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| 1 | +#!/usr/bin/env python3 |
| 2 | +# -*- coding: utf-8 -*- |
| 3 | +from celery import states |
| 4 | +from celery.backends.base import BaseBackend |
| 5 | +from celery.backends.database import retry, session_cleanup |
| 6 | +from celery.exceptions import ImproperlyConfigured |
| 7 | +from celery.utils.time import maybe_timedelta |
| 8 | + |
| 9 | +from backend.app.task.model.result import Task, TaskExtended, TaskSet |
| 10 | +from backend.app.task.session import SessionManager |
| 11 | + |
| 12 | +""" |
| 13 | +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 |
| 14 | +""" |
| 15 | + |
| 16 | + |
| 17 | +class DatabaseBackend(BaseBackend): |
| 18 | + """The database result backend.""" |
| 19 | + |
| 20 | + # ResultSet.iterate should sleep this much between each pool, |
| 21 | + # to not bombard the database with queries. |
| 22 | + subpolling_interval = 0.5 |
| 23 | + |
| 24 | + task_cls = Task |
| 25 | + taskset_cls = TaskSet |
| 26 | + |
| 27 | + def __init__(self, dburi=None, engine_options=None, url=None, **kwargs): |
| 28 | + # The `url` argument was added later and is used by |
| 29 | + # the app to set backend by url (celery.app.backends.by_url) |
| 30 | + super().__init__(expires_type=maybe_timedelta, url=url, **kwargs) |
| 31 | + conf = self.app.conf |
| 32 | + |
| 33 | + if self.extended_result: |
| 34 | + self.task_cls = TaskExtended |
| 35 | + |
| 36 | + self.url = url or dburi or conf.database_url |
| 37 | + self.engine_options = dict(engine_options or {}, **conf.database_engine_options or {}) |
| 38 | + self.short_lived_sessions = kwargs.get('short_lived_sessions', conf.database_short_lived_sessions) |
| 39 | + |
| 40 | + schemas = conf.database_table_schemas or {} |
| 41 | + tablenames = conf.database_table_names or {} |
| 42 | + self.task_cls.configure(schema=schemas.get('task'), name=tablenames.get('task')) |
| 43 | + self.taskset_cls.configure(schema=schemas.get('group'), name=tablenames.get('group')) |
| 44 | + |
| 45 | + if not self.url: |
| 46 | + raise ImproperlyConfigured( |
| 47 | + 'Missing connection string! Do you have the database_url setting set to a real value?' |
| 48 | + ) |
| 49 | + |
| 50 | + self.session_manager = SessionManager() |
| 51 | + |
| 52 | + create_tables_at_setup = conf.database_create_tables_at_setup |
| 53 | + if create_tables_at_setup is True: |
| 54 | + self._create_tables() |
| 55 | + |
| 56 | + @property |
| 57 | + def extended_result(self): |
| 58 | + return self.app.conf.find_value_for_key('extended', 'result') |
| 59 | + |
| 60 | + def _create_tables(self): |
| 61 | + """Create the task and taskset tables.""" |
| 62 | + self.ResultSession() |
| 63 | + |
| 64 | + def ResultSession(self, session_manager=None): |
| 65 | + if session_manager is None: |
| 66 | + session_manager = self.session_manager |
| 67 | + return session_manager.session_factory( |
| 68 | + dburi=self.url, short_lived_sessions=self.short_lived_sessions, **self.engine_options |
| 69 | + ) |
| 70 | + |
| 71 | + @retry |
| 72 | + def _store_result(self, task_id, result, state, traceback=None, request=None, **kwargs): |
| 73 | + """Store return value and state of an executed task.""" |
| 74 | + session = self.ResultSession() |
| 75 | + with session_cleanup(session): |
| 76 | + task = list(session.query(self.task_cls).filter(self.task_cls.task_id == task_id)) |
| 77 | + task = task and task[0] |
| 78 | + if not task: |
| 79 | + task = self.task_cls(task_id) |
| 80 | + task.task_id = task_id |
| 81 | + session.add(task) |
| 82 | + session.flush() |
| 83 | + |
| 84 | + self._update_result(task, result, state, traceback=traceback, request=request) |
| 85 | + session.commit() |
| 86 | + |
| 87 | + def _update_result(self, task, result, state, traceback=None, request=None): |
