ea272ee743
When engine changing state, the transition is now validated. This helps to avoid complex and error prone checks in engine._change_state and make validating code more reusable in different engines. Change-Id: I2a06823c532926bb3bd034f7252b14bdbbc1fa1d Implements: bp:transition-control
135 lines
4.0 KiB
Python
135 lines
4.0 KiB
Python
# -*- coding: utf-8 -*-
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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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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class TaskFlowException(Exception):
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"""Base class for exceptions emitted from this library."""
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pass
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class Duplicate(TaskFlowException):
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"""Raised when a duplicate entry is found."""
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pass
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class StorageError(TaskFlowException):
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"""Raised when logbook can not be read/saved/deleted."""
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def __init__(self, message, cause=None):
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super(StorageError, self).__init__(message)
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self.cause = cause
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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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pass
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class AlreadyExists(TaskFlowException):
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"""Raised when some entry in some object already exists."""
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pass
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class ClosedException(TaskFlowException):
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"""Raised when an access on a closed object occurs."""
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pass
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class InvalidStateException(TaskFlowException):
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"""Raised when a task/job/workflow is in an invalid state when an
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operation is attempting to apply to said task/job/workflow.
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"""
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pass
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class InvariantViolationException(TaskFlowException):
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"""Raised when flow invariant violation is attempted."""
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pass
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class UnclaimableJobException(TaskFlowException):
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"""Raised when a job can not be claimed."""
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pass
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class JobNotFound(TaskFlowException):
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"""Raised when a job entry can not be found."""
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pass
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class MissingDependencies(InvalidStateException):
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"""Raised when a entity has dependencies that can not be satisified."""
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message = ("%(who)s requires %(requirements)s but no other entity produces"
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" said requirements")
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def __init__(self, who, requirements):
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message = self.message % {'who': who, 'requirements': requirements}
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super(MissingDependencies, self).__init__(message)
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self.missing_requirements = requirements
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class DependencyFailure(TaskFlowException):
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"""Raised when flow can't resolve dependency."""
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pass
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class WrappedFailure(TaskFlowException):
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"""Wraps one or several failures
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When exception cannot be re-raised (for example, because
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the value and traceback is lost in serialization) or
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there are several exceptions, we wrap corresponding Failure
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objects into this exception class.
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"""
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def __init__(self, causes):
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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 exc_classes caused (part of) the failure.
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Arguments of this method can be exception types or type names
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(stings). If any of wrapped failures were caused by exception
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of given type, the corresponding argument is returned. Else,
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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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return 'WrappedFailure: %s' % [str(cause) for cause in self._causes]
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