A little theory, have a look at the observer-pattern. Basically the best way is to have an atomic float that you keep up to date from the process block, and from the editor using a timer read that value and display it.
I implemented this in my ff_meters module. You can use it or get inspiration from it. It calculates RMS and Max values in the LevelMeterSource - measureBlock, that are used to display in the LevelMeter component.