Addresses scheduling issues where a backend might be closed (or even
destroyed) before it processes a waveform signal from a worker. Requires
extra multithreading code.
- Replaces QLinkedList with std::list as recommended by Qt docs.
- Replaces QWheelEvent::delta() with QWheelEvent::angleDelta(). This
should also benefit trackpad behavior.
Implemented a smarter auto-cache that's context sensitive. Caching will
automatically pause when playback begins or values are being changed and resume
when inactive.
Made various changes and fixes to the task system:
- Tasks are built around QtConcurrent rather than QThread. Reduces
code complexity significantly.
- Task error reporting is now streamlined in both TaskManager and
TaskDialog.
- Moved ProjectImport/Save/LoadManager to the app/task folder
Turned the two-step PCM transcode into one step and simplified/removed much of
the unnecessary infrastructure that supported it. This makes the code cleaner
and generally improves the code paths.
Fixes a number of playback stuttering and general UI lag issues by setting all
background tasks to IdlePriority rather than LowPriority. While it was assumed
LowPriority tasks would always get scheduled below NormalPriority (e.g. main
thread) tasks, it turns out this is not always the case. If the background tasks
start consuming a lot of CPU cycles, the scheduler may use "dynamic scheduling"
to schedule them above the main thread regardless leading to UI lag. This is
apparently the case for all thread priorities apart from IdlePriority, which
is allegedly a special case where threads are *only* scheduled when other
threads aren't busy ensuring the main thread stays responsive.
The import function was written early on in the rewrite as a multithreaded
background task that was considered somewhat flawed. While it worked for the
most part, there were possibilities of race conditions that could have
potentially been fatal, particularly since media could theoretically be
deleted while the import/probe tasks were running in the background.
With the save/load functions coming in, it became even more complicated as
projects may include metadata about the footage that can't be implemented
easily when the footage is imported/probed in the background. Making importing
a modal task fixes all of these issues, it's still done in a background thread
to not hang the GUI thread, but the GUI thread can be briefly "paused" in a
user friendly way so that all these functions can be safer.
itsmattkc