[ARROW-10978] [Rust] Document use of unsafe in utils

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Component/s: Rust
• External issue URL: https://github.com/apache/arrow/issues/26901
• Assignee: Unassigned
• Reporter: Andy Grove
• Created: 19/Dec/20 15:03
• Updated: 11/Jan/23 08:16
• Resolved: 26/Apr/21 12:42

Description

There are ~18 uses of unsafe in src/utils and we should document them according to the guidelines in the Arrow crate README

 

// JUSTIFICATION
//  Benefit
//      Describe the benefit of using unsafe. E.g.
//      "30% performance degradation if the safe counterpart is used, see bench X."
//  Soundness
//      Describe why the code remains sound (according to the definition of rust's unsafe code guidelines). E.g.
//      "We bounded check these values at initialization and the array is immutable."
let ... = unsafe { ... };