574 lines
17 KiB
Python
574 lines
17 KiB
Python
# -*- Mode: Python -*-
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# vi:si:et:sw=4:sts=4:ts=4
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# Copyright (C) 2009 Thomas Vander Stichele
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# This file is part of whipper.
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#
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# whipper is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# whipper is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with whipper. If not, see <http://www.gnu.org/licenses/>.
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from __future__ import print_function
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import logging
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import sys
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from gi.repository import GLib as GLib
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logger = logging.getLogger(__name__)
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class TaskException(Exception):
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"""
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I wrap an exception that happened during task execution.
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"""
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exception = None # original exception
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def __init__(self, exception, message=None):
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self.exception = exception
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self.exceptionMessage = message
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self.args = (exception, message, )
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# lifted from flumotion log module
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def _getExceptionMessage(exception, frame=-1, filename=None):
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"""
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Return a short message based on an exception, useful for debugging.
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Tries to find where the exception was triggered.
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"""
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import traceback
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stack = traceback.extract_tb(sys.exc_info()[2])
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if filename:
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stack = [f for f in stack if f[0].find(filename) > -1]
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# badly raised exceptions can come without a stack
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if stack:
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(filename, line, func, text) = stack[frame]
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else:
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(filename, line, func, text) = ('no stack', 0, 'none', '')
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exc = exception.__class__.__name__
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msg = ""
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# a shortcut to extract a useful message out of most exceptions
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# for now
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if str(exception):
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msg = ": %s" % str(exception)
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return "exception %(exc)s at %(filename)s:%(line)s: %(func)s()%(msg)s" \
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% locals()
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class LogStub(object):
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"""
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I am a stub for a log interface.
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"""
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@staticmethod
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def log(message, *args):
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logger.info(message, *args)
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@staticmethod
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def debug(message, *args):
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logger.debug(message, *args)
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@staticmethod
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def warning(message, *args):
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logger.warning(message, *args)
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class Task(LogStub):
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"""
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I wrap a task in an asynchronous interface.
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I can be listened to for starting, stopping, description changes
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and progress updates.
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I communicate an error by setting self.exception to an exception and
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stopping myself from running.
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The listener can then handle the Task.exception.
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:cvar description: what am I doing
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:cvar exception: set if an exception happened during the task
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execution. Will be raised through run() at the end.
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"""
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logCategory = 'Task'
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description = 'I am doing something.'
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progress = 0.0
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increment = 0.01
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running = False
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runner = None
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exception = None
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exceptionMessage = None
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exceptionTraceback = None
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_listeners = None
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# subclass methods
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def start(self, runner):
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"""
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Start the task.
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Subclasses should chain up to me at the beginning.
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Subclass implementations should raise exceptions immediately in
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case of failure (using set(AndRaise)Exception) first, or do it later
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using those methods.
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If start doesn't raise an exception, the task should run until
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complete, or setException and stop().
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"""
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self.debug('starting')
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self.setProgress(self.progress)
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self.running = True
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self.runner = runner
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self._notifyListeners('started')
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def stop(self):
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"""
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Stop the task.
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Also resets the runner on the task.
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Subclasses should chain up to me at the end.
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It is important that they do so in all cases, even when
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they ran into an exception of their own.
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Listeners will get notified that the task is stopped,
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whether successfully or with an exception.
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"""
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self.debug('stopping')
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self.running = False
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if not self.runner:
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print('ERROR: stopping task which is already stopped')
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import traceback
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traceback.print_stack()
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self.runner = None
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self.debug('reset runner to None')
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self._notifyListeners('stopped')
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# base class methods
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def setProgress(self, value):
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"""
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Notify about progress changes bigger than the increment.
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Called by subclass implementations as the task progresses.
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"""
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if (value - self.progress > self.increment or
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value >= 1.0 or value == 0.0):
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self.progress = value
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self._notifyListeners('progressed', value)
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self.debug('notifying progress: %r on %r',
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value, self.description)
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def setDescription(self, description):
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if description != self.description:
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self._notifyListeners('described', description)
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self.description = description
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# FIXME: unify?
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def setExceptionAndTraceback(self, exception):
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"""
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Call this to set a synthetically created exception (and not one
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that was actually raised and caught)
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"""
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import traceback
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stack = traceback.extract_stack()[:-1]
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(filename, line, func, text) = stack[-1]
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exc = exception.__class__.__name__
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msg = ""
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# a shortcut to extract a useful message out of most exceptions
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# for now
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if str(exception):
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msg = ": %s" % str(exception)
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line = ("exception %(exc)s at %(filename)s:%(line)s: "
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"%(func)s()%(msg)s" % locals())
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self.exception = exception
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self.exceptionMessage = line
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self.exceptionTraceback = traceback.format_exc()
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self.debug('set exception, %r' % self.exceptionMessage)
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# FIXME: remove
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setAndRaiseException = setExceptionAndTraceback
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def setException(self, exception):
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"""
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Call this to set a caught exception on the task.
