Rc

Rc๋Š” ์ฐธ์กฐ ์นด์šดํŒ… ๊ณต์œ  ํฌ์ธํ„ฐ์ž…๋‹ˆ๋‹ค. ์—ฌ๋Ÿฌ ์œ„์น˜์—์„œ ๋™์ผํ•œ ๋ฐ์ดํ„ฐ๋ฅผ ์ฐธ์กฐํ•ด์•ผํ•  ๊ฒฝ์šฐ ์‚ฌ์šฉํ•ฉ๋‹ˆ๋‹ค:

use std::rc::Rc;

fn main() {
    let a = Rc::new(10);
    let b = Rc::clone(&a);

    println!("a: {a}");
    println!("b: {b}");
}
  • ๋ฉ€ํ‹ฐ์Šค๋ ˆ๋“œ ํ™˜๊ฒฝ์—์„œ ์ž‘์—…ํ•˜๋Š” ๊ฒฝ์šฐ Arc์™€ Mutex๋ฅผ ์ฐธ์กฐํ•˜์„ธ์š”.
  • drop ๊ฐ€๋Šฅํ•œ ์ˆœํ™˜ ๊ตฌ์กฐ๋ฅผ ๋งŒ๋“ค๊ธฐ ์œ„ํ•ด ๊ณต์œ  ํฌ์ธํ„ฐ๋ฅผ Weak ํฌ์ธํ„ฐ๋กœ _๋‹ค์šด๊ทธ๋ ˆ์ด๋“œ_ํ•  ์ˆ˜๋„ ์žˆ์Šต๋‹ˆ๋‹ค.
This slide should take about 5 minutes.
  • Rc๋Š” ์ฐธ์กฐ ์นด์šดํŠธ๋ฅผ ํ†ตํ•ด ์ฐธ์กฐ๊ฐ€ ์žˆ๋Š” ๋™์•ˆ์€ Rc๊ฐ€ ๊ฐ€๋ฆฌํ‚ค๊ณ  ์žˆ๋Š” ๊ฐ’์ด ๋ฉ”๋ชจ๋ฆฌ์—์„œ ํ•ด์ œ๋˜์ง€ ์•Š์Œ์„ ๋ณด์žฅํ•ฉ๋‹ˆ๋‹ค.
  • C++์˜ std::shared_ptr์™€ ์œ ์‚ฌํ•ฉ๋‹ˆ๋‹ค.
  • clone์€ ๋น„์šฉ์ด ๊ฑฐ์˜ ๋“ค์ง€ ์•Š์Šต๋‹ˆ๋‹ค. ๊ฐ™์€ ๊ณณ์„ ๊ฐ€๋ฆฌํ‚ค๋Š” ํฌ์ธํ„ฐ๋ฅผ ํ•˜๋‚˜ ๋” ๋งŒ๋“ค๊ณ , ์ฐธ์กฐ ์นด์šดํŠธ๋ฅผ ๋Š˜๋ฆฝ๋‹ˆ๋‹ค. ํฌ์ธํ„ฐ๊ฐ€ ๊ฐ€๋ฆฌํ‚ค๋Š” ๊ฐ’ ์ž์ฒด๊ฐ€ ๋ณต์ œ(๊นŠ์€ ๋ณต์ œ)๋˜์ง€๋Š” ์•Š์œผ๋ฉฐ, ๊ทธ๋ž˜์„œ ์ฝ”๋“œ์—์„œ ์„ฑ๋Šฅ ๋ฌธ์ œ๊ฐ€ ์žˆ๋Š”์ง€ ๊ฒ€ํ† ํ•  ๋•Œ ์ผ๋ฐ˜์ ์œผ๋กœ Rc๋ฅผ cloneํ•˜๋Š” ๊ฒƒ์€ ๋ฌด์‹œํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค.
  • make_mut๋Š” ์‹ค์ œ๋กœ ํ•„์š”ํ•œ ๊ฒฝ์šฐ์— ๋‚ด๋ถ€ ๊ฐ’์„ ๋ณต์ œํ•˜๊ณ (โ€œclone-on-writeโ€) ๊ฐ€๋ณ€ ์ฐธ์กฐ๋ฅผ ๋ฐ˜ํ™˜ํ•ฉ๋‹ˆ๋‹ค.
  • ์ฐธ์กฐ ์นด์šดํŠธ๋ฅผ ํ™•์ธํ•˜๋ ค๋ฉด Rc::strong_count๋ฅผ ์‚ฌ์šฉํ•˜์„ธ์š”.
  • Rc::downgrade gives you a weakly reference-counted object to create cycles that will be dropped properly (likely in combination with RefCell).