[doc] Installation, Usage example, License

Author: doublerebel

README.md

@@ -10,6 +10,62 @@ A helper class to expire keys from a sorted set in Redis, useful for timeseries
 
 [![NPM][npm-stats]][npm-package]
 
+## Installation
+```sh
+npm install --save redis-sorted-cache
+```
+
+## Usage
+
+##### Store a JSON object (timeseries event) in Redis and later retrieve all events within the cache TTL
+
+From [https://github.com/nextorigin/godot2/.../src/godot/reactor/redis-cache.coffee#L31](https://github.com/nextorigin/godot2/blob/be70857187d83ec66188609db2d12e8a9d5209ea/src/godot/reactor/redis-cache.coffee#L31)
+
+```coffee
+    SortedCache   = require "redis-sorted-cache"
+    @cache        = new SortedCache {redis: @client, name: @id, @ttl}
+
+  save: (redis, data, callback) ->
+    ideally = errify callback
+
+    data  = flatten data
+    saved = []
+    for key, val of data when key isnt "ttl"
+      val = JSON.stringify val if key in ["tags"]
+      saved.push key, val
+
+    key    = "godot:#{@id}:#{data.host}:#{data.service}:#{data.time}"
+    expire = @ttl or data.ttl
+    ttl    = if @changeTtl then @ttl else data.ttl
+
+    multi  = redis.multi()
+    multi.hmset key, "ttl", ttl, saved...
+         .EXPIRE key, expire
+    await multi.exec ideally defer()
+    @cache.addToSet key, data.time, callback
+
+  load: =>
+    ideally = errify @error
+
+    await @cache.keys ideally defer keys
+    multi = @client.multi()
+    multi.hgetall key for key in keys
+    await multi.exec ideally defer datas
+
+    for data in datas
+      data = unflatten data
+      continue unless data
+      types     = Producer::types
+      data[key] = JSON.parse data[key] for key, type of types when data[key] and typeof data[key] isnt type
+      @push data
+
+    return
+
+```
+
+## License
+
+MIT
 
   [ci-nextorigin]: https://img.shields.io/travis/nextorigin/redis-sorted-cache/master.svg?style=flat-square
   [travis-ci]: https://travis-ci.org/nextorigin/redis-sorted-cache