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"""
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import traceback
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self.exception = exception
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self.exceptionMessage = _getExceptionMessage(exception)
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self.exceptionTraceback = traceback.format_exc()
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self.debug('set exception, %r, %r' % (
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exception, self.exceptionMessage))
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def schedule(self, delta, callable_task, *args, **kwargs):
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if not self.runner:
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print("ERROR: scheduling on a task that's altready stopped")
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import traceback
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traceback.print_stack()
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return
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self.runner.schedule(self, delta, callable_task, *args, **kwargs)
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def addListener(self, listener):
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"""
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Add a listener for task status changes.
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Listeners should implement started, stopped, and progressed.
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"""
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self.debug('Adding listener %r', listener)
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if not self._listeners:
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self._listeners = []
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self._listeners.append(listener)
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def _notifyListeners(self, methodName, *args, **kwargs):
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if self._listeners:
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for l in self._listeners:
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method = getattr(l, methodName)
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try:
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method(self, *args, **kwargs)
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# FIXME: catching too general exception (Exception)
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except Exception as e:
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self.setException(e)
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# FIXME: should this become a real interface, like in zope ?
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class ITaskListener(object):
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"""
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I am an interface for objects listening to tasks.
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"""
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# listener callbacks
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def progressed(self, task, value):
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"""
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Implement me to be informed about progress.
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:type value: float
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:param value: progress, from 0.0 to 1.0
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"""
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def described(self, task, description):
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"""
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Implement me to be informed about description changes.
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:type description: str
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:param description: description
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"""
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def started(self, task):
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"""
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Implement me to be informed about the task starting.
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"""
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def stopped(self, task):
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"""
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Implement me to be informed about the task stopping.
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If the task had an error, task.exception will be set.
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"""
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# this is a Dummy task that can be used to test if this works at all
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class DummyTask(Task):
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def start(self, runner):
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Task.start(self, runner)
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self.schedule(1.0, self._wind)
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def _wind(self):
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self.setProgress(min(self.progress + 0.1, 1.0))
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if self.progress >= 1.0:
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self.stop()
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return
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self.schedule(1.0, self._wind)
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class BaseMultiTask(Task, ITaskListener):
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"""
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I perform multiple tasks.
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:ivar tasks: the tasks to run
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:type tasks: list of :any:`Task`
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"""
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description = 'Doing various tasks'
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tasks = None
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def __init__(self):
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self.tasks = []
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self._task = 0
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def addTask(self, task):
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"""
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Add a task.
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:type task: Task
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"""
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if self.tasks is None:
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self.tasks = []
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self.tasks.append(task)
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def start(self, runner):
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"""
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Start tasks.
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Tasks can still be added while running. For example,
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a first task can determine how many additional tasks to run.
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"""
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Task.start(self, runner)
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# initialize task tracking
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if not self.tasks:
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self.warning('no tasks')
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self._generic = self.description
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self.next()
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def next(self):
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"""
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Start the next task.
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"""
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try:
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# start next task
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task = self.tasks[self._task]
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self._task += 1
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self.debug('BaseMultiTask.next(): starting task %d of %d: %r',
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self._task, len(self.tasks), task)
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self.setDescription("%s (%d of %d) ..." % (
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task.description, self._task, len(self.tasks)))
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task.addListener(self)
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task.start(self.runner)
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self.debug('BaseMultiTask.next(): started task %d of %d: %r',
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self._task, len(self.tasks), task)
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# FIXME: catching too general exception (Exception)
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except Exception as e:
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self.setException(e)
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self.debug('Got exception during next: %r', self.exceptionMessage)
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self.stop()
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return
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# ITaskListener methods
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def started(self, task):
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pass
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def progressed(self, task, value):
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pass
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def stopped(self, task):
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"""
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Subclasses should chain up to me at the end of their implementation.
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They should fall through to chaining up if there is an exception.
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"""
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self.debug('BaseMultiTask.stopped: task %r (%d of %d)',
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task, self.tasks.index(task) + 1, len(self.tasks))
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if task.exception:
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self.warning('BaseMultiTask.stopped: exception %r',
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task.exceptionMessage)
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self.exception = task.exception
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self.exceptionMessage = task.exceptionMessage
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self.stop()
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return
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if self._task == len(self.tasks):
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self.debug('BaseMultiTask.stopped: all tasks done')
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self.stop()
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return
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# pick another
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self.debug('BaseMultiTask.stopped: pick next task')
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self.schedule(0, self.next)
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class MultiSeparateTask(BaseMultiTask):
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"""
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I perform multiple tasks.
