Add license and description for files

Signed-off-by: Pavel Abramov <[email protected]>

src/lib.rs

@@ -1,3 +1,9 @@
+// SPDX-License-Identifier: Apache-2.0
+
+// NkvClient is a structure which is used to
+// communicate with Server to get, put, subscribe
+// and unsubscribe to a value
+
 pub mod nkv;
 pub mod notifier;
 mod persist_value;

src/nkv.rs

@@ -1,3 +1,11 @@
+// SPDX-License-Identifier: Apache-2.0
+
+// NotifyKeyValue structure is a persistant key-value
+// storage with ability to notify clients about changes
+// made in a value. When created via new() it will try to
+// load values from folder. Underlying structure is a HashMap
+// and designed to be access synchronously.
+
 use std::collections::HashMap;
 use std::path::PathBuf;
 

src/notifier.rs

@@ -1,3 +1,19 @@
+// SPDX-License-Identifier: Apache-2.0
+
+// Notifier structure is a structure which broadcasts messages
+// to all subscribed clients (Subscriber structure). Possible
+// messages are following:
+//
+// - Hello -- is sent when the connection is established between
+// Subscriber and Notifier
+//
+// - Update -- sent new value converted into byte array
+//
+// - Close -- when the Notifier is closed
+//
+// - NotFound -- when Subscriber is trying to subscribe to Notifier
+// with a value which is not there
+
 extern crate serde;
 extern crate serde_json;
 

src/persist_value.rs

@@ -1,3 +1,9 @@
+// SPDX-License-Identifier: Apache-2.0
+
+// PersistValue stores a value of byte arrays
+// on a file system. Writing to a disk is an
+// atomic operation
+
 use std::fs;
 use std::io::Write;
 use std::path::{Path, PathBuf};

src/request_msg.rs

@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: Apache-2.0
+
+// This file contains common messages which are
+// used between NkvClient and Server
+
 use http::StatusCode;
 use serde::{Deserialize, Serialize};
 

src/server/srv.rs

@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: Apache-2.0
+
+// Server gives you an asynchronous access to a NotifyKeyValue storage.
+// You can get it within the same procees from same or another thread
+// using channels or from another program using tcp socket, for message
+// format you can check request_msg.rs
+
 use http::StatusCode;
 use std::net::SocketAddr;
 use std::sync::Arc;