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554 lines
19 KiB
554 lines
19 KiB
#
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# Copyright 2009 Facebook
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""A utility class to send to and recv from a non-blocking socket,
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using tornado.
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.. seealso::
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- :mod:`zmq.asyncio`
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- :mod:`zmq.eventloop.future`
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"""
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from __future__ import with_statement
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import sys
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import warnings
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import zmq
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from zmq.utils import jsonapi
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try:
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import cPickle as pickle
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except ImportError:
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import pickle
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from .ioloop import IOLoop, gen_log
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try:
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from tornado.stack_context import wrap as stack_context_wrap
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except ImportError:
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if "zmq.eventloop.minitornado" in sys.modules:
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from .minitornado.stack_context import wrap as stack_context_wrap
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else:
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# tornado 5 deprecates stack_context,
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# tornado 6 removes it
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def stack_context_wrap(callback):
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return callback
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try:
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from queue import Queue
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except ImportError:
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from Queue import Queue
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from zmq.utils.strtypes import basestring
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try:
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callable
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except NameError:
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callable = lambda obj: hasattr(obj, '__call__')
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class ZMQStream(object):
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"""A utility class to register callbacks when a zmq socket sends and receives
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For use with zmq.eventloop.ioloop
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There are three main methods
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Methods:
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* **on_recv(callback, copy=True):**
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register a callback to be run every time the socket has something to receive
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* **on_send(callback):**
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register a callback to be run every time you call send
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* **send(self, msg, flags=0, copy=False, callback=None):**
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perform a send that will trigger the callback
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if callback is passed, on_send is also called.
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There are also send_multipart(), send_json(), send_pyobj()
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Three other methods for deactivating the callbacks:
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* **stop_on_recv():**
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turn off the recv callback
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* **stop_on_send():**
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turn off the send callback
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which simply call ``on_<evt>(None)``.
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The entire socket interface, excluding direct recv methods, is also
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provided, primarily through direct-linking the methods.
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e.g.
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>>> stream.bind is stream.socket.bind
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True
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"""
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socket = None
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io_loop = None
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poller = None
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_send_queue = None
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_recv_callback = None
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_send_callback = None
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_close_callback = None
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_state = 0
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_flushed = False
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_recv_copy = False
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_fd = None
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def __init__(self, socket, io_loop=None):
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self.socket = socket
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self.io_loop = io_loop or IOLoop.current()
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self.poller = zmq.Poller()
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self._fd = self.socket.FD
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self._send_queue = Queue()
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self._recv_callback = None
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self._send_callback = None
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self._close_callback = None
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self._recv_copy = False
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self._flushed = False
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self._state = 0
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self._init_io_state()
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# shortcircuit some socket methods
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self.bind = self.socket.bind
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self.bind_to_random_port = self.socket.bind_to_random_port
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self.connect = self.socket.connect
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self.setsockopt = self.socket.setsockopt
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self.getsockopt = self.socket.getsockopt
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self.setsockopt_string = self.socket.setsockopt_string
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self.getsockopt_string = self.socket.getsockopt_string
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self.setsockopt_unicode = self.socket.setsockopt_unicode
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self.getsockopt_unicode = self.socket.getsockopt_unicode
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def stop_on_recv(self):
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"""Disable callback and automatic receiving."""
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return self.on_recv(None)
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def stop_on_send(self):
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"""Disable callback on sending."""
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return self.on_send(None)
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def stop_on_err(self):
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"""DEPRECATED, does nothing"""
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gen_log.warn("on_err does nothing, and will be removed")
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def on_err(self, callback):
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"""DEPRECATED, does nothing"""
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gen_log.warn("on_err does nothing, and will be removed")
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def on_recv(self, callback, copy=True):
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"""Register a callback for when a message is ready to recv.
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There can be only one callback registered at a time, so each
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call to `on_recv` replaces previously registered callbacks.
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on_recv(None) disables recv event polling.
