More Python 3 compatibility fixes.

IPython/parallel/controller/dependency.py

@@ -1,201 +1,203 b''
 """Dependency utilities
 
 Authors:
 
 * Min RK
 """
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2010-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 from types import ModuleType
 
 from IPython.parallel.client.asyncresult import AsyncResult
 from IPython.parallel.error import UnmetDependency
 from IPython.parallel.util import interactive
+from IPython.utils import py3compat
 
 class depend(object):
     """Dependency decorator, for use with tasks.
     
     `@depend` lets you define a function for engine dependencies
     just like you use `apply` for tasks.
     
     
     Examples
     --------
     ::
     
         @depend(df, a,b, c=5)
         def f(m,n,p)
         
         view.apply(f, 1,2,3)
     
     will call df(a,b,c=5) on the engine, and if it returns False or
     raises an UnmetDependency error, then the task will not be run
     and another engine will be tried.
     """
     def __init__(self, f, *args, **kwargs):
         self.f = f
         self.args = args
         self.kwargs = kwargs
     
     def __call__(self, f):
         return dependent(f, self.f, *self.args, **self.kwargs)
 
 class dependent(object):
     """A function that depends on another function.
     This is an object to prevent the closure used
     in traditional decorators, which are not picklable.
     """
 
     def __init__(self, f, df, *dargs, **dkwargs):
         self.f = f
         self.func_name = getattr(f, '__name__', 'f')
         self.df = df
         self.dargs = dargs
         self.dkwargs = dkwargs
 
     def __call__(self, *args, **kwargs):
         # if hasattr(self.f, 'func_globals') and hasattr(self.df, 'func_globals'):
         #     self.df.func_globals = self.f.func_globals
         if self.df(*self.dargs, **self.dkwargs) is False:
             raise UnmetDependency()
         return self.f(*args, **kwargs)
     
-    @property
-    def __name__(self):
-        return self.func_name
+    if not py3compat.PY3:
+        @property
+        def __name__(self):
+            return self.func_name
 
 @interactive
 def _require(*names):
     """Helper for @require decorator."""
     from IPython.parallel.error import UnmetDependency
     user_ns = globals()
     for name in names:
         if name in user_ns:
             continue
         try:
             exec 'import %s'%name in user_ns
         except ImportError:
             raise UnmetDependency(name)
     return True
 
 def require(*mods):
     """Simple decorator for requiring names to be importable.
     
     Examples
     --------
     
     In [1]: @require('numpy')
        ...: def norm(a):
        ...:     import numpy
        ...:     return numpy.linalg.norm(a,2)
     """
     names = []
     for mod in mods:
         if isinstance(mod, ModuleType):
             mod = mod.__name__
         
         if isinstance(mod, basestring):
             names.append(mod)
         else:
             raise TypeError("names must be modules or module names, not %s"%type(mod))
     
     return depend(_require, *names)
 
 class Dependency(set):
     """An object for representing a set of msg_id dependencies.
     
     Subclassed from set().
     
     Parameters
     ----------
     dependencies: list/set of msg_ids or AsyncResult objects or output of Dependency.as_dict()
         The msg_ids to depend on
     all : bool [default True]
         Whether the dependency should be considered met when *all* depending tasks have completed
         or only when *any* have been completed.
     success : bool [default True]
         Whether to consider successes as fulfilling dependencies.
     failure : bool [default False]
         Whether to consider failures as fulfilling dependencies.
     
     If `all=success=True` and `failure=False`, then the task will fail with an ImpossibleDependency
         as soon as the first depended-upon task fails.
     """
     
     all=True
     success=True
     failure=True
     
     def __init__(self, dependencies=[], all=True, success=True, failure=False):
         if isinstance(dependencies, dict):
             # load from dict
             all = dependencies.get('all', True)
             success = dependencies.get('success', success)
             failure = dependencies.get('failure', failure)
             dependencies = dependencies.get('dependencies', [])
         ids = []
         
         # extract ids from various sources:
         if isinstance(dependencies, (basestring, AsyncResult)):
             dependencies = [dependencies]
         for d in dependencies:
             if isinstance(d, basestring):
                 ids.append(d)
             elif isinstance(d, AsyncResult):
                 ids.extend(d.msg_ids)
             else:
                 raise TypeError("invalid dependency type: %r"%type(d))
         
         set.__init__(self, ids)
         self.all = all
         if not (success or failure):
             raise ValueError("Must depend on at least one of successes or failures!")
         self.success=success
         self.failure = failure
     
     def check(self, completed, failed=None):
         """check whether our dependencies have been met."""
         if len(self) == 0:
             return True
         against = set()
         if self.success:
             against = completed
         if failed is not None and self.failure:
             against = against.union(failed)
         if self.all:
             return self.issubset(against)
         else:
             return not self.isdisjoint(against)
     
     def unreachable(self, completed, failed=None):
         """return whether this dependency has become impossible."""
         if len(self) == 0:
             return False
         against = set()
         if not self.success:
             against = completed
         if failed is not None and not self.failure:
             against = against.union(failed)
         if self.all:
             return not self.isdisjoint(against)
         else:
             return self.issubset(against)
         
     
     def as_dict(self):
         """Represent this dependency as a dict. For json compatibility."""
         return dict(
             dependencies=list(self),
             all=self.all,
             success=self.success,
             failure=self.failure
         )
 
 
 __all__ = ['depend', 'require', 'dependent', 'Dependency']
 

IPython/zmq/kernelmanager.py

@@ -1,983 +1,983 b''
 """Base classes to manage the interaction with a running kernel.
 
 TODO
 * Create logger to handle debugging and console messages.
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2010  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 # Standard library imports.
 import atexit
 import errno
 from Queue import Queue, Empty
 from subprocess import Popen
 import signal
 import sys
 from threading import Thread
 import time
 import logging
 
 # System library imports.
 import zmq
 from zmq import POLLIN, POLLOUT, POLLERR
 from zmq.eventloop import ioloop
 
 # Local imports.
 from IPython.config.loader import Config
 from IPython.utils import io
 from IPython.utils.localinterfaces import LOCALHOST, LOCAL_IPS
 from IPython.utils.traitlets import HasTraits, Any, Instance, Type, TCPAddress
 from session import Session, Message
 
 #-----------------------------------------------------------------------------
 # Constants and exceptions
 #-----------------------------------------------------------------------------
 
 class InvalidPortNumber(Exception):
     pass
 
 #-----------------------------------------------------------------------------
 # Utility functions
 #-----------------------------------------------------------------------------
 
 # some utilities to validate message structure, these might get moved elsewhere
 # if they prove to have more generic utility
 
 def validate_string_list(lst):
     """Validate that the input is a list of strings.
 