| 88 | + meta = self._get_result_meta( |
| 89 | + result=result, state=state, traceback=traceback, request=request, format_date=False, encode=True |
| 90 | + ) |
| 91 | + |
| 92 | + # Exclude the primary key id and task_id columns |
| 93 | + # as we should not set it None |
| 94 | + columns = [column.name for column in self.task_cls.__table__.columns if column.name not in {'id', 'task_id'}] |
| 95 | + |
| 96 | + # Iterate through the columns name of the table |
| 97 | + # to set the value from meta. |
| 98 | + # If the value is not present in meta, set None |
| 99 | + for column in columns: |
| 100 | + value = meta.get(column) |
| 101 | + setattr(task, column, value) |
| 102 | + |
| 103 | + @retry |
| 104 | + def _get_task_meta_for(self, task_id): |
| 105 | + """Get task meta-data for a task by id.""" |
| 106 | + session = self.ResultSession() |
| 107 | + with session_cleanup(session): |
| 108 | + task = list(session.query(self.task_cls).filter(self.task_cls.task_id == task_id)) |
| 109 | + task = task and task[0] |
| 110 | + if not task: |
| 111 | + task = self.task_cls(task_id) |
| 112 | + task.status = states.PENDING |
| 113 | + task.result = None |
| 114 | + data = task.to_dict() |
| 115 | + if data.get('args', None) is not None: |
| 116 | + data['args'] = self.decode(data['args']) |
| 117 | + if data.get('kwargs', None) is not None: |
| 118 | + data['kwargs'] = self.decode(data['kwargs']) |
| 119 | + return self.meta_from_decoded(data) |
| 120 | + |
| 121 | + @retry |
| 122 | + def _save_group(self, group_id, result): |
| 123 | + """Store the result of an executed group.""" |
| 124 | + session = self.ResultSession() |
| 125 | + with session_cleanup(session): |
| 126 | + group = self.taskset_cls(group_id, result) |
| 127 | + session.add(group) |
| 128 | + session.flush() |
| 129 | + session.commit() |
| 130 | + return result |
| 131 | + |
| 132 | + @retry |
| 133 | + def _restore_group(self, group_id): |
| 134 | + """Get meta-data for group by id.""" |
| 135 | + session = self.ResultSession() |
| 136 | + with session_cleanup(session): |
| 137 | + group = session.query(self.taskset_cls).filter(self.taskset_cls.taskset_id == group_id).first() |
| 138 | + if group: |
| 139 | + return group.to_dict() |
| 140 | + |
| 141 | + @retry |
| 142 | + def _delete_group(self, group_id): |
| 143 | + """Delete meta-data for group by id.""" |
| 144 | + session = self.ResultSession() |
| 145 | + with session_cleanup(session): |
| 146 | + session.query(self.taskset_cls).filter(self.taskset_cls.taskset_id == group_id).delete() |
| 147 | + session.flush() |
| 148 | + session.commit() |
| 149 | + |
| 150 | + @retry |
| 151 | + def _forget(self, task_id): |
| 152 | + """Forget about result.""" |
| 153 | + session = self.ResultSession() |
| 154 | + with session_cleanup(session): |
| 155 | + session.query(self.task_cls).filter(self.task_cls.task_id == task_id).delete() |
| 156 | + session.commit() |
| 157 | + |
| 158 | + def cleanup(self): |
| 159 | + """Delete expired meta-data.""" |
| 160 | + session = self.ResultSession() |
| 161 | + expires = self.expires |
| 162 | + now = self.app.now() |
| 163 | + with session_cleanup(session): |
| 164 | + session.query(self.task_cls).filter(self.task_cls.date_done < (now - expires)).delete() |
| 165 | + session.query(self.taskset_cls).filter(self.taskset_cls.date_done < (now - expires)).delete() |
| 166 | + session.commit() |
| 167 | + |
| 168 | + def __reduce__(self, args=(), kwargs=None): |
| 169 | + kwargs = {} if not kwargs else kwargs |
| 170 | + kwargs.update({'dburi': self.url, 'expires': self.expires, 'engine_options': self.engine_options}) |
| 171 | + return super().__reduce__(args, kwargs) |
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