Swift atomics are rather awkward

[taylorswift]

@hassila

I also agree, but can just reflect that it’d be nice if we’d get locks and semaphores in some form in the standard library, but now we get atomics

right, lock implementations in swift are kind of a jungle if you’re not using Foundation.

@Joe_Groff

For something like what you're talking about, either a lightweight lock like os_unfair_lock or AtomicReference would be appropriate depending on the level of contention.

AtomicReference is the right way to go. allocating the object is expensive, but for something that is updated in second intervals that’s not really a concern.

AtomicReference doesn’t work with Array because Array is a struct wrapper around a pointer, and AtomicReference doesn’t know how to refcount a wrapped pointer. the low-effort, low-reward answer is to wrap the array in a class. the high-effort, marginally higher-reward answer is to roll your own immutable ManagedBuffer-backed immutable array type that contains the elements inline. but i wish it were not so difficult to do the latter.