The isolation technique is an area I’ve been interested in and following. It’s not too well documented as that area is a work in progress and not really useable

The isolation technique is an area I’ve been interested in and following. It’s not too well documented as that area is a work in progress and not really useable currently. Almost though! First it’s good to note that ARC improves upon the standard reference counting as in Obj-C or Swift by using move and sink‘s which removes many redundant ref’s/decr’s. That is if Swift hasn’t added it. The compiler can infer when ownership is moved or not. Simple ideas but put together in a powerful fashion! As I understand the isolation check, it is a compile time check that an object being moved to another thread is really isolated with no other external references. This can sometimes be done at compile time similar to acyclic structures though I don’t know the algorithm used. You can also use a runtime check which, appears related to cycle collection. Essentially you can count if the total internal references account for all the references in a given object graph — probably equivalent in cost to an ORC cycle check for that data sub-graph. Whether done at compile time or runtime the plan is to wrap the object in a special ‘Option’ like type ‘Isolated[T]’ that can be accepted by multithreaded constructs. So channels or concurrent queues, etc can declare that they only accept data that can safely be moved between threads using the standard move/sink annotations. This also lets users create their own. It boils down to ‘Isolated[T]’ just being a data check, and you can move data between threads at your own risk. That’s what I’m doing currently since I’m doing multithreaded embedded programming and using some C Queue constructs. The move/sink and ARC handle the actual data movement. In theory you could use Isolated runtime checks during testing (if your data structures are too tricky for compile time checks), but disable it for release. Similar to cycle checking. There’s a setting to use ORC to print detected cycles, then in release you can turn off ORC.