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[bug 954613] Introduce locking when updating slide display to avoid slidecontroller and display getting out of sync.

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Fixes: https://launchpad.net/bugs/954613
This commit is contained in:
Tomas Groth 2014-12-19 23:07:32 +00:00
parent b2f6eaf7d4
commit 321709d7a7
1 changed files with 13 additions and 5 deletions
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18
openlp/core/ui/slidecontroller.py
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@ -33,6 +33,7 @@ The :mod:`slidecontroller` module contains the most important part of OpenLP - t
import os import os
import copy import copy
from collections import deque from collections import deque
from threading import Lock
from PyQt4 import QtCore, QtGui from PyQt4 import QtCore, QtGui
@ -131,6 +132,8 @@ class SlideController(DisplayController, RegistryProperties):
self.ratio = self.screens.current['size'].width() / self.screens.current['size'].height() self.ratio = self.screens.current['size'].width() / self.screens.current['size'].height()
except ZeroDivisionError: except ZeroDivisionError:
self.ratio = 1 self.ratio = 1
self.process_queue_lock = Lock()
self.slide_selected_lock = Lock()
self.timer_id = 0 self.timer_id = 0
self.song_edit = False self.song_edit = False
self.selected_row = 0 self.selected_row = 0
@ -531,9 +534,9 @@ class SlideController(DisplayController, RegistryProperties):
Process the service item request queue. The key presses can arrive Process the service item request queue. The key presses can arrive
faster than the processing so implement a FIFO queue. faster than the processing so implement a FIFO queue.
""" """
if self.keypress_queue: # Make sure only one thread get in here. Just return if already locked.
while len(self.keypress_queue) and not self.keypress_loop: if self.keypress_queue and self.process_queue_lock.acquire(False):
self.keypress_loop = True while len(self.keypress_queue):
keypress_command = self.keypress_queue.popleft() keypress_command = self.keypress_queue.popleft()
if keypress_command == ServiceItemAction.Previous: if keypress_command == ServiceItemAction.Previous:
self.service_manager.previous_item() self.service_manager.previous_item()
@ -542,7 +545,7 @@ class SlideController(DisplayController, RegistryProperties):
self.service_manager.previous_item(last_slide=True) self.service_manager.previous_item(last_slide=True)
else: else:
self.service_manager.next_item() self.service_manager.next_item()
self.keypress_loop = False self.process_queue_lock.release()
def screen_size_changed(self): def screen_size_changed(self):
""" """
@ -1039,6 +1042,10 @@ class SlideController(DisplayController, RegistryProperties):
:param start: :param start:
""" """
# Only one thread should be in here at the time. If already locked just skip, since the update will be
# done by the thread holding the lock. If it is a "start" slide, we must wait for the lock.
if not self.slide_selected_lock.acquire(start):
return
row = self.preview_widget.current_slide_number() row = self.preview_widget.current_slide_number()
self.selected_row = 0 self.selected_row = 0
if -1 < row < self.preview_widget.slide_count(): if -1 < row < self.preview_widget.slide_count():
@ -1061,6 +1068,8 @@ class SlideController(DisplayController, RegistryProperties):
self.update_preview() self.update_preview()
self.preview_widget.change_slide(row) self.preview_widget.change_slide(row)
self.display.setFocus() self.display.setFocus()
# Release lock
self.slide_selected_lock.release()
def on_slide_change(self, row): def on_slide_change(self, row):
""" """
@ -1405,7 +1414,6 @@ class LiveController(RegistryMixin, OpenLPMixin, SlideController):
self.split = 1 self.split = 1
self.type_prefix = 'live' self.type_prefix = 'live'
self.keypress_queue = deque() self.keypress_queue = deque()
self.keypress_loop = False
self.category = UiStrings().LiveToolbar self.category = UiStrings().LiveToolbar
ActionList.get_instance().add_category(str(self.category), CategoryOrder.standard_toolbar) ActionList.get_instance().add_category(str(self.category), CategoryOrder.standard_toolbar)