     Raises ValueError if not."""
     if not isinstance(lst, list):
         raise ValueError('input %r must be a list' % lst)
     for x in lst:
         if not isinstance(x, basestring):
             raise ValueError('element %r in list must be a string' % x)
 
 
 def validate_string_dict(dct):
     """Validate that the input is a dict with string keys and values.
 
     Raises ValueError if not."""
     for k,v in dct.iteritems():
         if not isinstance(k, basestring):
             raise ValueError('key %r in dict must be a string' % k)
         if not isinstance(v, basestring):
             raise ValueError('value %r in dict must be a string' % v)
 
 
 #-----------------------------------------------------------------------------
 # ZMQ Socket Channel classes
 #-----------------------------------------------------------------------------
 
 class ZMQSocketChannel(Thread):
     """The base class for the channels that use ZMQ sockets.
     """
     context = None
     session = None
     socket = None
     ioloop = None
     iostate = None
     _address = None
 
     def __init__(self, context, session, address):
         """Create a channel
 
         Parameters
         ----------
         context : :class:`zmq.Context`
             The ZMQ context to use.
         session : :class:`session.Session`
             The session to use.
         address : tuple
             Standard (ip, port) tuple that the kernel is listening on.
         """
         super(ZMQSocketChannel, self).__init__()
         self.daemon = True
 
         self.context = context
         self.session = session
         if address[1] == 0:
             message = 'The port number for a channel cannot be 0.'
             raise InvalidPortNumber(message)
         self._address = address
 
     def _run_loop(self):
         """Run my loop, ignoring EINTR events in the poller"""
         while True:
             try:
                 self.ioloop.start()
             except zmq.ZMQError as e:
                 if e.errno == errno.EINTR:
                     continue
                 else:
                     raise
             else:
                 break
     
     def stop(self):
         """Stop the channel's activity.
 
         This calls :method:`Thread.join` and returns when the thread
         terminates. :class:`RuntimeError` will be raised if 
         :method:`self.start` is called again.
         """
         self.join()
 
     @property
     def address(self):
         """Get the channel's address as an (ip, port) tuple.
         
         By the default, the address is (localhost, 0), where 0 means a random
         port.
         """
         return self._address
 
     def add_io_state(self, state):
         """Add IO state to the eventloop.
 
         Parameters
         ----------
         state : zmq.POLLIN|zmq.POLLOUT|zmq.POLLERR
             The IO state flag to set.
 
         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.
 
         Parameters
         ----------
         state : zmq.POLLIN|zmq.POLLOUT|zmq.POLLERR
             The IO state flag to set.
 
         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 ShellSocketChannel(ZMQSocketChannel):
     """The XREQ channel for issues request/replies to the kernel.
     """
 
     command_queue = None
 
     def __init__(self, context, session, address):
         super(ShellSocketChannel, self).__init__(context, session, address)
         self.command_queue = Queue()
         self.ioloop = ioloop.IOLoop()
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.DEALER)
-        self.socket.setsockopt(zmq.IDENTITY, self.session.session)
+        self.socket.setsockopt(zmq.IDENTITY, self.session.session.encode("ascii"))
         self.socket.connect('tcp://%s:%i' % self.address)
         self.iostate = POLLERR|POLLIN
         self.ioloop.add_handler(self.socket, self._handle_events, 
                                 self.iostate)
         self._run_loop()
 
     def stop(self):
         self.ioloop.stop()
         super(ShellSocketChannel, self).stop()
 
     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 execute(self, code, silent=False,
                 user_variables=None, user_expressions=None):
         """Execute code in the kernel.
 
         Parameters
         ----------
         code : str
             A string of Python code.
             
         silent : bool, optional (default False)
             If set, the kernel will execute the code as quietly possible.
 
         user_variables : list, optional
             A list of variable names to pull from the user's namespace.  They
             will come back as a dict with these names as keys and their
             :func:`repr` as values.
             
         user_expressions : dict, optional
             A dict with string keys and  to pull from the user's
             namespace.  They will come back as a dict with these names as keys
             and their :func:`repr` as values.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         if user_variables is None:
             user_variables = []
         if user_expressions is None:
             user_expressions = {}
             
         # Don't waste network traffic if inputs are invalid
         if not isinstance(code, basestring):
             raise ValueError('code %r must be a string' % code)
         validate_string_list(user_variables)
         validate_string_dict(user_expressions)
 
         # Create class for content/msg creation. Related to, but possibly
         # not in Session.
         content = dict(code=code, silent=silent,
                        user_variables=user_variables,
                        user_expressions=user_expressions)
         msg = self.session.msg('execute_request', content)
         self._queue_request(msg)
         return msg['header']['msg_id']
 
     def complete(self, text, line, cursor_pos, block=None):
         """Tab complete text in the kernel's namespace.
 
         Parameters
         ----------
         text : str
             The text to complete.
         line : str
             The full line of text that is the surrounding context for the 
             text to complete.
         cursor_pos : int
             The position of the cursor in the line where the completion was
             requested.
         block : str, optional
             The full block of code in which the completion is being requested.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         content = dict(text=text, line=line, block=block, cursor_pos=cursor_pos)
         msg = self.session.msg('complete_request', content)
         self._queue_request(msg)
         return msg['header']['msg_id']
 
     def object_info(self, oname):
         """Get metadata information about an object.
 
         Parameters
         ----------
         oname : str
             A string specifying the object name.
         
         Returns
         -------
         The msg_id of the message sent.
         """
         content = dict(oname=oname)
         msg = self.session.msg('object_info_request', content)
         self._queue_request(msg)
         return msg['header']['msg_id']
 
     def history(self, raw=True, output=False, hist_access_type='range', **kwargs):
         """Get entries from the history list.
 
         Parameters
         ----------
         raw : bool
             If True, return the raw input.
         output : bool
             If True, then return the output as well.
         hist_access_type : str
             'range' (fill in session, start and stop params), 'tail' (fill in n)
              or 'search' (fill in pattern param).
         
         session : int
             For a range request, the session from which to get lines. Session
             numbers are positive integers; negative ones count back from the
             current session.
         start : int
             The first line number of a history range.
         stop : int
             The final (excluded) line number of a history range.
         
         n : int
             The number of lines of history to get for a tail request.
             
         pattern : str
             The glob-syntax pattern for a search request.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         content = dict(raw=raw, output=output, hist_access_type=hist_access_type,
                                                                     **kwargs)
         msg = self.session.msg('history_request', content)
         self._queue_request(msg)
         return msg['header']['msg_id']
 
     def shutdown(self, restart=False):
         """Request an immediate kernel shutdown.
 
