203 lines
6.4 KiB
Python
203 lines
6.4 KiB
Python
# DBus Task interface.
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#
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# Base class of tasks.
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# Task is used by modules to implement asynchronous time consuming installation
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# or configuration tasks.
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#
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# Copyright (C) 2017 Red Hat, Inc.
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#
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# This copyrighted material is made available to anyone wishing to use,
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# modify, copy, or redistribute it subject to the terms and conditions of
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# the GNU General Public License v.2, or (at your option) any later version.
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# This program is distributed in the hope that it will be useful, but WITHOUT
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# ANY WARRANTY expressed or implied, including the implied warranties of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
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# Public License for more details. You should have received a copy of the
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# GNU General Public License along with this program; if not, write to the
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# Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA. Any Red Hat trademarks that are incorporated in the
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# source code or documentation are not subject to the GNU General Public
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# License and may only be used or replicated with the express permission of
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# Red Hat, Inc.
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#
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import traceback
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from abc import abstractmethod
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from pyanaconda.core.constants import THREAD_DBUS_TASK
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from dasbus.server.publishable import Publishable
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from pyanaconda.modules.common.errors.task import NoResultError
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from pyanaconda.modules.common.task.task_interface import TaskInterface, ValidationTaskInterface
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from pyanaconda.modules.common.task.cancellable import Cancellable
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from pyanaconda.modules.common.task.progress import ProgressReporter
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from pyanaconda.modules.common.task.result import ResultProvider
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from pyanaconda.modules.common.task.runnable import Runnable
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from pyanaconda.core.threads import thread_manager
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from pyanaconda.anaconda_loggers import get_module_logger
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log = get_module_logger(__name__)
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__all__ = ['AbstractTask', 'Task', 'ValidationTask']
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class AbstractTask(Runnable, Cancellable, Publishable, ProgressReporter, ResultProvider):
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"""Abstract class for running a long-term task."""
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@property
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@abstractmethod
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def name(self):
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"""Name of this task.
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For example: "Install the payload"
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:returns: string with the task name
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"""
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return ""
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def for_publication(self):
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"""Return a DBus representation."""
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return TaskInterface(self)
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class Task(AbstractTask):
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"""Abstract class for running a long-term task in a thread."""
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_thread_counter = 0
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def __init__(self):
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super().__init__()
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self._thread_name = self._generate_thread_name()
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@property
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def steps(self):
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"""Total number of steps."""
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return 1
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@property
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def is_running(self):
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"""Is the task running."""
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return thread_manager.exists(self._thread_name)
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def start(self):
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"""Start the task in a new thread."""
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thread_manager.add_thread(
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name=self._thread_name,
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target=self._thread_run_callback,
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target_started=self._task_started_callback,
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target_stopped=self._task_stopped_callback,
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target_failed=self._thread_failed_callback,
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fatal=False
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)
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def _thread_run_callback(self):
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"""Run a task and report the success."""
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self._task_run_callback()
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self._task_succeeded_callback()
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def _task_run_callback(self):
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"""Report the first step and run the task.
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.
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Don't run the task if the task was canceled.
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"""
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if self.check_cancel():
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log.info("'%s' is canceled.", self.name)
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return
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log.info(self.name)
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self._set_result(self.run())
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def _task_succeeded_callback(self):
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"""Callback for a successful task.
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Don't report the success if the task was canceled.
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"""
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if not self.check_cancel():
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super()._task_succeeded_callback()
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def _thread_failed_callback(self, *exc_info):
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"""Log the error and report the failure."""
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# pylint: disable=no-value-for-parameter
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formatted_info = "".join(traceback.format_exception(*exc_info))
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log.error("Thread %s has failed: %s", self._thread_name, formatted_info)
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self._task_failed_callback()
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def run_with_signals(self):
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"""Run the task in the current thread with enabled signals.
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Call this method to run the task synchronously in the current
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thread. It will emit all signals in the same order as the start
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method.
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:raise: an error if the task fails
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:return: a result of the task if the task succeeds
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"""
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try:
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self._task_started_callback()
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self._task_run_callback()
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except Exception: # pylint: disable=broad-except
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self._task_failed_callback()
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raise
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else:
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self._task_succeeded_callback()
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finally:
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self._task_stopped_callback()
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try:
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return self.get_result()
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except NoResultError:
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return None
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@abstractmethod
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def run(self):
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"""The task implementation.
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Report the progress of the task with the self.report_progress
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method.
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Call self.check_cancel to check if the task should be canceled
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and terminate the task immediately if it returns True.
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Return a result of the task or None if the task doesn't provide
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a result.
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:return: a result of the task
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"""
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return None
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def finish(self):
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"""Finish the task run.
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Call this method after the task has stopped. If there was raised
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an exception during the task run, it will be raised here again.
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"""
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thread_manager.raise_if_error(self._thread_name)
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@classmethod
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def _generate_thread_name(cls):
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"""Generate the name of the thread."""
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cls._thread_counter += 1
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return "{}-{}-{}".format(
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THREAD_DBUS_TASK,
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cls.__name__,
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cls._thread_counter
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)
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class ValidationTask(Task):
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"""Abstract class for running a validation task."""
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def for_publication(self):
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"""Return a DBus representation."""
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return ValidationTaskInterface(self)
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@abstractmethod
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def run(self):
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"""The validation implementation.
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Run the validation and return an validation report
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with error and warning messages.
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:return: an instance of ValidationReport
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"""
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return None
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