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Use on_recv_stream(callback) instead, to register a callback that will receive
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both this ZMQStream and the message, instead of just the message.
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Parameters
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----------
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callback : callable
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callback must take exactly one argument, which will be a
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list, as returned by socket.recv_multipart()
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if callback is None, recv callbacks are disabled.
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copy : bool
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copy is passed directly to recv, so if copy is False,
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callback will receive Message objects. If copy is True,
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then callback will receive bytes/str objects.
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Returns : None
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"""
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self._check_closed()
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assert callback is None or callable(callback)
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self._recv_callback = stack_context_wrap(callback)
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self._recv_copy = copy
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if callback is None:
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self._drop_io_state(zmq.POLLIN)
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else:
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self._add_io_state(zmq.POLLIN)
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def on_recv_stream(self, callback, copy=True):
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"""Same as on_recv, but callback will get this stream as first argument
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callback must take exactly two arguments, as it will be called as::
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callback(stream, msg)
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Useful when a single callback should be used with multiple streams.
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"""
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if callback is None:
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self.stop_on_recv()
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else:
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self.on_recv(lambda msg: callback(self, msg), copy=copy)
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def on_send(self, callback):
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"""Register a callback to be called on each send
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There will be two arguments::
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callback(msg, status)
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* `msg` will be the list of sendable objects that was just sent
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* `status` will be the return result of socket.send_multipart(msg) -
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MessageTracker or None.
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Non-copying sends return a MessageTracker object whose
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`done` attribute will be True when the send is complete.
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This allows users to track when an object is safe to write to
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again.
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The second argument will always be None if copy=True
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on the send.
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Use on_send_stream(callback) to register a callback that will be passed
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this ZMQStream as the first argument, in addition to the other two.
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on_send(None) disables recv event polling.
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Parameters
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----------
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callback : callable
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callback must take exactly two arguments, which will be
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the message being sent (always a list),
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and the return result of socket.send_multipart(msg) -
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MessageTracker or None.
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if callback is None, send callbacks are disabled.
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"""
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self._check_closed()
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assert callback is None or callable(callback)
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self._send_callback = stack_context_wrap(callback)
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def on_send_stream(self, callback):
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"""Same as on_send, but callback will get this stream as first argument
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Callback will be passed three arguments::
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callback(stream, msg, status)
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Useful when a single callback should be used with multiple streams.
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"""
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if callback is None:
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self.stop_on_send()
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else:
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self.on_send(lambda msg, status: callback(self, msg, status))
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def send(self, msg, flags=0, copy=True, track=False, callback=None, **kwargs):
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"""Send a message, optionally also register a new callback for sends.
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See zmq.socket.send for details.
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"""
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return self.send_multipart([msg], flags=flags, copy=copy, track=track, callback=callback, **kwargs)
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def send_multipart(self, msg, flags=0, copy=True, track=False, callback=None, **kwargs):
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"""Send a multipart message, optionally also register a new callback for sends.
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See zmq.socket.send_multipart for details.
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"""
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kwargs.update(dict(flags=flags, copy=copy, track=track))
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self._send_queue.put((msg, kwargs))
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callback = callback or self._send_callback
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if callback is not None:
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self.on_send(callback)
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else:
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# noop callback
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self.on_send(lambda *args: None)
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self._add_io_state(zmq.POLLOUT)
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def send_string(self, u, flags=0, encoding='utf-8', callback=None, **kwargs):
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"""Send a unicode message with an encoding.
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See zmq.socket.send_unicode for details.
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"""
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if not isinstance(u, basestring):
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raise TypeError("unicode/str objects only")
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return self.send(u.encode(encoding), flags=flags, callback=callback, **kwargs)
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send_unicode = send_string
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def send_json(self, obj, flags=0, callback=None, **kwargs):
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"""Send json-serialized version of an object.
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See zmq.socket.send_json for details.
