@cacheable/utils

Table of Contents

Cacheble Utils

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@cacheable/utils is a collecton of utility functions, helpers, and types for cacheable and other caching libraries. It provides a robust set of features to enhance caching capabilities, including:

  • Data Types for Caching Items
  • Hash Functions for Key Generation
  • Coalesce Async for Handling Multiple Promises
  • Stats Helpers for Caching Statistics
  • Sleep / Delay for Testing and Timing
  • Memoization for wraping or get / set options
  • Time to Live (TTL) Helpers

Table of Contents

Getting Started

npm install @cacheable/utils --save

Cacheable Types

The @cacheable/utils package provides various types that are used throughout the caching library. These types help in defining the structure of cached items, ensuring type safety and consistency across your caching operations.


    /**
     * CacheableItem
     * @typedef {Object} CacheableItem
     * @property {string} key - The key of the cacheable item
     * @property {any} value - The value of the cacheable item
     * @property {number|string} [ttl] - Time to Live - If you set a number it is miliseconds, if you set a string it is a human-readable
     * format such as `1s` for 1 second or `1h` for 1 hour. Setting undefined means that it will use the default time-to-live. If both are
     * undefined then it will not have a time-to-live.
     */
    export type CacheableItem = {
    	key: string;
    	value: any;
    	ttl?: number | string;
    };
    
    /**
     * CacheableStoreItem
     * @typedef {Object} CacheableStoreItem
     * @property {string} key - The key of the cacheable store item
     * @property {any} value - The value of the cacheable store item
     * @property {number} [expires] - The expiration time in milliseconds since epoch. If not set, the item does not expire.
     */
    export type CacheableStoreItem = {
    	key: string;
    	value: any;
    	expires?: number;
    };

Coalesce Async

The coalesceAsync function is a utility that allows you to handle multiple asynchronous operations efficiently. It was designed by Douglas Cayers https://github.com/douglascayers/promise-coalesce. It helps in coalescing multiple promises into a single promise, ensuring that only one operation is executed at a time for the same key.

import { coalesceAsync } from '@cacheable/utils';
    
    const fetchData = async (key: string) => {
      // Simulate an asynchronous operation
      return new Promise((resolve) => setTimeout(() => resolve(`Data for ${key}`), 1000));
    };
    
    const result = await Promise.all([
    	coalesceAsync('my-key', fetchData),
    	coalesceAsync('my-key', fetchData),
    	coalesceAsync('my-key', fetchData),
    ]);
    console.log(result); // Data for my-key only executed once

Hash Functions

The @cacheable/utils package provides hash functions that can be used to generate unique keys for caching operations. These functions are useful for creating consistent and unique identifiers for cached items.

import { hash } from '@cacheable/utils';
    
    const key = hash('my-cache-key');
    console.log(key); // Unique hash for 'my-cache-key'

If you want to get a number hash you can use the hashToNumber function:

import { hash, hashToNumber } from '@cacheable/utils';
    
    const min = 0;
    const max = 10;
    
    const result = hashToNumber({foo: 'bar'}, min, max, HashAlgorithm.DJB2);
    console.log(result); // A number between 0 and 10 based on the hash value

Shorthand Time Helpers

The @cacheable/utils package provides a shorthand function to convert human-readable time strings into milliseconds. This is useful for setting time-to-live (TTL) values in caching operations.

You can also use the shorthandToMilliseconds function:

import { shorthandToMilliseconds } from '@cacheable/utils';
    
    const milliseconds = shorthandToMilliseconds('1h');
    console.log(milliseconds); // 3600000

You can also use the shorthandToTime function to get the current date plus the shorthand time:

import { shorthandToTime } from '@cacheable/utils';
    
    const currentDate = new Date();
    const timeInMs = shorthandToTime('1h', currentDate);
    console.log(timeInMs); // Current date + 1 hour in milliseconds since epoch

Sleep Helper

The sleep function is a utility that allows you to pause execution for a specified duration. This can be useful in testing scenarios or when you need to introduce delays in your code.

import { sleep } from '@cacheable/utils';
    
    await sleep(1000); // Pause for 1 second
    console.log('Execution resumed after 1 second');

Stats Helpers

The @cacheable/utils package provides statistics helpers that can be used to track and analyze caching operations. These helpers can be used to gather metrics such as hit rates, miss rates, and other performance-related statistics.

import { stats } from '@cacheable/utils';
    
    const cacheStats = stats();
    cacheStats.incrementHits();
    console.log(cacheStats.hits); // Get the hit rate of the cache

Time to Live (TTL) Helpers

The @cacheable/utils package provides helpers for managing time-to-live (TTL) values for cached items.