         Upon receipt of the (empty) reply, client code can safely assume that
         the kernel has shut down and it's safe to forcefully terminate it if
         it's still alive.
 
         The kernel will send the reply via a function registered with Python's
         atexit module, ensuring it's truly done as the kernel is done with all
         normal operation.
         """
         # Send quit message to kernel. Once we implement kernel-side setattr,
         # this should probably be done that way, but for now this will do.
         msg = self.session.msg('shutdown_request', {'restart':restart})
         self._queue_request(msg)
         return msg['header']['msg_id']
 
     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):
         ident,msg = self.session.recv(self.socket, 0)
         self.call_handlers(msg)
 
     def _handle_send(self):
         try:
             msg = self.command_queue.get(False)
         except Empty:
             pass
         else:
             self.session.send(self.socket,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):
         self.command_queue.put(msg)
         self.add_io_state(POLLOUT)
 
 
 class SubSocketChannel(ZMQSocketChannel):
     """The SUB channel which listens for messages that the kernel publishes.
     """
 
     def __init__(self, context, session, address):
         super(SubSocketChannel, self).__init__(context, session, address)
         self.ioloop = ioloop.IOLoop()
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.SUB)
-        self.socket.setsockopt(zmq.SUBSCRIBE,'')
-        self.socket.setsockopt(zmq.IDENTITY, self.session.session)
+        self.socket.setsockopt(zmq.SUBSCRIBE,b'')
+        self.socket.setsockopt(zmq.IDENTITY, self.session.session.encode("ascii"))
         self.socket.connect('tcp://%s:%i' % self.address)
         self.iostate = POLLIN|POLLERR
         self.ioloop.add_handler(self.socket, self._handle_events, 
                                 self.iostate)
         self._run_loop()
 
     def stop(self):
         self.ioloop.stop()
         super(SubSocketChannel, self).stop()
 
     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.
 
         Callers should use this method to ensure that :method:`call_handlers`
         has been called for all messages that have been received on the
         0MQ SUB socket of this 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 _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:
                 ident,msg = self.session.recv(self.socket)
             except zmq.ZMQError:
                 # Check the errno?
                 # Will this trigger POLLERR?
                 break
             else:
                 if msg is None:
                     break
                 self.call_handlers(msg)
 
     def _flush(self):
         """Callback for :method:`self.flush`."""
         self._flushed = True
 
 
 class StdInSocketChannel(ZMQSocketChannel):
     """A reply channel to handle raw_input requests that the kernel makes."""
 
     msg_queue = None
 
     def __init__(self, context, session, address):
         super(StdInSocketChannel, self).__init__(context, session, address)
         self.ioloop = ioloop.IOLoop()
         self.msg_queue = Queue()
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.DEALER)
-        self.socket.setsockopt(zmq.IDENTITY, self.session.session)
+        self.socket.setsockopt(zmq.IDENTITY, self.session.session.encode("ascii"))
         self.socket.connect('tcp://%s:%i' % self.address)
         self.iostate = POLLERR|POLLIN
         self.ioloop.add_handler(self.socket, self._handle_events, 
                                 self.iostate)
         self._run_loop()
 
     def stop(self):
         self.ioloop.stop()
         super(StdInSocketChannel, self).stop()
 
     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 input(self, string):
         """Send a string of raw input to the kernel."""
         content = dict(value=string)
         msg = self.session.msg('input_reply', content)
         self._queue_reply(msg)
 
     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):
         ident,msg = self.session.recv(self.socket, 0)
         self.call_handlers(msg)
 
     def _handle_send(self):
         try:
             msg = self.msg_queue.get(False)
         except Empty:
             pass
         else:
             self.session.send(self.socket,msg)
         if self.msg_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_reply(self, msg):
         self.msg_queue.put(msg)
         self.add_io_state(POLLOUT)
 
 
 class HBSocketChannel(ZMQSocketChannel):
     """The heartbeat channel which monitors the kernel heartbeat.
 
     Note that the heartbeat channel is paused by default. As long as you start
     this channel, the kernel manager will ensure that it is paused and un-paused
     as appropriate.
     """
 
     time_to_dead = 3.0
     socket = None
     poller = None
     _running = None
     _pause = None
 
     def __init__(self, context, session, address):
         super(HBSocketChannel, self).__init__(context, session, address)
         self._running = False
         self._pause = True
 
     def _create_socket(self):
         self.socket = self.context.socket(zmq.REQ)
-        self.socket.setsockopt(zmq.IDENTITY, self.session.session)
+        self.socket.setsockopt(zmq.IDENTITY, self.session.session.encode("ascii"))
         self.socket.connect('tcp://%s:%i' % self.address)
         self.poller = zmq.Poller()
         self.poller.register(self.socket, zmq.POLLIN)
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self._create_socket()
         self._running = True
         while self._running:
             if self._pause:
                 time.sleep(self.time_to_dead)
             else:
                 since_last_heartbeat = 0.0
                 request_time = time.time()
                 try:
                     #io.rprint('Ping from HB channel') # dbg
                     self.socket.send(b'ping')
                 except zmq.ZMQError, e:
                     #io.rprint('*** HB Error:', e) # dbg
                     if e.errno == zmq.EFSM:
                         #io.rprint('sleep...', self.time_to_dead) # dbg
                         time.sleep(self.time_to_dead)
                         self._create_socket()
                     else:
                         raise
                 else:
                     while True:
                         try:
                             self.socket.recv(zmq.NOBLOCK)
                         except zmq.ZMQError, e:
                             #io.rprint('*** HB Error 2:', e) # dbg
                             if e.errno == zmq.EAGAIN:
                                 before_poll = time.time()
                                 until_dead = self.time_to_dead - (before_poll -
                                                                   request_time)
 
                                 # When the return value of poll() is an empty
                                 # list, that is when things have gone wrong
                                 # (zeromq bug). As long as it is not an empty
                                 # list, poll is working correctly even if it
                                 # returns quickly. Note: poll timeout is in
                                 # milliseconds.
                                 if until_dead > 0.0:
                                     while True:
                                         try:
                                             self.poller.poll(1000 * until_dead)
                                         except zmq.ZMQError as e:
                                             if e.errno == errno.EINTR:
                                                 continue
                                             else:
                                                 raise
                                         else:
                                             break
                             