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"""
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if jsonapi is None:
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raise ImportError('jsonlib{1,2}, json or simplejson library is required.')
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else:
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msg = jsonapi.dumps(obj)
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return self.send(msg, flags=flags, callback=callback, **kwargs)
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def send_pyobj(self, obj, flags=0, protocol=-1, callback=None, **kwargs):
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"""Send a Python object as a message using pickle to serialize.
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See zmq.socket.send_json for details.
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"""
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msg = pickle.dumps(obj, protocol)
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return self.send(msg, flags, callback=callback, **kwargs)
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def _finish_flush(self):
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"""callback for unsetting _flushed flag."""
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self._flushed = False
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def flush(self, flag=zmq.POLLIN|zmq.POLLOUT, limit=None):
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"""Flush pending messages.
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This method safely handles all pending incoming and/or outgoing messages,
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bypassing the inner loop, passing them to the registered callbacks.
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A limit can be specified, to prevent blocking under high load.
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flush will return the first time ANY of these conditions are met:
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* No more events matching the flag are pending.
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* the total number of events handled reaches the limit.
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Note that if ``flag|POLLIN != 0``, recv events will be flushed even if no callback
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is registered, unlike normal IOLoop operation. This allows flush to be
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used to remove *and ignore* incoming messages.
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Parameters
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----------
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flag : int, default=POLLIN|POLLOUT
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0MQ poll flags.
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If flag|POLLIN, recv events will be flushed.
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If flag|POLLOUT, send events will be flushed.
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Both flags can be set at once, which is the default.
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limit : None or int, optional
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The maximum number of messages to send or receive.
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Both send and recv count against this limit.
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Returns
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-------
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int : count of events handled (both send and recv)
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"""
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self._check_closed()
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# unset self._flushed, so callbacks will execute, in case flush has
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# already been called this iteration
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already_flushed = self._flushed
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self._flushed = False
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# initialize counters
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count = 0
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def update_flag():
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"""Update the poll flag, to prevent registering POLLOUT events
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if we don't have pending sends."""
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return flag & zmq.POLLIN | (self.sending() and flag & zmq.POLLOUT)
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flag = update_flag()
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if not flag:
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# nothing to do
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return 0
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self.poller.register(self.socket, flag)
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events = self.poller.poll(0)
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while events and (not limit or count < limit):
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s,event = events[0]
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if event & zmq.POLLIN: # receiving
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self._handle_recv()
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count += 1
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if self.socket is None:
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# break if socket was closed during callback
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break
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if event & zmq.POLLOUT and self.sending():
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self._handle_send()
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count += 1
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if self.socket is None:
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# break if socket was closed during callback
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break
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flag = update_flag()
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if flag:
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self.poller.register(self.socket, flag)
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events = self.poller.poll(0)
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else:
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events = []
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if count: # only bypass loop if we actually flushed something
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# skip send/recv callbacks this iteration
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self._flushed = True
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# reregister them at the end of the loop
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if not already_flushed: # don't need to do it again
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self.io_loop.add_callback(self._finish_flush)
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elif already_flushed:
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self._flushed = True
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# update ioloop poll state, which may have changed
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self._rebuild_io_state()
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return count
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def set_close_callback(self, callback):
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"""Call the given callback when the stream is closed."""
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self._close_callback = stack_context_wrap(callback)
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def close(self, linger=None):
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"""Close this stream."""
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if self.socket is not None:
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if self.socket.closed:
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# fallback on raw fd for closed sockets
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# hopefully this happened promptly after close,
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# otherwise somebody else may have the FD
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warnings.warn(
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"Unregistering FD %s after closing socket. "
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"This could result in unregistering handlers for the wrong socket. "
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"Please use stream.close() instead of closing the socket directly."
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% self._fd,
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stacklevel=2,
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)
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self.io_loop.remove_handler(self._fd)
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else:
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self.io_loop.remove_handler(self.socket)
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self.socket.close(linger)
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self.socket = None
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if self._close_callback:
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self._run_callback(self._close_callback)
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def receiving(self):
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"""Returns True if we are currently receiving from the stream."""
