Native Containers as a ref with Burst?

[astral holly]

I'm probably screwing something up somewhere...

I need to read a managed component so I'm using SystemAPI.ManagedAPI, however I also want to use the Burst Compiler in the rest of the code so something like this:

[BurstCompile] 
public void OnUpdate(ref SystemState state)
{
    NativeList<E> E = new(Allocator.TempJob);
    method(ref E)  

    //schedule job with new values
}

[BurstDiscard] 
private void method(ref NativeList<E> E)
{
    //add to E with values from managed component
}```
When burst is disabled it works just fine but with Burst the referenced list isn't changed. Am I doing something wrong or do I cut my losses and just not use burst (considering I'm only scheduling a job, performance won't take a big hit. I just want to learn if I can do this in the future)

[vast monolith]

[BurstDiscard]
just means delete this code when using burst

it won't exist

[astral holly]

oh, I thought it just meant to not compile... (leave it as normal cs code)

bit misleading

[vast monolith]

you can't leave burst (without a bunch of work to pin methods and create function pointers)

[vast monolith]

yeah this has caused confusion quite a bit

but that is correct in that the method is just discarded when compiling it

[astral holly]

hmmm, is there a time when this would be used or do people just decide not to use burst in these situations at all?

[vast monolith]

you really need to know what you're doing

i would say it's done very very rarely

the overhead would usually cost more than the benefits

[astral holly]

would be like when a method needs something managed but also requires burst critically?

but at that point you'd just jobify it instead of having it all in OnUpdate for example

oh well... bye bye burst (and hello to +0.0001ms frame time)

[vast monolith]

there's very few cases where an alternative architecture wouldn't be better

i.e. splitting into 2 systems or something

it's also unlikely you'll find any tutorial or instructions on how to leave burst

which should kind of hint at how rare it is to do

[astral holly]

Thanks again!

[vast monolith]

but just for completeness you need to marshal a function pointer from your method

and just pass that via pointer to a function pointer

if you're marshalling a non-static method you'll need to pin the underlying class so the GC doesn't move/delete it

i.e. Marshal.GetFunctionPointerForDelegate