slixmpp/sleekxmpp/plugins/base.py
2012-06-19 01:29:48 -07:00

301 lines
9.8 KiB
Python

# -*- encoding: utf-8 -*-
"""
sleekxmpp.plugins.base
~~~~~~~~~~~~~~~~~~~~~~
This module provides XMPP functionality that
is specific to client connections.
Part of SleekXMPP: The Sleek XMPP Library
:copyright: (c) 2012 Nathanael C. Fritz
:license: MIT, see LICENSE for more details
"""
import sys
import logging
import threading
if sys.version_info >= (3, 0):
unicode = str
log = logging.getLogger(__name__)
#: Associate short string names of plugins with implementations. The
#: plugin names are based on the spec used by the plugin, such as
#: `'xep_0030'` for a plugin that implements XEP-0030.
PLUGIN_REGISTRY = {}
#: In order to do cascading plugin disabling, reverse dependencies
#: must be tracked.
PLUGIN_DEPENDENTS = {}
#: Only allow one thread to manipulate the plugin registry at a time.
REGISTRY_LOCK = threading.RLock()
class PluginNotFound(Exception):
"""Raised if an unknown plugin is accessed."""
def register_plugin(impl, name=None):
"""Add a new plugin implementation to the registry.
:param class impl: The plugin class.
The implementation class must provide a :attr:`~BasePlugin.name`
value that will be used as a short name for enabling and disabling
the plugin. The name should be based on the specification used by
the plugin. For example, a plugin implementing XEP-0030 would be
named `'xep_0030'`.
"""
if name is None:
name = impl.name
with REGISTRY_LOCK:
PLUGIN_REGISTRY[name] = impl
if name not in PLUGIN_DEPENDENTS:
PLUGIN_DEPENDENTS[name] = set()
for dep in impl.dependencies:
if dep not in PLUGIN_DEPENDENTS:
PLUGIN_DEPENDENTS[dep] = set()
PLUGIN_DEPENDENTS[dep].add(name)
def load_plugin(name, module=None):
"""Find and import a plugin module so that it can be registered.
This function is called to import plugins that have selected for
enabling, but no matching registered plugin has been found.
:param str name: The name of the plugin. It is expected that
plugins are in packages matching their name,
even though the plugin class name does not
have to match.
:param str module: The name of the base module to search
for the plugin.
"""
try:
if not module:
try:
module = 'sleekxmpp.plugins.%s' % name
__import__(module)
mod = sys.modules[module]
except:
module = 'sleekxmpp.features.%s' % name
__import__(module)
mod = sys.modules[module]
elif isinstance(module, (str, unicode)):
__import__(module)
mod = sys.modules[module]
else:
mod = module
# Add older style plugins to the registry.
if hasattr(mod, name):
plugin = getattr(mod, name)
if hasattr(plugin, 'xep') or hasattr(plugin, 'rfc'):
plugin.name = name
# Mark the plugin as an older style plugin so
# we can work around dependency issues.
plugin.old_style = True
register_plugin(plugin, name)
except:
log.exception("Unable to load plugin: %s", name)
class PluginManager(object):
def __init__(self, xmpp, config=None):
#: We will track all enabled plugins in a set so that we
#: can enable plugins in batches and pull in dependencies
#: without problems.
self._enabled = set()
#: Maintain references to active plugins.
self._plugins = {}
self._plugin_lock = threading.RLock()
#: Globally set default plugin configuration. This will
#: be used for plugins that are auto-enabled through
#: dependency loading.
self.config = config if config else {}
self.xmpp = xmpp
def register(self, plugin, enable=True):
"""Register a new plugin, and optionally enable it.
:param class plugin: The implementation class of the plugin
to register.
:param bool enable: If ``True``, immediately enable the
plugin after registration.
"""
register_plugin(plugin)
if enable:
self.enable(plugin.name)
def enable(self, name, config=None, enabled=None):
"""Enable a plugin, including any dependencies.
:param string name: The short name of the plugin.
