Fine-Grained Cache

This module provides a flexible caching utility designed to work with Redis and an in-memory cache (like LRUCache). It supports features like locking for preventing thundering herd problems, stale-while-revalidate patterns, timed invalidation, and fine-grained key invalidation.

FineGrainedCache Factory

The FineGrainedCache function is a factory that creates a cache instance configured with your Redis client and other options.

function FineGrainedCache<KeyPrefix extends string = "fine-cache-v1">(options: {
  redis: Redis;
  redLock?: {
    client: RedLock;
    maxExpectedTime?: StringValue;
    retryLockTime?: StringValue;
    /**
     * @default false
     */
    useByDefault?: boolean;
  };
  keyPrefix?: KeyPrefix;
  memoryCache?: MemoryCache<unknown>;
  onError?: (err: unknown) => void;
  /**
   * Enable event logging
   */
  logEvents?: {
    events: LoggedEvents;
    /**
     * @default console.log
     */

    log?: (args: LogEventArgs) => void;
  };
  /**
   * Set a maximum amount of milliseconds for getCached to wait for the GET redis response
   */
  GETRedisTimeout?: number;
  /**
   * Enable usage of redis pipelines for redis GET.
   *
   * If "number" is specified, that's the maximum amount of operations to be sent in a single pipeline
   */
  pipelineRedisGET?: boolean | number;
  /**
   * Enable usage of redis pipelines for redis SET.
   *
   * If "number" is specified, that's the maximum amount of operations to be sent in a single pipeline
   */

  pipelineRedisSET?: boolean | number;
  /**
   * Should `getCached` use memory cache by default?
   *
   * It can be overriden on `getCached`
   *
   * @default true
   */

  defaultUseMemoryCache?: boolean;
  /**
   * Should `getCached` await the Redis set
   *
   * @default process.env.NODE_ENV === "test"
   */

  awaitRedisSet?: boolean;
});

Parameters:

• options: An object containing configuration options for the cache.
  • redis: (Redis) The Redis client instance to use for caching.
  • redLock: ({ client: RedLock; maxExpectedTime?: StringValue; retryLockTime?: StringValue; useByDefault?: boolean; }, optional, if not specified, locking functionality is not enabled) Configuration for RedLock for distributed locking.
    • client: (RedLock) The RedLock client instance.
    • maxExpectedTime: (StringValue, optional) Maximum time to wait for the lock.
    • retryLockTime: (StringValue, optional) Time to wait between lock retry attempts.
    • useByDefault: (boolean, optional) Whether to use RedLock by default for getCached. Defaults to false.
  • keyPrefix: (KeyPrefix, optional) A prefix to use for all Redis keys managed by this cache instance. Defaults to "fine-cache-v1".
  • memoryCache: (MemoryCache<unknown>, optional) An instance of an in-memory cache (e.g., LRUCache) to use as a tier 1 cache.
  • onError: ((err: unknown) => void, optional) A callback function to handle errors that occur within the cache operations.
  • logEvents: ({ events: LoggedEvents; log?: (args: LogEventArgs) => void; }, optional) Configuration for logging cache events.
    • events: (LoggedEvents) An object specifying which events to log.
    • log: ((args: LogEventArgs) => void, optional) The logging function to use. Defaults to console.log.
  • GETRedisTimeout: (number, optional) The maximum amount of milliseconds for getCached to wait for a GET response from Redis.
  • pipelineRedisGET: (boolean | number, optional) Enables the use of Redis pipelines for GET operations. If a number is specified, it's the maximum number of operations per pipeline.
  • pipelineRedisSET: (boolean | number, optional) Enables the use of Redis pipelines for SET operations. If a number is specified, it's the maximum number of operations per pipeline.
  • defaultUseMemoryCache: (boolean, optional) Should getCached use the memory cache by default? Can be overridden per call. Defaults to true.
  • awaitRedisSet: (boolean, optional) Should getCached await the Redis SET operation? Defaults to process.env.NODE_ENV === "test".

Main Entry Points

These are the primary functions for interacting with the cache.

getCached

Fetches a value from the cache or generates it using the provided callback if a cache miss occurs. Supports timed invalidation, locking, and dynamic control over caching behavior via the callback options.

