| #!/usr/bin/env python3 |
| # |
| # Copyright (C) 2016 Codethink Limited |
| # |
| # This program is free software; you can redistribute it and/or |
| # modify it under the terms of the GNU Lesser General Public |
| # License as published by the Free Software Foundation; either |
| # version 2 of the License, or (at your option) any later version. |
| # |
| # This library 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 |
| # Lesser General Public License for more details. |
| # |
| # You should have received a copy of the GNU Lesser General Public |
| # License along with this library. If not, see <http://www.gnu.org/licenses/>. |
| # |
| # Authors: |
| # Tristan Van Berkom <tristan.vanberkom@codethink.co.uk> |
| |
| import os |
| import inspect |
| import pkg_resources |
| |
| from .exceptions import PluginError |
| from . import utils |
| |
| |
| # A Context for loading plugin types |
| # |
| # Args: |
| # plugin_base (PluginBase): The main PluginBase object to work with |
| # base_type (type): A base object type for this context |
| # searchpath (list): A list of paths to search for plugins |
| # |
| # Since multiple pipelines can be processed recursively |
| # within the same interpretor, it's important that we have |
| # one context associated to the processing of a given pipeline, |
| # this way sources and element types which are particular to |
| # a given BuildStream project are isolated to their respective |
| # Pipelines. |
| # |
| class PluginContext(): |
| |
| def __init__(self, plugin_base, base_type, searchpath=None, dependencies=None): |
| |
| if not searchpath: |
| raise PluginError("Cannot create plugin context without any searchpath") |
| |
| self.dependencies = dependencies |
| self.loaded_dependencies = [] |
| self.base_type = base_type # The base class plugins derive from |
| self.types = {} # Plugin type lookup table by kind |
| |
| # Raise an error if we have more than one plugin with the same name |
| self.assert_searchpath(searchpath) |
| |
| # The PluginSource object |
| self.plugin_base = plugin_base |
| self.source = plugin_base.make_plugin_source(searchpath=searchpath) |
| self.alternate_sources = [] |
| |
| # lookup(): |
| # |
| # Fetches a type loaded from a plugin in this plugin context |
| # |
| # Args: |
| # kind (str): The kind of Plugin to create |
| # |
| # Returns: the type associated with the given kind |
| # |
| # Raises: PluginError |
| # |
| def lookup(self, kind): |
| return self.ensure_plugin(kind) |
| |
| def ensure_plugin(self, kind): |
| |
| if kind not in self.types: |
| source = None |
| defaults = None |
| dist, package = self.split_name(kind) |
| |
| if dist: |
| # Find the plugin on disk using setuptools - this |
| # potentially unpacks the file and puts it in a |
| # temporary directory, but it is otherwise guaranteed |
| # to exist. |
| try: |
| plugin = pkg_resources.get_entry_info(dist, 'buildstream.plugins', package) |
| except pkg_resources.DistributionNotFound as e: |
| raise PluginError("Failed to load {} plugin '{}': {}" |
| .format(self.base_type.__name__, kind, e)) from e |
| |
| # Missing plugins will return as 'None' |
| if plugin is not None: |
| location = plugin.dist.get_resource_filename( |
| pkg_resources._manager, |
| plugin.module_name.replace('.', os.sep) + '.py' |
| ) |
| |
| # Also load the defaults - required since setuptools |
| # may need to extract the file. |
| defaults = plugin.dist.get_resource_filename( |
| pkg_resources._manager, |
| plugin.module_name.replace('.', os.sep) + '.yaml' |
| ) |
| |
| # Set the plugin-base source to the setuptools directory |
| source = self.plugin_base.make_plugin_source(searchpath=[os.path.dirname(location)]) |
| # Ensure the plugin sources aren't garbage |
| # collected - if they are, they take any loaded |
