More Subprocess Refactoring and Cancel Generate Operator

[NullSenseStudio]

• Cancel Generate operator allows for stopping without killing the subprocess and reloading everything next time
• Added send_intent() method to GeneratorProcess that mirrors what send_action() does
• Subprocess state is now managed by the Backend class to clean up main()
• Subprocess now uses a background thread for reading stdin so new intents can be processed while one is already running
• Intents are split into their own generator functions that allow for lazy loading their dependencies and models, won't have to wait on stable diffusion models if you're only starting the subprocess for upscaling
• Includes a fix for Setting "Precision" to a value other than "Automatic" causes the generator to load every time you generate #265

[carson-katri]

Subprocess now uses a background thread for reading stdin so new intents can be processed while one is already running

I assume this is meant for the stop generation action, but I also tried testing upscaling while the generator was running. This did not work:

  File "/Users/carsonkatri/Documents/Art/Add-ons/Custom/Blender/dream_textures/generator_process.py", line 518, in main
    back.main_loop()
  File "/Users/carsonkatri/Documents/Art/Add-ons/Custom/Blender/dream_textures/generator_process.py", line 480, in main_loop
    (intent, args) = self.queue.pop()

During handling of the above exception, another exception occurred:

  File "/Users/carsonkatri/Documents/Art/Add-ons/Custom/Blender/dream_textures/generator_process.py", line 255, in send_exception
    sys.exit(1)
  File "/Users/carsonkatri/Documents/Art/Add-ons/Custom/Blender/dream_textures/generator_process.py", line 522, in main
    back.send_exception()
  File "/Users/carsonkatri/Documents/Art/Add-ons/Custom/Blender/dream_textures/generator_process.py", line 525, in <module>
    main()

So perhaps we can either disable the UI for the upscaling panel while generator is running or look into a fix for this.

[NullSenseStudio]

I wasn't quite able to replicate your error case but looks like I didn't make it properly wait if it had more than one intent in the queue. That should be okay now.

There is still an issue of multiple operators polling the action queue at the same time that will need addressed. I'll see what I can do about that later. Either disabling the operator while another is running or perhaps attaching a unique id to link each action to the intent that caused it.

  File "C:\Users\NullSense\AppData\Roaming\Blender Foundation\Blender\3.3\scripts\addons\dream-textures\generator_process.py", line 147, in upscale
    callbacks[action](**tup[1])
KeyError: 4

[NullSenseStudio]

Blocking operators is the most practical for now. Intent session id tracking could be useful if the subprocess would split tasks up between multiple GPUs, but just an idea to save for later.

[carson-katri]

That's odd, since the scene is supposed to be in the global context, so all other contexts would be built on that (i assumed)

[NullSenseStudio]

I may have mixed up where it was getting context from, or completely forgetting what caused the issue in the first place. There actually seems to be a problem with the context that kill_generator() gives it, the default context argument is somehow different from bpy.context when called. It should stop being an issue if I just leave the default as None and replace with bpy.context when that is the case.

[carson-katri]

LGTM 👍