# -*- coding: utf-8 -*- # Copyright (C) 2013 Yahoo! Inc. All Rights Reserved. # # Licensed 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. import abc import futurist from taskflow import task as ta from taskflow.types import failure from taskflow.types import notifier # Execution and reversion outcomes. EXECUTED = 'executed' REVERTED = 'reverted' def _execute_retry(retry, arguments): try: result = retry.execute(**arguments) except Exception: result = failure.Failure() return (EXECUTED, result) def _revert_retry(retry, arguments): try: result = retry.revert(**arguments) except Exception: result = failure.Failure() return (REVERTED, result) def _execute_task(task, arguments, progress_callback=None): with notifier.register_deregister(task.notifier, ta.EVENT_UPDATE_PROGRESS, callback=progress_callback): try: task.pre_execute() result = task.execute(**arguments) except Exception: # NOTE(imelnikov): wrap current exception with Failure # object and return it. result = failure.Failure() finally: task.post_execute() return (EXECUTED, result) def _revert_task(task, arguments, result, failures, progress_callback=None): arguments = arguments.copy() arguments[ta.REVERT_RESULT] = result arguments[ta.REVERT_FLOW_FAILURES] = failures with notifier.register_deregister(task.notifier, ta.EVENT_UPDATE_PROGRESS, callback=progress_callback): try: task.pre_revert() result = task.revert(**arguments) except Exception: # NOTE(imelnikov): wrap current exception with Failure # object and return it. result = failure.Failure() finally: task.post_revert() return (REVERTED, result) class SerialRetryExecutor(object): """Executes and reverts retries.""" def __init__(self): self._executor = futurist.SynchronousExecutor() def start(self): """Prepare to execute retries.""" self._executor.restart() def stop(self): """Finalize retry executor.""" self._executor.shutdown() def execute_retry(self, retry, arguments): """Schedules retry execution.""" fut = self._executor.submit(_execute_retry, retry, arguments) fut.atom = retry return fut def revert_retry(self, retry, arguments): """Schedules retry reversion.""" fut = self._executor.submit(_revert_retry, retry, arguments) fut.atom = retry return fut class TaskExecutor(object, metaclass=abc.ABCMeta): """Executes and reverts tasks. This class takes task and its arguments and executes or reverts it. It encapsulates knowledge on how task should be executed or reverted: right now, on separate thread, on another machine, etc. """ @abc.abstractmethod def execute_task(self, task, task_uuid, arguments, progress_callback=None): """Schedules task execution.""" @abc.abstractmethod def revert_task(self, task, task_uuid, arguments, result, failures, progress_callback=None): """Schedules task reversion.""" def start(self): """Prepare to execute tasks.""" def stop(self): """Finalize task executor.""" class SerialTaskExecutor(TaskExecutor): """Executes tasks one after another.""" def __init__(self): self._executor = futurist.SynchronousExecutor() def start(self): self._executor.restart() def stop(self): self._executor.shutdown() def execute_task(self, task, task_uuid, arguments, progress_callback=None): fut = self._executor.submit(_execute_task, task, arguments, progress_callback=progress_callback) fut.atom = task return fut def revert_task(self, task, task_uuid, arguments, result, failures, progress_callback=None): fut = self._executor.submit(_revert_task, task, arguments, result, failures, progress_callback=progress_callback) fut.atom = task return fut class ParallelTaskExecutor(TaskExecutor): """Executes tasks in parallel. Submits tasks to an executor which should provide an interface similar to concurrent.Futures.Executor. """ constructor_options = [ ('max_workers', lambda v: v if v is None else int(v)), ] """ Optional constructor keyword arguments this executor supports. These will typically be passed via engine options (by a engine user) and converted into the correct type before being sent into this classes ``__init__`` method. """ def __init__(self, executor=None, max_workers=None): self._executor = executor self._max_workers = max_workers self._own_executor = executor is None @abc.abstractmethod def _create_executor(self, max_workers=None): """Called when an executor has not been provided to make one.""" def _submit_task(self, func, task, *args, **kwargs): fut = self._executor.submit(func, task, *args, **kwargs) fut.atom = task return fut def execute_task(self, task, task_uuid, arguments, progress_callback=None): return self._submit_task(_execute_task, task, arguments, progress_callback=progress_callback) def revert_task(self, task, task_uuid, arguments, result, failures, progress_callback=None): return self._submit_task(_revert_task, task, arguments, result, failures, progress_callback=progress_callback) def start(self): if self._own_executor: self._executor = self._create_executor( max_workers=self._max_workers) def stop(self): if self._own_executor: self._executor.shutdown(wait=True) self._executor = None class ParallelThreadTaskExecutor(ParallelTaskExecutor): """Executes tasks in parallel using a thread pool executor.""" def _create_executor(self, max_workers=None): return futurist.ThreadPoolExecutor(max_workers=max_workers) class ParallelGreenThreadTaskExecutor(ParallelThreadTaskExecutor): """Executes tasks in parallel using a greenthread pool executor.""" DEFAULT_WORKERS = 1000 """ Default number of workers when ``None`` is passed; being that greenthreads don't map to native threads or processors very well this is more of a guess/somewhat arbitrary, but it does match what the eventlet greenpool default size is (so at least it's consistent with what eventlet does). """ def _create_executor(self, max_workers=None): if max_workers is None: max_workers = self.DEFAULT_WORKERS return futurist.GreenThreadPoolExecutor(max_workers=max_workers)