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0 pointsmasklinn6y ago0 comments

Given it's a cache the entries would not have an existing natural owner… except for the cache itself.

There would be no need for a GC to traverse the entire map, but that's because rust doesn't use a GC.

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6 comments · 1 top-level

falcolas6y ago· 5 in thread

While Rust does not have a discrete runtime GC process, it does utilize reference counting for dynamic memory cleanup.

So you could argue that they are still going to suffer some of the downsides of a GC'ed memory allocation. Some potential issues include non-deterministic object lifespan, and ensuring that any unsafe code they write which interacts with the cache does the "right thing" with the reference counts (potentially including de-allocation; I'm not sure what unsafe code needs to do when referencing reference counted boxes).

masklinnOP6y ago

> While Rust does not have a discrete runtime GC process, it does utilize reference counting for dynamic memory cleanup.

That's so misleading as to essentially be a lie.

Rust uses reference counting if and only if you opt into it via reference-counted pointers. Using Rc or Arc is not the normal or default course of action, and I'm not aware of any situation where it is ubiquitous.

> So you could argue [nonsense]

No, you really could not.

mcguire6y ago

On the other hand, Rust's RAII management model behaves similarly to a reference counting system where the counts are limited to 0 and 1 (well, for a loose approximation of the 0 state), right?

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falcolas6y ago

I was making an assumpotion that using a vector of ARC<T> would be the best way to handle a global LRU cache. Perhaps I should have specified it, but it seemed pretty obvious. Sorry if it wasn’t.

If there’s a better way to handle a global LRU cache, I’m all ears.

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iknowstuff6y ago

I think you're confusing Rust's ownership model with Swift's ARC. Rust doesn't do reference counting unless you use Rc<T> or Arc<T>.

falcolas6y ago

Given the model of memory we are discussing (a global per-process LRU cache), that’s exactly what I was discussing using. Unless there’s another way to handle such global caches.

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