Cachify-wrapper NPM

cachify-wrapper

Wraps a function with a caching layer

Usage

callback

Wraps a function with a caching layer

Parameters

fn function callback-last style function
storage Storage\<K, RecordPacked\> cache storage (optional, default InMemoryStorageCb)
options Options (optional, default {})
hasher Function creates key for KV-storage from fn arguments (optional, default JSON.stringify)

Examples

const wrapper = require('cachify-wrapper').default;
class Storage {
	constructor() {
		this.data = new Map();
	}
	get = (key, cb) => cb(null, this.data.get(key))
	set = (key, value, ttl, cb) => {
		this.data.set(key, value);
		if (ttl > 0) setTimeout(() => this.data.delete(key), ttl);
		cb(null, true);
	}
	del = (key, cb) => cb(null, this.data.delete(key))
}
const storage = new Storage();
let count = 0;
const inc = (a, cb) => cb(null, count += a);
const cached = wrapper(inc, storage, {expire: 100});
setTimeout(() => cached(1, (_error, payload) => console.info(payload)), 0); // Invokes request
setTimeout(() => cached(1, (_error, payload) => console.info(payload)), 100); // Takes cached result
setTimeout(() => cached(1, (_error, payload) => console.info(payload)), 200); // Invokes second request

cached.set(2, 'manual value', 1000, () =>
	cached.get(2, (_, result) => {
		console.info(result);
		cached.del(2, () =>
			cached.get(2, (_, result) => console.info(result)))
	}));

Returns function

promise

Wraps a function with a caching layer

Parameters

fn function
storage Storage\<K, RecordPacked\>?
options Options?
hasher Function?

Examples

const wrapperPromise = require('cachify-wrapper').promise;
let count = 0;
const inc = async(a) => count += a;
const cached = wrapperPromise(inc, storage, {expire: 1000});
const p1 = cached(1).then((payload) => console.info(payload)); // Invokes request
const p2 = p1.then(() => cached(1).then((payload) => console.info(payload))); // Takes cached result

Returns function (...any): Promise\

Options

Type: Object

Properties

storage Object?
- storage.timeout number? max storage response time before considering it as failed, and invoking fn
source Object?
- source.timeout number? max fn response time before considering it as failed
expire number? time to consider cached data expired [in milliseconds]
spread number? expire time spread (prevents simultaneous deletions saved items from storage)
lock number? lock timeout (prevents simultaneous concurrent invoke of fn at initial period)
stale number? additional ttl for stale data
ttl number? forced ttl (TimeToLive) for data (useful if storage is using from multiply services with different expire)
retries number? number of storage requests passes before fn call
error number? ttl for erroneous state cache (prevents frequent call of fn)
verbose number? verbosity flag