from celery import states from celery.backends.base import BaseBackend from celery.backends.database import retry, session_cleanup from celery.exceptions import ImproperlyConfigured from celery.utils.time import maybe_timedelta from sqlalchemy import PickleType from sqlalchemy.orm import Session from backend.app.task.model.result import Task, TaskExtended, TaskSet from backend.app.task.session import SessionManager """ 重写 from celery.backends.database 内部 DatabaseBackend 类，此类实现与模型配合不佳，导致 fba 创建表和 alembic 迁移困难 """ class DatabaseBackend(BaseBackend): """The database result backend.""" # ResultSet.iterate should sleep this much between each pool, # to not bombard the database with queries. subpolling_interval = 0.5 task_cls = Task taskset_cls = TaskSet def __init__(self, dburi=None, engine_options=None, url=None, **kwargs) -> None: # noqa: ANN001 # The `url` argument was added later and is used by # the app to set backend by url (celery.app.backends.by_url) super().__init__(expires_type=maybe_timedelta, url=url, **kwargs) conf = self.app.conf if self.extended_result: self.task_cls = TaskExtended self.url = url or dburi or conf.database_url self.engine_options = dict(engine_options or {}, **conf.database_engine_options or {}) self.short_lived_sessions = kwargs.get('short_lived_sessions', conf.database_short_lived_sessions) schemas = conf.database_table_schemas or {} tablenames = conf.database_table_names or {} self.task_cls.configure(schema=schemas.get('task'), name=tablenames.get('task')) self.taskset_cls.configure(schema=schemas.get('group'), name=tablenames.get('group')) if not self.url: raise ImproperlyConfigured( 'Missing connection string! Do you have the database_url setting set to a real value?', ) self.session_manager = SessionManager() create_tables_at_setup = conf.database_create_tables_at_setup if create_tables_at_setup is True: self._create_tables() @property def extended_result(self): # noqa: ANN201 return self.app.conf.find_value_for_key('extended', 'result') def _create_tables(self) -> None: """Create the task and taskset tables.""" self.result_session() def result_session(self, session_manager=None) -> Session: # noqa: ANN001 if session_manager is None: session_manager = self.session_manager return session_manager.session_factory( dburi=self.url, short_lived_sessions=self.short_lived_sessions, **self.engine_options, ) @retry def _store_result(self, task_id, result, state, traceback=None, request=None, **kwargs) -> None: # noqa: ANN001 """Store return value and state of an executed task.""" session = self.result_session() with session_cleanup(session): task = list(session.query(self.task_cls).filter(self.task_cls.task_id == task_id)) task = task and task[0] if not task: task = self.task_cls(task_id) task.task_id = task_id session.add(task) session.flush() self._update_result(task, result, state, traceback=traceback, request=request) session.commit() def _update_result(self, task, result, state, traceback=None, request=None) -> None: # noqa: ANN001 meta = self._get_result_meta( result=result, state=state, traceback=traceback, request=request, format_date=False, encode=True, ) # Exclude the primary key id and task_id columns # as we should not set it None columns = [column.name for column in self.task_cls.__table__.columns if column.name not in {'id', 'task_id'}] # Iterate through the columns name of the table # to set the value from meta. # If the value is not present in meta, set None for column in columns: value = meta.get(column) setattr(task, column, value) @retry def _get_task_meta_for(self, task_id: str): # noqa: ANN202 """Get task meta-data for a task by id.""" session = self.result_session() with session_cleanup(session): task = list(session.query(self.task_cls).filter(self.task_cls.task_id == task_id)) task = task and task[0] if not task: task = self.task_cls(task_id) task.status = states.PENDING task.result = None data = task.to_dict() if data.get('args', None) is not None: data['args'] = self.decode(data['args']) if data.get('kwargs', None) is not None: data['kwargs'] = self.decode(data['kwargs']) return self.meta_from_decoded(data) @retry def _save_group(self, group_id: str, result: PickleType): # noqa: ANN202 """Store the result of an executed group.""" session = self.result_session() with session_cleanup(session): group = self.taskset_cls(group_id, result) session.add(group) session.flush() session.commit() return result @retry def _restore_group(self, group_id: str) -> dict | None: """Get meta-data for group by id.""" session = self.result_session() with session_cleanup(session): group = session.query(self.taskset_cls).filter(self.taskset_cls.taskset_id == group_id).first() if group: return group.to_dict() @retry def _delete_group(self, group_id: str) -> None: """Delete meta-data for group by id.""" session = self.result_session() with session_cleanup(session): session.query(self.taskset_cls).filter(self.taskset_cls.taskset_id == group_id).delete() session.flush() session.commit() @retry def _forget(self, task_id: str) -> None: """Forget about result.""" session = self.result_session() with session_cleanup(session): session.query(self.task_cls).filter(self.task_cls.task_id == task_id).delete() session.commit() def cleanup(self) -> None: """Delete expired meta-data.""" session = self.result_session() expires = self.expires now = self.app.now() with session_cleanup(session): session.query(self.task_cls).filter(self.task_cls.date_done < (now - expires)).delete() session.query(self.taskset_cls).filter(self.taskset_cls.date_done < (now - expires)).delete() session.commit() def __reduce__(self, args=(), kwargs=None): # noqa: ANN001, ANN204 kwargs = kwargs or {} kwargs.update({'dburi': self.url, 'expires': self.expires, 'engine_options': self.engine_options}) return super().__reduce__(args, kwargs)