# Introduction
`SimpleCache` class provides simple cache features. It provides `read`, `write`, `fetch` methods.
## Usage
```
SimpleCache.fetch(:key1) { 123 }
SimpleCache.read(:key1) # => 123
SimpleCache.write(:key1, 321)
SimpleCache.read(:key1) # => 321
SimpleCache.write(:key2, 321)
```
# Configuration
```
SimpleCache.config = { backend: SomeBackEndClass, expiration_time_millis: 123 }
```
# Backend
Backend class should implement such methods:
* `def []=(key, expiration_time_millis, value)`
* `def [](key)`
Optional method to implement is `def cleanup!`.
# DRb
Provided DRb server and client allow to run the Hash-like backend in a separate
process and communicate with it from the client in another process. Thus Ruby
hash-like in-memory storage can save data and serve as cache backend until its
process is shut down.
## Usage
See `main.rb` file for example.