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# vim: set fenc=utf-8 ft=python sw=4 ts=4 sts=4 et:
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# Copyright 2019, Battelle Memorial Institute.
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import functools
import logging
import random
import string
import weakref
import gevent
from zmq import green as zmq
from zmq import ZMQError
from .base import SubsystemBase
__all__ = ['Channel']
[docs]class Channel(SubsystemBase):
ADDRESS = 'inproc://subsystem/channel'
def __init__(self, core):
self.context = zmq.Context()
self.socket = None
self.greenlet = None
self._channels = {}
core.register('channel', self._handle_subsystem)
def setup(sender, **kwargs):
# pylint: disable=unused-argument
self.socket = self.context.socket(zmq.ROUTER)
core.onsetup.connect(setup, self)
def start(sender, **kwargs):
# pylint: disable=unused-argument
self.greenlet = gevent.getcurrent()
vip_sock = core.socket
chan_sock = self.socket
chan_sock.bind(self.ADDRESS)
while True:
message = chan_sock.recv_multipart(copy=False)
if not message:
continue
ident = bytes(message[0])
try:
peer, name = self._channels[ident]
except KeyError:
# XXX: Handle channel not found
continue
message[0] = name
vip_sock.send_vip(peer, 'channel', message, copy=False)
core.onstart.connect(start, self)
def stop(sender, **kwargs):
# pylint: disable=unused-argument
if self.greenlet is not None:
self.greenlet.kill(block=False)
try:
self.socket.unbind(self.ADDRESS)
except ZMQError:
pass
core.onstop.connect(stop, self)
def _handle_subsystem(self, message):
frames = message.args
try:
name = frames[0]
except IndexError:
return
channel = (bytes(message.peer), bytes(name))
try:
ident = self._channels[channel]
except KeyError:
# XXX: Handle channel not found
return
frames[0] = ident
self.socket.send_multipart(frames, copy=False)
[docs] def create(self, peer, name=None):
if name is None:
while True:
name = ''.join(random.choice(string.printable[:-5])
for i in range(30))
channel = (peer, name)
if channel not in self._channels:
break
else:
channel = (peer, name)
if channel in self._channels:
raise ValueError('channel %r is unavailable' % (name,))
sock = self.context.socket(zmq.DEALER)
sock.hwm = 1
sock.identity = ident = ('%s.%s' % (hash(channel), hash(sock)))
sockref = weakref.ref(sock, self._destroy)
object.__setattr__(sock, 'peer', peer)
object.__setattr__(sock, 'name', name)
self._channels[channel] = ident
self._channels[ident] = channel
self._channels[sockref] = (ident, peer, name)
close_socket = sock.close
@functools.wraps(close_socket)
def close(linger=None):
self._destroy(sockref)
sock.close = close_socket
return close_socket(linger=linger)
sock.close = close
sock.connect(self.ADDRESS)
return sock
__call__ = create
def _destroy(self, sockref):
try:
ident, peer, name = self._channels.pop(sockref)
except KeyError:
return
self._channels.pop(ident, None)
self._channels.pop((peer, name), None)