# range-lock - Multithread range lock for Vec

[Project home](https://bues.ch/)

[Git repository](https://bues.ch/cgit/rangelockrs.git)

[Github repository](https://github.com/mbuesch/rangelockrs)

This crate provides locks/mutexes for multi-threaded access to a single
Vec\<T\> instance.

Any thread can request exclusive access to a slice of the Vec. Such
access is granted, if no other thread is simultaneously holding the
permission to access an overlapping slice.

# Usage

Add this to your Cargo.toml:

``` toml
[dependencies]
range-lock = "0.2"
```

## VecRangeLock example usage

General purpose VecRangeLock:

``` rust
use range_lock::VecRangeLock;
use std::sync::Arc;
use std::thread;

let lock = Arc::new(VecRangeLock::new(vec![1, 2, 3, 4, 5]));

thread::spawn(move || {
    let mut guard = lock.try_lock(2..4).expect("Failed to lock range 2..4");
    assert_eq!(guard[0], 3);
    guard[0] = 10;
});
```

## RepVecRangeLock example usage

The RepVecRangeLock is a restricted range lock, that provides access to
interleaved patterns of slices to the threads.

Locking a RepVecRangeLock is more lightweight than locking a
VecRangeLock. The threads can not freely choose slice ranges, but only
choose a repeating slice pattern by specifying a pattern offset.

Please see the example below.

``` rust
use range_lock::RepVecRangeLock;
use std::sync::Arc;
use std::thread;

let data = vec![1, 2, 3,  // <- cycle 0
                4, 5, 6]; // <- cycle 1
//              ^  ^  ^
//              |  |  |
//              |  |  offset-2
//       offset-0  offset-1

let lock = Arc::new(RepVecRangeLock::new(data,
                                         1,    // slice_len: Each slice has 1 element.
                                         3));  // cycle_len: Each cycle has 3 slices (offsets).
thread::spawn(move || {
    // Lock slice offset 1:
    let mut guard = lock.try_lock(1).expect("Failed to lock offset.");

    assert_eq!(guard[0][0], 2);     // Cycle 0, Slice element 0
    assert_eq!(guard[1][0], 5);     // Cycle 1, Slice element 0

    guard[0][0] = 20;               // Cycle 0, Slice element 0
    guard[1][0] = 50;               // Cycle 1, Slice element 0
});
```

# TODOs for future releases

The following new features might be candidates for future releases:

-   Sleeping lock, in case of lock contention.
-   Add support for arrays.

# License

Copyright (c) 2021-2023 Michael Büsch \<<m@bues.ch>\>

Licensed under the Apache License version 2.0 or the MIT license, at
your option.