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# atomic_once_cell

`atomic_once_cell` provides two new types, [`AtomicOnceCell`] and
[`AtomicLazy`], which are thread-safe and mostly lock-free drop-in
replacements of [`core::lazy::OnceCell`] and [`core::lazy::Lazy`]
suitable for use in `#[no_std]` environments.

### Blocking

Because dereferencing [`AtomicLazy`] can't fail, it can't be
lock-free (if you know a way, please tell me).

Both types can be used in a non-blocking way, but there are some
blocking calls that should not be used from interrupt handlers or
other contexts where blocking will lead to a deadlock. Blocking is
based on
[`crossbeam::utils::Backoff`](https://docs.rs/crossbeam/latest/crossbeam/utils/struct.Backoff.html),
and will be reduced to a spinlock in `#[no_std]` environments.

### Examples
#### `AtomicOnceCell`

```rust
use atomic_once_cell::AtomicOnceCell;

static CELL: AtomicOnceCell<String> = AtomicOnceCell::new();

fn main() {
    CELL.set("Hello, World!".to_owned()).unwrap();

    assert_eq!(*CELL.get().unwrap(), "Hello, World!");
}
```

#### `AtomicLazy`

```rust
use atomic_once_cell::AtomicLazy;

static LAZY: AtomicLazy<String> = AtomicLazy::new(|| "Hello, World!".to_owned());

fn main() {
    assert_eq!(*LAZY, "Hello, World!");
}
```

For more details, see [docs](https://docs.rs/atomic_once_cell/).

# Usage

Add this to your Cargo.toml:

```toml
[dependencies]
atomic_once_cell = "0.1.6"
```

# License

MPL-2.0