buffering-cache

buffering-cache

Cache a little cold? Cache misses slowing you down?

buffering-cache keeps your cache warm asynchronously. Minimizing cache misses and keeping the entries from becoming stale.

Currently works with Redis only. Requires an 'ioredis' Redis client to be provided.

Also offers a multi-level cache option. In addition to Redis, you can use local memory cache courtesy of lru-cache before failing over to a remote Redis instance.

Installation:

npm install --save buffering-cache

Simple Example:

const BufferingCache = require('buffering-cache');
const rp = require('request-promise');
const Redis = require('ioredis');

const bufferingCache = new BufferingCache({
  // Required:
  redisClient: new Redis({
    host: 'localhost',
    port: 6379,
    db: 0,
  }),
  ttlMsec: 5000, // Redis ttl. Must be a number gte 0

  // Optional:
  bufferTtlMsec: 2500, // Buffer TTL in msec. Defaults to ttlMsec / 2. Must be gt 0 and lt ttlMsec
  localCacheSize: 0,  // Local LRU cache size. Defaults to 0 (disabled). Must be gt 0.
  localTtlMsec: 500   // Local LRU cache TTL. Defaults to 500 ms, or bufferTtlMsec, whichever is less
});

const rawFunction = () => rp('http://www.google.com');

const bufferedAndCachedFunction = bufferingCache.wrapFunction(rawFunction);

bufferedAndCachedFunction()
.then((response) => {
  // No cache yet
  // 'response' returned after round-trip to google.com. 
})
.delay(3000) // Wait a bit 
.then(() => {
  return bufferedAndCachedFunction();
})
.then(() => {
  // Returns results from cache
  // By default bufferTtlMsec = ttlMsec / 2. 
  // So at 3000 ms the cache is refreshed after the result is returned
  return bufferedAndCachedFunction();
})
.delay(3000)
.then(() => {
  // Returns results from cache again. 
  // This time returns the result from the previous refresh.
  // Refreshes the cache again
  return bufferedAndCachedFunction();
})