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plugable: Move plugin base class and override logic to API

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Each API object now maintains its own view of registered plugins. This change
removes the need to register plugin base classes.

This reverts commit 2db741e847.

https://fedorahosted.org/freeipa/ticket/3090
https://fedorahosted.org/freeipa/ticket/5073

Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>
This commit is contained in:
Jan Cholasta
2015-06-24 15:14:54 +00:00
parent e21dad4e1c
commit f87ba5ee08
5 changed files with 147 additions and 267 deletions
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3
ipalib/backend.py
View File

@@ -27,10 +27,7 @@ import os
from errors import PublicError, InternalError, CommandError
from request import context, Connection, destroy_context
register = plugable.Registry()
@register.base()
class Backend(plugable.Plugin):
"""
Base class for all backend plugins.

9
ipalib/frontend.py
View File

@@ -27,7 +27,7 @@ from distutils import version
from ipapython.version import API_VERSION
from ipapython.ipa_log_manager import root_logger
from base import NameSpace
from plugable import Plugin, Registry, is_production_mode
from plugable import Plugin, is_production_mode
from parameters import create_param, Param, Str, Flag, Password
from output import Output, Entry, ListOfEntries
from text import _
@@ -40,9 +40,6 @@ from textwrap import wrap
RULE_FLAG = 'validation_rule'
register = Registry()
def rule(obj):
assert not hasattr(obj, RULE_FLAG)
setattr(obj, RULE_FLAG, True)
@@ -369,7 +366,6 @@ class HasParam(Plugin):
setattr(self, name, namespace)
@register.base()
class Command(HasParam):
"""
A public IPA atomic operation.
@@ -1124,7 +1120,6 @@ class Local(Command):
return self.forward(*args, **options)
@register.base()
class Object(HasParam):
finalize_early = False
@@ -1283,7 +1278,6 @@ class Attribute(Plugin):
super(Attribute, self)._on_finalize()
@register.base()
class Method(Attribute, Command):
"""
A command with an associated object.
@@ -1370,7 +1364,6 @@ class Method(Attribute, Command):
yield param
@register.base()
class Updater(Plugin):
"""
An LDAP update with an associated object (always update).

