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# coding: utf-8
"""Python bindings for 0MQ."""
# Copyright (C) PyZMQ Developers
# Distributed under the terms of the Modified BSD License.
import atexit
import weakref
from zmq.backend import Context as ContextBase
from . import constants
from .attrsettr import AttributeSetter
from .constants import ENOTSUP, ctx_opt_names
from .socket import Socket
from zmq.error import ZMQError
from zmq.utils.interop import cast_int_addr
class Context(ContextBase, AttributeSetter):
"""Create a zmq Context
A zmq Context creates sockets via its ``ctx.socket`` method.
"""
sockopts = None
_instance = None
_shadow = False
_exiting = False
def __init__(self, io_threads=1, **kwargs):
super(Context, self).__init__(io_threads=io_threads, **kwargs)
if kwargs.get('shadow', False):
self._shadow = True
else:
self._shadow = False
self.sockopts = {}
self._exiting = False
if not self._shadow:
ctx_ref = weakref.ref(self)
def _notify_atexit():
ctx = ctx_ref()
if ctx is not None:
ctx._exiting = True
atexit.register(_notify_atexit)
def __del__(self):
"""deleting a Context should terminate it, without trying non-threadsafe destroy"""
if not self._shadow and not self._exiting:
self.term()
def __enter__(self):
return self
def __exit__(self, *args, **kwargs):
self.term()
@classmethod
def shadow(cls, address):
"""Shadow an existing libzmq context
address is the integer address of the libzmq context
or an FFI pointer to it.
.. versionadded:: 14.1
"""
address = cast_int_addr(address)
return cls(shadow=address)
@classmethod
def shadow_pyczmq(cls, ctx):
"""Shadow an existing pyczmq context
ctx is the FFI `zctx_t *` pointer
.. versionadded:: 14.1
"""
from pyczmq import zctx
underlying = zctx.underlying(ctx)
address = cast_int_addr(underlying)
return cls(shadow=address)
# static method copied from tornado IOLoop.instance
@classmethod
def instance(cls, io_threads=1):
"""Returns a global Context instance.
Most single-threaded applications have a single, global Context.
Use this method instead of passing around Context instances
throughout your code.
A common pattern for classes that depend on Contexts is to use
a default argument to enable programs with multiple Contexts
but not require the argument for simpler applications:
class MyClass(object):
def __init__(self, context=None):
self.context = context or Context.instance()
"""
if cls._instance is None or cls._instance.closed:
cls._instance = cls(io_threads=io_threads)
return cls._instance
#-------------------------------------------------------------------------
# Hooks for ctxopt completion
#-------------------------------------------------------------------------
def __dir__(self):
keys = dir(self.__class__)
for collection in (
ctx_opt_names,
):
keys.extend(collection)
return keys
#-------------------------------------------------------------------------
# Creating Sockets
#-------------------------------------------------------------------------
@property
def _socket_class(self):
return Socket
def socket(self, socket_type):
"""Create a Socket associated with this Context.
Parameters
----------
socket_type : int
The socket type, which can be any of the 0MQ socket types:
REQ, REP, PUB, SUB, PAIR, DEALER, ROUTER, PULL, PUSH, etc.
"""
if self.closed:
raise ZMQError(ENOTSUP)
s = self._socket_class(self, socket_type)
for opt, value in self.sockopts.items():
try:
s.setsockopt(opt, value)
except ZMQError:
# ignore ZMQErrors, which are likely for socket options
# that do not apply to a particular socket type, e.g.
# SUBSCRIBE for non-SUB sockets.
pass
return s
def setsockopt(self, opt, value):
"""set default socket options for new sockets created by this Context
.. versionadded:: 13.0
"""
self.sockopts[opt] = value
def getsockopt(self, opt):
"""get default socket options for new sockets created by this Context
.. versionadded:: 13.0
"""
return self.sockopts[opt]
def _set_attr_opt(self, name, opt, value):
"""set default sockopts as attributes"""
if name in constants.ctx_opt_names:
return self.set(opt, value)
else:
self.sockopts[opt] = value
def _get_attr_opt(self, name, opt):
"""get default sockopts as attributes"""
if name in constants.ctx_opt_names:
return self.get(opt)
else:
if opt not in self.sockopts:
raise AttributeError(name)
else:
return self.sockopts[opt]
def __delattr__(self, key):
"""delete default sockopts as attributes"""
key = key.upper()
try:
opt = getattr(constants, key)
except AttributeError:
raise AttributeError("no such socket option: %s" % key)
else:
if opt not in self.sockopts:
raise AttributeError(key)
else:
del self.sockopts[opt]
__all__ = ['Context']
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