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return self._recv_callback is not None
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def sending(self):
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"""Returns True if we are currently sending to the stream."""
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return not self._send_queue.empty()
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def closed(self):
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if self.socket is None:
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return True
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if self.socket.closed:
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# underlying socket has been closed, but not by us!
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# trigger our cleanup
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self.close()
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return True
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def _run_callback(self, callback, *args, **kwargs):
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"""Wrap running callbacks in try/except to allow us to
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close our socket."""
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try:
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# Use a NullContext to ensure that all StackContexts are run
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# inside our blanket exception handler rather than outside.
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callback(*args, **kwargs)
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except:
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gen_log.error("Uncaught exception in ZMQStream callback",
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exc_info=True)
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# Re-raise the exception so that IOLoop.handle_callback_exception
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# can see it and log the error
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raise
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def _handle_events(self, fd, events):
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"""This method is the actual handler for IOLoop, that gets called whenever
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an event on my socket is posted. It dispatches to _handle_recv, etc."""
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if not self.socket:
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gen_log.warning("Got events for closed stream %s", fd)
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return
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zmq_events = self.socket.EVENTS
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try:
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# dispatch events:
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if zmq_events & zmq.POLLIN and self.receiving():
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self._handle_recv()
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if not self.socket:
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return
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if zmq_events & zmq.POLLOUT and self.sending():
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self._handle_send()
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if not self.socket:
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return
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# rebuild the poll state
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self._rebuild_io_state()
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except Exception:
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gen_log.error("Uncaught exception in zmqstream callback",
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exc_info=True)
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raise
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|
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def _handle_recv(self):
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"""Handle a recv event."""
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if self._flushed:
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return
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try:
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msg = self.socket.recv_multipart(zmq.NOBLOCK, copy=self._recv_copy)
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except zmq.ZMQError as e:
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if e.errno == zmq.EAGAIN:
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# state changed since poll event
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pass
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else:
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raise
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else:
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if self._recv_callback:
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callback = self._recv_callback
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self._run_callback(callback, msg)
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|
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def _handle_send(self):
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"""Handle a send event."""
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if self._flushed:
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return
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if not self.sending():
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gen_log.error("Shouldn't have handled a send event")
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return
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msg, kwargs = self._send_queue.get()
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try:
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status = self.socket.send_multipart(msg, **kwargs)
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except zmq.ZMQError as e:
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gen_log.error("SEND Error: %s", e)
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status = e
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if self._send_callback:
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callback = self._send_callback
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self._run_callback(callback, msg, status)
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def _check_closed(self):
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if not self.socket:
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raise IOError("Stream is closed")
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def _rebuild_io_state(self):
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"""rebuild io state based on self.sending() and receiving()"""
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if self.socket is None:
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return
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state = 0
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if self.receiving():
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state |= zmq.POLLIN
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if self.sending():
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state |= zmq.POLLOUT
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self._state = state
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self._update_handler(state)
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def _add_io_state(self, state):
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"""Add io_state to poller."""
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self._state = self._state | state
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self._update_handler(self._state)
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def _drop_io_state(self, state):
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"""Stop poller from watching an io_state."""
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self._state = self._state & (~state)
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self._update_handler(self._state)
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|
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def _update_handler(self, state):
|
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"""Update IOLoop handler with state."""
|
|
if self.socket is None:
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return
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|
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if state & self.socket.events:
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# events still exist that haven't been processed
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# explicitly schedule handling to avoid missing events due to edge-triggered FDs
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self.io_loop.add_callback(lambda : self._handle_events(self.socket, 0))
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def _init_io_state(self):
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"""initialize the ioloop event handler"""
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self.io_loop.add_handler(self.socket, self._handle_events, self.io_loop.READ)
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