62e95ddc1e
* convert map to list in heat.engine.api. This is done because stacks are garbage collected once we go out of scope using weakrefs. However, in python 3, since everything is lazily loaded, when we iterate over the stack['resources'] iterable, we end up referencing the previously garbage collected stack object. So resolve everything before returning the list. * sort the __repr__ of dependencies to return a consistent string * Don't encode support_status. There is no need to encode it. Without * this, in py3, we'd effectively be comparing a unicode string to byte string and thus breaking the environment.get_types() API partially. * test_case: explcitly cast strings to int before comparing them with integers. * test_case: use a more accurate sorted expression partial blueprint heat-python34-support Change-Id: Ic9d78034b7e5478c4cb14344d64b9e838a12bf57
299 lines
9.4 KiB
Python
299 lines
9.4 KiB
Python
#
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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 collections
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import itertools
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import six
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from heat.common import exception
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from heat.common.i18n import _
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class CircularDependencyException(exception.HeatException):
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msg_fmt = _("Circular Dependency Found: %(cycle)s")
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@six.python_2_unicode_compatible
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class Node(object):
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'''A node in a dependency graph.'''
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def __init__(self, requires=None, required_by=None):
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'''
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Initialise the node, optionally with a set of keys this node
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requires and/or a set of keys that this node is required by.
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'''
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self.require = requires and requires.copy() or set()
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self.satisfy = required_by and required_by.copy() or set()
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def copy(self):
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'''Return a copy of the node.'''
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return Node(self.require, self.satisfy)
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def reverse_copy(self):
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'''Return a copy of the node with the edge directions reversed.'''
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return Node(self.satisfy, self.require)
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def required_by(self, source=None):
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'''
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List the keys that require this node, and optionally add a
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new one.
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'''
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if source is not None:
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self.satisfy.add(source)
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return iter(self.satisfy)
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def requires(self, target=None):
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'''
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Add a key that this node requires, and optionally add a
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new one.
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'''
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if target is not None:
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self.require.add(target)
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return iter(self.require)
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def __isub__(self, target):
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'''Remove a key that this node requires.'''
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self.require.remove(target)
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return self
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def __nonzero__(self):
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'''Return True if this node is not a leaf (it requires other nodes).'''
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return bool(self.require)
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def __bool__(self):
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'''Return True if this node is not a leaf (it requires other nodes).'''
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return self.__nonzero__()
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def stem(self):
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'''Return True if this node is a stem (required by nothing).'''
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return not bool(self.satisfy)
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def disjoint(self):
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'''Return True if this node is both a leaf and a stem.'''
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return (not self) and self.stem()
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def __len__(self):
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'''Count the number of keys required by this node.'''
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return len(self.require)
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def __iter__(self):
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'''Iterate over the keys required by this node.'''
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return iter(self.require)
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def __str__(self):
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'''Return a human-readable string representation of the node.'''
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text = '{%s}' % ', '.join(str(n) for n in self)
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return six.text_type(text)
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def __repr__(self):
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'''Return a string representation of the node.'''
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return repr(self.require)
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@six.python_2_unicode_compatible
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class Graph(collections.defaultdict):
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'''A mutable mapping of objects to nodes in a dependency graph.'''
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def __init__(self, *args):
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super(Graph, self).__init__(Node, *args)
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def map(self, func):
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'''
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Return a dictionary derived from mapping the supplied function onto
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each node in the graph.
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'''
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return dict((k, func(n)) for k, n in self.items())
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def copy(self):
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'''Return a copy of the graph.'''
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return Graph(self.map(lambda n: n.copy()))
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def reverse_copy(self):
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'''Return a copy of the graph with the edges reversed.'''
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return Graph(self.map(lambda n: n.reverse_copy()))
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def edges(self):
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'''Return an iterator over all of the edges in the graph.'''
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def outgoing_edges(rqr, node):
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if node.disjoint():
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yield (rqr, None)
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else:
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for rqd in node:
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yield (rqr, rqd)
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return itertools.chain.from_iterable(outgoing_edges(*i)
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for i in six.iteritems(self))
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def __delitem__(self, key):
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'''Delete the node given by the specified key from the graph.'''
