frida-java-bridge/lib/lru.js

Java runtime interop from Frida

// Based on https://stackoverflow.com/a/46432113

export default class LRU {
  constructor (capacity, destroy) {
    this.items = new Map();
    this.capacity = capacity;
    this.destroy = destroy;
  }

  dispose (env) {
    const { items, destroy } = this;
    items.forEach(val => { destroy(val, env); });
    items.clear();
  }

  get (key) {
    const { items } = this;

    const item = items.get(key);
    if (item !== undefined) {
      items.delete(key);
      items.set(key, item);
    }

    return item;
  }

  set (key, val, env) {
    const { items } = this;

    const existingVal = items.get(key);
    if (existingVal !== undefined) {
      items.delete(key);
      this.destroy(existingVal, env);
    } else if (items.size === this.capacity) {
      const oldestKey = items.keys().next().value;
      const oldestVal = items.get(oldestKey);
      items.delete(oldestKey);
      this.destroy(oldestVal, env);
    }

    items.set(key, val);
  }
}