You can use the calculateTtlFromExpiration function to calculate the TTL based on an expiration date:

import { calculateTtlFromExpiration } from '@cacheable/utils';
    
    const expirationDate = new Date(Date.now() + 1000 * 60 * 5); // 5 minutes from now
    const ttl = calculateTtlFromExpiration(Date.now(), expirationDate);
    console.log(ttl); // 300000

You can also use getTtlFromExpires to get the TTL from an expiration date:

import { getTtlFromExpires } from '@cacheable/utils';
    
    const expirationDate = new Date(Date.now() + 1000 * 60 * 5); // 5 minutes from now
    const ttl = getTtlFromExpires(expirationDate);
    console.log(ttl); // 300000

You can use getCascadingTtl to get the TTL for cascading cache operations:

import { getCascadingTtl } from '@cacheable/utils';
    const cacheableTtl = 1000 * 60 * 5; // 5 minutes
    const primaryTtl = 1000 * 60 * 2; // 2 minutes
    const secondaryTtl = 1000 * 60; // 1 minute
    const ttl = getCascadingTtl(cacheableTtl, primaryTtl, secondaryTtl);

Run if Function Helper

The runIfFn utility function provides a convenient way to conditionally execute functions or return values based on whether the input is a function or not. This pattern is commonly used in UI libraries and configuration systems where values can be either static or computed.

import { runIfFn } from '@cacheable/utils';
    
    // Static value - returns the value as-is
    const staticValue = runIfFn('hello world');
    console.log(staticValue); // 'hello world'
    
    // Function with no arguments - executes the function
    const dynamicValue = runIfFn(() => new Date().toISOString());
    console.log(dynamicValue); // Current timestamp
    
    // Function with arguments - executes with provided arguments
    const sum = runIfFn((a: number, b: number) => a + b, 5, 10);
    console.log(sum); // 15
    
    // Complex example with conditional logic
    const getConfig = (isDevelopment: boolean) => ({
      apiUrl: isDevelopment ? 'http://localhost:3000' : 'https://api.example.com',
      timeout: isDevelopment ? 5000 : 30000
    });
    
    const config = runIfFn(getConfig, true);
    console.log(config); // { apiUrl: 'http://localhost:3000', timeout: 5000 }

Less Than Helper

The lessThan utility function provides a safe way to compare two values and determine if the first value is less than the second. It only performs the comparison if both values are valid numbers, returning false for any non-number inputs.

import { lessThan } from '@cacheable/utils';
    
    // Basic number comparisons
    console.log(lessThan(1, 2)); // true
    console.log(lessThan(2, 1)); // false
    console.log(lessThan(1, 1)); // false
    
    // Works with negative numbers
    console.log(lessThan(-1, 0)); // true
    console.log(lessThan(-2, -1)); // true
    
    // Works with decimal numbers
    console.log(lessThan(1.5, 2.5)); // true
    console.log(lessThan(2.7, 2.7)); // false
    
    // Safe handling of non-number values
    console.log(lessThan("1", 2)); // false
    console.log(lessThan(1, "2")); // false
    console.log(lessThan(null, 1)); // false
    console.log(lessThan(undefined, 1)); // false
    console.log(lessThan(NaN, 1)); // false
    
    // Useful in filtering and sorting operations
    const numbers = [5, 2, 8, 1, 9];
    const lessThanFive = numbers.filter(n => lessThan(n, 5));
    console.log(lessThanFive); // [2, 1]
    
    // Safe comparison in conditional logic
    function processValue(a?: number, b?: number) {
      if (lessThan(a, b)) {
        return `${a} is less than ${b}`;
      }
      return 'Invalid comparison or a >= b';
    }

This utility is particularly useful when dealing with potentially undefined or invalid numeric values, ensuring type safety in comparison operations.

Is Object Helper

The isObject utility function provides a type-safe way to determine if a value is a plain object. It returns true for objects but false for arrays, null, functions, and primitive types. This function also serves as a TypeScript type guard.

import { isObject } from '@cacheable/utils';
    
    // Basic object detection
    console.log(isObject({})); // true
    console.log(isObject({ name: 'John', age: 30 })); // true
    console.log(isObject(Object.create(null))); // true
    
    // Arrays are not considered objects
    console.log(isObject([])); // false
    console.log(isObject([1, 2, 3])); // false
    
    // null is not considered an object (despite typeof null === 'object')
    console.log(isObject(null)); // false
    
    // Primitive types return false
    console.log(isObject('string')); // false
    console.log(isObject(123)); // false
    console.log(isObject(true)); // false
    console.log(isObject(undefined)); // false
    
    // Functions return false
    console.log(isObject(() => {})); // false
    console.log(isObject(Date)); // false
    
    // Built-in object types return true
    console.log(isObject(new Date())); // true
    console.log(isObject(/regex/)); // true
    console.log(isObject(new Error('test'))); // true
    console.log(isObject(new Map())); // true
    
