"""Kernel frontend classes. TODO: Create logger to handle debugging and console messages. """ # Standard library imports. from Queue import Queue, Empty from subprocess import Popen from threading import Thread import time import traceback # System library imports. import zmq from zmq import POLLIN, POLLOUT, POLLERR from zmq.eventloop import ioloop # Local imports. from IPython.utils.traitlets import HasTraits, Any, Bool, Int, Instance, Str, \ Type from kernel import launch_kernel from session import Session # Constants. LOCALHOST = '127.0.0.1' class MissingHandlerError(Exception): pass class ZmqSocketChannel(Thread): """ The base class for the channels that use ZMQ sockets. """ context = None session = None socket = None ioloop = None iostate = None def __init__(self, context, session, address=None): super(ZmqSocketChannel, self).__init__() self.daemon = True self.context = context self.session = session self.address = address def stop(self): """Stop the thread's activity. Returns when the thread terminates. The thread will raise :class:`RuntimeError` if :method:`self.start` is called again. """ self.join() def get_address(self): """ Get the channel's address. By the default, a channel is on localhost with no port specified (a negative port number). """ return self._address def set_adresss(self, address): """ Set the channel's address. Should be a tuple of form: (ip address [str], port [int]). or None, in which case the address is reset to its default value. """ # FIXME: Validate address. if self.is_alive(): # This is Thread.is_alive raise RuntimeError("Cannot set address on a running channel!") else: if address is None: address = (LOCALHOST, 0) self._address = address address = property(get_address, set_adresss) def add_io_state(self, state): """Add IO state to the eventloop. This is thread safe as it uses the thread safe IOLoop.add_callback. """ def add_io_state_callback(): if not self.iostate & state: self.iostate = self.iostate | state self.ioloop.update_handler(self.socket, self.iostate) self.ioloop.add_callback(add_io_state_callback) def drop_io_state(self, state): """Drop IO state from the eventloop. This is thread safe as it uses the thread safe IOLoop.add_callback. """ def drop_io_state_callback(): if self.iostate & state: self.iostate = self.iostate & (~state) self.ioloop.update_handler(self.socket, self.iostate) self.ioloop.add_callback(drop_io_state_callback) class SubSocketChannel(ZmqSocketChannel): def __init__(self, context, session, address=None): super(SubSocketChannel, self).__init__(context, session, address) def run(self): self.socket = self.context.socket(zmq.SUB) self.socket.setsockopt(zmq.SUBSCRIBE,'') self.socket.setsockopt(zmq.IDENTITY, self.session.session) self.socket.connect('tcp://%s:%i' % self.address) self.ioloop = ioloop.IOLoop() self.iostate = POLLIN|POLLERR self.ioloop.add_handler(self.socket, self._handle_events, self.iostate) self.ioloop.start() def stop(self): self.ioloop.stop() super(SubSocketChannel, self).stop() def _handle_events(self, socket, events): # Turn on and off POLLOUT depending on if we have made a request if events & POLLERR: self._handle_err() if events & POLLIN: self._handle_recv() def _handle_err(self): # We don't want to let this go silently, so eventually we should log. raise zmq.ZMQError() def _handle_recv(self): # Get all of the messages we can while True: try: msg = self.socket.recv_json(zmq.NOBLOCK) except zmq.ZMQError: # Check the errno? # Will this tigger POLLERR? break else: self.call_handlers(msg) def call_handlers(self, msg): """This method is called in the ioloop thread when a message arrives. Subclasses should override this method to handle incoming messages. It is important to remember that this method is called in the thread so that some logic must be done to ensure that the application leve handlers are called in the application thread. """ raise NotImplementedError('call_handlers must be defined in a subclass.') def flush(self, timeout=1.0): """Immediately processes all pending messages on the SUB channel. This method is thread safe. Parameters ---------- timeout : float, optional The maximum amount of time to spend flushing, in seconds. The default is one second. """ # We do the IOLoop callback process twice to ensure that the IOLoop # gets to perform at least one full poll. stop_time = time.time() + timeout for i in xrange(2): self._flushed = False self.ioloop.add_callback(self._flush) while not self._flushed and time.time() < stop_time: time.sleep(0.01) def _flush(self): """Called in this thread by the IOLoop to indicate that all events have been processed. """ self._flushed = True class XReqSocketChannel(ZmqSocketChannel): handler_queue = None command_queue = None handlers = None _overriden_call_handler = None def __init__(self, context, session, address=None): self.handlers = {} self.handler_queue = Queue() self.command_queue = Queue() super(XReqSocketChannel, self).