[GitHub] [arrow-rs] jhorstmann opened a new issue, #3960: Add a feature to allow creating Buffers from Vec with custom allocators (allocator_api)

["jhorstmann (via GitHub)" <gi...@apache.org>]

jhorstmann opened a new issue, #3960:
URL: https://github.com/apache/arrow-rs/issues/3960

   **Is your feature request related to a problem or challenge? Please describe what you are trying to do.**
   
   in #3920 and #3917 support was added to to create buffers from standard Rust vectors. The currently instable `allocator_api` feature extends `Vec` to support custom allocators, using functions such as [`new_in`](https://doc.rust-lang.org/std/vec/struct.Vec.html#method.new_in). In our product we are using such custom allocators to track the memory usage of individual queries. I'd like to add a similarly named feature to arrow-rs which would generalize the `Buffer::from_vec` and `MutableBuffer::from_vec` functions.
   
   **Describe the solution you'd like**
   
    - Add a feature named `allocator-api` to `arrow-buffer`
    - If that feature is active, a different impl of `from_vec` would be enabled (via cfg attribute), which has a generic parameter for the allocator
    - `Deallocation::Standard` would additionally store the allocator (note the default `Global` allocator is zero-sized)
    - The feature would require a nightly rust compiler, just as the feature of the standard library
   
   **Describe alternatives you've considered**
   
   Something similar can be achieved using `Buffer::from_custom_allocation` but requires unsafe and dealing with pointers.
   
   **Additional context**
   


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