# Double Mapped Circular Buffer

- Thread-safe.
- Supports multiple readers.
- Generic over the item type.
- Provides access to all items (not n-1).
- Supports Linux, macOS, Windows, and Android.
- Sync, async, and non-blocking implementations.
- Generic variant that allows specifying custom `Notifiers` to ease integration.
- Underlying data structure (i.e., `DoubleMappedBuffer`) is exported to allow custom implementations.

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[crates-url]: https://crates.io/crates/vmcircbuffer
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[apache-url]: https://github.com/futuresdr/vmcircbuffer/blob/main/LICENSE
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[actions-url]: https://github.com/futuresdr/vmcircbuffer/actions?query=workflow%3ACI+branch%3Amain

## Overview

This circular buffer implementation maps the underlying buffer twice,
back-to-back into the virtual address space of the process. This arrangement
allows the circular buffer to present the available data sequentially, (i.e., as
a slice) without having to worry about wrapping.

## Example

```rust
use vmcircbuffer::sync;

let mut w = sync::Circular::new::<u32>()?;
let mut r = w.add_reader();

// delay producing by 1 sec
let now = std::time::Instant::now();
let delay = std::time::Duration::from_millis(1000);

// producer thread
std::thread::spawn(move || {
    std::thread::sleep(delay);
    let w_buff = w.slice();
    for v in w_buff.iter_mut() {
        *v = 23;
    }
    let l = w_buff.len();
    w.produce(l);
});

// blocks until data becomes available
let r_buff = r.slice().unwrap();
assert!(now.elapsed() > delay);
for v in r_buff {
    assert_eq!(*v, 23);
}
let l = r_buff.len();
r.consume(l);
```

## Contributions

Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the project, shall be licensed as Apache 2.0, without any
additional terms or conditions.