simple-forgetting-map

A simple class to provide a thread-safe key-value map which removes entries when increased beyond its maximum size

Written in Java using minimal third-party libraries

Usage

• Created with constructor new ForgettingMap<K, V>(maxSize)
• An entry can be added with add(key, value)
• An entry can be read using find(key)
• When a new entry is added to the map which would increase the number of entries to beyond its maximum size, the least-used entry is removed
  • Least-used is defined as the entry which has been accessed the least number of times using the find(key) method
  • In the event of multiple least-used entries, the oldest (earliest-added) entry will be removed
  • Updating an existing entry is considered to be creating a new entry, i.e. if the most-used entry is overwritten with the add(key, value) method then this new entry will now be the least-used entry
  • This behaviour is verified by the unit and functional tests
• See JavaDoc for further detail

Extension Ideas

• Implement the Map interface and its other methods
• Add the option to toggle oldest/newest removal in the event of multiple least-used entries
• Add the option to update a value without resetting the usage count