"""Loader base class."""
import importlib
import os
import re
import sys
from datetime import datetime, timezone
from kombu.utils import json
from kombu.utils.objects import cached_property
from celery import signals
from celery.exceptions import reraise
from celery.utils.collections import DictAttribute, force_mapping
from celery.utils.functional import maybe_list
from celery.utils.imports import NotAPackage, find_module, import_from_cwd, symbol_by_name
__all__ = ('BaseLoader',)
_RACE_PROTECTION = False
CONFIG_INVALID_NAME = """\
Error: Module '{module}' doesn't exist, or it's not a valid \
Python module name.
"""
CONFIG_WITH_SUFFIX = CONFIG_INVALID_NAME + """\
Did you mean '{suggest}'?
"""
unconfigured = object()
class BaseLoader:
"""Base class for loaders.
Loaders handles,
* Reading celery client/worker configurations.
* What happens when a task starts?
See :meth:`on_task_init`.
* What happens when the worker starts?
See :meth:`on_worker_init`.
* What happens when the worker shuts down?
See :meth:`on_worker_shutdown`.
* What modules are imported to find tasks?
"""
builtin_modules = frozenset()
configured = False
override_backends = {}
worker_initialized = False
_conf = unconfigured
def __init__(self, app, **kwargs):
self.app = app
self.task_modules = set()
def now(self, utc=True):
if utc:
return datetime.now(timezone.utc)
return datetime.now()
def on_task_init(self, task_id, task):
"""Called before a task is executed."""
def on_process_cleanup(self):
"""Called after a task is executed."""
def on_worker_init(self):
"""Called when the worker (:program:`celery worker`) starts."""
def on_worker_shutdown(self):
"""Called when the worker (:program:`celery worker`) shuts down."""
def on_worker_process_init(self):
"""Called when a child process starts."""
def import_task_module(self, module):
self.task_modules.add(module)
return self.import_from_cwd(module)
def import_module(self, module, package=None):
return importlib.import_module(module, package=package)
def import_from_cwd(self, module, imp=None, package=None):
return import_from_cwd(
module,
self.import_module if imp is None else imp,
package=package,
)
def import_default_modules(self):
responses = signals.import_modules.send(sender=self.app)
# Prior to this point loggers are not yet set up properly, need to
# check responses manually and reraised exceptions if any, otherwise
# they'll be silenced, making it incredibly difficult to debug.
for _, response in responses:
if isinstance(response, Exception):
raise response
return [self.import_task_module(m) for m in self.default_modules]
def init_worker(self):
if not self.worker_initialized:
self.worker_initialized = True
self.import_default_modules()
self.on_worker_init()
def shutdown_worker(self):
self.on_worker_shutdown()
def init_worker_process(self):
self.on_worker_process_init()
def config_from_object(self, obj, silent=False):
if isinstance(obj, str):
try:
obj = self._smart_import(obj, imp=self.import_from_cwd)
except (ImportError, AttributeError):
if silent:
return False
raise
self._conf = force_mapping(obj)
if self._conf.get('override_backends') is not None:
self.override_backends = self._conf['override_backends']
return True
def _smart_import(self, path, imp=None):
imp = self.import_module if imp is None else imp
if ':' in path:
# Path includes attribute so can just jump
# here (e.g., ``os.path:abspath``).
return symbol_by_name(path, imp=imp)
# Not sure if path is just a module name or if it includes an
# attribute name (e.g., ``os.path``, vs, ``os.path.abspath``).
try:
return imp(path)
except ImportError:
# Not a module name, so try module + attribute.
return symbol_by_name(path, imp=imp)
def _import_config_module(self, name):
try:
self.find_module(name)
except NotAPackage as exc:
if name.endswith('.py'):
reraise(NotAPackage, NotAPackage(CONFIG_WITH_SUFFIX.format(
module=name, suggest=name[:-3])), sys.exc_info()[2])
raise NotAPackage(CONFIG_INVALID_NAME.format(module=name)) from exc
else:
return self.import_from_cwd(name)
def find_module(self, module):
return find_module(module)
def cmdline_config_parser(self, args, namespace='celery',
re_type=re.compile(r'\((\w+)\)'),
extra_types=None,
override_types=None):
extra_types = extra_types if extra_types else {'json': json.loads}
override_types = override_types if override_types else {
'tuple': 'json',
'list': 'json',
'dict': 'json'
}
from celery.app.defaults import NAMESPACES, Option
namespace = namespace and namespace.lower()
typemap = dict(Option.typemap, **extra_types)
def getarg(arg):
"""Parse single configuration from command-line."""
# ## find key/value
# ns.key=value|ns_key=value (case insensitive)
key, value = arg.split('=', 1)
key = key.lower().replace('.', '_')
# ## find name-space.
# .key=value|_key=value expands to default name-space.
if key[0] == '_':
ns, key = namespace, key[1:]
else:
# find name-space part of key
ns, key = key.split('_', 1)
ns_key = (ns and ns + '_' or '') + key
# (type)value makes cast to custom type.
cast = re_type.match(value)
if cast:
type_ = cast.groups()[0]
type_ = override_types.get(type_, type_)
value = value[len(cast.group()):]
value = typemap[type_](value)
else:
try:
value = NAMESPACES[ns.lower()][key].to_python(value)
except ValueError as exc:
# display key name in error message.
raise ValueError(f'{ns_key!r}: {exc}')
return ns_key, value
return dict(getarg(arg) for arg in args)
def read_configuration(self, env='CELERY_CONFIG_MODULE'):
try:
custom_config = os.environ[env]
except KeyError:
pass
else:
if custom_config:
usercfg = self._import_config_module(custom_config)
return DictAttribute(usercfg)
def autodiscover_tasks(self, packages, related_name='tasks'):
self.task_modules.update(
mod.__name__ for mod in autodiscover_tasks(packages or (),
related_name) if mod)
@cached_property
def default_modules(self):
return (
tuple(self.builtin_modules) +
tuple(maybe_list(self.app.conf.imports)) +
tuple(maybe_list(self.app.conf.include))
)
@property
def conf(self):
"""Loader configuration."""
if self._conf is unconfigured:
self._conf = self.read_configuration()
return self._conf
def autodiscover_tasks(packages, related_name='tasks'):
global _RACE_PROTECTION
if _RACE_PROTECTION:
return ()
_RACE_PROTECTION = True
try:
return [find_related_module(pkg, related_name) for pkg in packages]
finally:
_RACE_PROTECTION = False
def find_related_module(package, related_name):
"""Find module in package."""
# Django 1.7 allows for specifying a class name in INSTALLED_APPS.
# (Issue #2248).
try:
# Return package itself when no related_name.
module = importlib.import_module(package)
if not related_name and module:
return module
except ModuleNotFoundError:
# On import error, try to walk package up one level.
package, _, _ = package.rpartition('.')
if not package:
raise
module_name = f'{package}.{related_name}'
try:
# Try to find related_name under package.
return importlib.import_module(module_name)
except ModuleNotFoundError as e:
import_exc_name = getattr(e, 'name', None)
# If candidate does not exist, then return None.
if import_exc_name and module_name == import_exc_name:
return
# Otherwise, raise because error probably originated from a nested import.
raise e