42a665d06f
To at least try to support things like windows it's better if we can make an attempt to use the platform neutral characters for line separator(s) where appropriate. Change-Id: Icc533ed4d4c94f461b7f19600b74146221f17b18
253 lines
8.5 KiB
Python
253 lines
8.5 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2012 Yahoo! Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import os
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import traceback
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import six
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class TaskFlowException(Exception):
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"""Base class for *most* exceptions emitted from this library.
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NOTE(harlowja): in later versions of python we can likely remove the need
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to have a cause here as PY3+ have implemented PEP 3134 which handles
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chaining in a much more elegant manner.
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:param message: the exception message, typically some string that is
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useful for consumers to view when debugging or analyzing
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failures.
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:param cause: the cause of the exception being raised, when provided this
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should itself be an exception instance, this is useful for
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creating a chain of exceptions for versions of python where
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this is not yet implemented/supported natively.
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"""
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def __init__(self, message, cause=None):
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super(TaskFlowException, self).__init__(message)
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self._cause = cause
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@property
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def cause(self):
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return self._cause
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def pformat(self, indent=2, indent_text=" "):
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"""Pretty formats a taskflow exception + any connected causes."""
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if indent < 0:
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raise ValueError("indent must be greater than or equal to zero")
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return os.linesep.join(self._pformat(self, [], 0,
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indent=indent,
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indent_text=indent_text))
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@classmethod
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def _pformat(cls, excp, lines, current_indent, indent=2, indent_text=" "):
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line_prefix = indent_text * current_indent
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for line in traceback.format_exception_only(type(excp), excp):
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# We'll add our own newlines on at the end of formatting.
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#
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# NOTE(harlowja): the reason we don't search for os.linesep is
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# that the traceback module seems to only use '\n' (for some
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# reason).
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if line.endswith("\n"):
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line = line[0:-1]
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lines.append(line_prefix + line)
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try:
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cause = excp.cause
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except AttributeError:
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pass
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else:
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if cause is not None:
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cls._pformat(cause, lines, current_indent + indent,
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indent=indent, indent_text=indent_text)
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return lines
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# Errors related to storage or operations on storage units.
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class StorageFailure(TaskFlowException):
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"""Raised when storage backends can not be read/saved/deleted."""
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# Conductor related errors.
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class ConductorFailure(TaskFlowException):
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"""Errors related to conducting activities."""
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# Job related errors.
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class JobFailure(TaskFlowException):
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"""Errors related to jobs or operations on jobs."""
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class UnclaimableJob(JobFailure):
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"""Raised when a job can not be claimed."""
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# Engine/ during execution related errors.
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class ExecutionFailure(TaskFlowException):
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"""Errors related to engine execution."""
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class RequestTimeout(ExecutionFailure):
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"""Raised when a worker request was not finished within allotted time."""
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class InvalidState(ExecutionFailure):
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"""Raised when a invalid state transition is attempted while executing."""
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# Other errors that do not fit the above categories (at the current time).
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class DependencyFailure(TaskFlowException):
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"""Raised when some type of dependency problem occurs."""
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class AmbiguousDependency(DependencyFailure):
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"""Raised when some type of ambiguous dependency problem occurs."""
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class MissingDependencies(DependencyFailure):
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"""Raised when a entity has dependencies that can not be satisfied.
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:param who: the entity that caused the missing dependency to be triggered.
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:param requirements: the dependency which were not satisfied.
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Further arguments are interpreted as for in
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:py:class:`~taskflow.exceptions.TaskFlowException`.
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"""
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#: Exception message template used when creating an actual message.
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MESSAGE_TPL = ("%(who)s requires %(requirements)s but no other entity"
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" produces said requirements")
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def __init__(self, who, requirements, cause=None):
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message = self.MESSAGE_TPL % {'who': who, 'requirements': requirements}
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super(MissingDependencies, self).__init__(message, cause=cause)
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self.missing_requirements = requirements
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class CompilationFailure(TaskFlowException):
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"""Raised when some type of compilation issue is found."""
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class IncompatibleVersion(TaskFlowException):
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"""Raised when some type of version incompatibility is found."""
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class Duplicate(TaskFlowException):
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"""Raised when a duplicate entry is found."""
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class NotFound(TaskFlowException):
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"""Raised when some entry in some object doesn't exist."""
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class Empty(TaskFlowException):
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"""Raised when some object is empty when it shouldn't be."""
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class MultipleChoices(TaskFlowException):
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"""Raised when some decision can't be made due to many possible choices."""
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class InvalidFormat(TaskFlowException):
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"""Raised when some object/entity is not in the expected format."""
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# Others.
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class NotImplementedError(NotImplementedError):
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"""Exception for when some functionality really isn't implemented.
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This is typically useful when the library itself needs to distinguish
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internal features not being made available from users features not being
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made available/implemented (and to avoid misinterpreting the two).
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"""
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class WrappedFailure(Exception):
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"""Wraps one or several failure objects.
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When exception/s cannot be re-raised (for example, because the value and
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traceback are lost in serialization) or there are several exceptions active
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at the same time (due to more than one thread raising exceptions), we will
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wrap the corresponding failure objects into this exception class and
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*may* reraise this exception type to allow users to handle the contained
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failures/causes as they see fit...
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See the failure class documentation for a more comprehensive set of reasons
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why this object *may* be reraised instead of the original exception.
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:param causes: the :py:class:`~taskflow.types.failure.Failure` objects
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that caused this this exception to be raised.
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"""
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def __init__(self, causes):
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super(WrappedFailure, self).__init__()
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self._causes = []
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for cause in causes:
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if cause.check(type(self)) and cause.exception:
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# NOTE(imelnikov): flatten wrapped failures.
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self._causes.extend(cause.exception)
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else:
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self._causes.append(cause)
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def __iter__(self):
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"""Iterate over failures that caused the exception."""
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return iter(self._causes)
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def __len__(self):
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"""Return number of wrapped failures."""
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return len(self._causes)
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def check(self, *exc_classes):
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"""Check if any of exception classes caused the failure/s.
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:param exc_classes: exception types/exception type names to
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search for.
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If any of the contained failures were caused by an exception of a
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given type, the corresponding argument that matched is returned. If
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not then none is returned.
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"""
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if not exc_classes:
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return None
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for cause in self:
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result = cause.check(*exc_classes)
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if result is not None:
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return result
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return None
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def __str__(self):
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causes = [exception_message(cause) for cause in self._causes]
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return 'WrappedFailure: %s' % causes
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def exception_message(exc):
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"""Return the string representation of exception.
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:param exc: exception object to get a string representation of.
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"""
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# NOTE(imelnikov): Dealing with non-ascii data in python is difficult:
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# https://bugs.launchpad.net/taskflow/+bug/1275895
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# https://bugs.launchpad.net/taskflow/+bug/1276053
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try:
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return six.text_type(exc)
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except UnicodeError:
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return str(exc)
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