Some refactorings

[dkumsh]

Hi Tom, we are using your crate and I proposes this set of changes, some micro optimizations and code cleanup. Please have a look. I hope you'll like it.

[HaveFunTrading]

hi Dmitry! thank you for raising the PR. I had a quick look and the proposed changes make a lot of sense. I will aim to review in detail over this weekend.

[HaveFunTrading]

@dkumsh the pipeline failed (looks mostly because of clippy/code format), I always run these commands before commit

cargo clippy --no-deps --all-targets --all-features  -- -D warnings
cargo fmt

The msrv you would need to bump in Cargo.toml to next min supported version

[dkumsh]

Hi Tom,

I fixed the PR by making MetricsHandle explicitly Send/Sync (with a safety note that backends must be thread‑safe or used strictly single‑threaded). This resolves the LazyLock Sync error from the allocator. I also moved the [release] table to [workspace.metadata.release] to silence the Cargo warning and removed an extra blank line in the Histogram docs that Clippy flagged.

[HaveFunTrading]

@dkumsh I have finished the review, added few comments; otherwise looks very good

[dkumsh]

@HaveFunTrading Thanks for the review. I don't see the inline comments yet - could you please resubmit the review so I can address them.

[HaveFunTrading]

thanks for addressing @dkumsh , I have merged and released new version 0.0.16. Let me know if you notice any issue.