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# -*- coding: utf-8 -*-
#
# This file is part of Linux Show Player
#
# Copyright 2012-2016 Francesco Ceruti <ceppofrancy@gmail.com>
#
# Linux Show Player is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Linux Show Player is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Linux Show Player. If not, see <http://www.gnu.org/licenses/>.
import time
from threading import Event
from lisp.core.signal import Signal
class RWait:
"""Provide a resumeable-wait mechanism."""
def __init__(self):
self._elapsed = 0
self._start_time = 0
self._ended = False
self._waiting = Event()
self._waiting.set()
self._is_waiting = Event()
self._is_waiting.set()
self.start = Signal()
self.ended = Signal()
self.paused = Signal()
self.stopped = Signal()
def wait(self, timeout, lock=None):
"""Block until the timeout is elapsed or `pause` or `stop` are called.
If the wait is paused, the next time this function is called the timeout
will be `total_timeout - elapsed_time`.
:param timeout: time to wait
:param lock: lock to release before and re-acquired after the wait
:return: True if the wait has not been interrupted by `pause` or `stop`
:rtype: bool
"""
if self._is_waiting.is_set():
# Clear the events
self._waiting.clear()
self._is_waiting.clear()
# Set the start-time
self._start_time = time.monotonic() - self._elapsed
self.start.emit()
if lock is not None:
lock.release()
# Wait for the "remaining" time
self._ended = not self._waiting.wait(timeout - self._elapsed)
# If the wait is ended by timeout
if self._ended:
self._elapsed = 0
self.ended.emit()
# Notify that we are not waiting anymore
self._is_waiting.set()
if lock is not None:
lock.acquire()
return self._ended
return False
def stop(self):
"""Stop the wait."""
if self.current_time() > 0:
self._waiting.set()
self._is_waiting.wait()
# Check self._ended to ensure that the wait is not ended by timeout
# before `self._waiting.set()` is called in this method.
if not self._ended:
self._elapsed = 0
self.stopped.emit()
def pause(self):
"""Pause the wait."""
if not self._is_waiting.is_set():
# Calculate elapsed time ASAP
elapsed = time.monotonic() - self._start_time
self._waiting.set()
self._is_waiting.wait()
# Check self._ended to ensure that the wait is not ended by timeout
# before `self._waiting.set()` is called in this method.
if not self._ended:
self._elapsed = elapsed
self.paused.emit()
def current_time(self):
"""Return the currently elapsed time."""
if self._is_waiting.is_set():
return self._elapsed
return time.monotonic() - self._start_time
def is_waiting(self):
return not self._is_waiting.is_set()
def is_paused(self):
return self._is_waiting.is_set() and self.current_time() > 0
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