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node = self[key]
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for src in node.required_by():
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src_node = self[src]
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if key in src_node:
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src_node -= key
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return super(Graph, self).__delitem__(key)
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def __str__(self):
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'''Convert the graph to a human-readable string.'''
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pairs = ('%s: %s' % (str(k), str(v)) for k, v in six.iteritems(self))
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text = '{%s}' % ', '.join(pairs)
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return six.text_type(text)
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@staticmethod
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def toposort(graph):
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'''
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Return a topologically sorted iterator over a dependency graph.
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This is a destructive operation for the graph.
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'''
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for iteration in six.moves.xrange(len(graph)):
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for key, node in six.iteritems(graph):
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if not node:
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yield key
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del graph[key]
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break
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else:
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# There are nodes remaining, but none without
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# dependencies: a cycle
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raise CircularDependencyException(cycle=six.text_type(graph))
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@six.python_2_unicode_compatible
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class Dependencies(object):
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'''Helper class for calculating a dependency graph.'''
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def __init__(self, edges=None):
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'''
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Initialise, optionally with a list of edges, in the form of
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(requirer, required) tuples.
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'''
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edges = edges or []
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self._graph = Graph()
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for e in edges:
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self += e
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def __iadd__(self, edge):
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'''Add another edge, in the form of a (requirer, required) tuple.'''
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requirer, required = edge
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if required is None:
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# Just ensure the node is created by accessing the defaultdict
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self._graph[requirer]
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else:
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self._graph[required].required_by(requirer)
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self._graph[requirer].requires(required)
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return self
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def required_by(self, last):
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'''
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List the keys that require the specified node.
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'''
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if last not in self._graph:
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raise KeyError
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return self._graph[last].required_by()
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def requires(self, target):
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'''
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List the keys that require the specified node.
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'''
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if target not in self._graph:
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raise KeyError
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return self._graph[target].requires()
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def __getitem__(self, last):
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'''
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Return a partial dependency graph consisting of the specified node and
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all those that require it only.
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'''
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if last not in self._graph:
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raise KeyError
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def get_edges(key):
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def requirer_edges(rqr):
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# Concatenate the dependency on the current node with the
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# recursive generated list
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return itertools.chain([(rqr, key)], get_edges(rqr))
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# Get the edge list for each node that requires the current node
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edge_lists = six.moves.map(requirer_edges,
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self._graph[key].required_by())
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# Combine the lists into one long list
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return itertools.chain.from_iterable(edge_lists)
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if self._graph[last].stem():
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# Nothing requires this, so just add the node itself
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edges = [(last, None)]
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else:
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edges = get_edges(last)
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return Dependencies(edges)
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def leaves(self):
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'''
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Return an iterator over all of the leaf nodes in the graph.
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'''
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return (requirer for requirer, required in self._graph.items()
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if not required)
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def roots(self):
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'''
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Return an iterator over all of the root nodes in the graph.
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'''
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return (requirer for requirer, required in self.graph(
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reverse=True).items() if not required)
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def translate(self, transform):
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'''
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Translate all of the nodes using a transform function.
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Returns a new Dependencies object.
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'''
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def transform_key(key):
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return transform(key) if key is not None else None
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edges = self._graph.edges()
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return type(self)(tuple(map(transform_key, e)) for e in edges)
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def __str__(self):
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'''
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Return a human-readable string representation of the dependency graph
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'''
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return six.text_type(self._graph)
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def __repr__(self):
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'''Return a consistent string representation of the object.'''
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edge_reprs = list(repr(e) for e in self._graph.edges())
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edge_reprs.sort()
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text = 'Dependencies([%s])' % ', '.join(edge_reprs)
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return text
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def graph(self, reverse=False):
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'''Return a copy of the underlying dependency graph.'''
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if reverse:
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return self._graph.reverse_copy()
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else:
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return self._graph.copy()
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def __iter__(self):
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'''Return a topologically sorted iterator.'''
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return Graph.toposort(self.graph())
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def __reversed__(self):
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'''Return a reverse topologically sorted iterator.'''
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return Graph.toposort(self.graph(reverse=True))
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