Wraps any asynchronous function and provides caching of the result
npm install --save ceych
'use strict';
const request = require('request');
const Catbox = require('@hapi/catbox').Client;
const Redis = require('@hapi/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 cacheCeych 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.
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 |
Creates a ceych client.
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
Returns a wrapped function that implements caching.
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.
Disables the cache client to allow for wrapped methods to be tested as normal.