| commit | d0600dcf1d840a1cf276c203b7b4c0bd23085d93 | [log] [tgz] |
|---|---|---|
| author | James Farrell <[email protected]> | Wed May 22 23:28:05 2024 +0000 |
| committer | Automerger Merge Worker <[email protected]> | Wed May 22 23:28:05 2024 +0000 |
| tree | f67ef3c4c452f0883030736fe109ed62ba31f812 | |
| parent | 6ec56f78349a76e2ff3af91ae9645be1807ee69a [diff] | |
| parent | f2c59ce3ea1b3e9f6d9ed6b7e0ec391644d6f373 [diff] |
Update Android.bp by running cargo_embargo am: 5e33db2a8a am: f2c59ce3ea Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/once_cell/+/3095900 Change-Id: Ic844ca1391c0651c4a545ddf013d2167ed02c5b5 Signed-off-by: Automerger Merge Worker <[email protected]>
once_cell provides two new cell-like types, unsync::OnceCell and sync::OnceCell. OnceCell might store arbitrary non-Copy types, can be assigned to at most once and provide direct access to the stored contents. In a nutshell, API looks roughly like this:
impl OnceCell<T> { fn new() -> OnceCell<T> { ... } fn set(&self, value: T) -> Result<(), T> { ... } fn get(&self) -> Option<&T> { ... } }
Note that, like with RefCell and Mutex, the set method requires only a shared reference. Because of the single assignment restriction get can return an &T instead of Ref<T> or MutexGuard<T>.
once_cell also has a Lazy<T> type, build on top of OnceCell which provides the same API as the lazy_static! macro, but without using any macros:
use std::{sync::Mutex, collections::HashMap}; use once_cell::sync::Lazy; static GLOBAL_DATA: Lazy<Mutex<HashMap<i32, String>>> = Lazy::new(|| { let mut m = HashMap::new(); m.insert(13, "Spica".to_string()); m.insert(74, "Hoyten".to_string()); Mutex::new(m) }); fn main() { println!("{:?}", GLOBAL_DATA.lock().unwrap()); }
More patterns and use-cases are in the docs!
The API of once_cell is being proposed for inclusion in std.