dyna-cache

DynaCache v3

Caches something and provides it immediately.

Preload, refresh features out of the box.

createDynaCache

This factory function creates another function that uses the cache behind this.

Example

Suppose we have this interface of articles

interface ITestArticle {
  title: string;
  body: string;
}

And this api method that loads the articles from the backend

const apiLoadArticles = async (args: {lang: string, group: string}): Promise<ITestArticle[]> => [];

Let's make api method cacheable version of it

const apiLoadArticlesCacheEngine = createDynaCache({
  load: apiLoadArticles,
  expireAfterMinutes: 10,
});

The apiLoadArticlesCacheEngine is na object, with the load(args: TArgs) method that returns data.

Thanks to typescript, the function has all types obtained from the load method, for the args and for the output. So we don't have to define anything to the generics of the createDynaCache.

Let's use it

apiLoadArticlesCacheEngine.load({lang: 'en', group: 'fashion'})     // We pass the object as we do with the apiLoadArticles
  .then(articles => {
    // We have types articles here
    articles.forEach(article => {
      console.log('Title', article.title);
    });
  });

Configuration object of the createDynaCache

interface ICreateDynaCacheConfig<TArgs, TData, > {
  load: (args: TArgs) => Promise<TData>; // The load operation
  expireAfterMinutes?: number;            // When the cache expires, undefined for none
  preload?: boolean;                      // Preload the data on start
  refreshEveryMinutes?: number;           // Refresh the data silently on background
}

Invalidate the cache

To invalidate the cache (to clear the content of the cache) call the invalidate()

apiLoadArticlesCacheEngine.invalidate();

Don't forget to free() it!

Cache keeps resources for refreshing, etc.

If you are going to free the owner of it, your have to call the .free() also!

Just apiLoadArticlesCacheEngine.free().

How does it works internally?

The apiLoadArticlesCacheEngine creates internally small caches for each different args.

If you ask the same args, then the cached version will be served.

DynaCache

This is how to create a DynaCache class.

Config

 interface IDynaCacheConfig<TData> {
  load: () => Promise<TData>;       // The load operation

  expireAfterMinutes?: number;      // When the cache expires, undefined for none
  preload?: boolean;                // Preload the data on start
  refreshEveryMinutes?: number;     // Refresh the data silently on background
  onLoad?: (data: TData) => void;   // Called when the data are loaded for any reason
}

Methods

• load(): Promise<TData> load from cache or from source if it is not yet cached
• loadFresh(): Promise<TData> load fresh data (not from cache)
• invalidate(): void clear the cache, all further loads will be new
• free(): void destroy the cache (cleans up auto refresh cache)

Properties

• get size(): number returns the size of the cache in bytes
• get loadedAt(): number timestamp when the last load took place
• get lastUsedAt(): number timestamp when the cache read last time
• get loadCount(): number how many the cache was updated
• get lastError(): any last load error

Example

// Factory function that create a DynaCache with specific args and api method
// This function just connects that arguments with the api method
const createLoadArticlesCache = (lang: string, group: string) =>
  new DynaCache({
    expireAfterMinutes: 10,
    load: () => apiLoadArticles(lang, group),
  });

// Lets create a cache for the epi
const loadArticlesCache = createLoadArticlesCache('en', 'fashion');

// Lets use it
loadArticlesCache.load(); // The return is always up to date and fast

// Don't forget to free() it to avoid memory leaks!
// This is needed when `expireAfterMinutes` or `refreshEveryMinutes`
loadArticlesCache.free();
// Note, now you cannot use it anymore

Change log

v3

V3 is totally different approach than V2.

V3 offers plus

• preload
• refresh
• cache factory (cache key by args object)
• simpler code (1/4 of the previous one)

v2

For v2 open this page.