cache-memory

Node module for in memory caching.

Installation

With npm

$ npm i cache-memory@3.0.3

Example usage

const cache = require('cache-memory')
  .ttl(60)
  .storeUndefinedObjects(false)
  .cleanup(60)
  .create({ id: 'snacks' });

function standardGetAndSetExample() {
   const key = 'the_key1';
   let result = cache.get(key);

   if (!result) {
      cache.set(key, { snack: 'crisps'});
      result = cache.get(key);
   }

   return { value: result, expiry: cache.getExpiry(key) };
}

async function getData() {
   return { snack: 'chocolate' };
}

async function getAndSetWithDataRetrievalExample() {
   const key = 'the_key2';
   let result = await cache.getAndSet(key, getData);
   return { value: result, expiry: cache.getExpiry(key) };
}

async function test() {
   console.log(`Result 1: ${JSON.stringify(standardGetAndSetExample())}`);
   console.log(`Result 2: ${JSON.stringify(await getAndSetWithDataRetrievalExample())}`);
}

test()
  .then(() => process.exit(0))

Example console output of executed code:

Result 1: {"value":{"snack":"crisps"},"expiry":"2023-03-24T12:11:07.171Z"}
Result 2: {"value":{"snack":"chocolate"},"expiry":"2023-03-24T12:11:07.176Z"}

API

Cache - cache-memory object

Object is used to create cache instances, default configuration variables and scheduled object cleanup.

create

const cache = require('cache-memory')
    .create([options]);

Creates a new cache instance.

options

This argument is optional.

• clone: (default: true) Defines whether objects should be cloned when set in and retrieved from cache.
• id: (optional string) The id of the cache. If no id is supplied it will be generated.
• storeUndefinedObjects: (default: false) Defines whether undefined objects should be stored in memory.
• ttl: (default: 0) Defines in seconds how long an object should be stored in memory. 0 = Forever
• hit: Function called every time an object is retrieved from cache.
• miss: Function called every time an object is not from cache.
• added: Function called every time an object is added to cache.
• removed: Function called every time an object is removed from cache.
• count: Function called every time an object is added or removed from cache.

** hit, miss, added, removed functions are all called with the following object structure.

{
  id: 'some-id',
  key: 'some-key'
}

** count function is called with the following object structure.

{
  id: 'some-id',
  count: 123
}

clone

require('cache-memory')
    .clone(false);

Turns off object cloning (default true).

storeUndefinedObjects

require('cache-memory')
    .storeUndefinedItems(true);

Allows undefined objects to be stored in cache (default false).

ttl

require('cache-memory')
    .ttl(true);

Defines in seconds how long an object should be stored in memory.

cleanup

require('cache-memory')
    .cleanup(60);

Forces expired objects to be removed from cache every 60 seconds. By default no cleanup is performed.

clear

require('cache-memory')
  .clear();

Clears the in memory cache of all active cache instances.

cachers

const cachers = require('cache-memory').cachers();

Gets all active cache instances.

cacher

const cacher = require('cache-memory').cacher('snacks');

Gets an active cacher by it's id.

stats

const stats = require('cache-memory').stats();

Gets an array of stats across all active cachers.

[
  {
    id: '1',
    stats: {
      count: 5,
      hits: 17123,
      misses: 57,
      hitRate: 0.9966821885913854
    }
  }
]

dispose

require('cache-memory').dispose();

Clears all in memory cacher instances and also clears the cleanup task if defined using the cleanup function.

Cache - created cache-memory instance

It's functions are defined below.

get

const obj = cache.get(key, [options]);

Gets an object from cache, undefined will be returned if object does not exist.

options

This argument is optional.

• clone: (default: true) Defines whether objects should be cloned when set in and retrieved from cache.
• id: The id of the cacher (string value).
• storeUndefinedObjects: (default: false) Defines whether undefined objects should be stored in memory.
• ttl: (default: 0) Defines in seconds how long an object should be stored in memory. 0 = Forever
• hit: (optional) Function called every time an object is retrieved from cache.
• miss: (optional) Function called every time an object is not from cache.
• added: (optional) Function called every time an object is added to cache.
• removed: (optional) Function called every time an object is removed from cache.
• count: (optional) Function called every time an object is added or removed from cache.

** hit, miss, added, removed functions are all called with the following object structure.

{
  id: 'some-id',
  key: 'some-key'
}

** count function is called with the following object structure.

{
  id: 'some-id',
  count: 123
}

getExpiry

const expiry = cache.getExpiry(key);

Gets the expiry DateTime of an object in cache, undefined is returned if object is not found.

set

cache.set(key, value, [options]);

Stores an object in cache.

options

This argument is optional.

• storeUndefinedObjects: (default: global or instance level definition) Defines whether undefined objects should be stored in memory.
• ttl: (default: global or instance level definition) Defines in seconds how long an object should be stored in memory. 0 = Forever

If 'storeUndefinedObjects' is false. undefined, null and objects with an IsNull function that returns true will not be stored.

getAndSet

async function getter() {
  return 'hello-world-' + Math.random(0, 100);
}

await cache.getAndSet(key, getter, [options]);

Gets and sets an object in cache. The getAndSet function is an async function so should be awaited. It can also refresh its data in the background.

options

This argument is optional.

• storeUndefinedObjects: (default: global or instance level definition) Defines whether undefined objects should be stored in memory.
• ttl: (default: global or instance level definition) Defines in seconds how long an object should be stored in memory. 0 = Forever
• refreshIntervalInMilliseconds: (optional) Defines whether the cache should be refreshed using the getter every so many milliseconds.
• refreshIntervalWhenRefreshFailsInMilliseconds: (optional) If refreshIntervalInMilliseconds is set and a failure occurs when refreshing the cache the refresh delay will change to refreshIntervalWhenRefreshFailsInMilliseconds if set otherwise refreshIntervalInMilliseconds.

clear

cache.clear();

Removes all objects from the cache instance.

remove

cache.remove(key);

Remove the object from cache.

stats

const stats = cache.stats();

Gets the stats for the cache instance.

Example return value:

{
  count: 5,
  hits: 17123,
  misses: 57,
  hitRate: 0.9966821885913854
}

keys

const keys = cache.keys();

Gets all keys for objects stored in the cache instance.

options

const options = cache.options();

Gets all configured options for a cache instance.

Example return value:

{
  ttl: 60,
  clone: true,
  storeUndefinedObjects: false
}

License

(MIT)

Copyright (c) 2023 Lee Crowe

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.