:param dict config: Optional settings dictionary for
configuring plugin behaviour.
"""
top_level = False
if enabled is None:
enabled = set()
with self._plugin_lock:
if name not in self._enabled:
enabled.add(name)
self._enabled.add(name)
if not self.registered(name):
load_plugin(name)
plugin_class = PLUGIN_REGISTRY.get(name, None)
if not plugin_class:
raise PluginNotFound(name)
if config is None:
config = self.config.get(name, None)
plugin = plugin_class(self.xmpp, config)
self._plugins[name] = plugin
for dep in plugin.dependencies:
self.enable(dep, enabled=enabled)
plugin.plugin_init()
log.debug("Loaded Plugin: %s", plugin.description)
if top_level:
for name in enabled:
if hasattr(self.plugins[name], 'old_style'):
# Older style plugins require post_init()
# to run just before stream processing begins,
# so we don't call it here.
pass
self.plugins[name].post_init()
def enable_all(self, names=None, config=None):
"""Enable all registered plugins.
:param list names: A list of plugin names to enable. If
none are provided, all registered plugins
will be enabled.
:param dict config: A dictionary mapping plugin names to
configuration dictionaries, as used by
:meth:`~PluginManager.enable`.
"""
names = names if names else PLUGIN_REGISTRY.keys()
if config is None:
config = {}
for name in names:
self.enable(name, config.get(name, {}))
def enabled(self, name):
"""Check if a plugin has been enabled.
:param string name: The name of the plugin to check.
:return: boolean
"""
return name in self._enabled
def registered(self, name):
"""Check if a plugin has been registered.
:param string name: The name of the plugin to check.
:return: boolean
"""
return name in PLUGIN_REGISTRY
def disable(self, name, _disabled=None):
"""Disable a plugin, including any dependent upon it.
:param string name: The name of the plugin to disable.
:param set _disabled: Private set used to track the
disabled status of plugins during
the cascading process.
"""
if _disabled is None:
_disabled = set()
with self._plugin_lock:
if name not in _disabled and name in self._enabled:
_disabled.add(name)
plugin = self._plugins.get(name, None)
if plugin is None:
raise PluginNotFound(name)
for dep in PLUGIN_DEPENDENTS[name]:
self.disable(dep, _disabled)
plugin.plugin_end()
if name in self._enabled:
self._enabled.remove(name)
del self._plugins[name]
def __keys__(self):
"""Return the set of enabled plugins."""
return self._plugins.keys()
def __getitem__(self, name):
"""
Allow plugins to be accessed through the manager as if
it were a dictionary.
"""
plugin = self._plugins.get(name, None)
if plugin is None:
raise PluginNotFound(name)
return plugin
def __iter__(self):
"""Return an iterator over the set of enabled plugins."""
return self._plugins.__iter__()
def __len__(self):
"""Return the number of enabled plugins."""
return len(self._plugins)
class BasePlugin(object):
#: A short name for the plugin based on the implemented specification.
#: For example, a plugin for XEP-0030 would use `'xep_0030'`.
name = ''
#: A longer name for the plugin, describing its purpose. For example,
#: a plugin for XEP-0030 would use `'Service Discovery'` as its
#: description value.
description = ''
#: Some plugins may depend on others in order to function properly.
#: Any plugin names included in :attr:`~BasePlugin.dependencies` will
#: be initialized as needed if this plugin is enabled.
dependencies = set()
def __init__(self, xmpp, config=None):
self.xmpp = xmpp
if self.xmpp:
self.api = self.xmpp.api.wrap(self.name)
#: A plugin's behaviour may be configurable, in which case those
#: configuration settings will be provided as a dictionary.
self.config = config if config is not None else {}
def plugin_init(self):
"""Initialize plugin state, such as registering event handlers."""
pass
def plugin_end(self):
"""Cleanup plugin state, and prepare for plugin removal."""
pass
def post_init(self):
"""Initialize any cross-plugin state.
Only needed if the plugin has circular dependencies.
"""
pass
base_plugin = BasePlugin