| # plugins with them, regardless of whether those |
| # have remaining references or not. |
| self.alternate_sources.append(source) |
| |
| elif package in self.source.list_plugins(): |
| source = self.source |
| |
| if not source: |
| raise PluginError("No {} type registered for kind '{}'" |
| .format(self.base_type.__name__, kind)) |
| self.types[kind] = self.load_plugin(source, package, defaults) |
| |
| if dist: |
| self.loaded_dependencies.append(kind) |
| |
| return self.types[kind] |
| |
| def load_plugin(self, source, kind, defaults): |
| |
| try: |
| plugin = source.load_plugin(kind) |
| |
| if not defaults: |
| plugin_file = inspect.getfile(plugin) |
| plugin_dir = os.path.dirname(plugin_file) |
| plugin_conf_name = "{}.yaml".format(kind) |
| defaults = os.path.join(plugin_dir, plugin_conf_name) |
| |
| except ImportError as e: |
| raise PluginError("Failed to load {} plugin '{}': {}" |
| .format(self.base_type.__name__, kind, e)) from e |
| |
| try: |
| plugin_type = plugin.setup() |
| except AttributeError as e: |
| raise PluginError("{} plugin '{}' did not provide a setup() function" |
| .format(self.base_type.__name__, kind)) from e |
| except TypeError as e: |
| raise PluginError("setup symbol in {} plugin '{}' is not a function" |
| .format(self.base_type.__name__, kind)) from e |
| |
| self.assert_plugin(kind, plugin_type) |
| self.assert_version(kind, plugin_type) |
| return (plugin_type, defaults) |
| |
| def split_name(self, name): |
| if name.count(':') > 1: |
| raise PluginError("Plugin and package names must not contain ':'") |
| |
| try: |
| dist, kind = name.split(':', maxsplit=1) |
| except ValueError: |
| dist = None |
| kind = name |
| |
| return dist, kind |
| |
| def assert_plugin(self, kind, plugin_type): |
| if kind in self.types: |
| raise PluginError("Tried to register {} plugin for existing kind '{}' " |
| "(already registered {})" |
| .format(self.base_type.__name__, kind, self.types[kind].__name__)) |
| try: |
| if not issubclass(plugin_type, self.base_type): |
| raise PluginError("{} plugin '{}' returned type '{}', which is not a subclass of {}" |
| .format(self.base_type.__name__, kind, |
| plugin_type.__name__, |
| self.base_type.__name__)) |
| except TypeError as e: |
| raise PluginError("{} plugin '{}' returned something that is not a type (expected subclass of {})" |
| .format(self.base_type.__name__, kind, |
| self.base_type.__name__)) from e |
| |
| def assert_version(self, kind, plugin_type): |
| |
| # Now assert BuildStream version |
| bst_major, bst_minor = utils.get_bst_version() |
| |
| if bst_major < plugin_type.BST_REQUIRED_VERSION_MAJOR or \ |
| (bst_major == plugin_type.BST_REQUIRED_VERSION_MAJOR and |
| bst_minor < plugin_type.BST_REQUIRED_VERSION_MINOR): |
| raise PluginError("BuildStream {}.{} is too old for {} plugin '{}' (requires {}.{})" |
| .format( |
| bst_major, bst_minor, |
| self.base_type.__name__, kind, |
| plugin_type.BST_REQUIRED_VERSION_MAJOR, |
| plugin_type.BST_REQUIRED_VERSION_MINOR)) |
| |
| # We want a PluginError when trying to create a context |
| # where more than one plugin has the same name |
| def assert_searchpath(self, searchpath): |
| names = [] |
| fullnames = [] |
| for path in searchpath: |
| for filename in os.listdir(path): |
| basename = os.path.basename(filename) |
| name, extension = os.path.splitext(basename) |
| if extension == '.py' and name != '__init__': |
| fullname = os.path.join(path, filename) |
| |
| if name in names: |
| idx = names.index(name) |
| raise PluginError("Failed to register {} plugin '{}' from: {}\n" |
| "{} plugin '{}' is already registered by: {}" |
| .format(self.base_type.__name__, name, fullname, |
| self.base_type.__name__, name, fullnames[idx])) |
| |
| names.append(name) |
| fullnames.append(fullname) |
