| # Licensed to the Apache Software Foundation (ASF) under one or more |
| # contributor license agreements. See the NOTICE file distributed with |
| # this work for additional information regarding copyright ownership. |
| # The ASF licenses this file to You under the Apache License, Version 2.0 |
| # (the "License"); you may not use this file except in compliance with |
| # the License. You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| """ |
| The workflow engine. Executes workflows |
| """ |
| |
| import time |
| from datetime import datetime |
| |
| from aria import logger |
| from aria.modeling import models |
| from aria.orchestrator import events |
| from aria.orchestrator.context import operation |
| |
| from .. import exceptions |
| from ..executor.base import StubTaskExecutor |
| # Import required so all signals are registered |
| from . import events_handler # pylint: disable=unused-import |
| |
| |
| class Engine(logger.LoggerMixin): |
| """ |
| The workflow engine. Executes workflows |
| """ |
| |
| def __init__(self, executors, **kwargs): |
| super(Engine, self).__init__(**kwargs) |
| self._executors = executors.copy() |
| self._executors.setdefault(StubTaskExecutor, StubTaskExecutor()) |
| |
| def execute(self, ctx, resuming=False): |
| """ |
| execute the workflow |
| """ |
| executing_tasks = [] |
| |
| if resuming: |
| events.on_resume_workflow_signal.send(ctx) |
| |
| try: |
| events.start_workflow_signal.send(ctx) |
| while True: |
| cancel = self._is_cancel(ctx) |
| if cancel: |
| break |
| for task in self._ended_tasks(ctx, executing_tasks): |
| self._handle_ended_tasks(ctx, task, executing_tasks) |
| for task in self._executable_tasks(ctx): |
| self._handle_executable_task(ctx, task, executing_tasks) |
| if self._all_tasks_consumed(ctx): |
| break |
| else: |
| time.sleep(0.1) |
| if cancel: |
| events.on_cancelled_workflow_signal.send(ctx) |
| else: |
| events.on_success_workflow_signal.send(ctx) |
| except BaseException as e: |
| events.on_failure_workflow_signal.send(ctx, exception=e) |
| raise |
| |
| @staticmethod |
| def cancel_execution(ctx): |
| """ |
| Send a cancel request to the engine. If execution already started, execution status |
| will be modified to 'cancelling' status. If execution is in pending mode, execution status |
| will be modified to 'cancelled' directly. |
| """ |
| events.on_cancelling_workflow_signal.send(ctx) |
| |
| @staticmethod |
| def _is_cancel(ctx): |
| execution = ctx.model.execution.refresh(ctx.execution) |
| return execution.status in (models.Execution.CANCELLING, models.Execution.CANCELLED) |
| |
| def _executable_tasks(self, ctx): |
| now = datetime.utcnow() |
| return ( |
| task for task in self._tasks_iter(ctx) |
| if task.is_waiting() and task.due_at <= now and \ |
| not self._task_has_dependencies(ctx, task) |
| ) |
| |
| @staticmethod |
| def _ended_tasks(ctx, executing_tasks): |
| for task in executing_tasks: |
| if task.has_ended() and task in ctx._graph: |
| yield task |
| |
| @staticmethod |
| def _task_has_dependencies(ctx, task): |
| return len(ctx._graph.pred.get(task, [])) > 0 |
| |
| @staticmethod |
| def _all_tasks_consumed(ctx): |
| return len(ctx._graph.node) == 0 |
| |
| @staticmethod |
| def _tasks_iter(ctx): |
| for task in ctx.execution.tasks: |
| yield ctx.model.task.refresh(task) |
| |
| def _handle_executable_task(self, ctx, task, executing_tasks): |
| task_executor = self._executors[task._executor] |
| |
| # If the task is a stub, a default context is provided, else it should hold the context cls |
| context_cls = operation.BaseOperationContext if task._stub_type else task._context_cls |
| op_ctx = context_cls( |
| model_storage=ctx.model, |
| resource_storage=ctx.resource, |
| workdir=ctx._workdir, |
| task_id=task.id, |
| actor_id=task.actor.id if task.actor else None, |
| service_id=task.execution.service.id, |
| execution_id=task.execution.id, |
| name=task.name |
| ) |
| |
| executing_tasks.append(task) |
| |
| if not task._stub_type: |
| events.sent_task_signal.send(op_ctx) |
| task_executor.execute(op_ctx) |
| |
| @staticmethod |
| def _handle_ended_tasks(ctx, task, executing_tasks): |
| executing_tasks.remove(task) |
| if task.status == models.Task.FAILED and not task.ignore_failure: |
| raise exceptions.ExecutorException('Workflow failed') |
| else: |
| ctx._graph.remove_node(task) |