CachedCallback Definition

The callback function provided to getCached has the following definition:

export type CachedCallback<T> = (options: {
  setTTL(options: {
    /**
     * Set TTL to `null` to disable caching
     */
    ttl?: StringValue | "Infinity" | null;
    timedInvalidation?: null | Date | (() => Date | Promise<Date>);
  }): void;
  getTTL(): {
    ttl: StringValue | "Infinity" | null;
    timedInvalidation: undefined | null | Date | (() => Date | Promise<Date>);
  };
}) => T;

The callback function cb is expected to return the value to be cached (it does not need to return a Promise directly, getCached handles the async aspect). It receives an object with the following functions:

• setTTL: ((options: { ttl?: StringValue | "Infinity" | null; timedInvalidation?: null | Date | (() => Date | Promise<Date>); }) => void) A function that allows you to dynamically set or change the Time-To-Live (ttl) and the timedInvalidation date for the cache entry based on the result of the callback's execution.
  • Setting ttl to null will disable caching for this specific execution.
  • Setting timedInvalidation to null will remove any previously set timed invalidation for this entry.
• getTTL: (() => { ttl: StringValue | "Infinity" | null; timedInvalidation: undefined | null | Date | (() => Date | Promise<Date>); }) A function to retrieve the currently configured ttl and timedInvalidation values.

<T>(
  cb: CachedCallback<T>,
  options: {
    timedInvalidation?: Date | (() => Date | Promise<Date>);
    ttl: StringValue | "Infinity";
    keys: string | [string, ...(string | number)[]];
    maxExpectedTime?: StringValue;
    retryLockTime?: StringValue;
    checkShortMemoryCache?: boolean;
    useRedlock?: boolean;
    forceUpdate?: boolean;
  }
) => Awaited<T> | Promise<Awaited<T>>;

Parameters:

• cb: (CachedCallback<T>) An asynchronous function that generates the value to be cached.
• options: An object containing options for this specific cache retrieval.
  • timedInvalidation: (Date | (() => Date | Promise<Date>), optional) Specifies a future date or a function that returns a future date when the cache entry should be considered invalid, even if the ttl has not expired. This can be overridden dynamically by calling setTTL within the cb callback.
  • ttl: (StringValue | "Infinity") The initial time-to-live for the cache entry in Redis. Can be a string like "1m", "1h", "1d", or "Infinity". This value can be overridden dynamically by calling setTTL within the cb callback.
  • keys: (string | [string, ...(string | number)[]]) A string or an array of strings and numbers used to generate the cache key.
  • maxExpectedTime: (StringValue, optional) Overrides the default RedLock maxExpectedTime for this operation.
  • retryLockTime: (StringValue, optional) Overrides the default RedLock retryLockTime for this operation.
  • checkShortMemoryCache: (boolean, optional) Should the memory cache be checked before hitting Redis? Overrides the default.
  • useRedlock: (boolean, optional) Should RedLock be used for this operation to prevent thundering herd? Overrides the default.
  • forceUpdate: (boolean, optional) Forces the cache to regenerate the value using the callback, ignoring any existing cache entry.

Returns:

(Awaited<T> | Promise<Awaited<T>>) The cached or newly generated value.

getStaleWhileRevalidate

Fetches a value using the stale-while-revalidate pattern. It immediately returns a potentially stale value from the cache while asynchronously updating it in the background.

StaleWhileRevalidateCallback Definition

The callback function provided to getStaleWhileRevalidate has the following definition:

export type StaleWhileRevalidateCallback<T> = (options: {
  setTTL(options: {
    /**
     * Set TTL to `null` to disable updating revalidation time
     */
    revalidationTTL?: StringValue | null;

    /**
     * Set TTL to `null` to disable caching
     */
    dataTTL?: StringValue | "Infinity" | null;
  }): void;
  getTTL(): {
    revalidationTTL: StringValue | null;

    dataTTL: StringValue | "Infinity" | null;
  };
}) => T;

The callback function cb is expected to return the fresh value (it does not need to return a Promise directly). It receives an object with the following functions:

• setTTL: ((options: { revalidationTTL?: StringValue | null; dataTTL?: StringValue | "Infinity" | null; }) => void) A function that allows you to dynamically set or change the revalidationTTL and dataTTL for the cache entry based on the result of the callback's execution.
  • Setting revalidationTTL to null will disable updating the revalidation time for this specific execution.
  • Setting dataTTL to null will disable caching the data altogether for this execution.
• getTTL: (() => { revalidationTTL: StringValue | null; dataTTL: StringValue | "Infinity" | null; }) A function to retrieve the currently configured revalidationTTL and dataTTL values.

<T>(
  cb: StaleWhileRevalidateCallback<T>,
  options: {
    revalidationTTL: StringValue;
    dataTTL?: StringValue | "Infinity";
    keys: string | [string, ...(string | number)[]];
    forceUpdate?: boolean;
  }
) => Promise<Awaited<T>>;

Parameters:

• cb: (StaleWhileRevalidateCallback<T>) An asynchronous function that generates the fresh value
• options: An object containing options for this SWR operation.
  • revalidationTTL: (StringValue) The duration after which the cached data is considered stale and a background revalidation is triggered. This can be overridden dynamically by calling setTTL within the cb callback.
  • dataTTL: (StringValue | "Infinity", optional) The maximum time the data is allowed to live in the cache, even if not revalidated. Defaults to Infinity. This can be overridden dynamically by calling setTTL within the cb callback.
  • keys: (string | [string, ...(string | number)[]]) A string or an array of strings and numbers used to generate the cache key.
  • forceUpdate: (boolean, optional) Forces the cache to regenerate the value using the callback immediately, ignoring any existing cache entry.

