# arcache
A crate which implements a variety of caches with different eviction policies. All cache implementations are thread-safe and can be used in a multi-threaded environment. Cache implementations all share the `Cache` trait which means that they are interchangeable once instantiated.
The cache store values in an `Arc` (hence `arccache`) so that they can be shared between threads without needing to clone the value. Caches all implement an internal mutability pattern to make them easy to use in multi-threaded applications.
```rust
use arcache::{Cache, LRUCache};
fn main() {
let cache = LRUCache::<&str, String>::new(10); // mutability is internally handled so you can use `let` instead of `let mut`
// like std::collections::HashMap, you can use the `set` returns the previous value if it exists
let original_value = cache.set("key", "value".to_string());
assert!(original_value.is_none());
// get returns an Option<Arc<V>> where V is the value type
let value = cache.get(&"key");
assert!(value.is_some());
assert_eq!(*value.unwrap(), "value".to_string()); // value is wrapped in an Arc so you need to dereference it
println!("{:?}", cache.stats());
}
```
The `Cache` trait lets you write functions with generic signatures and swap cache implementations, this is useful if you want to uses multiple cache types with the same code.
```rust
use arcache::{Cache, LFUCache, LRUCache};
use std::{hash::Hash, sync::Arc};
fn do_something<C>(cache: C)
where
C: Cache<&'static str, String>,
{
cache.set("hello", "world".to_string());
if let Some(val) = cache.get(&"hello") {
println!("Got: {}", val);
}
}
fn main() {
let lru_cache = LRUCache::<&'static str, String>::new(2);
do_something(lru_cache);
let lfu_cache = LFUCache::<&'static str, String>::new(2);
do_something(lfu_cache);
}
```
## Implemented caches
+ `LRUCache`
+ `LFUCache`
+ `MRUCache`
+ `TTLCache`
+ `FIFOCache`
+ `LIFOCache`
+ `RandomReplacementCache`
### On the roadmap
+ `ARCCache`
+ `LFUTTLCache` (LFU with expiration)
## Usage
See `/examples` for example usage. You can run these like so:
```bash
cargo run --example lru_example --release
cargo run --example lfu_example --release
```
etc.