m12-lifecycle
Use when designing resource lifecycles. Keywords: RAII, Drop, resource lifecycle, connection pool, lazy initialization, connection pool design, resource cleanup patterns, cleanup, scope, OnceCell, Lazy, oncecell, OnceLock, transaction, session management, when is Drop called, cleanup on error, guard pattern, scope guard, 资源生命周期, 连接池, 惰性初始化, 资源清理, RAII 模式
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/actionbook/rust-skills --skill m12-lifecycle- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads m12-lifecycle automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
Resource Lifecycle
Layer 2: Design Choices
Core Question
When should this resource be created, used, and cleaned up?
Before implementing lifecycle:
- What's the resource's scope?
- Who owns the cleanup responsibility?
- What happens on error?
Lifecycle Pattern → Implementation
| Pattern | When | Implementation |
|---|---|---|
| RAII | Auto cleanup | Drop trait |
| Lazy init | Deferred creation | OnceLock, LazyLock |
| Pool | Reuse expensive resources | r2d2, deadpool |
| Guard | Scoped access | MutexGuard pattern |
| Scope | Transaction boundary | Custom struct + Drop |
Thinking Prompt
Before designing lifecycle:
-
What's the resource cost?
- Cheap → create per use
- Expensive → pool or cache
- Global → lazy singleton
-
What's the scope?
- Function-local → stack allocation
- Request-scoped → passed or extracted
- Application-wide → static or Arc
-
What about errors?
- Cleanup must happen → Drop
- Cleanup is optional → explicit close
- Cleanup can fail → Result from close
Trace Up ↑
To domain constraints (Layer 3):
"How should I manage database connections?"
↑ Ask: What's the connection cost?
↑ Check: domain-* (latency requirements)
↑ Check: Infrastructure (connection limits)
| Question | Trace To | Ask |
|---|---|---|
| Connection pooling | domain-* | What's acceptable latency? |
| Resource limits | domain-* | What are infra constraints? |
| Transaction scope | domain-* | What must be atomic? |
Trace Down ↓
To implementation (Layer 1):
"Need automatic cleanup"
↓ m02-resource: Implement Drop
↓ m01-ownership: Clear owner for cleanup
"Need lazy initialization"
↓ m03-mutability: OnceLock for thread-safe
↓ m07-concurrency: LazyLock for sync
"Need connection pool"
↓ m07-concurrency: Thread-safe pool
↓ m02-resource: Arc for sharing
Quick Reference
| Pattern | Type | Use Case |
|---|---|---|
| RAII | Drop trait | Auto cleanup on scope exit |
| Lazy Init | OnceLock, LazyLock | Deferred initialization |
| Pool | r2d2, deadpool | Connection reuse |
| Guard | MutexGuard | Scoped lock release |
| Scope | Custom struct | Transaction boundaries |
Lifecycle Events
| Event | Rust Mechanism |
|---|---|
| Creation | new(), Default |
| Lazy Init | OnceLock::get_or_init |
| Usage | &self, &mut self |
| Cleanup | Drop::drop() |
Pattern Templates
RAII Guard
struct FileGuard {
path: PathBuf,
_handle: File,
}
impl Drop for FileGuard {
fn drop(&mut self) {
// Cleanup: remove temp file
let _ = std::fs::remove_file(&self.path);
}
}
Lazy Singleton
use std::sync::OnceLock;
static CONFIG: OnceLock<Config> = OnceLock::new();
fn get_config() -> &'static Config {
CONFIG.get_or_init(|| {
Config::load().expect("config required")
})
}
Common Errors
| Error | Cause | Fix |
|---|---|---|
| Resource leak | Forgot Drop | Implement Drop or RAII wrapper |
| Double free | Manual memory | Let Rust handle |
| Use after drop | Dangling reference | Check lifetimes |
| E0509 move out of Drop | Moving owned field | Option::take() |
| Pool exhaustion | Not returned | Ensure Drop returns |
Anti-Patterns
| Anti-Pattern | Why Bad | Better |
|---|---|---|
| Manual cleanup | Easy to forget | RAII/Drop |
lazy_static! | External dep | std::sync::OnceLock |
| Global mutable state | Thread unsafety | OnceLock or proper sync |
| Forget to close | Resource leak | Drop impl |
Related Skills
| When | See |
|---|---|
| Smart pointers | m02-resource |
| Thread-safe init | m07-concurrency |
| Domain scopes | m09-domain |
| Error in cleanup | m06-error-handling |
FAQ
What does the m12-lifecycle skill do?
Use when designing resource lifecycles. Keywords: RAII, Drop, resource lifecycle, connection pool, lazy initialization, connection pool design, resource cleanup patterns, cleanup, scope, OnceCell, Lazy, oncecell, OnceLock, transaction, session management, when is Drop called, cleanup on error, guard pattern, scope guard, 资源生命周期, 连接池, 惰性初始化, 资源清理, RAII 模式
How do I install m12-lifecycle?
Run npx skills add https://github.com/actionbook/rust-skills --skill m12-lifecycle in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/m12-lifecycle/ (personal) or .claude/skills/m12-lifecycle/ (project).
Which AI agents can use m12-lifecycle?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is m12-lifecycle safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains m12-lifecycle?
It is published by actionbook in actionbook/rust-skills. It has 3,343 recorded installs.
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