# Kash

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Caching structures and simplified function memoization, using [`#[kash]`](kash) macro.

```rust
use kash::kash;

/// Defines a function named `fib` that uses a cache implicitly named `FIB`.
/// By default, the cache will be the function's name in all caps.
#[kash]
fn fib(n: u64) -> u64 {
    if n == 0 || n == 1 { return n }
    fib(n-1) + fib(n-2)
}
```

Or if you want to limit the size and time-to-live:

```rust
use kash::kash;

const TTL: u64 = 1000;
#[kash(size = "100", ttl = "TTL")]
fn fib(n: u64) -> u64 {
    if n == 0 || n == 1 { return n }
    fib(n-1) + fib(n-2)
}
```

## Features

- `default`: Includes `ahash` feature.
- `ahash`: Enable `ahash` hasher as default hashing algorithm.
- `async`: Include support for async functions.
- `redis_store`: Include Redis cache store.
- `redis_async_std`: Include async Redis support using `async-std` and `async-std` tls support, implies `redis_store` and `async`.
- `redis_tokio`: Include async Redis support using `tokio` and `tokio` tls support, implies `redis_store` and `async`.
- `redis_connection_manager`: Enable the optional `connection-manager` feature of `redis`. Any async redis caches created
                              will use a connection manager instead of a `MultiplexedConnection`.
- `redis_ahash`: Enable the optional `ahash` feature of `redis`.
- `disk_store`: Include disk cache store.

----

```rust
use std::thread::sleep;
use std::time::Duration;
use kash::kash;

/// Use an explicit cache-type with a custom creation block and custom cache-key generating block
#[kash(
    size = "100",
    key(ty = "String", expr = r#"{ format!("{}{}", a, b) }"#)
)]
fn keyed(a: &str, b: &str) -> usize {
    let size = a.len() + b.len();
    sleep(Duration::new(size as u64, 0));
    size
}
```

----

```rust
use kash::{kash, RedisCacheError};
use kash::AsyncRedisCache;
use thiserror::Error;

#[derive(Error, Debug, PartialEq, Clone)]
enum ExampleError {
    #[error("error with redis cache `{0}`")]
    RedisError(String),
}

impl From<RedisCacheError> for ExampleError {
    fn from(e: RedisCacheError) -> Self {
        ExampleError::RedisError(format!("{:?}", e))
    }
}

/// Cache the results of an async function in redis. Cache
/// keys will be prefixed with `cache_redis_prefix`.
#[kash(redis)]
async fn async_kash_sleep_secs(secs: u64) -> Result<String, ExampleError> {
    std::thread::sleep(std::time::Duration::from_secs(secs));
    Ok(secs.to_string())
}
```

----

```rust
use kash::{kash, DiskCacheError};
use kash::DiskCache;
use thiserror::Error;

#[derive(Error, Debug, PartialEq, Clone)]
enum ExampleError {
    #[error("error with disk cache `{0}`")]
    DiskError(String),
}

impl From<DiskCacheError> for ExampleError {
    fn from(e: DiskCacheError) -> Self {
        ExampleError::DiskError(format!("{:?}", e))
    }
}

/// Cache the results of a function on disk.
/// Cache files will be stored under the system cache dir
/// unless otherwise specified with `dir` or the `create` argument.
#[kash(disk)]
fn kash_sleep_secs(secs: u64) -> Result<String, ExampleError> {
    std::thread::sleep(std::time::Duration::from_secs(secs));
    Ok(secs.to_string())
}
```

Functions defined via macros will have their result, cached using the
function's arguments as a key by default.

When a macro-defined function is called, the function's cache is first checked for an already
computed (and still valid) value before evaluating the function body.

See [`examples`](https://github.com/omid/kash/tree/master/examples) directory for more examples.

## License
MIT
