Description
I'm currently writing (or, trying to write 🙄) a lua script that will generate the preview cache for selected images (without leaving dt to start the external program...). Basically, it seems to work but I see two strange things that I don't understand right now.
First, the essential parts of my script:
local function stop_job( job )
job.valid = false
end
local function create_previews()
job = dt.gui.create_job( "generating previews", true, stop_job )
local images = dt.gui.action_images
for i,image in pairs(images) do
if job.valid then
image:generate_cache( true, 0, 8 )
job.percent = i / #images
dt.control.sleep( 1 ) -- without this, the job cannot be aborted
else
break
end
end
if job.valid then -- without this, dt crashes with an exception in dt_pthread_mutex_destroy() after aborting the job
job.valid = false
end
end
the create_previews function will be called from a registered action.
My two questions:
-
Without the sleep() I cannot stop the running job. After starting the job, the progress bar is shown and when I hit the 'X' nothing happens until the for loop processed all images. Then the stop_job() is called. With the sleep the stop_job is called after processing the current image and the job terminates as desired.
-
When I set the job.valid to false after the loop it only works as long as the job is not terminated via the stop_job function. As this already sets the job to invalid I guess it is already destroyed and in the second job.valid=false dt crashes with an exception in dt_pthread_mutex_destroy.
Both phenomena are completely understandable, but: I see a lot of scripts that execute job.valid=false twice (when aborted) and seem to rely on stopping without a call to sleep(). Hmmm. What I'm missing here?
I hope you can clarify this,
thanks a lot!
Christian