cachify-wrapper

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<V>> 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<V>>?
• 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<any>

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

CacheAbsentError

Extends Error

no cache error

Functions

Storage

storage interface

get

Parameters

• key K
• cb CB<V>

set

Parameters

• key K
• value V
• ttl number
• cb CB<boolean>

del

Parameters

• key K
• cb CB<boolean>

RecordPacked

Type: Object

Properties

• e string?
• v V?
• t number?
• l number?

InMemoryStorageCb

get

Parameters

• key K
• cb CB<V>

set

Parameters

• key K
• value V
• ttl number
• cb CB<boolean>

del

Parameters

• key K
• cb CB<boolean>

InMemoryStorageSerializable

Extends InMemoryStorage

expire

Parameters

• key K
• ttl number

export

Returns Iterable<KRecordTuple<K, V>>

import

Parameters

• dump Iterable<KRecordTuple<K, V>>

InMemoryStorageRecord

Type: Object

Properties

• value V?
• timestamp number?
• ttl number?

InMemoryStorage

Parameters

• source Iterable<KRecordTuple<K, V>>?

get

Parameters

• key K

set

Parameters

• key K
• value V

del

Parameters

• key K

has

Parameters

• key K

expire

Parameters

• key K
• ttl number