293 lines
9.3 KiB
Python
293 lines
9.3 KiB
Python
# Copyright 2018 - Nokia Networks.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import copy
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import datetime
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import eventlet
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import random
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import sys
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import threading
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from oslo_config import cfg
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from oslo_log import log as logging
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from oslo_utils import importutils
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from mistral import context
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from mistral.db import utils as db_utils
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from mistral.db.v2 import api as db_api
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from mistral import exceptions as exc
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from mistral.scheduler import base
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from mistral import utils
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LOG = logging.getLogger(__name__)
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CONF = cfg.CONF
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class DefaultScheduler(base.Scheduler):
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def __init__(self, fixed_delay, random_delay, batch_size):
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self._fixed_delay = fixed_delay
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self._random_delay = random_delay
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self._batch_size = batch_size
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# Dictionary containing {GreenThread: ScheduledJob} pairs that
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# represent in-memory jobs.
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self.memory_jobs = {}
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self._job_store_checker_thread = threading.Thread(
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target=self._job_store_checker
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)
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self._job_store_checker_thread.daemon = True
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self._stopped = True
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def start(self):
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self._stopped = False
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self._job_store_checker_thread.start()
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def stop(self, graceful=False):
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self._stopped = True
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if graceful:
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self._job_store_checker_thread.join()
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def _job_store_checker(self):
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while not self._stopped:
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LOG.debug(
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"Starting Scheduler Job Store checker [scheduler=%s]...", self
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)
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try:
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self._process_store_jobs()
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except Exception:
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LOG.exception(
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"Scheduler failed to process delayed calls"
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" due to unexpected exception."
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)
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# For some mysterious reason (probably eventlet related)
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# the exception is not cleared from the context automatically.
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# This results in subsequent log.warning calls to show invalid
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# info.
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if sys.version_info < (3,):
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sys.exc_clear()
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eventlet.sleep(
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self._fixed_delay +
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random.Random().randint(0, self._random_delay * 1000) * 0.001
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)
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def _process_store_jobs(self):
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# Select and capture eligible jobs.
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with db_api.transaction():
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candidate_jobs = db_api.get_scheduled_jobs_to_start(
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utils.utc_now_sec(),
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self._batch_size
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)
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captured_jobs = [
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job for job in candidate_jobs
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if self._capture_scheduled_job(job)
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]
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# Invoke and delete scheduled jobs.
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for job in captured_jobs:
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auth_ctx, func, func_args = self._prepare_job(job)
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self._invoke_job(auth_ctx, func, func_args)
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self._delete_scheduled_job(job)
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def schedule(self, job, allow_redistribute=False):
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scheduled_job = DefaultScheduler._persist_job(job)
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self._schedule_in_memory(job.run_after, scheduled_job)
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@classmethod
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def _persist_job(cls, job):
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ctx_serializer = context.RpcContextSerializer()
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ctx = (
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ctx_serializer.serialize_context(context.ctx())
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if context.has_ctx() else {}
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)
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execute_at = (utils.utc_now_sec() +
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datetime.timedelta(seconds=job.run_after))
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args = job.func_args
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arg_serializers = job.func_arg_serializers
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if arg_serializers:
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for arg_name, serializer_path in arg_serializers.items():
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if arg_name not in args:
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raise exc.MistralException(
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"Serializable function argument %s"
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" not found in func_args=%s"
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% (arg_name, args))
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try:
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serializer = importutils.import_class(serializer_path)()
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except ImportError as e:
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raise ImportError(
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"Cannot import class %s: %s" % (serializer_path, e)
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)
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args[arg_name] = serializer.serialize(args[arg_name])
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values = {
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'run_after': job.run_after,
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'target_factory_func_name': job.target_factory_func_name,
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'func_name': job.func_name,
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'func_args': args,
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'func_arg_serializers': arg_serializers,
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'auth_ctx': ctx,
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'execute_at': execute_at,
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'captured_at': None
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}
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return db_api.create_scheduled_job(values)
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def _schedule_in_memory(self, run_after, scheduled_job):
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green_thread = eventlet.spawn_after(
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run_after,
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self._process_memory_job,
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scheduled_job
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)
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self.memory_jobs[green_thread] = scheduled_job
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def _process_memory_job(self, scheduled_job):
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# 1. Capture the job in Job Store.
