# 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 sys
import time
import traceback
import warnings
from typing import Callable, Dict, Optional, Any, List
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
_PLUGIN_REGISTRY_INIT = dict()
# Mapping of xcube entry point names
# to JSON-serializable plugin meta-information.
_PLUGIN_REGISTRY: Dict[str, Dict[str, Any]] = _PLUGIN_REGISTRY_INIT
def init_plugins() -> None:
"""Load plugins if not already done."""
global _PLUGIN_REGISTRY
if _PLUGIN_REGISTRY is _PLUGIN_REGISTRY_INIT:
_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]):
# Note: Consider turning this into debug log,
# but logging is not yet configured at this point.
# 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: Optional[ExtensionRegistry] = None
) -> Dict[str, Dict[str, Any]]:
if ext_registry is None:
from xcube.util.extension import get_extension_registry
ext_registry = get_extension_registry()
plugins = {}
if entry_points:
_collect_plugins(
entry_points,
ext_registry,
True,
plugins
)
else:
# verbose=True for specified xcube plugins.
_collect_plugins(
list(iter_entry_points(group=PLUGIN_ENTRY_POINT_GROUP_NAME,
name=None)),
ext_registry,
True,
plugins
)
# verbose=False for auto-detected xcube plugins,
# where package name starts with "xcube_" but an
# entry point is not explicitly specified.
_collect_plugins(
discover_plugin_modules(),
ext_registry,
False,
plugins
)
return plugins
def _collect_plugins(entry_points: List[Any],
ext_registry: ExtensionRegistry,
verbose: bool,
plugins: Dict[str, Dict[str, Any]]):
for entry_point in entry_points:
# Note: Consider turning this into debug log,
# but logging is not yet configured at this point.
# 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:
if verbose:
_emit_warning_for_error(entry_point, e)
continue
if plugin_init_function is None:
# Not a plugin
continue
if verbose:
millis = int(1000 * (time.perf_counter() - t0))
if millis >= PLUGIN_LOAD_TIME_WARN_LIMIT:
_emit_warning_for_slow_load(entry_point, millis)
if not callable(plugin_init_function):
if verbose:
_emit_warning_on_init_function(entry_point,
plugin_init_function)
continue
t0 = time.perf_counter()
# noinspection PyBroadException
try:
plugin_init_function(ext_registry)
except Exception as e:
if verbose:
_emit_warning_for_error(entry_point, e)
continue
if verbose:
millis = int(1000 * (time.perf_counter() - t0))
if millis >= PLUGIN_INIT_TIME__WARN_LIMIT:
_emit_warning_for_slow_load(entry_point, millis)
plugins[entry_point.name] = {'name': entry_point.name,
'doc': plugin_init_function.__doc__}
def _emit_warning_on_init_function(entry_point, 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'
f' but got a {type(plugin_init_function)!r}')
def _emit_warning_for_slow_load(entry_point, millis):
warnings.warn(
f'Initializing xcube plugin {entry_point.name!r}'
f' took {millis} ms,'
f' consider code optimization.'
f' (For example, avoid eager import of packages,'
f' consider lazy loading of resources, etc.)'
)
def _emit_warning_for_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'
f' xcube plugin {entry_point.name!r}: {e}')
traceback.print_exc(file=sys.stderr)
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(
f'{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 ''