Re: [pbs-devel] [PATCH backup 08/13] snapshot_reader: use Rc for structs that are not Send+Sync

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

On February 12, 2024 2:17 pm, Maximiliano Sandoval wrote:
> Fixes the clippy lint:
> 
> ```
> warning: usage of an `Arc` that is not `Send` and `Sync`
>    --> pbs-datastore/src/snapshot_reader.rs:156:52
>     |
> 156 |                         self.current_index = Some((Arc::new(index), 0, order));
>     |                                                    ^^^^^^^^^^^^^^^
>     |
>     = note: `Arc<Box<dyn IndexFile + Send>>` is not `Send` and `Sync` as:
>     = note: - the trait `Sync` is not implemented for `Box<dyn IndexFile + Send>`
>     = help: consider using an `Rc` instead. `Arc` does not provide benefits for non `Send` and `Sync` types
>     = note: if you intend to use `Arc` with `Send` and `Sync` traits
>     = note: wrap the inner type with a `Mutex` or implement `Send` and `Sync` for `Box<dyn IndexFile + Send>`
>     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#arc_with_non_send_sync
>     = note: `#[warn(clippy::arc_with_non_send_sync)]` on by default
> ```

while this fixes the lint, isn't Rc also unneeded here? or am I missing
something..

> 
> Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>
> ---
>  pbs-datastore/src/snapshot_reader.rs | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/pbs-datastore/src/snapshot_reader.rs b/pbs-datastore/src/snapshot_reader.rs
> index ec7a48e5..816df310 100644
> --- a/pbs-datastore/src/snapshot_reader.rs
> +++ b/pbs-datastore/src/snapshot_reader.rs
> @@ -1,6 +1,7 @@
>  use std::fs::File;
>  use std::os::unix::io::{AsRawFd, FromRawFd};
>  use std::path::Path;
> +use std::rc::Rc;
>  use std::sync::Arc;
>  
>  use anyhow::{bail, Error};
> @@ -126,7 +127,7 @@ pub struct SnapshotChunkIterator<'a, F: Fn(&[u8; 32]) -> bool> {
>      todo_list: Vec<String>,
>      skip_fn: F,
>      #[allow(clippy::type_complexity)]
> -    current_index: Option<(Arc<Box<dyn IndexFile + Send>>, usize, Vec<(usize, u64)>)>,
> +    current_index: Option<(Rc<Box<dyn IndexFile + Send>>, usize, Vec<(usize, u64)>)>,
>  }
>  
>  impl<'a, F: Fn(&[u8; 32]) -> bool> Iterator for SnapshotChunkIterator<'a, F> {
> @@ -153,7 +154,7 @@ impl<'a, F: Fn(&[u8; 32]) -> bool> Iterator for SnapshotChunkIterator<'a, F> {
>                          let order =
>                              datastore.get_chunks_in_order(&*index, &self.skip_fn, |_| Ok(()))?;
>  
> -                        self.current_index = Some((Arc::new(index), 0, order));
> +                        self.current_index = Some((Rc::new(index), 0, order));
>                      } else {
>                          return Ok(None);
>                      }
> -- 
> 2.39.2