Rust Ecosystem

Async Runtimes

# Web services
tokio = { version = "1", features = ["full"] }
axum = "0.7"

# Lightweight
async-std = "1"

# Minimal
smol = "2"

Solution Patterns

Pattern 1: Web Service Stack

[dependencies]
# Async runtime
tokio = { version = "1", features = ["full"] }

# Web framework
axum = "0.7"

# Database
sqlx = { version = "0.7", features = ["runtime-tokio", "postgres"] }

# Serialization
serde = { version = "1", features = ["derive"] }
serde_json = "1"

# Error handling
anyhow = "1"
thiserror = "1"

# Tracing
tracing = "0.1"
tracing-subscriber = "0.3"

Pattern 2: CLI Tool Stack

[dependencies]
# Argument parsing
clap = { version = "4", features = ["derive"] }

# Error handling
anyhow = "1"

# Config
config = "0.13"
dotenvy = "0.15"

# Progress
indicatif = "0.17"

# Terminal colors
colored = "2"

Pattern 3: Data Processing

[dependencies]
# Parallelism
rayon = "1"

# CSV
csv = "1"

# Serialization
serde = { version = "1", features = ["derive"] }
serde_json = "1"

# HTTP client
reqwest = { version = "0.11", features = ["json", "blocking"] }

Web Frameworks

// axum example
use axum::{Router, routing::get, Json};
use serde::Serialize;

#[derive(Serialize)]
struct User {
    id: u64,
    name: String,
}

async fn get_user() -> Json<User> {
    Json(User {
        id: 1,
        name: "Alice".to_string(),
    })
}

let app = Router::new()
    .route("/user", get(get_user));

Serialization

use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct User {
    id: u64,
    name: String,
}

// JSON
let json = serde_json::to_string(&user)?;
let user: User = serde_json::from_str(&json)?;

// Binary (more efficient)
let bytes = bincode::serialize(&user)?;
let user: User = bincode::deserialize(&bytes)?;

HTTP Clients

// reqwest - async
let response = reqwest::Client::new()
    .post("https://api.example.com")
    .json(&payload)
    .send()
    .await?
    .json::<Response>()
    .await?;

// ureq - sync (no async runtime needed)
let response: Response = ureq::post("https://api.example.com")
    .send_json(&payload)?
    .into_json()?;

Databases

// sqlx with compile-time checked queries
use sqlx::PgPool;

let pool = PgPool::connect(&database_url).await?;

let user = sqlx::query_as!(
    User,
    "SELECT id, name FROM users WHERE id = $1",
    user_id
)
.fetch_one(&pool)
.await?;

Concurrency & Parallelism

// rayon - easy parallelism
use rayon::prelude::*;

let sum: i32 = data
    .par_iter()
    .map(|x| expensive_computation(x))
    .sum();

Error Handling

// thiserror - for libraries
use thiserror::Error;

#[derive(Error, Debug)]
pub enum MyError {
    #[error("I/O error: {0}")]
    Io(#[from] std::io::Error),

    #[error("Invalid data: {msg}")]
    Invalid { msg: String },
}

// anyhow - for applications
use anyhow::{Context, Result};

fn load_config() -> Result<Config> {
    let content = std::fs::read_to_string("config.toml")
        .context("failed to read config file")?;

    toml::from_str(&content)
        .context("failed to parse config")
}

Common Tools

Crate Selection Principles

1. Active maintenance: Check GitHub activity, recent updates
2. Download count: Reference crates.io downloads
3. MSRV: Minimum Supported Rust Version compatibility
4. Dependencies: Number and security of dependencies
5. Documentation: Complete docs and examples
6. License: MIT/Apache2 compatibility

# Check crate info
cargo info <crate-name>

# Check dependencies
cargo tree

# Security audit
cargo audit

# License check
cargo deny check licenses

Workflow

Step 1: Identify Need

What problem to solve?
  → Web service? Choose framework (axum/actix)
  → CLI tool? Use clap + anyhow
  → Data processing? Use rayon
  → Database access? Use sqlx

Step 2: Evaluate Options

Check:
  → crates.io download count
  → GitHub stars and activity
  → Documentation quality
  → Recent releases
  → Community support

Step 3: Verify Safety

# Security audit
cargo audit

# License compatibility
cargo deny check

# Dependency tree
cargo tree -i <crate>

Deprecated Patterns → Modern

Quick Reference

Review Checklist

When selecting crates:

• Crate is actively maintained (updated within 6 months)
• Good documentation and examples
• Reasonable dependency count
• No known security issues (cargo audit)
• Compatible license (MIT/Apache2)
• MSRV compatible with project
• High download count and community usage
• Stable API (1.0+ or widely used)

Verification Commands

# Search crates
cargo search <keyword>

# Get crate info
cargo info <crate-name>

# Check dependencies
cargo tree

# Security audit
cargo audit

# License check
cargo deny check

# Check for updates
cargo outdated

Common Pitfalls

1. Too Many Dependencies

Symptom: Long compile times, dependency conflicts

# ❌ Avoid: unnecessary dependencies
[dependencies]
# Don't need full tokio if only using channels
tokio = { version = "1", features = ["full"] }

# ✅ Better: minimal features
tokio = { version = "1", features = ["sync"] }

2. Unmaintained Crates

Symptom: Security vulnerabilities, incompatibilities

# Check last update
cargo info <crate-name>

# Check for alternatives
cargo search <similar-crate>

3. Version Conflicts

Symptom: Build failures, duplicate dependencies

# Diagnose conflicts
cargo tree -d

# Use same version across workspace
[workspace.dependencies]
serde = "1"

Related Skills

• rust-async - Async runtime patterns
• rust-web - Web framework usage
• rust-error - Error handling libraries
• rust-testing - Testing libraries
• rust-performance - Performance-critical crates

Localized Reference

• Chinese version: SKILL_ZH.md - 完整中文版本，包含所有内容

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