Returns:

(Promise<Awaited<T>>) A promise that resolves with the cached (potentially stale) or newly generated value.

invalidateCache

Invalidates (deletes) cache entries based on the provided keys.

(...keys: [string, ...(string | number)[]]) => Promise<void>;

Parameters:

• ...keys: ([string, ...(string | number)[]]) One or more arrays of strings and numbers representing the keys to invalidate.

Returns:

(Promise<void>) A promise that resolves when the invalidation is complete.

Secondary Utility Functions

These functions provide lower-level access and additional flexibility for developers.

generateCacheKey

Generates a standardized cache key string based on the provided keys and the factory's keyPrefix.

(keys: string | [string, ...(string | number)[]]) => string;

Parameters:

• keys: (string | [string, ...(string | number)[]]) A string or an array of strings and numbers to be included in the key.

Returns:

(string) The generated cache key.

generateSWRDataKey

Generates a standardized key string specifically for storing SWR data, based on the provided keys and the factory's swrKeyPrefix.

(keys: string | [string, ...(string | number)[]]) => string;

Parameters:

• keys: (string | [string, ...(string | number)[]]) A string or an array of strings and numbers to be included in the key.

Returns:

(string) The generated SWR data key.

keyPrefix

The key prefix configured for this cache instance.

KeyPrefix;

Type: KeyPrefix

swrKeyPrefix

The key prefix used specifically for Stale-While-Revalidate data.

`${KeyPrefix}-swr`;

Type: `${KeyPrefix}-swr`

memoryCache

The in-memory cache instance used by this cache utility.

MemoryCache<unknown>;

Type: MemoryCache<unknown>

setCache

Manually sets a value in the cache.

<T = unknown>(options: {
  populateMemoryCache?: boolean;
  ttl: StringValue | "Infinity";
  keys: string | [string, ...(string | number)[]];
  value: T;
  swr?: boolean;
}) => Promise<void>;

Parameters:

• options: An object containing options for setting the cache value.
  • populateMemoryCache: (boolean, optional) Whether to also set the value in the in-memory cache. Defaults to the factory's defaultUseMemoryCache setting.
  • ttl: (StringValue | "Infinity") The time-to-live for the cache entry in Redis.
  • keys: (string | [string, ...(string | number)[]]) A string or an array of strings and numbers used to generate the cache key.
  • value: (T) The value to cache.
  • swr: (boolean, optional) If true, sets the value using the SWR key prefix.

Returns:

(Promise<void>) A promise that resolves when the value has been set in the cache.

readCache

Reads a value directly from the cache without using a callback to generate it.

<T = unknown>(options: {
  keys: string | [string, ...(string | number)[]];
  swr?: boolean;
}) =>
  Promise<{
    found: boolean;
    value: Awaited<T>;
  }>;

Parameters:

• options: An object containing options for reading the cache value.
  • keys: (string | [string, ...(string | number)[]]) A string or an array of strings and numbers used to generate the cache key.
  • swr: (boolean, optional) If true, reads the value using the SWR key prefix.

Returns:

(Promise<{ found: boolean; value: Awaited<T>; }>) A promise that resolves with an object indicating if the key was found and the cached value.

getRedisValue

Gets a raw value directly from Redis using a specific key (without applying the key prefix).

(key: string) => Promise<string | null>;

Parameters:

• key: (string) The exact Redis key to retrieve.

Returns:

(Promise<string | null>) A promise that resolves with the value from Redis, or null if the key does not exist.

setRedisValue

Sets a raw value directly in Redis using a specific key (without applying the key prefix).

({
  key,
  value,
  ttl,
  nx,
}: {
  key: string;
  value: string;
  ttl?: number;
  nx?: boolean;
}) => Promise<unknown>;

Parameters:

• options: An object containing options for setting the Redis value.
  • key: (string) The exact Redis key to set.
  • value: (string) The string value to store.
  • ttl: (number, optional) The time-to-live for the key in seconds.
  • nx: (boolean, optional) If true, set the key only if it does not already exist.

Returns:

(Promise<unknown>) A promise that resolves with the result of the Redis SET command.

clearRedisValues

Deletes one or more raw keys directly from Redis (without applying the key prefix).

({ keys }: { keys: string | string[] }) => Promise<number>;

Parameters:

• options: An object containing the keys to clear.
  • keys: (string | string[]) A single string key or an array of string keys to delete.

Returns:

(Promise<number>) A promise that resolves with the number of keys that were removed.