                                 since_last_heartbeat = time.time()-request_time
                                 if since_last_heartbeat > self.time_to_dead:
                                     self.call_handlers(since_last_heartbeat)
                                     break
                             else:
                                 # FIXME: We should probably log this instead.
                                 raise
                         else:
                             until_dead = self.time_to_dead - (time.time() -
                                                               request_time)
                             if until_dead > 0.0:
                                 #io.rprint('sleep...', self.time_to_dead) # dbg
                                 time.sleep(until_dead)
                             break
 
     def pause(self):
         """Pause the heartbeat."""
         self._pause = True
 
     def unpause(self):
         """Unpause the heartbeat."""
         self._pause = False
 
     def is_beating(self):
         """Is the heartbeat running and not paused."""
         if self.is_alive() and not self._pause:
             return True
         else:
             return False
 
     def stop(self):
         self._running = False
         super(HBSocketChannel, self).stop()
 
     def call_handlers(self, since_last_heartbeat):
         """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.')
 
 
 #-----------------------------------------------------------------------------
 # Main kernel manager class
 #-----------------------------------------------------------------------------
 
 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.
     """
     # config object for passing to child configurables
     config = Instance(Config)
     
     # The PyZMQ Context to use for communication with the kernel.
     context = Instance(zmq.Context)
     def _context_default(self):
         return zmq.Context.instance()
 
     # The Session to use for communication with the kernel.
     session = Instance(Session)
 
     # The kernel process with which the KernelManager is communicating.
     kernel = Instance(Popen)
 
     # The addresses for the communication channels. 
     shell_address = TCPAddress((LOCALHOST, 0))
     sub_address = TCPAddress((LOCALHOST, 0))
     stdin_address = TCPAddress((LOCALHOST, 0))
     hb_address = TCPAddress((LOCALHOST, 0))
 
     # The classes to use for the various channels.
     shell_channel_class = Type(ShellSocketChannel)
     sub_channel_class = Type(SubSocketChannel)
     stdin_channel_class = Type(StdInSocketChannel)
     hb_channel_class = Type(HBSocketChannel)
 
     # Protected traits.
     _launch_args = Any
     _shell_channel = Any
     _sub_channel = Any
     _stdin_channel = Any
     _hb_channel = Any
 
     def __init__(self, **kwargs):
         super(KernelManager, self).__init__(**kwargs)
         if self.session is None:
             self.session = Session(config=self.config)
         # Uncomment this to try closing the context.
         # atexit.register(self.context.term)
 
     #--------------------------------------------------------------------------
     # Channel management methods:
     #--------------------------------------------------------------------------
 
     def start_channels(self, shell=True, sub=True, stdin=True, hb=True):
         """Starts the channels for this kernel.
 
         This will create the channels if they do not exist and then start
         them. If port numbers of 0 are being used (random ports) then you
         must first call :method:`start_kernel`. If the channels have been
         stopped and you call this, :class:`RuntimeError` will be raised.
         """
         if shell:
             self.shell_channel.start()
         if sub:
             self.sub_channel.start()
         if stdin:
             self.stdin_channel.start()
         if hb:
             self.hb_channel.start()
 
     def stop_channels(self):
         """Stops all the running channels for this kernel.
         """
         if self.shell_channel.is_alive():
             self.shell_channel.stop()
         if self.sub_channel.is_alive():
             self.sub_channel.stop()
         if self.stdin_channel.is_alive():
             self.stdin_channel.stop()
         if self.hb_channel.is_alive():
             self.hb_channel.stop()
 
     @property
     def channels_running(self):
         """Are any of the channels created and running?"""
         return (self.shell_channel.is_alive() or self.sub_channel.is_alive() or
                 self.stdin_channel.is_alive() or self.hb_channel.is_alive())
 
     #--------------------------------------------------------------------------
     # Kernel process management methods:
     #--------------------------------------------------------------------------
 
     def start_kernel(self, **kw):
         """Starts a kernel process and configures the manager to use it.
 
         If random ports (port=0) are being used, this method must be called
         before the channels are created.
 
         Parameters:
         -----------
         ipython : bool, optional (default True)
              Whether to use an IPython kernel instead of a plain Python kernel.
 
         launcher : callable, optional (default None)
              A custom function for launching the kernel process (generally a
              wrapper around ``entry_point.base_launch_kernel``). In most cases,
              it should not be necessary to use this parameter.
 
         **kw : optional
              See respective options for IPython and Python kernels.
         """
         shell, sub, stdin, hb = self.shell_address, self.sub_address, \
             self.stdin_address, self.hb_address
         if shell[0] not in LOCAL_IPS or sub[0] not in LOCAL_IPS or \
                 stdin[0] not in LOCAL_IPS or hb[0] not in LOCAL_IPS:
             raise RuntimeError("Can only launch a kernel on a local interface. "
                                "Make sure that the '*_address' attributes are "
                                "configured properly. "
                                "Currently valid addresses are: %s"%LOCAL_IPS
                                )
                     
         self._launch_args = kw.copy()
         launch_kernel = kw.pop('launcher', None)
         if launch_kernel is None:
             if kw.pop('ipython', True):
                 from ipkernel import launch_kernel
             else:
                 from pykernel import launch_kernel
         self.kernel, xrep, pub, req, _hb = launch_kernel(
             shell_port=shell[1], iopub_port=sub[1],
             stdin_port=stdin[1], hb_port=hb[1], **kw)
         self.shell_address = (shell[0], xrep)
         self.sub_address = (sub[0], pub)
         self.stdin_address = (stdin[0], req)
         self.hb_address = (hb[0], _hb)
 
     def shutdown_kernel(self, restart=False):
         """ Attempts to the stop the kernel process cleanly. If the kernel
         cannot be stopped, it is killed, if possible.
         """
         # FIXME: Shutdown does not work on Windows due to ZMQ errors!
         if sys.platform == 'win32':
             self.kill_kernel()
             return
 
         # Pause the heart beat channel if it exists.
         if self._hb_channel is not None:
             self._hb_channel.pause()
 
         # Don't send any additional kernel kill messages immediately, to give
         # the kernel a chance to properly execute shutdown actions. Wait for at
         # most 1s, checking every 0.1s.
         self.shell_channel.shutdown(restart=restart)
         for i in range(10):
             if self.is_alive:
                 time.sleep(0.1)
             else:
                 break
         else:
             # OK, we've waited long enough.
             if self.has_kernel:
                 self.kill_kernel()
     
     def restart_kernel(self, now=False, **kw):
         """Restarts a kernel with the arguments that were used to launch it.
         