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if not self._capture_scheduled_job(scheduled_job):
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LOG.warning(
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"Unable to capture a scheduled job [scheduled_job=%s]",
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scheduled_job
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)
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return
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# 2. Invoke the target function.
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auth_ctx, func, func_args = self._prepare_job(scheduled_job)
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self._invoke_job(auth_ctx, func, func_args)
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self._delete_scheduled_job(scheduled_job)
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# 3. Delete the job from Job Store, if success.
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# TODO(rakhmerov):
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# 3.1 What do we do if invocation wasn't successful?
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# Delete from a local collection of in-memory jobs.
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del self.memory_jobs[eventlet.getcurrent()]
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@staticmethod
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def _capture_scheduled_job(scheduled_job):
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"""Capture a scheduled persistent job in a job store.
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:param scheduled_job: Job.
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:return: True if the job has been captured, False if not.
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"""
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# Mark this job as captured in order to prevent calling from
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# a parallel transaction. We don't use query filter
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# {'captured_at': None} to account for a case when the job needs
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# to be recaptured after a maximum capture time has elapsed. If this
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# method was called for job that has non-empty "captured_at" then
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# it means that it is already eligible for recapturing and the
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# Job Store selected it.
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_, updated_cnt = db_api.update_scheduled_job(
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id=scheduled_job.id,
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values={'captured_at': utils.utc_now_sec()},
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query_filter={'captured_at': scheduled_job.captured_at}
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)
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# If updated_cnt != 1 then another scheduler
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# has already updated it.
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return updated_cnt == 1
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@staticmethod
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@db_utils.retry_on_db_error
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def _delete_scheduled_job(scheduled_job):
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db_api.delete_scheduled_job(scheduled_job.id)
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@staticmethod
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def _prepare_job(scheduled_job):
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"""Prepares a scheduled job for invocation.
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To make an invocation of a delayed call it needs to be prepared for
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further usage, we need to reconstruct a final target func
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and deserialize arguments, if needed.
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:param scheduled_job: Persistent scheduled job.
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:return: A tuple (auth_ctx, func, args) where all data is properly
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deserialized.
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"""
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LOG.debug(
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'Preparing a scheduled job. [ID=%s, target_factory_func_name=%s,'
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' func_name=%s, func_args=%s]',
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scheduled_job.id,
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scheduled_job.target_factory_func_name,
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scheduled_job.func_name,
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scheduled_job.func_args
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)
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auth_ctx = copy.deepcopy(scheduled_job.auth_ctx)
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if scheduled_job.target_factory_func_name:
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factory = importutils.import_class(
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scheduled_job.target_factory_func_name
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)
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func = getattr(factory(), scheduled_job.func_name)
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else:
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func = importutils.import_class(scheduled_job.func_name)
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args = copy.deepcopy(scheduled_job.func_args)
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serializers_dict = scheduled_job.func_arg_serializers
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if serializers_dict:
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# Deserialize arguments.
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for arg_name, ser_path in serializers_dict.items():
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serializer = importutils.import_class(ser_path)()
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deserialized = serializer.deserialize(args[arg_name])
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args[arg_name] = deserialized
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return auth_ctx, func, args
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@staticmethod
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def _invoke_job(auth_ctx, func, args):
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ctx_serializer = context.RpcContextSerializer()
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try:
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# Set the correct context for the function.
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ctx_serializer.deserialize_context(auth_ctx)
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# Invoke the function.
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func(**args)
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except Exception as e:
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LOG.exception(
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"Scheduled job failed, method: %s, exception: %s",
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func,
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e
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)
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finally:
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# Remove context.
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context.set_ctx(None)
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