cachify-wrapper

Wraps a function with a caching layer

Usage

$3

Wraps a function with a caching layer

#### Parameters

* fn function callback-last style function
* storage Storage\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

``javascript
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

$3

Wraps a function with a caching layer

#### Parameters

* fn function
* storage Storage\RecordPacked\>?
* options Options?
* hasher Function?

#### Examples

`javascript
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\

$3

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

$3

Extends Error

no cache error

$3

$3

storage interface

#### get

##### Parameters

* key K
* cb CB\

#### set

##### Parameters

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

#### del

##### Parameters

* key K
* cb CB<boolean>

$3

Type: Object

#### Properties

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

$3

#### get

##### Parameters

* key K
* cb CB\

#### set

##### Parameters

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

#### del

##### Parameters

* key K
* cb CB<boolean>

$3

Extends InMemoryStorage

#### expire

##### Parameters

* key K
* ttl number

#### export

Returns Iterable\>

#### import

##### Parameters

* dump Iterable\>

$3

Type: Object

#### Properties

* value V?
* timestamp number?
* ttl number?

$3

#### Parameters

* source Iterable\>?

#### get

##### Parameters

* key K

#### set

##### Parameters

* key K
* value V

#### del

##### Parameters

* key K

#### has

##### Parameters

* key K

#### expire

##### Parameters

* key K
* ttl` number