         If the old kernel was launched with random ports, the same ports will be
         used for the new kernel.
 
         Parameters
         ----------
         now : bool, optional
             If True, the kernel is forcefully restarted *immediately*, without
             having a chance to do any cleanup action.  Otherwise the kernel is
             given 1s to clean up before a forceful restart is issued.
 
             In all cases the kernel is restarted, the only difference is whether
             it is given a chance to perform a clean shutdown or not.
 
         **kw : optional
             Any options specified here will replace those used to launch the
             kernel.
         """
         if self._launch_args is None:
             raise RuntimeError("Cannot restart the kernel. "
                                "No previous call to 'start_kernel'.")
         else:
             # Stop currently running kernel.
             if self.has_kernel:
                 if now:
                     self.kill_kernel()
                 else:
                     self.shutdown_kernel(restart=True)
 
             # Start new kernel.
             self._launch_args.update(kw)
             self.start_kernel(**self._launch_args)
 
             # FIXME: Messages get dropped in Windows due to probable ZMQ bug
             # unless there is some delay here.
             if sys.platform == 'win32':
                 time.sleep(0.2)
 
     @property
     def has_kernel(self):
         """Returns whether a kernel process has been specified for the kernel
         manager.
         """
         return self.kernel is not None
 
     def kill_kernel(self):
         """ Kill the running kernel. """
         if self.has_kernel:
             # Pause the heart beat channel if it exists.
             if self._hb_channel is not None:
                 self._hb_channel.pause()
 
             # Attempt to kill the kernel.
             try:
                 self.kernel.kill()
             except OSError, e:
                 # In Windows, we will get an Access Denied error if the process
                 # has already terminated. Ignore it.
                 if sys.platform == 'win32':
                     if e.winerror != 5:
                         raise
                 # On Unix, we may get an ESRCH error if the process has already
                 # terminated. Ignore it.
                 else:
                     from errno import ESRCH
                     if e.errno != ESRCH:
                         raise
             self.kernel = None
         else:
             raise RuntimeError("Cannot kill kernel. No kernel is running!")
 
     def interrupt_kernel(self):
         """ Interrupts the kernel. Unlike ``signal_kernel``, this operation is
         well supported on all platforms.
         """
         if self.has_kernel:
             if sys.platform == 'win32':
                 from parentpoller import ParentPollerWindows as Poller
                 Poller.send_interrupt(self.kernel.win32_interrupt_event)
             else:
                 self.kernel.send_signal(signal.SIGINT)
         else:
             raise RuntimeError("Cannot interrupt kernel. No kernel is running!")
 
     def signal_kernel(self, signum):
         """ Sends a signal to the kernel. Note that since only SIGTERM is
         supported on Windows, this function is only useful on Unix systems.
         """
         if self.has_kernel:
             self.kernel.send_signal(signum)
         else:
             raise RuntimeError("Cannot signal kernel. No kernel is running!")
 
     @property
     def is_alive(self):
         """Is the kernel process still running?"""
         # FIXME: not using a heartbeat means this method is broken for any
         # remote kernel, it's only capable of handling local kernels.
         if self.has_kernel:
             if self.kernel.poll() is None:
                 return True
             else:
                 return False
         else:
             # We didn't start the kernel with this KernelManager so we don't
             # know if it is running. We should use a heartbeat for this case.
             return True
 
     #--------------------------------------------------------------------------
     # Channels used for communication with the kernel:
     #--------------------------------------------------------------------------
 
     @property
     def shell_channel(self):
         """Get the REQ socket channel object to make requests of the kernel."""
         if self._shell_channel is None:
             self._shell_channel = self.shell_channel_class(self.context,
                                                          self.session,
                                                          self.shell_address)
         return self._shell_channel
 
     @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,
                                                        self.sub_address)
         return self._sub_channel
 
     @property
     def stdin_channel(self):
         """Get the REP socket channel object to handle stdin (raw_input)."""
         if self._stdin_channel is None:
             self._stdin_channel = self.stdin_channel_class(self.context,
                                                        self.session,
                                                        self.stdin_address)
         return self._stdin_channel
 
     @property
     def hb_channel(self):
         """Get the heartbeat socket channel object to check that the
         kernel is alive."""
         if self._hb_channel is None:
             self._hb_channel = self.hb_channel_class(self.context, 
                                                        self.session,
                                                        self.hb_address)
         return self._hb_channel

IPython/zmq/session.py

@@ -1,704 +1,704 b''
 """Session object for building, serializing, sending, and receiving messages in
 IPython. The Session object supports serialization, HMAC signatures, and
 metadata on messages.
 
 Also defined here are utilities for working with Sessions:
 * A SessionFactory to be used as a base class for configurables that work with
 Sessions.
 * A Message object for convenience that allows attribute-access to the msg dict.
 
 Authors:
 
 * Min RK
 * Brian Granger
 * Fernando Perez
 """
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2010-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import hmac
 import logging
 import os
 import pprint
 import uuid
 from datetime import datetime
 
 try:
     import cPickle
     pickle = cPickle
 except:
     cPickle = None
     import pickle
 
 import zmq
 from zmq.utils import jsonapi
 from zmq.eventloop.ioloop import IOLoop
 from zmq.eventloop.zmqstream import ZMQStream
 
 from IPython.config.configurable import Configurable, LoggingConfigurable
 from IPython.utils.importstring import import_item
 from IPython.utils.jsonutil import extract_dates, squash_dates, date_default
 from IPython.utils.py3compat import str_to_bytes
 from IPython.utils.traitlets import (CBytes, Unicode, Bool, Any, Instance, Set,
-                                        DottedObjectName)
+                                        DottedObjectName, CUnicode)
 
 #-----------------------------------------------------------------------------
 # utility functions
 #-----------------------------------------------------------------------------
 
 def squash_unicode(obj):
     """coerce unicode back to bytestrings."""
     if isinstance(obj,dict):
         for key in obj.keys():
             obj[key] = squash_unicode(obj[key])
             if isinstance(key, unicode):
                 obj[squash_unicode(key)] = obj.pop(key)
     elif isinstance(obj, list):
         for i,v in enumerate(obj):
             obj[i] = squash_unicode(v)
     elif isinstance(obj, unicode):
         obj = obj.encode('utf8')
     return obj
 
