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# Copyright 1999-2018 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
from _emerge.AsynchronousTask import AsynchronousTask
from portage import os
class CompositeTask(AsynchronousTask):
__slots__ = ("_current_task",)
def _cancel(self):
if self._current_task is not None:
if self._current_task is self._TASK_QUEUED:
self.returncode = 1
self._current_task = None
elif self.returncode is None:
# Assume that the task has not started yet.
def _poll(self):
This does a loop calling self._current_task.poll()
repeatedly as long as the value of self._current_task
keeps changing. It calls poll() a maximum of one time
for a given self._current_task instance. This is useful
since calling poll() on a task can trigger advance to
the next task could eventually lead to the returncode
being set in cases when polling only a single task would
not have the same effect.
prev = None
while True:
task = self._current_task
if task is None or task is self._TASK_QUEUED or task is prev:
# don't poll the same task more than once
prev = task
return self.returncode
def _assert_current(self, task):
Raises an AssertionError if the given task is not the
same one as self._current_task. This can be useful
for detecting bugs.
if task is not self._current_task:
raise AssertionError("Unrecognized task: %s" % (task,))
def _default_exit(self, task):
Calls _assert_current() on the given task and then sets the
composite returncode attribute if task.returncode != os.EX_OK.
If the task failed then self._current_task will be set to None.
Subclasses can use this as a generic task exit callback.
@rtype: int
@return: The task.returncode attribute.
if task.returncode != os.EX_OK:
self.returncode = task.returncode
self.cancelled = task.cancelled
self._current_task = None
return task.returncode
def _final_exit(self, task):
Assumes that task is the final task of this composite task.
Calls _default_exit() and sets self.returncode to the task's
returncode and sets self._current_task to None.
self._current_task = None
self.returncode = task.returncode
return self.returncode
def _default_final_exit(self, task):
This calls _final_exit() and then wait().
Subclasses can use this as a generic final task exit callback.
return self.wait()
def _start_task(self, task, exit_handler):
Register exit handler for the given task, set it
as self._current_task, and call task.start().
Subclasses can use this as a generic way to start
a task.
task.scheduler = self.scheduler
except AttributeError:
self._current_task = task
def _task_queued(self, task):
self._current_task = self._TASK_QUEUED
def _task_queued_start_handler(self, task):
self._current_task = task
def _task_queued_wait(self):
return (
self._current_task is not self._TASK_QUEUED
or self.cancelled
or self.returncode is not None