Replace _waitVar.notify_one() with _waitVar.notify_all(). This was the
only hurdle to documenting ConcurrentQueue::waitAll() as thread-safe.
ConcurrentQueueTest::waitAllFromMultipleThreads() passes instead of
hanging now.
The return value can be used to make
ConcurrentQueueTest::cancelPending1UserThread() non-flaky. It may also
be useful to non-testing code.
Improve the performance of cancelPending() by locking the two mutexes
separately and minimizing the locking time.
Worker threads may well be executing jobs while this function is being
called. If ConcurrentQueue::waitAll() is called soon enough after
cancelPending(), the worker threads may still be running, but waitAll()
would return immediately as jobsLeft would be nonpositive.
Subtracting _queue.size() from jobsLeft sets this variable to the number
of worker threads that are executing jobs at the moment.
ConcurrentQueueTest::cancelPending1UserThread() passes most of the time
now. But it still fails occasionally because it depends on the timing of
thread scheduling, which is unreliable.
A comic always belongs to a Folder, but when we open one its siblings may be different in we are opening it from a Reading List. I am not sure that Tags should keep the reading order because their purpose is abstract, so their behaviour will be opening the comics from theirs container folders.
Moving the initialization of defaultTexture out of the member
initializer list gets rid of a GCC's -Wreorder warning.
Initialize other texture pointers to improve safety and consistency.
Qt OpenGL in Qt5 is a deprecated module that is discouraged for
new code usage. We have been including this module in our builds
despite not relying on its functionality for a long time now -
probably an oversight from porting to the newer functions.
Time to remove it.
IMPORTANT INFORMATION: In Qt6, a lot of functionality that was
provided by Qt GUI was moved into the 'new' Qt6 Qt OpenGL module.
Thus, even if it makes perfectly sense to remove it for Qt5 builds
we will likely have to restore it for Qt6 builds at a later time.
