IPython/kernel/error.py

# encoding: utf-8

"""Classes and functions for kernel related errors and exceptions."""

__docformat__ = "restructuredtext en"

# Tell nose to skip this module
__test__ = {}

#-------------------------------------------------------------------------------
#  Copyright (C) 2008  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
#-------------------------------------------------------------------------------
from twisted.python import failure

from IPython.kernel.core import error

#-------------------------------------------------------------------------------
# Error classes
#-------------------------------------------------------------------------------

class KernelError(error.IPythonError):
    pass

class NotDefined(KernelError):
    def __init__(self, name):
        self.name = name
        self.args = (name,)

    def __repr__(self):
        return '<NotDefined: %s>' % self.name
    
    __str__ = __repr__

class QueueCleared(KernelError):
    pass

class IdInUse(KernelError):
    pass

class ProtocolError(KernelError):
    pass

class ConnectionError(KernelError):
    pass

class InvalidEngineID(KernelError):
    pass
    
class NoEnginesRegistered(KernelError):
    pass
    
class InvalidClientID(KernelError):
    pass
    
class InvalidDeferredID(KernelError):
    pass
    
class SerializationError(KernelError):
    pass
    
class MessageSizeError(KernelError):
    pass
    
class PBMessageSizeError(MessageSizeError):
    pass
    
class ResultNotCompleted(KernelError):
    pass
    
class ResultAlreadyRetrieved(KernelError):
    pass
    
class ClientError(KernelError):
    pass

class TaskAborted(KernelError):
    pass

class TaskTimeout(KernelError):
    pass

class NotAPendingResult(KernelError):
    pass

class UnpickleableException(KernelError):
    pass

class AbortedPendingDeferredError(KernelError):
    pass

class InvalidProperty(KernelError):
    pass

class MissingBlockArgument(KernelError):
    pass

class StopLocalExecution(KernelError):
    pass

class SecurityError(KernelError):
    pass

class FileTimeoutError(KernelError):
    pass

class TaskRejectError(KernelError):
    """Exception to raise when a task should be rejected by an engine.
    
    This exception can be used to allow a task running on an engine to test
    if the engine (or the user's namespace on the engine) has the needed
    task dependencies.  If not, the task should raise this exception.  For
    the task to be retried on another engine, the task should be created
    with the `retries` argument > 1.
    
    The advantage of this approach over our older properties system is that
    tasks have full access to the user's namespace on the engines and the
    properties don't have to be managed or tested by the controller.
    """

class CompositeError(KernelError):
    def __init__(self, message, elist):
        Exception.__init__(self, *(message, elist))
        # Don't use pack_exception because it will conflict with the .message
        # attribute that is being deprecated in 2.6 and beyond.
        self.msg = message
        self.elist = elist

    def _get_engine_str(self, ev):
        try:
            ei = ev._ipython_engine_info
        except AttributeError:
            return '[Engine Exception]'
        else:
            return '[%i:%s]: ' % (ei['engineid'], ei['method'])

    def _get_traceback(self, ev):
        try:
            tb = ev._ipython_traceback_text
        except AttributeError:
            return 'No traceback available'
        else:
            return tb

    def __str__(self):
        s = str(self.msg)
        for et, ev, etb in self.elist:
            engine_str = self._get_engine_str(ev)
            s = s + '\n' + engine_str + str(et.__name__) + ': ' + str(ev)
        return s

    def print_tracebacks(self, excid=None):
        if excid is None:
            for (et,ev,etb) in self.elist:
                print self._get_engine_str(ev)
                print self._get_traceback(ev)
                print
        else:
            try:
                et,ev,etb = self.elist[excid]
            except:
                raise IndexError("an exception with index %i does not exist"%excid)
            else:
                print self._get_engine_str(ev)
                print self._get_traceback(ev)
    
    def raise_exception(self, excid=0):
        try:
            et,ev,etb = self.elist[excid]
        except:
            raise IndexError("an exception with index %i does not exist"%excid)
        else:
            raise et, ev, etb

def collect_exceptions(rlist, method):
    elist = []
    for r in rlist:
        if isinstance(r, failure.Failure):
            r.cleanFailure()
            et, ev, etb = r.type, r.value, r.tb
            # Sometimes we could have CompositeError in our list.  Just take
            # the errors out of them and put them in our new list.  This 
            # has the effect of flattening lists of CompositeErrors into one
            # CompositeError
            if et==CompositeError:
                for e in ev.elist:
                    elist.append(e)
            else:
                elist.append((et, ev, etb))
    if len(elist)==0:
        return rlist
    else:
        msg = "one or more exceptions from call to method: %s" % (method)
        # This silliness is needed so the debugger has access to the exception
        # instance (e in this case)
        try:
            raise CompositeError(msg, elist)
        except CompositeError, e:
            raise e