cache-memory

mem-cache

Node module for in memory caching.

Installation

With npm do

$ npm install mem-cache --save

Example usage

'use strict';
const cache = require('mem-cache')
  .create({ ttl: 60});

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

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) };
}

function * generatorGetAndSetExample() {
  const key = 'the_key2';

  let result = yield* cache.getAndSet(key, {
    generator: function * () {
      return yield* getData();
    }
  });

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

console.log(`Result 1: ${JSON.stringify(standardGetAndSetExample())}`);
console.log(`Result 2: ${JSON.stringify(generatorGetAndSetExample().next().value)}`);

Example console output of executed code:

Result 1: {"value":{"snack":"crisps"},"expiry":"2017-04-18T08:15:19.087Z"}
Result 2: {"value":{"snack":"chocolate"},"expiry":"2017-04-18T08:15:19.091Z"}

##API

Cache

create

let cacher = require('mem-cache')
    .clone(false );

Creates a new cacher instance.

options

• 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

clone

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

Turns off object cloning (default true).

storeUndefinedObjects

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

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

cleanup

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

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

clear

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

Clears the in memory cache of all active cache instances.

cachers

let cachers = require('mem-cache').cachers();

Gets all active cache instances.

cacher

let cacher = require('mem-cache').cacher('snacks');

Gets an active cacher by it's id.

cachedItemsCount

let count = require('mem-cache').cachedItemsCount();

Gets the total count of cached objects across all active cachers.

Cache instance

get

cache.get(key, [options]);

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

options

• 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

getExpiry

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

• 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

cache.getAndSet(key, [options]);

Gets and sets an object in cache. The getAndSet function is a generator function so should be yielded or Promisied etc.

options

• generator: A generator function that will be yielded to return the object value to store in cache.
• 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

clear

cache.clear();

Removes all objects from the cache instance.

remove

cache.remove(key);

Remove the object from cache.

cachedItemsCount

cache.cachedItemsCount();

Gets the number of objects stored in the cache instance.

keys

cache.keys();

Gets all keys for objects stored in the cache instance.

License

(MIT)

Copyright (c) 2017 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.