No get_mut method on AtomicPtr

[jrmuizel]

The AtomicPtr implementation seems to be missing an implementation of get_mut

[Restioson]

Would a PR to implement this be accepted?

[hawkw]

@Restioson

Would a PR to implement this be accepted?

Yes, that would be great! It should probably be simulated using Atomic::unsync_load:

loom/src/rt/atomic.rs

Lines 200 to 216 in 73e6c14

	/// Loads a value from the atomic cell without performing synchronization
	pub(crate) fn unsync_load(&self, location: Location) -> T {
	rt::execution(|execution| {
	let state = self.state.get_mut(&mut execution.objects);
	state
	.unsync_loaded_locations
	.track(location, &execution.threads);
	// An unsync load counts as a "read" access
	state.track_unsync_load(&execution.threads);
	// Return the value
	let index = index(state.cnt - 1);
	T::from_u64(state.stores[index].value)
	})
	}

We might want to add get_mut methods to the other loom atomic types, like AtomicUsize, since they also have get_mut methods.

[carllerche]

If we do get_mut() it needs to return a guard type and not the ptr itself. loom needs to know when the ptr is no longer accessible in order to ensure correctness. This is why other types have with_mut but that can be changed to a guard type return as well instead of a closure.

[Restioson]

Would the logic be essentially the same as with_mut otherwise? The cleanup moved to the drop impl and the setup to the get_mut function?