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SelfRefreshingCache

SelfRefreshingCache​

@vendure/coreself-refreshing-cache.ts

A cache which automatically refreshes itself if the value is found to be stale.

Signature
interface SelfRefreshingCache<V, RefreshArgs extends any[] = []> {
    value(...refreshArgs: RefreshArgs | [undefined] | []): Promise<V>;
    memoize<Args extends any[], R>(
        args: Args,
        refreshArgs: RefreshArgs,
        fn: (value: V, ...args: Args) => R,
    ): Promise<R>;
    refresh(...args: RefreshArgs): Promise<V>;
}

value​

method
(refreshArgs: RefreshArgs | [undefined] | []) => Promise<V>

The current value of the cache. If the value is stale, the data will be refreshed and then the fresh value will be returned.

memoize​

method
(args: Args, refreshArgs: RefreshArgs, fn: (value: V, ...args: Args) => R) => Promise<R>

Allows a memoized function to be defined. For the given arguments, the fn function will be invoked only once and its output cached and returned. The results cache is cleared along with the rest of the cache according to the configured ttl value.

refresh​

method
(args: RefreshArgs) => Promise<V>

Force a refresh of the value, e.g. when it is known that the value has changed such as after an update operation to the source data in the database.

SelfRefreshingCacheConfig​

@vendure/coreself-refreshing-cache.ts

Configuration options for creating a SelfRefreshingCache.

Signature
interface SelfRefreshingCacheConfig<V, RefreshArgs extends any[]> {
    name: string;
    ttl: number;
    refresh: {
        fn: (...args: RefreshArgs) => Promise<V>;
        /**
         * Default arguments, passed to refresh function
         */
        defaultArgs: RefreshArgs;
    };
    getTimeFn?: () => number;
}

name​

property
string

The name of the cache, used for logging purposes. e.g. 'MyService.cachedValue'.

ttl​

property
number

The time-to-live (ttl) in milliseconds for the cache. After this time, the value will be considered stale and will be refreshed the next time it is accessed.

refresh​

property
{ fn: (...args: RefreshArgs) => Promise<V>; /** * Default arguments, passed to refresh function */ defaultArgs: RefreshArgs; }

The function which is used to refresh the value of the cache. This function should return a Promise which resolves to the new value.

getTimeFn​

property
() => number

Intended for unit testing the SelfRefreshingCache only. By default uses () => new Date().getTime()

createSelfRefreshingCache​

@vendure/coreself-refreshing-cache.ts

Creates a SelfRefreshingCache object, which is used to cache a single frequently-accessed value. In this type of cache, the function used to populate the value (refreshFn) is defined during the creation of the cache, and it is immediately used to populate the initial value.

From there, when the .value property is accessed, it will return a value from the cache, and if the value has expired, it will automatically run the refreshFn to update the value and then return the fresh value.

Example

Example of creating a SelfRefreshingCache
import { createSelfRefreshingCache } from '@vendure/core';

@Injectable()
export class PublicChannelService {
  private publicChannel: SelfRefreshingCache<Channel, [RequestContext]>;

  async init() {
    this.publicChannel = await createSelfRefreshingCache<Channel, [RequestContext]>({
     name: 'PublicChannelService.publicChannel',
     ttl: 1000 * 60 * 60, // 1 hour
     refresh: {
       fn: async (ctx: RequestContext) => {
        return this.channelService.getPublicChannel(ctx);
      },
     defaultArgs: [RequestContext.empty()],
    },
  });
}
Signature
function createSelfRefreshingCache<V, RefreshArgs extends any[]>(config: SelfRefreshingCacheConfig<V, RefreshArgs>, refreshArgs?: RefreshArgs): Promise<SelfRefreshingCache<V, RefreshArgs>>

Parameters

config​

parameter
SelfRefreshingCacheConfig<V, RefreshArgs>

refreshArgs​

parameter
RefreshArgs