name: memory-safety-optimization-patterns description: "Instructions for memory safety optimization patterns."

priority: high

Memory Safety & Optimization Patterns

Zero-Copy

• &str over String, &[T] over Vec<T> in function params
• Cow<T> for conditional ownership (borrow when possible, clone only on mutation)
• Arc<T> for shared immutable data across threads

RAII

Resources released automatically on scope exit via Drop. Mutex/RwLock guards auto-unlock. No manual cleanup needed.

String Handling

• Cow<str> for conditional String/&str ownership
• Arc<str> for cheap cloning of shared immutable strings
• String::with_capacity() to pre-allocate

Buffer Reuse

• Vec::clear() + reuse instead of new allocation
• Pre-allocate with Vec::with_capacity() in hot loops
• SmallVec for stack-allocated small collections

Lifetimes

• Default to references in function params
• Minimize lifetimes in structs (prefer owned data)
• Use '_ wildcard for unused lifetime bounds

Verification Tools

Anti-Patterns

• Clone instead of &T (unnecessary allocation)
• format!() when borrowing suffices
• Holding mutex guards across .await points
• Box<T> for simple owned data (unnecessary indirection)
• No buffer pre-allocation in hot paths