Persistent cachios + lru-cache usage for https://github.com/AlbinoDrought/cachios/issues/59

index.js

const axios = require('axios');
const cachios = require('cachios');
const LRU = require('lru-cache');
const fs = require('fs');

//// this part is for debugging purposes:

// build an axios client that logs outbound requests
const axiosClient = axios.create();

axiosClient.interceptors.request.use((config) => {
  console.log('uncached outbound request to', config.url);
  return config;
});

// use it in our cachios client
const cachiosClient = cachios.create(axiosClient);

//// this part is for https://github.com/AlbinoDrought/cachios/issues/59

// configure our cachios client with custom cache
const customCache = new LRU(500);
cachiosClient.cache = customCache;

// load cache from cache.json into lru-cache instance
const readCache = (lruCache) => new Promise((resolve, reject) => {
  fs.readFile('cache.json', 'utf8', (err, data) => {
    if (err) {
      return reject(err);
    }

    try {
      const parsedCache = JSON.parse(data);
      lruCache.load(parsedCache);
      return resolve();
    } catch (ex) {
      return reject(ex);
    }
  });
});

// dump cache from lru-cache instance into cache.json
const writeCache = (lruCache) => new Promise((resolve, reject) => {
  const data = JSON.stringify(lruCache.dump());
  fs.writeFile('cache.json', data, null, (err) => {
    if (err) {
      reject(err);
    } else {
      resolve();
    }
  })
});

(async () => {
  // load cache on boot once
  try {
    await readCache(customCache);
    console.log('read', customCache.itemCount, 'items from disk');
  } catch (ex) {
    console.error('error reading cache (probably the first uncached run), continuing', ex);
  }

  // make our requests
  await cachiosClient.get('http://example.com/');
  await cachiosClient.get('http://example.com/');
  await cachiosClient.get('http://example.com/');

  // write cache on process end
  await writeCache(customCache);
  // alternatively, write cache automatically:
  // setInterval(() => writeCache(customCache), 30000);
})();

package.json

{
  "license": "PUBLIC DOMAIN",
  "dependencies": {
    "axios": "^0.21.1",
    "cachios": "^2.2.5",
    "lru-cache": "^6.0.0"
  }
}