in-memoriam

Easy to use, high-speed O(1) to O(n) for all operations, in-memory key-value cache with both ttl and capacity support. This caching system has been used in multiple production systems for a while now and has proven stable, quietly improving performance for a host of scenarios, such as:

• Caching security tokens
• Caching frequently read/infrequently updated database objects
• Caching lookup data fetched from remote REST services

This module exports the cache constructor, making usage as simple as:

  var Cache = require('in-memoriam');
  // Create a 
  var capacity = 1000; // Least recently accessed/oldest items are removed when capacity is exceeded
  var ttl = 10000; // TTL is in milliseconds. Items not accessed by end of TTL are evicted.
  var cache = new Cache(capacity, ttl);
  cache.set('names', [ 'joe', 'jim', 'jill', 'jane' ]);
  var names = cache.get('names');

The number of cache instances that can be created is limited only by memory. Note that caches will execute a callback every ttl ms to execute eviction logic, so very high capacity caches with a high degree of churn may have CPU impact. Use caches wisely, and tune them using real world data.

Caches maintain metrics to help with tuning and management; a call to cache.stats will return something like:

  {
    "hits":         235,
    "misses":       312,
    "inserts":      255,
    "updates":      42,
    "evictions":    122,
    "expirations":  12,
    "size":         199
  };