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# spin-sync

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spin-sync is a module providing synchronization primitives using spinlock. ([Wikipedia Spinlock](https://en.wikipedia.org/wiki/Spinlock))

The main features are as follows.

* Declaring public structs `Mutex` , `RwLock` , `Once` , `Barrier` . The interfaces are resembles those of `std::sync` .
* Ensuring safety as much as `std::sync` , including poisoning strategy and marker traits.
* Declaring public struct `Mutex8` , which behaves like a set of 8 `Mutex` instances except for
  it gives up poison strategy. It is possible to acquire 2 or more than 2 locks of 1 `Mutex8`
  instance at once.
* Unlike to `std::sync`, the constructors of the public structs are const. For example, it is
  possible to declare static `Mutex<T>` as long as T can be build statically.

## Examples

Declare `static spin_sync::Mutex<u64>` variable and update from multi threads.
It is impossible in case of `std::sync::Mutex` .

```rust
extern crate spin_sync;

use spin_sync::Mutex;
use std::thread;

// Declare static mut Mutex<u64> variable.
static COUNT: Mutex<u64> = Mutex::new(0);

fn main() {
    let num_thread = 10;
    let mut handles = Vec::new();

    // Create worker threads to inclement COUNT by 1.
    for _ in 0..10 {
        let handle = thread::spawn(move || {
            let mut count = COUNT.lock().unwrap();
            *count += 1;
        });

        handles.push(handle);
    }

    // Wait for all the workers.
    for handle in handles {
        handle.join().unwrap();
    }

    // Make sure the value is incremented by the worker count.
    let count = COUNT.lock().unwrap();
    assert_eq!(num_thread, *count);
}
```

License: LGPL-3.0-or-later OR Apache-2.0 OR BSD-2-Clause