 #-----------------------------------------------------------------------------
 # globals and defaults
 #-----------------------------------------------------------------------------
 key = 'on_unknown' if jsonapi.jsonmod.__name__ == 'jsonlib' else 'default'
 json_packer = lambda obj: jsonapi.dumps(obj, **{key:date_default})
 json_unpacker = lambda s: extract_dates(jsonapi.loads(s))
 
 pickle_packer = lambda o: pickle.dumps(o,-1)
 pickle_unpacker = pickle.loads
 
 default_packer = json_packer
 default_unpacker = json_unpacker
 
 
 DELIM=b"<IDS|MSG>"
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
 
 class SessionFactory(LoggingConfigurable):
     """The Base class for configurables that have a Session, Context, logger,
     and IOLoop.
     """
     
     logname = Unicode('')
     def _logname_changed(self, name, old, new):
         self.log = logging.getLogger(new)
     
     # not configurable:
     context = Instance('zmq.Context')
     def _context_default(self):
         return zmq.Context.instance()
     
     session = Instance('IPython.zmq.session.Session')
     
     loop = Instance('zmq.eventloop.ioloop.IOLoop', allow_none=False)
     def _loop_default(self):
         return IOLoop.instance()
     
     def __init__(self, **kwargs):
         super(SessionFactory, self).__init__(**kwargs)
         
         if self.session is None:
             # construct the session
             self.session = Session(**kwargs)
     
 
 class Message(object):
     """A simple message object that maps dict keys to attributes.
 
     A Message can be created from a dict and a dict from a Message instance
     simply by calling dict(msg_obj)."""
     
     def __init__(self, msg_dict):
         dct = self.__dict__
         for k, v in dict(msg_dict).iteritems():
             if isinstance(v, dict):
                 v = Message(v)
             dct[k] = v
 
     # Having this iterator lets dict(msg_obj) work out of the box.
     def __iter__(self):
         return iter(self.__dict__.iteritems())
     
     def __repr__(self):
         return repr(self.__dict__)
 
     def __str__(self):
         return pprint.pformat(self.__dict__)
 
     def __contains__(self, k):
         return k in self.__dict__
 
     def __getitem__(self, k):
         return self.__dict__[k]
 
 
 def msg_header(msg_id, msg_type, username, session):
     date = datetime.now()
     return locals()
 
 def extract_header(msg_or_header):
     """Given a message or header, return the header."""
     if not msg_or_header:
         return {}
     try:
         # See if msg_or_header is the entire message.
         h = msg_or_header['header']
     except KeyError:
         try:
             # See if msg_or_header is just the header
             h = msg_or_header['msg_id']
         except KeyError:
             raise
         else:
             h = msg_or_header
     if not isinstance(h, dict):
         h = dict(h)
     return h
 
 class Session(Configurable):
     """Object for handling serialization and sending of messages.
     
     The Session object handles building messages and sending them
     with ZMQ sockets or ZMQStream objects.  Objects can communicate with each
     other over the network via Session objects, and only need to work with the
     dict-based IPython message spec. The Session will handle 
     serialization/deserialization, security, and metadata.
     
     Sessions support configurable serialiization via packer/unpacker traits,
     and signing with HMAC digests via the key/keyfile traits.
     
     Parameters
     ----------
     
     debug : bool
         whether to trigger extra debugging statements
     packer/unpacker : str : 'json', 'pickle' or import_string
         importstrings for methods to serialize message parts.  If just
         'json' or 'pickle', predefined JSON and pickle packers will be used.
         Otherwise, the entire importstring must be used.
         
         The functions must accept at least valid JSON input, and output *bytes*.
         
         For example, to use msgpack:
         packer = 'msgpack.packb', unpacker='msgpack.unpackb'
     pack/unpack : callables
         You can also set the pack/unpack callables for serialization directly.
     session : bytes
         the ID of this Session object.  The default is to generate a new UUID.
     username : unicode
         username added to message headers.  The default is to ask the OS.
     key : bytes
         The key used to initialize an HMAC signature.  If unset, messages
         will not be signed or checked.
     keyfile : filepath
         The file containing a key.  If this is set, `key` will be initialized
         to the contents of the file.
     
     """
     
     debug=Bool(False, config=True, help="""Debug output in the Session""")
     
     packer = DottedObjectName('json',config=True,
             help="""The name of the packer for serializing messages.
             Should be one of 'json', 'pickle', or an import name
             for a custom callable serializer.""")
     def _packer_changed(self, name, old, new):
         if new.lower() == 'json':
             self.pack = json_packer
             self.unpack = json_unpacker
         elif new.lower() == 'pickle':
             self.pack = pickle_packer
             self.unpack = pickle_unpacker
         else:
             self.pack = import_item(str(new))
 
     unpacker = DottedObjectName('json', config=True,
         help="""The name of the unpacker for unserializing messages.
         Only used with custom functions for `packer`.""")
     def _unpacker_changed(self, name, old, new):
         if new.lower() == 'json':
             self.pack = json_packer
             self.unpack = json_unpacker
         elif new.lower() == 'pickle':
             self.pack = pickle_packer
             self.unpack = pickle_unpacker
         else:
             self.unpack = import_item(str(new))
         
-    session = CBytes(b'', config=True,
+    session = CUnicode(u'', config=True,
         help="""The UUID identifying this session.""")
     def _session_default(self):
-        return bytes(uuid.uuid4())
+        return unicode(uuid.uuid4())
     
     username = Unicode(os.environ.get('USER',u'username'), config=True,
         help="""Username for the Session. Default is your system username.""")
     
     # message signature related traits:
     key = CBytes(b'', config=True,
         help="""execution key, for extra authentication.""")
     def _key_changed(self, name, old, new):
         if new:
             self.auth = hmac.HMAC(new)
         else:
             self.auth = None
     auth = Instance(hmac.HMAC)
     digest_history = Set()
     
     keyfile = Unicode('', config=True,
         help="""path to file containing execution key.""")
     def _keyfile_changed(self, name, old, new):
         with open(new, 'rb') as f:
             self.key = f.read().strip()
 
     pack = Any(default_packer) # the actual packer function
     def _pack_changed(self, name, old, new):
         if not callable(new):
             raise TypeError("packer must be callable, not %s"%type(new))
     
     unpack = Any(default_unpacker) # the actual packer function
     def _unpack_changed(self, name, old, new):
         # unpacker is not checked - it is assumed to be 
         if not callable(new):
             raise TypeError("unpacker must be callable, not %s"%type(new))
 
     def __init__(self, **kwargs):
         """create a Session object
         
         Parameters
         ----------
 
         debug : bool
             whether to trigger extra debugging statements
         packer/unpacker : str : 'json', 'pickle' or import_string
             importstrings for methods to serialize message parts.  If just
             'json' or 'pickle', predefined JSON and pickle packers will be used.
             Otherwise, the entire importstring must be used.
 
