D2iQ Take Home Challenge

Overview

This is a simple in-memory cache service utilizing a least recently used (LRU) policy.

Limitations

• Data is not durable by design and will be lost on system failure. An easily implemented solution would be to persist this data to disk or use a service like Redis for less frequently accessed keys.
• In a real life implementation, this cache would support additional data types instead of just strings.

Requirements

You should have docker and make installed.

The following make commands are available:

• make build: Run unit tests and create the docker image
• make run: Execute make build and run the container in the background
• make stop: Stop the active container

Configuration Variables

Variable	Default
LOG_LEVEL	info
CACHE_SIZE	250

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Cache with eviction policy

Problem Statement: Create an in-memory cache in Go for storing String values based on a String key. Expect that the cache will continually have previously unseen keys added to it, and that some keys will be fetched more frequently than others.

Your cache should have the following signature (in pseudocode):

type Cache {
    // Inserts the provided key/value pair into the cache, making it
    // available for future get() calls.
    void put(String key, String value);
    
    // Returns a value previously provided via put(). An empty Option
    // may be returned if the requested data was never inserted or is
    // no longer available.
    Option[String] get(String key);
}

The choice of eviction policy is up to you, but you could consider least recently used or time to live policies, a combination of the two, or any other eviction policy you choose.

The code should at least contain:

• A README.md explaining how to build the project and how to use the library (and any other details you think are important, e.g. limitations)
• A Makefile
• Tests 🙂

Good luck! 🎉