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151 lines
4.7 KiB
Python
151 lines
4.7 KiB
Python
# Copyright (C) 2014, Sugarlabs
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2 of the License, or (at your option) any later version.
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#
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# This library 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 GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the
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# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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# Boston, MA 02111-1307, USA.
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"""
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The power module provides an interface to *powerd*, a daemon that
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manages the aggressive suspend and wakeup policies for early OLPC
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laptops.
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The module does nothing if *powerd* is not present. *powerd* is not
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required on laptops other than OLPC XO-1, XO-1.5, XO-1.75 and XO-4.
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Distributions of Sugar on other hardware need not include the *powerd*
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package.
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"""
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import os
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import logging
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_POWERD_INHIBIT_DIR = '/var/run/powerd-inhibit-suspend'
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_power_manager = None
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def get_power_manager():
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"""
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Get the power manager instance. Only one instance exists, and
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will always be returned.
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Returns:
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an instance of :class:`sugar3.power.PowerManager`.
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"""
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global _power_manager
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if _power_manager is None:
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_power_manager = PowerManager()
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return _power_manager
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class PowerManager():
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"""
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Control of automatic idle suspend, with reference counting.
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:class:`sugar3.activity.activity.Activity` calls
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:py:meth:`inhibit_suspend` before speaking text, or when an
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activity collaboration begins.
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Activities may call :py:meth:`inhibit_suspend` before playing
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music, video, speaking large amounts of text, collaborating, or
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waiting for response to network operations.
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As an example, the Clock activity inhibits automatic idle suspend
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while it is active, so that the displayed clock-face continues to
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change. Otherwise it would freeze.
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:class:`sugar3.activity.activity.Activity` calls
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:py:meth:`shutdown` as an activity terminates, in case the
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activity has failed to call :py:meth:`restore_suspend`.
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While automatic idle suspend is inhibited, *powerd* will
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continue to dim and blank the display.
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Both the :py:meth:`inhibit_suspend` and :py:meth:`restore_suspend`
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methods are reference counted; automatic idle suspend is not
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restored until the same number of calls to restore are made.
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*powerd* is resilient against failure to restore automatic idle
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suspend; it verifies an inhibit request and deletes it if the
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requesting process has terminated.
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"""
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def __init__(self):
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self._suspend_inhibit_counter = 0
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if os.path.exists(_POWERD_INHIBIT_DIR):
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self._path = os.path.join(_POWERD_INHIBIT_DIR, str(os.getpid()))
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else:
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self._path = None
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def __del__(self):
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self._remove_flag_file()
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def suspend_breaks_collaboration(self):
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"""
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Does automatic idle suspend break collaboration with this
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toolkit? Yes. For future use by a toolkit with more
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resilient collaboration.
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Returns:
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True
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"""
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return True
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def inhibit_suspend(self):
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"""
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Inhibit automatic idle suspend until restored.
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"""
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if self._path and self._suspend_inhibit_counter == 0:
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try:
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with open(self._path, 'w') as flag_file:
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flag_file.write('')
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except IOError:
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logging.error("Inhibit Suspend: Could not create file %s",
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self._path)
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self._suspend_inhibit_counter += 1
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def restore_suspend(self):
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"""
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Possibly restore automatic idle suspend.
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"""
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self._suspend_inhibit_counter -= 1
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if self._suspend_inhibit_counter > 0:
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return
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self._remove_flag_file()
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def is_suspend_inhibited(self):
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"""
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Check if automatic idle suspend is inhibited.
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Returns:
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inhibited (bool): whether automatic idle suspend is inhibited.
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"""
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return self._suspend_inhibit_counter > 0
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def shutdown(self):
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"""
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Shutdown the power manager.
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Restores automatic idle suspend regardless of reference counting.
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"""
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self._remove_flag_file()
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def _remove_flag_file(self):
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if self._path:
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try:
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os.unlink(self._path)
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except OSError:
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pass
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self._suspend_inhibit_counter = 0
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