3 ms·

Cannot understand your complain. It written in Rust, but for you it looks like C. So what?

by oneshtein 2y ago

Alifatisk 2y ago
So, it is basically like it was written in C.
- oneshtein 2y ago
  Yes, it's possible to write in Rust like in C. This code is example of that. You can even use automatic code converter to convert C into Rust.
ajross 2y ago
It doesn't exploit (and in fact deliberately evades) Rust's signature memory safety features. The impression from the headline is "Rust is as fast as C now!", but in fact the subset of the language that has been shown to be as fast as C is the subset that is basically isomorphic to C. The impression a naive reader might take is that idiomatic/safe/best-practices Rust has now closed the performance gap. But clearly that's not happening here.
- sedatk 2y ago
  Rust's many memory safety features (including the borrow checker) are still enabled in unsafe Rust blocks. For more information: https://news.ycombinator.com/item?id=43382176 https://news.ycombinator.com/item?id=43382176
  - ajross 2y ago
    But again, not exploited by the code in question. This isn't using the Rust runtime heap, it's doing its own thing with raw pointers/indexing, and even seems to have its own allocator.
    - steveklabnik 2y ago
      > This isn't using the Rust runtime heap, Rust does not have a specific "Rust runtime heap."
      - IshKebab 2y ago
        It does, it has a default global heap allocator.
        simonask 2y ago
        That's not a "Rust runtime", that's an extension point. The default setting is `malloc()`.
        steveklabnik 2y ago
        That's not part of Rust, that's a feature of its standard library. This is the same as C, where a freestanding implementation doesn't include malloc. Put another way, there's no issues with a library using its own heap if it wants to.
    - ComputerGuru 2y ago
      That is not correct; in another comment you can see where the code takes advantage of the rust-specific &mut notation to use a fast memcpy for non-overlapping pointers.

Cannot understand your complain. It written in Rust, but for you it looks like C. So what?

Alifatisk 2y ago

So, it is basically like it was written in C.

oneshtein 2y ago
Yes, it's possible to write in Rust like in C. This code is example of that. You can even use automatic code converter to convert C into Rust.

ajross 2y ago

It doesn't exploit (and in fact deliberately evades) Rust's signature memory safety features. The impression from the headline is "Rust is as fast as C now!", but in fact the subset of the language that has been shown to be as fast as C is the subset that is basically isomorphic to C. The impression a naive reader might take is that idiomatic/safe/best-practices Rust has now closed the performance gap. But clearly that's not happening here.

sedatk 2y ago
Rust's many memory safety features (including the borrow checker) are still enabled in unsafe Rust blocks. For more information: https://news.ycombinator.com/item?id=43382176 https://news.ycombinator.com/item?id=43382176
- ajross 2y ago
  But again, not exploited by the code in question. This isn't using the Rust runtime heap, it's doing its own thing with raw pointers/indexing, and even seems to have its own allocator.
  - steveklabnik 2y ago
    > This isn't using the Rust runtime heap, Rust does not have a specific "Rust runtime heap."
    - IshKebab 2y ago
      It does, it has a default global heap allocator.
      - simonask 2y ago
        That's not a "Rust runtime", that's an extension point. The default setting is `malloc()`.
      - steveklabnik 2y ago
        That's not part of Rust, that's a feature of its standard library. This is the same as C, where a freestanding implementation doesn't include malloc. Put another way, there's no issues with a library using its own heap if it wants to.
  - ComputerGuru 2y ago
    That is not correct; in another comment you can see where the code takes advantage of the rust-specific &mut notation to use a fast memcpy for non-overlapping pointers.