             The functions must accept at least valid JSON input, and output
             *bytes*.
 
             For example, to use msgpack:
             packer = 'msgpack.packb', unpacker='msgpack.unpackb'
         pack/unpack : callables
             You can also set the pack/unpack callables for serialization
             directly.
         session : bytes
             the ID of this Session object.  The default is to generate a new 
             UUID.
         username : unicode
             username added to message headers.  The default is to ask the OS.
         key : bytes
             The key used to initialize an HMAC signature.  If unset, messages
             will not be signed or checked.
         keyfile : filepath
             The file containing a key.  If this is set, `key` will be 
             initialized to the contents of the file.
         """
         super(Session, self).__init__(**kwargs)
         self._check_packers()
         self.none = self.pack({})
 
     @property
     def msg_id(self):
         """always return new uuid"""
         return str(uuid.uuid4())
 
     def _check_packers(self):
         """check packers for binary data and datetime support."""
         pack = self.pack
         unpack = self.unpack
         
         # check simple serialization
         msg = dict(a=[1,'hi'])
         try:
             packed = pack(msg)
         except Exception:
             raise ValueError("packer could not serialize a simple message")
         
         # ensure packed message is bytes
         if not isinstance(packed, bytes):
             raise ValueError("message packed to %r, but bytes are required"%type(packed))
         
         # check that unpack is pack's inverse
         try:
             unpacked = unpack(packed)
         except Exception:
             raise ValueError("unpacker could not handle the packer's output")
         
         # check datetime support
         msg = dict(t=datetime.now())
         try:
             unpacked = unpack(pack(msg))
         except Exception:
             self.pack = lambda o: pack(squash_dates(o))
             self.unpack = lambda s: extract_dates(unpack(s))
     
     def msg_header(self, msg_type):
         return msg_header(self.msg_id, msg_type, self.username, self.session)
 
     def msg(self, msg_type, content=None, parent=None, subheader=None, header=None):
         """Return the nested message dict.
 
         This format is different from what is sent over the wire. The
         serialize/unserialize methods converts this nested message dict to the wire
         format, which is a list of message parts.
         """
         msg = {}
         header = self.msg_header(msg_type) if header is None else header
         msg['header'] = header
         msg['msg_id'] = header['msg_id']
         msg['msg_type'] = header['msg_type']
         msg['parent_header'] = {} if parent is None else extract_header(parent)
         msg['content'] = {} if content is None else content
         sub = {} if subheader is None else subheader
         msg['header'].update(sub)
         return msg
 
     def sign(self, msg_list):
         """Sign a message with HMAC digest. If no auth, return b''.
 
         Parameters
         ----------
         msg_list : list
             The [p_header,p_parent,p_content] part of the message list. 
         """
         if self.auth is None:
             return b''
         h = self.auth.copy()
         for m in msg_list:
             h.update(m)
         return str_to_bytes(h.hexdigest())
     
     def serialize(self, msg, ident=None):
         """Serialize the message components to bytes.
 
         This is roughly the inverse of unserialize. The serialize/unserialize
         methods work with full message lists, whereas pack/unpack work with
         the individual message parts in the message list.
 
         Parameters
         ----------
         msg : dict or Message
             The nexted message dict as returned by the self.msg method.
 
         Returns
         -------
         msg_list : list
             The list of bytes objects to be sent with the format:
             [ident1,ident2,...,DELIM,HMAC,p_header,p_parent,p_content,
              buffer1,buffer2,...]. In this list, the p_* entities are
             the packed or serialized versions, so if JSON is used, these
             are utf8 encoded JSON strings.
         """
         content = msg.get('content', {})
         if content is None:
             content = self.none
         elif isinstance(content, dict):
             content = self.pack(content)
         elif isinstance(content, bytes):
             # content is already packed, as in a relayed message
             pass
         elif isinstance(content, unicode):
             # should be bytes, but JSON often spits out unicode
             content = content.encode('utf8')
         else:
             raise TypeError("Content incorrect type: %s"%type(content))
         
         real_message = [self.pack(msg['header']), 
                         self.pack(msg['parent_header']), 
                         content
         ]
         
         to_send = []
 
         if isinstance(ident, list):
             # accept list of idents
             to_send.extend(ident)
         elif ident is not None:
             to_send.append(ident)
         to_send.append(DELIM)
         
         signature = self.sign(real_message)
         to_send.append(signature)
         
         to_send.extend(real_message)
 
         return to_send
         
     def send(self, stream, msg_or_type, content=None, parent=None, ident=None,
              buffers=None, subheader=None, track=False, header=None):
         """Build and send a message via stream or socket.
 
         The message format used by this function internally is as follows:
 
         [ident1,ident2,...,DELIM,HMAC,p_header,p_parent,p_content,
          buffer1,buffer2,...] 
 
         The serialize/unserialize methods convert the nested message dict into this
         format.
 
         Parameters
         ----------
         
         stream : zmq.Socket or ZMQStream
             The socket-like object used to send the data.
         msg_or_type : str or Message/dict
             Normally, msg_or_type will be a msg_type unless a message is being 
             sent more than once. If a header is supplied, this can be set to
             None and the msg_type will be pulled from the header.
         
         content : dict or None
             The content of the message (ignored if msg_or_type is a message).
         header : dict or None
             The header dict for the message (ignores if msg_to_type is a message).
         parent : Message or dict or None
             The parent or parent header describing the parent of this message
             (ignored if msg_or_type is a message).
         ident : bytes or list of bytes
             The zmq.IDENTITY routing path.
         subheader : dict or None
             Extra header keys for this message's header (ignored if msg_or_type
             is a message).
         buffers : list or None
             The already-serialized buffers to be appended to the message.
         track : bool
             Whether to track.  Only for use with Sockets, because ZMQStream
             objects cannot track messages.
         