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I track progress of each individual task, going back to 0 for each task.
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"""
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description = 'Doing various tasks separately'
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def start(self, runner):
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self.debug('MultiSeparateTask.start()')
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BaseMultiTask.start(self, runner)
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def next(self):
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self.debug('MultiSeparateTask.next()')
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# start next task
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self.progress = 0.0 # reset progress for each task
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BaseMultiTask.next(self)
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# ITaskListener methods
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def progressed(self, task, value):
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self.setProgress(value)
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def described(self, description):
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self.setDescription("%s (%d of %d) ..." % (
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description, self._task, len(self.tasks)))
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class MultiCombinedTask(BaseMultiTask):
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"""
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I perform multiple tasks.
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I track progress as a combined progress on all tasks on task granularity.
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"""
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description = 'Doing various tasks combined'
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_stopped = 0
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# ITaskListener methods
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def progressed(self, task, value):
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self.setProgress(float(self._stopped + value) / len(self.tasks))
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def stopped(self, task):
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self._stopped += 1
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self.setProgress(float(self._stopped) / len(self.tasks))
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BaseMultiTask.stopped(self, task)
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class TaskRunner(LogStub):
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"""
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I am a base class for task runners.
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Task runners should be reusable.
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"""
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logCategory = 'TaskRunner'
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def run(self, task):
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"""
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Run the given task.
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:type task: Task
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"""
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raise NotImplementedError
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# methods for tasks to call
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def schedule(self, delta, callable_task, *args, **kwargs):
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"""
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Schedule a single future call.
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Subclasses should implement this.
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:type delta: float
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:param delta: time in the future to schedule call for, in seconds.
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"""
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raise NotImplementedError
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class SyncRunner(TaskRunner, ITaskListener):
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"""
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I run the task synchronously in a GObject MainLoop.
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"""
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def __init__(self, verbose=True):
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self._verbose = verbose
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self._longest = 0 # longest string shown; for clearing
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def run(self, task, verbose=None, skip=False):
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self.debug('run task %r', task)
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self._task = task
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self._verboseRun = self._verbose
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if verbose is not None:
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self._verboseRun = verbose
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self._skip = skip
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self._loop = GLib.MainLoop()
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self._task.addListener(self)
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# only start the task after going into the mainloop,
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# otherwise the task might complete before we are in it
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GLib.timeout_add(0L, self._startWrap, self._task)
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self.debug('run loop')
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self._loop.run()
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self.debug('done running task %r', task)
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if task.exception:
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# catch the exception message
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# FIXME: this gave a traceback in the logging module
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self.debug('raising TaskException for %r, %r' % (
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task.exceptionMessage, task.exceptionTraceback))
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msg = task.exceptionMessage
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if task.exceptionTraceback:
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msg += "\n" + task.exceptionTraceback
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raise TaskException(task.exception, message=msg)
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def _startWrap(self, task):
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# wrap task start such that we can report any exceptions and
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# never hang
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try:
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self.debug('start task %r' % task)
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task.start(self)
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# FIXME: catching too general exception (Exception)
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except Exception as e:
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# getExceptionMessage uses global exception state that doesn't
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# hang around, so store the message
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task.setException(e)
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self.debug('exception during start: %r', task.exceptionMessage)
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self.stopped(task)
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def schedule(self, task, delta, callable_task, *args, **kwargs):
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def c():
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try:
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callable_task(*args, **kwargs)
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return False
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except Exception as e:
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self.debug('exception when calling scheduled callable %r',
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callable_task)
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task.setException(e)
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self.stopped(task)
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raise
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GLib.timeout_add(int(delta * 1000L), c)
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# ITaskListener methods
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def progressed(self, task, value):
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if not self._verboseRun:
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return
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self._report()
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if value >= 1.0:
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if self._skip:
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self._output('%s %3d %%' % (
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self._task.description, 100.0))
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else:
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# clear with whitespace
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print(("%s\r" % (' ' * self._longest, )), end='')
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def _output(self, what, newline=False, ret=True):
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print(what, end='')
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print((' ' * (self._longest - len(what))), end='')
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if ret:
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print('\r', end='')
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if newline:
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print('')
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sys.stdout.flush()
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if len(what) > self._longest:
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self._longest = len(what)
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def described(self, task, description):
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if self._verboseRun:
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self._report()
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def stopped(self, task):
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self.debug('stopped task %r', task)
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self.progressed(task, 1.0)
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self._loop.quit()
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def _report(self):
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self._output('%s %3d %%' % (
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self._task.description, self._task.progress * 100.0))
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if __name__ == '__main__':
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task = DummyTask()
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runner = SyncRunner()
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runner.run(task)
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