ceych

Wraps any asynchronous function and provides caching of the result

Installation

npm install --save ceych

Usage

'use strict';

const request = require('request');
const Catbox = require('catbox').Client;
const Redis = require('catbox-redis');

const ceych = require('ceych').createClient({
  cacheClient: new Catbox(new Redis({
    port: 6379,
    host: '127.0.0.1',
    partition: 'cache'
  })),
  defaultTTL: 30
});

function loadData(cb) {
  request.get('https://www.big-data.com/datum.csv', cb);
}

const loadDataCached = ceych.wrap(loadData);

const miss = loadDataCached(); // returned from the server and stored in the cache
const hit = loadDataCached(); // returned from the server and stored in the cache

How does it work?

Ceych automatically creates cache keys based on the wrapped function's body and the arguments passed. This saves you from having to create a unique cache key every time you want the result of a function to be cached.

Return values and arguments need to be serializable to/from JSON. This means that while strings, numbers and basic objects are supported, objects with custom constructors or prototypes are not.

StatsD integration

When using a node-statsd client, ceych will increment a counter each time there is a cache hit or miss. The following metrics are sent:

|Metric|Type|Description| |------|----|-----------| |ceych.hits|counter|Incremented whenever there is a cache hit| |ceych.misses|counter|Incremented whenever there is a cache miss|

API

Ceych.createClient(opts)

Creates a ceych client.

Parameters

• cacheClient - optional - A Catbox client (defaults to an in-memory client).
• defaultTTL - optional - The default TTL for caching in seconds (default 30).
• statsClient - optional - An instance of the node-statsd client

ceych.wrap(fn, ttl, suffix)

Returns a wrapped function that implements caching.

Parameters

• fn - An asynchronous function to be wrapped.
• ttl - optional - Overrides the default TTL.
• suffix - optional - A string appended to cache keys to differentiate between identical functions.

ceych.disableCache()

Disables the cache client to allow for wrapped methods to be tested as normal.