kvstore-asynchrony

A multi-threaded, persistent key/value store server and client with asynchronous networking over a custom protocol.

KvsEngine trait presents a futures-based API, by using #[async_trait] attribute macro to make async fn in traits work.

#[async_trait]
pub trait KvsEngine: Clone + Send + 'static {
    async fn set(&self, key: String, value: String) -> Result<()>;
    async fn get(&self, key: String) -> Result<Option<String>>;
    async fn remove(&self, key: String) -> Result<()>;
}

Both the client and server are converted to asyncronous;
KvsServer is based on the tokio runtime, which handles the distribution of asynchronous work to multiple threads on its own (tokio itself contains a thread pool).
- Replaced the serde with tokio-serde for Tokio transport serialization and deserialization of frame values.
KvStore handles file I/O using tokio::spawn;