commit | 534bb63d44a6cc1a104d6f2b451d9717bb92e0ab | [log] [tgz] |
---|---|---|
author | easoncylee <easoncylee@google.com> | Tue Jul 06 02:18:07 2021 +0000 |
committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | Tue Jul 06 02:18:07 2021 +0000 |
tree | 63f5be40a8868b2928fc1d473b5c19e1f4de3301 | |
parent | bcd0bcf6629680a8e31ca5a3eadea0a2ec588e6d [diff] | |
parent | 8c646e6fdf71c2c72a949b581f9eb189258891ff [diff] |
Update vpnprofilestore_test to legacykeystore_test in TEST_MAPPING am: 5566498e5b am: a53e576e6c am: 34da9f0c4b am: 8c646e6fdf Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/once_cell/+/1755952 Change-Id: I800fd3be55ecb45bc23ad390049ced97c229c8ae
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
.