         Returns
         -------
         msg : dict
             The constructed message.
         (msg,tracker) : (dict, MessageTracker)
             if track=True, then a 2-tuple will be returned, 
             the first element being the constructed
             message, and the second being the MessageTracker
             
         """
 
         if not isinstance(stream, (zmq.Socket, ZMQStream)):
             raise TypeError("stream must be Socket or ZMQStream, not %r"%type(stream))
         elif track and isinstance(stream, ZMQStream):
             raise TypeError("ZMQStream cannot track messages")
         
         if isinstance(msg_or_type, (Message, dict)):
             # We got a Message or message dict, not a msg_type so don't
             # build a new Message.
             msg = msg_or_type
         else:
             msg = self.msg(msg_or_type, content=content, parent=parent, 
                            subheader=subheader, header=header)
 
         buffers = [] if buffers is None else buffers
         to_send = self.serialize(msg, ident)
         flag = 0
         if buffers:
             flag = zmq.SNDMORE
             _track = False
         else:
             _track=track
         if track:
             tracker = stream.send_multipart(to_send, flag, copy=False, track=_track)
         else:
             tracker = stream.send_multipart(to_send, flag, copy=False)
         for b in buffers[:-1]:
             stream.send(b, flag, copy=False)
         if buffers:
             if track:
                 tracker = stream.send(buffers[-1], copy=False, track=track)
             else:
                 tracker = stream.send(buffers[-1], copy=False)
 
         # omsg = Message(msg)
         if self.debug:
             pprint.pprint(msg)
             pprint.pprint(to_send)
             pprint.pprint(buffers)
         
         msg['tracker'] = tracker
         
         return msg
 
     def send_raw(self, stream, msg_list, flags=0, copy=True, ident=None):
         """Send a raw message via ident path.
 
         This method is used to send a already serialized message.
 
         Parameters
         ----------
         stream : ZMQStream or Socket
             The ZMQ stream or socket to use for sending the message.
         msg_list : list
             The serialized list of messages to send. This only includes the
             [p_header,p_parent,p_content,buffer1,buffer2,...] portion of
             the message.
         ident : ident or list
             A single ident or a list of idents to use in sending.
         """
         to_send = []
         if isinstance(ident, bytes):
             ident = [ident]
         if ident is not None:
             to_send.extend(ident)
 
         to_send.append(DELIM)
         to_send.append(self.sign(msg_list))
         to_send.extend(msg_list)
         stream.send_multipart(msg_list, flags, copy=copy)
     
     def recv(self, socket, mode=zmq.NOBLOCK, content=True, copy=True):
         """Receive and unpack a message.
 
         Parameters
         ----------
         socket : ZMQStream or Socket
             The socket or stream to use in receiving.
 
         Returns
         -------
         [idents], msg
             [idents] is a list of idents and msg is a nested message dict of
             same format as self.msg returns.
         """
         if isinstance(socket, ZMQStream):
             socket = socket.socket
         try:
             msg_list = socket.recv_multipart(mode)
         except zmq.ZMQError as e:
             if e.errno == zmq.EAGAIN:
                 # We can convert EAGAIN to None as we know in this case
                 # recv_multipart won't return None.
                 return None,None
             else:
                 raise
         # split multipart message into identity list and message dict
         # invalid large messages can cause very expensive string comparisons
         idents, msg_list = self.feed_identities(msg_list, copy)
         try:
             return idents, self.unserialize(msg_list, content=content, copy=copy)
         except Exception as e:
             # TODO: handle it
             raise e
     
     def feed_identities(self, msg_list, copy=True):
         """Split the identities from the rest of the message.
 
         Feed until DELIM is reached, then return the prefix as idents and
         remainder as msg_list. This is easily broken by setting an IDENT to DELIM,
         but that would be silly.
         
         Parameters
         ----------
         msg_list : a list of Message or bytes objects
             The message to be split.
         copy : bool
             flag determining whether the arguments are bytes or Messages
         
         Returns
         -------
         (idents, msg_list) : two lists
             idents will always be a list of bytes, each of which is a ZMQ
             identity. msg_list will be a list of bytes or zmq.Messages of the
             form [HMAC,p_header,p_parent,p_content,buffer1,buffer2,...] and
             should be unpackable/unserializable via self.unserialize at this
             point.
         """
         if copy:
             idx = msg_list.index(DELIM)
             return msg_list[:idx], msg_list[idx+1:]
         else:
             failed = True
             for idx,m in enumerate(msg_list):
                 if m.bytes == DELIM:
                     failed = False
                     break
             if failed:
                 raise ValueError("DELIM not in msg_list")
             idents, msg_list = msg_list[:idx], msg_list[idx+1:]
             return [m.bytes for m in idents], msg_list
     
     def unserialize(self, msg_list, content=True, copy=True):
         """Unserialize a msg_list to a nested message dict.
 
         This is roughly the inverse of serialize. The serialize/unserialize
         methods work with full message lists, whereas pack/unpack work with
         the individual message parts in the message list.
 
         Parameters:
         -----------
         msg_list : list of bytes or Message objects
             The list of message parts of the form [HMAC,p_header,p_parent,
             p_content,buffer1,buffer2,...].
         content : bool (True)
             Whether to unpack the content dict (True), or leave it packed
             (False).
         copy : bool (True)
             Whether to return the bytes (True), or the non-copying Message
             object in each place (False).
 
         Returns
         -------
         msg : dict
             The nested message dict with top-level keys [header, parent_header,
             content, buffers].
         """
         minlen = 4
         message = {}
         if not copy:
             for i in range(minlen):
                 msg_list[i] = msg_list[i].bytes
         if self.auth is not None:
             signature = msg_list[0]
             if not signature:
                 raise ValueError("Unsigned Message")
             if signature in self.digest_history:
                 raise ValueError("Duplicate Signature: %r"%signature)
             self.digest_history.add(signature)
             check = self.sign(msg_list[1:4])
             if not signature == check:
                 raise ValueError("Invalid Signature: %r"%signature)
         if not len(msg_list) >= minlen:
             raise TypeError("malformed message, must have at least %i elements"%minlen)
         header = self.unpack(msg_list[1])
         message['header'] = header
         message['msg_id'] = header['msg_id']
         message['msg_type'] = header['msg_type']
         message['parent_header'] = self.unpack(msg_list[2])
         if content:
             message['content'] = self.unpack(msg_list[3])
         else:
             message['content'] = msg_list[3]
         
         message['buffers'] = msg_list[4:]
         return message
 
 def test_msg2obj():
     am = dict(x=1)
     ao = Message(am)
     assert ao.x == am['x']
 
     am['y'] = dict(z=1)
     ao = Message(am)
     assert ao.y.z == am['y']['z']
     
     k1, k2 = 'y', 'z'
     assert ao[k1][k2] == am[k1][k2]
     
     am2 = dict(ao)
     assert am['x'] == am2['x']
     assert am['y']['z'] == am2['y']['z']