Synchronization primitives and BURST (lock, mutex, atomics etc.)

Unity Engine
1

Hi,

It seems that Burst currently does not support any of these. Are there any plans to add such support in the future?

Thanks

2

Interlocked class is supported (used by NativeHashMap) e.g. Interlocked.Exchange, Interlocked.CompareExchange

3

Thanks @mike_acton . I have implemented atomic adds on floats using CAS:

        public static float AtomicAdd(ref float location1, float value)
        {
            float newCurrentValue = location1; // non-volatile read, so may be stale
            while (true)
            {
                float currentValue = newCurrentValue;
                float newValue = currentValue + value;
                newCurrentValue = Interlocked.CompareExchange(ref location1, newValue, currentValue);
                if (newCurrentValue == currentValue)
                    return newValue;
            }
        }

However, I am getting:

The argument type `System.Single` for the method `CompareExchange` is not supported by burst
4

Unfortunately, Interlocked atomics on floats are currently not supported by burst

5

Does this mean you are planning to support this in the future?

6

There is no plan yet. This particular function is annoying because there is no existing HW intrinsics handling this, so we would need to emulate it.

1 Like
7

I see. Thanks for informing us.