"""Classes for running 0MQ Devices in the background.""" # Copyright (C) PyZMQ Developers # Distributed under the terms of the Modified BSD License. import time from threading import Thread from multiprocessing import Process from zmq import device, QUEUE, Context, ETERM, ZMQError class Device: """A 0MQ Device to be run in the background. You do not pass Socket instances to this, but rather Socket types:: Device(device_type, in_socket_type, out_socket_type) For instance:: dev = Device(zmq.QUEUE, zmq.DEALER, zmq.ROUTER) Similar to zmq.device, but socket types instead of sockets themselves are passed, and the sockets are created in the work thread, to avoid issues with thread safety. As a result, additional bind_{in|out} and connect_{in|out} methods and setsockopt_{in|out} allow users to specify connections for the sockets. Parameters ---------- device_type : int The 0MQ Device type {in|out}_type : int zmq socket types, to be passed later to context.socket(). e.g. zmq.PUB, zmq.SUB, zmq.REQ. If out_type is < 0, then in_socket is used for both in_socket and out_socket. Methods ------- bind_{in_out}(iface) passthrough for ``{in|out}_socket.bind(iface)``, to be called in the thread connect_{in_out}(iface) passthrough for ``{in|out}_socket.connect(iface)``, to be called in the thread setsockopt_{in_out}(opt,value) passthrough for ``{in|out}_socket.setsockopt(opt, value)``, to be called in the thread Attributes ---------- daemon : int sets whether the thread should be run as a daemon Default is true, because if it is false, the thread will not exit unless it is killed context_factory : callable (class attribute) Function for creating the Context. This will be Context.instance in ThreadDevices, and Context in ProcessDevices. The only reason it is not instance() in ProcessDevices is that there may be a stale Context instance already initialized, and the forked environment should *never* try to use it. """ context_factory = Context.instance """Callable that returns a context. Typically either Context.instance or Context, depending on whether the device should share the global instance or not. """ def __init__(self, device_type=QUEUE, in_type=None, out_type=None): self.device_type = device_type if in_type is None: raise TypeError("in_type must be specified") if out_type is None: raise TypeError("out_type must be specified") self.in_type = in_type self.out_type = out_type self._in_binds = [] self._in_connects = [] self._in_sockopts = [] self._out_binds = [] self._out_connects = [] self._out_sockopts = [] self.daemon = True self.done = False def bind_in(self, addr): """Enqueue ZMQ address for binding on in_socket. See zmq.Socket.bind for details. """ self._in_binds.append(addr) def connect_in(self, addr): """Enqueue ZMQ address for connecting on in_socket. See zmq.Socket.connect for details. """ self._in_connects.append(addr) def setsockopt_in(self, opt, value): """Enqueue setsockopt(opt, value) for in_socket See zmq.Socket.setsockopt for details. """ self._in_sockopts.append((opt, value)) def bind_out(self, addr): """Enqueue ZMQ address for binding on out_socket. See zmq.Socket.bind for details. """ self._out_binds.append(addr) def connect_out(self, addr): """Enqueue ZMQ address for connecting on out_socket. See zmq.Socket.connect for details. """ self._out_connects.append(addr) def setsockopt_out(self, opt, value): """Enqueue setsockopt(opt, value) for out_socket See zmq.Socket.setsockopt for details. """ self._out_sockopts.append((opt, value)) def _setup_sockets(self): ctx = self.context_factory() self._context = ctx # create the sockets ins = ctx.socket(self.in_type) if self.out_type < 0: outs = ins else: outs = ctx.socket(self.out_type) # set sockopts (must be done first, in case of zmq.IDENTITY) for opt,value in self._in_sockopts: ins.setsockopt(opt, value) for opt,value in self._out_sockopts: outs.setsockopt(opt, value) for iface in self._in_binds: ins.bind(iface) for iface in self._out_binds: outs.bind(iface) for iface in self._in_connects: ins.connect(iface) for iface in self._out_connects: outs.connect(iface) return ins,outs def run_device(self): """The runner method. Do not call me directly, instead call ``self.start()``, just like a Thread. """ ins,outs = self._setup_sockets() device(self.device_type, ins, outs) def run(self): """wrap run_device in try/catch ETERM""" try: self.run_device() except ZMQError as e: if e.errno == ETERM: # silence TERM errors, because this should be a clean shutdown pass else: raise finally: self.done = True def start(self): """Start the device. Override me in subclass for other launchers.""" return self.run() def join(self,timeout=None): """wait for me to finish, like Thread.join. Reimplemented appropriately by subclasses.""" tic = time.time() toc = tic while not self.done and not (timeout is not None and toc-tic > timeout): time.sleep(.001) toc = time.time() class BackgroundDevice(Device): """Base class for launching Devices in background processes and threads.""" launcher=None _launch_class=None def start(self): self.launcher = self._launch_class(target=self.run) self.launcher.daemon = self.daemon return self.launcher.start() def join(self, timeout=None): return self.launcher.join(timeout=timeout) class ThreadDevice(BackgroundDevice): """A Device that will be run in a background Thread. See Device for details. """ _launch_class=Thread class ProcessDevice(BackgroundDevice): """A Device that will be run in a background Process. See Device for details. """ _launch_class=Process context_factory = Context """Callable that returns a context. Typically either Context.instance or Context, depending on whether the device should share the global instance or not. """ __all__ = ['Device', 'ThreadDevice', 'ProcessDevice']