279
ipalib/plugable.py
View File

@@ -35,6 +35,7 @@ import subprocess
import optparse
import errors
import textwrap
import collections
from config import Env
import util
@@ -74,94 +75,13 @@ class Registry(object):
For forward compatibility, make sure that the module-level instance of
this object is named "register".
"""
__allowed = {}
__registered = set()
def base(self):
def decorator(base):
if not inspect.isclass(base):
raise TypeError('plugin base must be a class; got %r' % base)
if base in self.__allowed:
raise errors.PluginDuplicateError(plugin=base)
self.__allowed[base] = {}
return base
def __call__(self):
def decorator(cls):
API.register(cls)
return cls
return decorator
def __findbases(self, klass):
"""
Iterates through allowed bases that ``klass`` is a subclass of.
Raises `errors.PluginSubclassError` if ``klass`` is not a subclass of
any allowed base.
:param klass: The plugin class to find bases for.
"""
found = False
for (base, sub_d) in self.__allowed.iteritems():
if issubclass(klass, base):
found = True
yield (base, sub_d)
if not found:
raise errors.PluginSubclassError(
plugin=klass, bases=self.__allowed.keys()
)
def __call__(self, override=False):
def decorator(klass):
if not inspect.isclass(klass):
raise TypeError('plugin must be a class; got %r' % klass)
# Raise DuplicateError if this exact class was already registered:
if klass in self.__registered:
raise errors.PluginDuplicateError(plugin=klass)
# Find the base class or raise SubclassError:
for (base, sub_d) in self.__findbases(klass):
# Check override:
if klass.__name__ in sub_d:
if not override:
# Must use override=True to override:
raise errors.PluginOverrideError(
base=base.__name__,
name=klass.__name__,
plugin=klass,
)
else:
if override:
# There was nothing already registered to override:
raise errors.PluginMissingOverrideError(
base=base.__name__,
name=klass.__name__,
plugin=klass,
)
# The plugin is okay, add to sub_d:
sub_d[klass.__name__] = klass
# The plugin is okay, add to __registered:
self.__registered.add(klass)
return klass
return decorator
def __base_iter(self, *allowed):
for base in allowed:
sub_d = self.__allowed[base]
subclasses = set(sub_d.itervalues())
yield (base, subclasses)
def iter(self, *allowed):
for base in allowed:
if base not in self.__allowed:
raise TypeError("unknown plugin base %r" % base)
return self.__base_iter(*allowed)
class SetProxy(ReadOnly):
"""
@@ -441,28 +361,60 @@ class Plugin(ReadOnly):
)
class API(DictProxy):
class Registrar(collections.Mapping):
"""
Dynamic API object through which `Plugin` instances are accessed.
Collects plugin classes as they are registered.
The Registrar does not instantiate plugins... it only implements the
override logic and stores the plugins in a namespace per allowed base
class.
The plugins are instantiated when `API.finalize()` is called.
"""
def __init__(self):
self.__registry = collections.OrderedDict()
def __init__(self, allowed, packages):
self.__allowed = allowed
self.packages = packages
self.__d = dict()
self.__done = set()
self.__registry = Registry()
self.env = Env()
super(API, self).__init__(self.__d)
def register(self, klass, override=False):
def __call__(self, klass, override=False):
"""
Register the plugin ``klass``.
:param klass: A subclass of `Plugin` to attempt to register.
:param override: If true, override an already registered plugin.
"""
self.__registry(override)(klass)
if not inspect.isclass(klass):
raise TypeError('plugin must be a class; got %r' % klass)
# Raise DuplicateError if this exact class was already registered:
if klass in self.__registry:
raise errors.PluginDuplicateError(plugin=klass)
# The plugin is okay, add to __registry:
self.__registry[klass] = dict(override=override)
def __getitem__(self, key):
return self.__registry[key]
def __iter__(self):
return iter(self.__registry)
def __len__(self):
return len(self.__registry)
class API(DictProxy):
"""
Dynamic API object through which `Plugin` instances are accessed.
"""
register = Registrar()
def __init__(self, allowed, packages):
self.__plugins = {base: {} for base in allowed}
self.packages = packages
self.__d = dict()
self.__done = set()
self.env = Env()
super(API, self).__init__(self.__d)
def __doing(self, name):
if name in self.__done:
@@ -638,6 +590,8 @@ class API(DictProxy):
return
for package in self.packages:
self.import_plugins(package)
for klass, kwargs in self.register.iteritems():
self.add_plugin(klass, **kwargs)
# FIXME: This method has no unit test
def import_plugins(self, package):
@@ -686,6 +640,51 @@ class API(DictProxy):
self.log.error('could not load plugin module %r\n%s', pyfile, traceback.format_exc())
raise
def add_plugin(self, klass, override=False):
"""
Add the plugin ``klass``.
:param klass: A subclass of `Plugin` to attempt to add.
:param override: If true, override an already added plugin.
"""
if not inspect.isclass(klass):
raise TypeError('plugin must be a class; got %r' % klass)
# Find the base class or raise SubclassError:
found = False
for (base, sub_d) in self.__plugins.iteritems():
if not issubclass(klass, base):
continue
found = True
# Check override:
if klass.__name__ in sub_d:
if not override:
# Must use override=True to override:
raise errors.PluginOverrideError(
base=base.__name__,
name=klass.__name__,
plugin=klass,
)
else:
if override:
# There was nothing already registered to override:
raise errors.PluginMissingOverrideError(
base=base.__name__,
name=klass.__name__,
plugin=klass,
)
# The plugin is okay, add to sub_d:
sub_d[klass.__name__] = klass
if not found:
raise errors.PluginSubclassError(
plugin=klass,
bases=self.__plugins.keys(),
)
def finalize(self):
"""
Finalize the registration, instantiate the plugins.
@@ -696,56 +695,25 @@ class API(DictProxy):
self.__doing('finalize')
self.__do_if_not_done('load_plugins')
class PluginInstance(object):
"""
Represents a plugin instance.
"""
i = 0
def __init__(self, klass):
self.created = self.next()
self.klass = klass
self.instance = klass()
self.bases = []
@classmethod
def next(cls):
cls.i += 1
return cls.i
class PluginInfo(ReadOnly):
def __init__(self, p):
assert isinstance(p, PluginInstance)
self.created = p.created
self.name = p.klass.__name__
self.module = str(p.klass.__module__)
self.plugin = '%s.%s' % (self.module, self.name)
self.bases = tuple(b.__name__ for b in p.bases)
if not is_production_mode(self):
lock(self)
plugins = {}
tofinalize = set()
def plugin_iter(base, subclasses):
for klass in subclasses:
assert issubclass(klass, base)
if klass not in plugins:
plugins[klass] = PluginInstance(klass)
p = plugins[klass]
if not is_production_mode(self):
assert base not in p.bases
p.bases.append(base)
if klass.finalize_early or not self.env.plugins_on_demand:
tofinalize.add(p)
yield p.instance
production_mode = is_production_mode(self)
for base, subclasses in self.__registry.iter(*self.__allowed):
plugins = {}
plugin_info = {}
for base, sub_d in self.__plugins.iteritems():
name = base.__name__
namespace = NameSpace(
plugin_iter(base, subclasses)
)
members = []
for klass in sub_d.itervalues():
try:
instance = plugins[klass]
except KeyError:
instance = plugins[klass] = klass()
members.append(instance)
plugin_info.setdefault(
'%s.%s' % (klass.__module__, klass.__name__),
[]).append(name)
namespace = NameSpace(members)
if not production_mode:
assert not (
name in self.__d or hasattr(self, name)
@@ -753,19 +721,20 @@ class API(DictProxy):
self.__d[name] = namespace
object.__setattr__(self, name, namespace)
for p in plugins.itervalues():
p.instance.set_api(self)
if not production_mode:
assert p.instance.api is self
for instance in plugins.itervalues():
instance.set_api(self)
for p in tofinalize:
p.instance.ensure_finalized()
for klass, instance in plugins.iteritems():
if not production_mode:
assert islocked(p.instance) is True
assert instance.api is self
if klass.finalize_early or not self.env.plugins_on_demand:
instance.ensure_finalized()
if not production_mode:
assert islocked(instance)
object.__setattr__(self, '_API__finalized', True)
tuple(PluginInfo(p) for p in plugins.itervalues())
object.__setattr__(self, 'plugins',
tuple(PluginInfo(p) for p in plugins.itervalues())
tuple((k, tuple(v)) for k, v in plugin_info.iteritems())
)