__init__(context, session, address) def run(self): self.socket = self.context.socket(zmq.XREQ) self.socket.setsockopt(zmq.IDENTITY, self.session.session) self.socket.connect('tcp://%s:%i' % self.address) self.ioloop = ioloop.IOLoop() self.iostate = POLLERR|POLLIN self.ioloop.add_handler(self.socket, self._handle_events, self.iostate) self.ioloop.start() def stop(self): self.ioloop.stop() super(XReqSocketChannel, self).stop() def _handle_events(self, socket, events): if events & POLLERR: self._handle_err() if events & POLLOUT: self._handle_send() if events & POLLIN: self._handle_recv() def _handle_recv(self): msg = self.socket.recv_json() self.call_handlers(msg) def _handle_send(self): try: msg = self.command_queue.get(False) except Empty: pass else: self.socket.send_json(msg) if self.command_queue.empty(): self.drop_io_state(POLLOUT) def _handle_err(self): # We don't want to let this go silently, so eventually we should log. raise zmq.ZMQError() def _queue_request(self, msg, callback): handler = self._find_handler(msg['msg_type'], callback) self.handler_queue.put(handler) self.command_queue.put(msg) self.add_io_state(POLLOUT) def execute(self, code, callback=None): # Create class for content/msg creation. Related to, but possibly # not in Session. content = dict(code=code) msg = self.session.msg('execute_request', content) self._queue_request(msg, callback) return msg['header']['msg_id'] def complete(self, text, line, block=None, callback=None): content = dict(text=text, line=line) msg = self.session.msg('complete_request', content) self._queue_request(msg, callback) return msg['header']['msg_id'] def object_info(self, oname, callback=None): content = dict(oname=oname) msg = self.session.msg('object_info_request', content) self._queue_request(msg, callback) return msg['header']['msg_id'] def _find_handler(self, name, callback): if callback is not None: return callback handler = self.handlers.get(name) if handler is None: raise MissingHandlerError( 'No handler defined for method: %s' % name) return handler def override_call_handler(self, func): """Permanently override the call_handler. The function func will be called as:: func(handler, msg) And must call:: handler(msg) in the main thread. """ assert callable(func), "not a callable: %r" % func self._overriden_call_handler = func def call_handlers(self, msg): try: handler = self.handler_queue.get(False) except Empty: print "Message received with no handler!!!" print msg else: self.call_handler(handler, msg) def call_handler(self, handler, msg): if self._overriden_call_handler is not None: self._overriden_call_handler(handler, msg) elif hasattr(self, '_call_handler'): call_handler = getattr(self, '_call_handler') call_handler(handler, msg) else: raise RuntimeError('no handler!') class RepSocketChannel(ZmqSocketChannel): def on_raw_input(self): pass class KernelManager(HasTraits): """ Manages a kernel for a frontend. The SUB channel is for the frontend to receive messages published by the kernel. The REQ channel is for the frontend to make requests of the kernel. The REP channel is for the kernel to request stdin (raw_input) from the frontend. """ # Whether the kernel manager is currently listening on its channels. is_listening = Bool(False) # The PyZMQ Context to use for communication with the kernel. context = Instance(zmq.Context, ()) # The Session to use for communication with the kernel. session = Instance(Session, ()) # The classes to use for the various channels. sub_channel_class = Type(SubSocketChannel) xreq_channel_class = Type(XReqSocketChannel) rep_channel_class = Type(RepSocketChannel) # Protected traits. _kernel = Instance(Popen) _sub_channel = Any _xreq_channel = Any _rep_channel = Any #-------------------------------------------------------------------------- # Channel management methods: #-------------------------------------------------------------------------- def start_listening(self): """Starts listening on the specified ports. If already listening, raises a RuntimeError. """ if self.is_listening: raise RuntimeError("Cannot start listening. Already listening!") else: self.is_listening = True self.sub_channel.start() self.xreq_channel.start() self.rep_channel.start() @property def is_alive(self): """ Returns whether the kernel is alive. """ if self.is_listening: # TODO: check if alive. return True else: return False def stop_listening(self): """Stops listening. If not listening, does nothing. """ if self.is_listening: self.is_listening = False self.sub_channel.stop() self.xreq_channel.stop() self.rep_channel.stop() #-------------------------------------------------------------------------- # Kernel process management methods: #-------------------------------------------------------------------------- def start_kernel(self): """Starts a kernel process and configures the manager to use it. If ports have been specified via the address attributes, they are used. Otherwise, open ports are chosen by the OS and the channel port attributes are configured as appropriate. """ xreq, sub = self.xreq_address, self.sub_address if xreq[0] != LOCALHOST or sub[0] != LOCALHOST: raise RuntimeError("Can only launch a kernel on localhost." "Make sure that the '*_address' attributes are " "configured properly.") kernel, xrep, pub = launch_kernel(xrep_port=xreq[1], pub_port=sub[1]) self.set_kernel(kernel) self.xreq_address = (LOCALHOST, xrep) self.sub_address = (LOCALHOST, pub) def set_kernel(self, kernel): """Sets the kernel manager's kernel to an existing kernel process. It is *not* necessary to a set a kernel to communicate with it via the channels, and those objects must be configured separately. It *is* necessary to set a kernel if you want to use the manager (or frontends that use the manager) to signal and/or kill the kernel. Parameters: ----------- kernel : Popen An existing kernel process. """ self._kernel = kernel @property def has_kernel(self): """Returns whether a kernel process has been specified for the kernel manager. A kernel process can be set via 'start_kernel' or 'set_kernel'. """ return self._kernel is not None def kill_kernel(self): """ Kill the running kernel. """ if self._kernel: self._kernel.kill() self._kernel = None else: raise RuntimeError("Cannot kill kernel. No kernel is running!") def signal_kernel(self, signum): """ Sends a signal to the kernel. """ if self._kernel: self._kernel.send_signal(signum) else: raise RuntimeError("Cannot signal kernel. No kernel is running!") #-------------------------------------------------------------------------- # Channels used for communication with the kernel: #-------------------------------------------------------------------------- @property def sub_channel(self): """Get the SUB socket channel object.""" if self._sub_channel is None: self._sub_channel = self.sub_channel_class(self.context, self.session) return self._sub_channel @property def xreq_channel(self): """Get the REQ socket channel object to make requests of the kernel.""" if self._xreq_channel is None: self._xreq_channel = self.xreq_channel_class(self.context, self.session) return self._xreq_channel @property def rep_channel(self): """Get the REP socket channel object to handle stdin (raw_input).""" if self._rep_channel is None: self._rep_channel = self.rep_channel_class(self.context, self.session) return self._rep_channel #-------------------------------------------------------------------------- # Delegates for the Channel address attributes: #-------------------------------------------------------------------------- def get_sub_address(self): return self.sub_channel.address def set_sub_address(self, address): self.sub_channel.address = address sub_address = property(get_sub_address, set_sub_address, doc="The address used by SUB socket channel.") def get_xreq_address(self): return self.xreq_channel.address def set_xreq_address(self, address): self.xreq_channel.address = address xreq_address = property(get_xreq_address, set_xreq_address, doc="The address used by XREQ socket channel.") def get_rep_address(self): return self.rep_channel.address def set_rep_address(self, address): self.rep_channel.address = address rep_address = property(get_rep_address, set_rep_address, doc="The address used by REP socket channel.")