evc

A lock-free (when reading), eventually consistent synchronization primitive.

This primitive makes reading and writing possible at the same time, although refreshing is needed to make writes visible to the readers.

This crate is very similar to evmap, but generalized to any type. Unlike evmap, which wraps a HashMap, evc is lower level, meaning that you need to be able to cache all possible mutations on the inner type (OperationCache). Therefore making an extension trait and implementing it for WriteHandle<YourType> is encouraged, so that accessing the inner data can be done using regular methods (like evmap does internally).

Examples

VecWrapper

use evc::OperationCache;

#[derive(Clone, Debug, Default)]
struct VecWrapper(Vec<u16>);

#[derive(Clone, Copy, Debug)]
enum Operation {
    Push(u16),
    Remove(usize),
    Clear,
}

impl OperationCache for VecWrapper {
    type Operation = Operation;

    fn apply_operation(&mut self, operation: Self::Operation) {
        match operation {
            Operation::Push(value) => self.0.push(value),
            Operation::Remove(index) => { self.0.remove(index); },
            Operation::Clear => self.0.clear(),
        }
    }
}

let (mut w_handle, r_handle) = evc::new(VecWrapper::default());

w_handle.write(Operation::Push(42));
w_handle.write(Operation::Push(24));

assert_eq!(r_handle.read().0, &[]);

w_handle.refresh();

assert_eq!(r_handle.read().0, &[42, 24]);

w_handle.write(Operation::Push(55));
w_handle.write(Operation::Remove(0));
w_handle.refresh();

assert_eq!(r_handle.read().0, &[24, 55]);

w_handle.write(Operation::Clear);

assert_eq!(r_handle.read().0, &[24, 55]);

w_handle.refresh();

assert_eq!(r_handle.read().0, &[]);

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.