thin-status

Disclaimer: This is a personal project. The views, code, and opinions expressed here are my own and do not represent those of my current or past employers.

A low-overhead, production-grade error status type for Rust, heavily inspired by Abseil's absl::Status.

It is designed specifically for high-throughput network programming and RPC frameworks where minimizing memory overhead, optimizing cache locality, and eliminating happy-path heap allocations are critical performance requirements.

Features

• Single-Pointer Memory Footprint: ThinStatus occupies exactly one pointer word (the size of a usize). Niche optimization guarantees that Option<ThinStatus> and Result<(), ThinStatus> fit into that same single word without increasing data size.
• Zero-Allocation for Inlined Codes: Standard production error codes matching ErrorCode that fit within the tagged pointer boundaries require absolutely zero heap allocation.
• Production RPC and gRPC Alignment: Built directly around canonical RPC status models. Includes out-of-the-box support for translating standard POSIX errno codes (via libc) and converting to/from google-cloud-rpc models.
• Extensible Structured Details: Supports attaching rich, production-tier diagnostic messages and structured arbitrary payloads via google_cloud_wkt::Any (gated under the use_any feature) when an error path demands complex telemetry.

Usage

use thin_status::{ThinStatus, ErrorCode};
use std::num::NonZeroI32;

// Zero-allocation status for inline RPC error codes
let status = ThinStatus::from_code(ErrorCode::NotFound);
assert_eq!(std::mem::size_of_val(&status), std::mem::size_of::<usize>());

// Rich errors (with messages) cleanly fallback to thread-safe heap allocation
let rpc_err = ThinStatus::builder(ErrorCode::PermissionDenied)
    .message("Token expired or missing required IAM scope.")
    .build();

// Directly maps to native POSIX subsystem failures
if let Some(err_code) = ErrorCode::from_errno(2) { // ENOENT
    let status = ThinStatus::from_code(err_code);
}