CODEWITHSUNDEEP
rust
William Taylor
William Taylor

Reputation: 629

What is the different between alloc::sync::Arc and std::sync::Arc?

I'm trying to use Arc in my code, but as i read the document, there is 2 places Arc is defined: std crate and alloc crate. So, what is the different between alloc::sync::Arc and std::sync::Arc?

Upvotes: 1

Views: 1316

Answers (2)

realkstrawn93
realkstrawn93

Reputation: 796

The core and alloc crates exist if you’re writing a kernel or some other low-level piece of software and still need to use those APIs. Unless you’re writing something that is low-level enough to declare #![no_std], there’s no advantage to using alloc over std since the structures are identical.

Upvotes: 0

Mac O'Brien
Mac O'Brien

Reputation: 2907

From the alloc crate documentation:

This library provides smart pointers and collections for managing heap-allocated values.

This library, like libcore, normally doesn’t need to be used directly since its contents are re-exported in the std crate. Crates that use the #![no_std] attribute however will typically not depend on std, so they’d use this crate instead.

So there's no difference between std::sync::Arc and alloc::sync::Arc.

alloc also provides Box, Vec, String, the collections module, and basically anything in the standard library that requires allocations (hence alloc) but not an underlying OS (filesystem, networking, etc). alloc is there if you want to write bare-metal (unhosted) software that still gets to use the nice standard library data structures.

Upvotes: 3

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