Replace compact_str with smol_str throughout the codebase

[awgn]

Rationale

Currently, Orion utilizes a variety of string types, each chosen for specific performance or ergonomic reasons:

String: Used for general-purpose, heap-allocated string data.
CompactStr: Mostly adopted for component names (e.g., listeners, clusters) due to its clone efficiency over the standard String.
SmolStr: Used in the access logger as it proved to be more performant than CompactStr and offers a more ergonomic API.
&'static str (via a String Interner): Recently, we introduced a string interner to represent component names as &'static str. This was a requirement for using them as long-lived tags in our OpenTelemetry integration (note: component's names have not been replaced but rather paired with their static str versions).

To make our string handling more consistent and streamlined, and to reduce the cognitive load of dealing with a large number of string-handling libraries, this pull request replaces compact_str with the more modern and efficient smol_str.

Advantages of smol_str over compact_str:

1. It is slightly more efficient when cloning a short string. It is much more efficient when cloning a string > 23 characters long.
2. Clone never involves dynamic memory allocation.
3. Construction is more efficient in some circumstances.
4. The interface is more nice.
5. Higher quality. Used as the core library in rust-analyzer.

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[gemini-code-assist]

Summary of Changes

Hello @awgn, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refactors the project's string handling by systematically replacing the compact_str crate with the smol_str crate. The primary goal is to unify string management, leveraging smol_str's superior performance characteristics, particularly in cloning and memory allocation, and its more ergonomic API. This change aims to enhance the overall efficiency and consistency of string operations throughout the application, contributing to a more robust and maintainable codebase.

Highlights

• String Type Standardization: Replaced compact_str with smol_str across the codebase to achieve more consistent and streamlined string handling, reducing cognitive load associated with multiple string libraries.
• Performance and Efficiency Improvements: The switch to smol_str brings several advantages, including more efficient cloning (especially for strings longer than 23 characters) and construction, with cloning operations never involving dynamic memory allocation. This contributes to overall performance gains.
• Codebase Quality and Maintainability: smol_str is noted for its higher quality and is used as a core library in rust-analyzer, indicating a robust and well-maintained choice. This change improves the maintainability and reliability of the project's string operations.
• Dependency Updates and Cleanup: Numerous Cargo.toml and Cargo.lock files were updated to reflect the removal of compact_str and the addition/promotion of smol_str as a workspace dependency. This also involved updating several other related dependencies and removing unused ones like castaway and overload.
• Minor Behavioral Adjustments: Adjustments were made in orion-lib/src/listeners/listener.rs for comparing route_id with id, changing route_id == id to route_id == &id. This reflects a subtle change in how string comparisons are handled with the new SmolStr type.

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[gemini-code-assist]

Code Review

This pull request systematically replaces compact_str with smol_str throughout the codebase to improve performance and streamline string handling. The changes are comprehensive, covering dependencies in Cargo.toml and Cargo.lock, as well as all usages in the source code. The migration has been handled carefully, correctly adapting to the API differences between the two crates. The rationale for this change is well-explained in the pull request description. The implementation is clean, and I have not found any issues. This is a solid improvement for the project.

[hzxuzhonghu]

This type from the smol_str crate implements a form of small string optimization. It aims to store small strings (up to 23 bytes on 64-bit systems) directly on the stack, avoiding heap allocation.

However, not sure if the string length exceed 23, how much performance will be degragated

[awgn]

There are several reasons for replacing compact_str with smol_str, and perhaps the most important is that this reduces our dependencies by one, since smol_str is already used in orion-format.

[hzxuzhonghu]

Not sure the performance influcen to long string, it is very common the xds name exceed 23 characters