283 lines
8.9 KiB
Python
283 lines
8.9 KiB
Python
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# coding: utf-8
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"""Python bindings for 0MQ."""
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# Copyright (C) PyZMQ Developers
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# Distributed under the terms of the Modified BSD License.
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import atexit
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import os
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from threading import Lock
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from weakref import WeakSet
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from zmq.backend import Context as ContextBase
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from . import constants
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from .attrsettr import AttributeSetter
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from .constants import ENOTSUP, LINGER, ctx_opt_names
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from .socket import Socket
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from zmq.error import ZMQError
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# notice when exiting, to avoid triggering term on exit
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_exiting = False
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def _notice_atexit():
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global _exiting
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_exiting = True
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atexit.register(_notice_atexit)
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class Context(ContextBase, AttributeSetter):
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"""Create a zmq Context
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A zmq Context creates sockets via its ``ctx.socket`` method.
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"""
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sockopts = None
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_instance = None
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_instance_lock = Lock()
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_instance_pid = None
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_shadow = False
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_sockets = None
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def __init__(self, io_threads=1, **kwargs):
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super(Context, self).__init__(io_threads=io_threads, **kwargs)
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if kwargs.get('shadow', False):
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self._shadow = True
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else:
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self._shadow = False
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self.sockopts = {}
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self._sockets = WeakSet()
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def __del__(self):
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"""deleting a Context should terminate it, without trying non-threadsafe destroy"""
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# Calling locals() here conceals issue #1167 on Windows CPython 3.5.4.
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locals()
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if not self._shadow and not _exiting:
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self.term()
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def __enter__(self):
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return self
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def __exit__(self, *args, **kwargs):
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self.term()
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def __copy__(self, memo=None):
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"""Copying a Context creates a shadow copy"""
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return self.__class__.shadow(self.underlying)
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__deepcopy__ = __copy__
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@classmethod
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def shadow(cls, address):
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"""Shadow an existing libzmq context
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address is the integer address of the libzmq context
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or an FFI pointer to it.
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.. versionadded:: 14.1
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"""
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from zmq.utils.interop import cast_int_addr
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address = cast_int_addr(address)
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return cls(shadow=address)
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@classmethod
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def shadow_pyczmq(cls, ctx):
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"""Shadow an existing pyczmq context
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ctx is the FFI `zctx_t *` pointer
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.. versionadded:: 14.1
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"""
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from pyczmq import zctx
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from zmq.utils.interop import cast_int_addr
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underlying = zctx.underlying(ctx)
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address = cast_int_addr(underlying)
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return cls(shadow=address)
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# static method copied from tornado IOLoop.instance
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@classmethod
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def instance(cls, io_threads=1):
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"""Returns a global Context instance.
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Most single-threaded applications have a single, global Context.
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Use this method instead of passing around Context instances
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throughout your code.
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A common pattern for classes that depend on Contexts is to use
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a default argument to enable programs with multiple Contexts
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but not require the argument for simpler applications::
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class MyClass(object):
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def __init__(self, context=None):
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self.context = context or Context.instance()
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.. versionchanged:: 18.1
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When called in a subprocess after forking,
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a new global instance is created instead of inheriting
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a Context that won't work from the parent process.
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"""
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if (
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cls._instance is None
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or cls._instance_pid != os.getpid()
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or cls._instance.closed
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):
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with cls._instance_lock:
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if (
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cls._instance is None
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or cls._instance_pid != os.getpid()
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or cls._instance.closed
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):
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cls._instance = cls(io_threads=io_threads)
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cls._instance_pid = os.getpid()
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return cls._instance
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def term(self):
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"""Close or terminate the context.
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Context termination is performed in the following steps:
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- Any blocking operations currently in progress on sockets open within context shall
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raise :class:`zmq.ContextTerminated`.
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With the exception of socket.close(), any further operations on sockets open within this context
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shall raise :class:`zmq.ContextTerminated`.
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- After interrupting all blocking calls, term shall block until the following conditions are satisfied:
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- All sockets open within context have been closed.
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- For each socket within context, all messages sent on the socket have either been
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physically transferred to a network peer,
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or the socket's linger period set with the zmq.LINGER socket option has expired.
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For further details regarding socket linger behaviour refer to libzmq documentation for ZMQ_LINGER.
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This can be called to close the context by hand. If this is not called,
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the context will automatically be closed when it is garbage collected.
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"""
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return super(Context, self).term()
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#-------------------------------------------------------------------------
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# Hooks for ctxopt completion
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#-------------------------------------------------------------------------
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def __dir__(self):
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keys = dir(self.__class__)
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for collection in (
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ctx_opt_names,
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):
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keys.extend(collection)
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return keys
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#-------------------------------------------------------------------------
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# Creating Sockets
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#-------------------------------------------------------------------------
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def _add_socket(self, socket):
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self._sockets.add(socket)
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def _rm_socket(self, socket):
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if self._sockets:
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self._sockets.discard(socket)
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def destroy(self, linger=None):
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"""Close all sockets associated with this context and then terminate
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the context.
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.. warning::
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destroy involves calling ``zmq_close()``, which is **NOT** threadsafe.
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If there are active sockets in other threads, this must not be called.
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Parameters
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----------
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linger : int, optional
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If specified, set LINGER on sockets prior to closing them.
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"""
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if self.closed:
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return
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sockets = self._sockets
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self._sockets = WeakSet()
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for s in sockets:
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if s and not s.closed:
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if linger is not None:
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s.setsockopt(LINGER, linger)
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s.close()
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self.term()
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@property
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def _socket_class(self):
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return Socket
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def socket(self, socket_type, **kwargs):
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"""Create a Socket associated with this Context.
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Parameters
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----------
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socket_type : int
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The socket type, which can be any of the 0MQ socket types:
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REQ, REP, PUB, SUB, PAIR, DEALER, ROUTER, PULL, PUSH, etc.
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kwargs:
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will be passed to the __init__ method of the socket class.
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"""
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if self.closed:
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raise ZMQError(ENOTSUP)
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s = self._socket_class(self, socket_type, **kwargs)
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for opt, value in self.sockopts.items():
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try:
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s.setsockopt(opt, value)
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except ZMQError:
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# ignore ZMQErrors, which are likely for socket options
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# that do not apply to a particular socket type, e.g.
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# SUBSCRIBE for non-SUB sockets.
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pass
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self._add_socket(s)
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return s
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def setsockopt(self, opt, value):
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"""set default socket options for new sockets created by this Context
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.. versionadded:: 13.0
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"""
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self.sockopts[opt] = value
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def getsockopt(self, opt):
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"""get default socket options for new sockets created by this Context
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.. versionadded:: 13.0
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"""
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return self.sockopts[opt]
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def _set_attr_opt(self, name, opt, value):
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"""set default sockopts as attributes"""
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if name in constants.ctx_opt_names:
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return self.set(opt, value)
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else:
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self.sockopts[opt] = value
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def _get_attr_opt(self, name, opt):
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"""get default sockopts as attributes"""
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if name in constants.ctx_opt_names:
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return self.get(opt)
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else:
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if opt not in self.sockopts:
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raise AttributeError(name)
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else:
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return self.sockopts[opt]
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def __delattr__(self, key):
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"""delete default sockopts as attributes"""
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key = key.upper()
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try:
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opt = getattr(constants, key)
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except AttributeError:
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raise AttributeError("no such socket option: %s" % key)
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else:
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if opt not in self.sockopts:
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raise AttributeError(key)
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else:
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del self.sockopts[opt]
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__all__ = ['Context']
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