139 lines
5.1 KiB
Python
139 lines
5.1 KiB
Python
# -*- coding: utf-8 -*-
|
|
#
|
|
# 2011 Steven Armstrong (steven-cdist at armstrong.cc)
|
|
#
|
|
# This file is part of cdist.
|
|
#
|
|
# cdist is free software: you can redistribute it and/or modify
|
|
# it under the terms of the GNU General Public License as published by
|
|
# the Free Software Foundation, either version 3 of the License, or
|
|
# (at your option) any later version.
|
|
#
|
|
# cdist is distributed in the hope that it will be useful,
|
|
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
# GNU General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU General Public License
|
|
# along with cdist. If not, see <http://www.gnu.org/licenses/>.
|
|
#
|
|
#
|
|
|
|
import logging
|
|
import os
|
|
import itertools
|
|
import fnmatch
|
|
|
|
import cdist
|
|
|
|
log = logging.getLogger(__name__)
|
|
|
|
|
|
class CircularReferenceError(cdist.Error):
|
|
def __init__(self, cdist_object, required_object):
|
|
self.cdist_object = cdist_object
|
|
self.required_object = required_object
|
|
|
|
def __str__(self):
|
|
return 'Circular reference detected: %s -> %s' % (self.cdist_object.name, self.required_object.name)
|
|
|
|
|
|
class RequirementNotFoundError(cdist.Error):
|
|
def __init__(self, requirement):
|
|
self.requirement = requirement
|
|
|
|
def __str__(self):
|
|
return 'Requirement could not be found: %s' % self.requirement
|
|
|
|
|
|
class DependencyResolver(object):
|
|
"""Cdist's dependency resolver.
|
|
|
|
Usage:
|
|
resolver = DependencyResolver(list_of_objects)
|
|
from pprint import pprint
|
|
pprint(resolver.graph)
|
|
|
|
for cdist_object in resolver:
|
|
do_something_with(cdist_object)
|
|
|
|
"""
|
|
def __init__(self, objects, logger=None):
|
|
self.objects = list(objects) # make sure we store as list, not generator
|
|
self._object_index = dict((o.name, o) for o in self.objects)
|
|
self._graph = None
|
|
self.log = logger or log
|
|
|
|
@property
|
|
def graph(self):
|
|
"""Build the dependency graph.
|
|
|
|
Returns a dict where the keys are the object names and the values are
|
|
lists of all dependencies including the key object itself.
|
|
"""
|
|
if self._graph is None:
|
|
graph = {}
|
|
for o in self.objects:
|
|
resolved = []
|
|
unresolved = []
|
|
self.resolve_object_dependencies(o, resolved, unresolved)
|
|
graph[o.name] = resolved
|
|
self._graph = graph
|
|
return self._graph
|
|
|
|
def find_requirements_by_name(self, requirements):
|
|
"""Takes a list of requirement patterns and returns a list of matching object instances.
|
|
|
|
Patterns are expected to be Unix shell-style wildcards for use with fnmatch.filter.
|
|
|
|
find_requirements_by_name(['__type/object_id', '__other_type/*']) ->
|
|
[<Object __type/object_id>, <Object __other_type/any>, <Object __other_type/match>]
|
|
"""
|
|
object_names = self._object_index.keys()
|
|
for pattern in requirements:
|
|
found = False
|
|
for requirement in fnmatch.filter(object_names, pattern):
|
|
found = True
|
|
yield self._object_index[requirement]
|
|
if not found:
|
|
# FIXME: get rid of the singleton object_id, it should be invisible to the code -> hide it in Object
|
|
singleton = os.path.join(pattern, 'singleton')
|
|
if singleton in self._object_index:
|
|
yield self._object_index[singleton]
|
|
else:
|
|
raise RequirementNotFoundError(pattern)
|
|
|
|
def resolve_object_dependencies(self, cdist_object, resolved, unresolved):
|
|
"""Resolve all dependencies for the given cdist_object and store them
|
|
in the list which is passed as the 'resolved' arguments.
|
|
|
|
e.g.
|
|
resolved = []
|
|
unresolved = []
|
|
resolve_object_dependencies(some_object, resolved, unresolved)
|
|
print("Dependencies for %s: %s" % (some_object, resolved))
|
|
"""
|
|
self.log.debug('Resolving dependencies for: %s' % cdist_object.name)
|
|
try:
|
|
unresolved.append(cdist_object)
|
|
for required_object in self.find_requirements_by_name(cdist_object.requirements):
|
|
self.log.debug("Object %s requires %s", cdist_object, required_object)
|
|
if required_object not in resolved:
|
|
if required_object in unresolved:
|
|
raise CircularReferenceError(cdist_object, required_object)
|
|
self.resolve_object_dependencies(required_object, resolved, unresolved)
|
|
resolved.append(cdist_object)
|
|
unresolved.remove(cdist_object)
|
|
except RequirementNotFoundError as e:
|
|
raise cdist.CdistObjectError(cdist_object, "requires non-existing " + e.requirement)
|
|
|
|
def __iter__(self):
|
|
"""Iterate over all unique objects while resolving dependencies.
|
|
"""
|
|
iterable = itertools.chain(*self.graph.values())
|
|
# Keep record of objects that have already been seen
|
|
seen = set()
|
|
seen_add = seen.add
|
|
for cdist_object in itertools.filterfalse(seen.__contains__, iterable):
|
|
seen_add(cdist_object)
|
|
yield cdist_object
|