# The MIT License (MIT)
# Copyright (c) 2019 by the xcube development team and contributors
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to
# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
# of the Software, and to permit persons to whom the Software is furnished to do
# so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
import abc
import importlib
import pkgutil
import time
import traceback
import warnings
from typing import Callable, Dict, Optional, Any
from pkg_resources import iter_entry_points
from xcube.constants import PLUGIN_ENTRY_POINT_GROUP_NAME
from xcube.constants import PLUGIN_INIT_TIME__WARN_LIMIT
from xcube.constants import PLUGIN_LOAD_TIME_WARN_LIMIT
from xcube.constants import PLUGIN_MODULE_FUNCTION_NAME
from xcube.constants import PLUGIN_MODULE_NAME
from xcube.constants import PLUGIN_MODULE_PREFIX
from xcube.util.extension import Extension
from xcube.util.extension import ExtensionRegistry
#: Mapping of xcube entry point names to JSON-serializable plugin meta-information.
_PLUGIN_REGISTRY = None
def init_plugins() -> None:
"""Load plugins if not already done."""
global _PLUGIN_REGISTRY
if _PLUGIN_REGISTRY is None:
_PLUGIN_REGISTRY = load_plugins()
[docs]def get_plugins() -> Dict[str, Dict]:
"""Get mapping of "xcube_plugins" entry point names to JSON-serializable plugin meta-information."""
init_plugins()
global _PLUGIN_REGISTRY
return dict(_PLUGIN_REGISTRY)
[docs]def get_extension_registry() -> ExtensionRegistry:
"""Get populated extension registry."""
from xcube.util.extension import get_extension_registry
init_plugins()
return get_extension_registry()
def discover_plugin_modules(module_prefixes=None):
module_prefixes = module_prefixes or [PLUGIN_MODULE_PREFIX]
entry_points = []
for module_finder, module_name, ispkg in pkgutil.iter_modules():
if any([module_name.startswith(module_prefix) for module_prefix in module_prefixes]):
# TODO (forman): Consider turning this into debug log:
# print(f'xcube plugin module found: {module_name}')
entry_points.append(_ModuleEntryPoint(module_name))
return entry_points
def load_plugins(entry_points=None, ext_registry=None):
if entry_points is None:
entry_points = list(iter_entry_points(group=PLUGIN_ENTRY_POINT_GROUP_NAME, name=None)) \
+ discover_plugin_modules()
if ext_registry is None:
from xcube.util.extension import get_extension_registry
ext_registry = get_extension_registry()
plugins = {}
for entry_point in entry_points:
# TODO (forman): Consider turning this into debug log:
# print(f'loading xcube plugin {entry_point.name!r}')
t0 = time.perf_counter()
# noinspection PyBroadException
try:
plugin_init_function = entry_point.load()
except Exception as e:
_handle_error(entry_point, e)
continue
if plugin_init_function is None:
# Not a plugin
continue
millis = int(1000 * (time.perf_counter() - t0))
if millis >= PLUGIN_LOAD_TIME_WARN_LIMIT:
warnings.warn(f'loading xcube plugin {entry_point.name!r} took {millis} ms, '
f'consider code optimization!')
if not callable(plugin_init_function):
# We use warning and not raise to allow loading xcube despite a broken plugin. Raise would stop xcube.
warnings.warn(f'xcube plugin {entry_point.name!r} '
f'must be callable but got a {type(plugin_init_function)!r}')
continue
t0 = time.perf_counter()
# noinspection PyBroadException
try:
plugin_init_function(ext_registry)
except Exception as e:
_handle_error(entry_point, e)
continue
millis = int(1000 * (time.perf_counter() - t0))
if millis >= PLUGIN_INIT_TIME__WARN_LIMIT:
warnings.warn(f'initializing xcube plugin {entry_point.name!r} took {millis} ms, '
f'consider code optimization!')
plugins[entry_point.name] = {'name': entry_point.name, 'doc': plugin_init_function.__doc__}
return plugins
def _handle_error(entry_point, e):
# We use warning and not raise to allow loading xcube despite a broken plugin. Raise would stop xcube.
warnings.warn(f'Unexpected exception while loading xcube plugin {entry_point.name!r}: {e}')
traceback.print_exc()
class _ModuleEntryPoint:
def __init__(self, module_name: str):
self._module_name = module_name
@property
def name(self) -> str:
return self._module_name
def load(self) -> Optional[Callable]:
"""
Load function "init_plugin()" either from "<module_name>.plugin" or "<module_name>"
:return: plugin init function
"""
try:
plugin_module = importlib.import_module(self._module_name + '.' + PLUGIN_MODULE_NAME)
except ModuleNotFoundError:
plugin_module = importlib.import_module(self._module_name)
module_func_name = PLUGIN_MODULE_FUNCTION_NAME
if hasattr(plugin_module, module_func_name):
module_func = getattr(plugin_module, module_func_name)
if callable(module_func):
return module_func
# Here: The module name looks like an xcube-plugin
# but lacks a callable named module_func_name
return None
class ExtensionComponent(metaclass=abc.ABCMeta):
"""
Utility base class for extension components.
"""
def __init__(self, extension_point: str, name: str):
if not extension_point:
raise ValueError('extension_point must be given')
if not name:
raise ValueError('name must be given')
self._extension_point = extension_point
self._name = name
@property
def name(self) -> str:
return self._name
@property
def extension_point(self) -> str:
"""
:return: The extension point for this component.
"""
return self._extension_point
@property
def extension(self) -> Optional[Extension]:
"""
:return: The extension for this component. None, if it has not (yet) been registered as an extension.
"""
return get_extension_registry().get_extension(self._extension_point, self._name)
def get_metadata_attr(self, key: str, default: Any = None) -> Any:
"""
:return: A metadata attribute for *key* and given *default* value.
"""
extension = self.extension
return extension.metadata.get(key, default) if extension is not None else ''