cachify-wrapper

Wraps a function with a caching layer

Usage no npm install needed!

<script type="module">
  import cachifyWrapper from 'https://cdn.skypack.dev/cachify-wrapper';
</script>

README

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

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

del

Parameters

RecordPacked

Type: Object

Properties

InMemoryStorageCb

get

Parameters
  • key K
  • cb CB<V>

set

Parameters

del

Parameters

InMemoryStorageSerializable

Extends InMemoryStorage

expire

Parameters

export

Returns Iterable<KRecordTuple<K, V>>

import

Parameters
  • dump Iterable<KRecordTuple<K, V>>

InMemoryStorageRecord

Type: Object

Properties

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