existing callback.
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"""
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self._msg_callback = callback
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# handling of incoming messages
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def handle_close(self, msg):
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"""Handle a comm_close message"""
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logger.debug("handle_close[%s](%s)", self.comm_id, msg)
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if self._close_callback:
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self._close_callback(msg)
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def handle_msg(self, msg):
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"""Handle a comm_msg message"""
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logger.debug("handle_msg[%s](%s)", self.comm_id, msg)
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if self._msg_callback:
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from IPython import get_ipython
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shell = get_ipython()
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if shell:
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shell.events.trigger("pre_execute")
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self._msg_callback(msg)
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if shell:
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shell.events.trigger("post_execute")
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class CommManager:
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"""Default CommManager singleton implementation for Comms in the Kernel"""
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# Public APIs
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def __init__(self):
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self.comms = {}
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self.targets = {}
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def register_target(self, target_name, f):
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"""Register a callable f for a given target name
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f will be called with two arguments when a comm_open message is received with `target`:
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- the Comm instance
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- the `comm_open` message itself.
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f can be a Python callable or an import string for one.
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"""
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if isinstance(f, str):
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f = import_item(f)
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self.targets[target_name] = f
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def unregister_target(self, target_name, f):
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"""Unregister a callable registered with register_target"""
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return self.targets.pop(target_name)
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def register_comm(self, comm):
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"""Register a new comm"""
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comm_id = comm.comm_id
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self.comms[comm_id] = comm
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return comm_id
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def unregister_comm(self, comm):
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"""Unregister a comm, and close its counterpart"""
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# unlike get_comm, this should raise a KeyError
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comm = self.comms.pop(comm.comm_id)
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def get_comm(self, comm_id):
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"""Get a comm with a particular id
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Returns the comm if found, otherwise None.
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This will not raise an error,
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it will log messages if the comm cannot be found.
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"""
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try:
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return self.comms[comm_id]
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except KeyError:
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logger.warning("No such comm: %s", comm_id)
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if logger.isEnabledFor(logging.DEBUG):
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# don't create the list of keys if debug messages aren't enabled
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logger.debug("Current comms: %s", list(self.comms.keys()))
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# Message handlers
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def comm_open(self, stream, ident, msg):
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"""Handler for comm_open messages"""
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from comm import create_comm
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content = msg["content"]
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comm_id = content["comm_id"]
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target_name = content["target_name"]
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f = self.targets.get(target_name, None)
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comm = create_comm(
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comm_id=comm_id,
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primary=False,
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target_name=target_name,
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)
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self.register_comm(comm)
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if f is None:
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logger.error("No such comm target registered: %s", target_name)
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else:
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try:
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f(comm, msg)
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return
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except Exception:
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logger.error(
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"Exception opening comm with target: %s", target_name, exc_info=True
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)
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# Failure.
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try:
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comm.close()
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except Exception:
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logger.error(
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"""Could not close comm during `comm_open` failure
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clean-up. The comm may not have been opened yet.""",
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exc_info=True,
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)
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def comm_msg(self, stream, ident, msg):
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"""Handler for comm_msg messages"""
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content = msg["content"]
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comm_id = content["comm_id"]
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comm = self.get_comm(comm_id)
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if comm is None:
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return
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try:
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comm.handle_msg(msg)
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except Exception:
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logger.error("Exception in comm_msg for %s", comm_id, exc_info=True)
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def comm_close(self, stream, ident, msg):
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"""Handler for comm_close messages"""
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content = msg["content"]
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comm_id = content["comm_id"]
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comm = self.get_comm(comm_id)
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if comm is None:
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return
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self.comms[comm_id]._closed = True
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del self.comms[comm_id]
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try:
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comm.handle_close(msg)
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except Exception:
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logger.error("Exception in comm_close for %s", comm_id, exc_info=True)
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__all__ = ["CommManager", "BaseComm"]
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