    // TypeScript type guard usage
    function processValue(value: unknown) {
      if (isObject<{ name: string; age: number }>(value)) {
        // TypeScript now knows value is an object with name and age properties
        console.log(`Name: ${value.name}, Age: ${value.age}`);
      }
    }
    
    // Useful for configuration validation
    function validateConfig(config: unknown) {
      if (!isObject(config)) {
        throw new Error('Configuration must be an object');
      }
      
      // Safe to access object properties
      return config;
    }
    
    // Filtering arrays for objects only
    const mixedArray = [1, 'string', {}, [], null, { valid: true }];
    const objectsOnly = mixedArray.filter(isObject);
    console.log(objectsOnly); // [{}', { valid: true }]

This utility is particularly useful for:

  • Type validation - Ensuring values are objects before accessing properties
  • TypeScript type guarding - Narrowing types in conditional blocks
  • Configuration parsing - Validating that configuration values are objects
  • Data filtering - Separating objects from other data types

Wrap / Memoization for Sync and Async Functions

The @cacheable/utils package provides two main functions: wrap and wrapSync. These functions are used to memoize asynchronous and synchronous functions, respectively.

import { Cacheable } from 'cacheable';
    const asyncFunction = async (value: number) => {
      return Math.random() * value;
    };
    
    const cache = new Cacheable();
    const options = {
      ttl: '1h', // 1 hour
      keyPrefix: 'p1', // key prefix. This is used if you have multiple functions and need to set a unique prefix.
      cache,
    }
    const wrappedFunction = wrap(asyncFunction, options);
    console.log(await wrappedFunction(2)); // 4
    console.log(await wrappedFunction(2)); // 4 from cache

With wrap we have also included stampede protection so that a Promise based call will only be called once if multiple requests of the same are executed at the same time. Here is an example of how to test for stampede protection:

import { Cacheable } from 'cacheable';
    const asyncFunction = async (value: number) => {
      return value;
    };
    
    const cache = new Cacheable();
    const options = {
      ttl: '1h', // 1 hour
      keyPrefix: 'p1', // key prefix. This is used if you have multiple functions and need to set a unique prefix.
      cache,
    }
    
    const wrappedFunction = wrap(asyncFunction, options);
    const promises = [];
    for (let i = 0; i < 10; i++) {
      promises.push(wrappedFunction(i));
    }
    
    const results = await Promise.all(promises); // all results should be the same
    
    console.log(results); // [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

In this example we are wrapping an async function in a cache with a ttl of 1 hour. This will cache the result of the function for 1 hour and then expire the value. You can also wrap a sync function in a cache:

import { CacheableMemory } from 'cacheable';
    const syncFunction = (value: number) => {
      return value * 2;
    };
    
    const cache = new CacheableMemory();
    const wrappedFunction = wrap(syncFunction, { ttl: '1h', key: 'syncFunction', cache });
    console.log(wrappedFunction(2)); // 4
    console.log(wrappedFunction(2)); // 4 from cache

In this example we are wrapping a sync function in a cache with a ttl of 1 hour. This will cache the result of the function for 1 hour and then expire the value. You can also set the key property in the wrap() options to set a custom key for the cache.

When an error occurs in the function it will not cache the value and will return the error. This is useful if you want to cache the results of a function but not cache the error. If you want it to cache the error you can set the cacheError property to true in the wrap() options. This is disabled by default.

import { CacheableMemory } from 'cacheable';
    const syncFunction = (value: number) => {
      throw new Error('error');
    };
    
    const cache = new CacheableMemory();
    const wrappedFunction = wrap(syncFunction, { ttl: '1h', key: 'syncFunction', cacheError: true, cache });
    console.log(wrappedFunction()); // error
    console.log(wrappedFunction()); // error from cache

If you would like to generate your own key for the wrapped function you can set the createKey property in the wrap() options. This is useful if you want to generate a key based on the arguments of the function or any other criteria.

  const cache = new Cacheable();
      const options: WrapOptions = {
        cache,
        keyPrefix: 'test',
        createKey: (function_, arguments_, options: WrapOptions) => `customKey:${options?.keyPrefix}:${arguments_[0]}`,
      };
    
      const wrapped = wrap((argument: string) => `Result for ${argument}`, options);
    
      const result1 = await wrapped('arg1');
      const result2 = await wrapped('arg1'); // Should hit the cache
    
      console.log(result1); // Result for arg1
      console.log(result2); // Result for arg1 (from cache)

We will pass in the function that is being wrapped, the arguments passed to the function, and the options used to wrap the function. You can then use these to generate a custom key for the cache.

Get Or Set Memoization Function

The getOrSet method provides a convenient way to implement the cache-aside pattern. It attempts to retrieve a value from cache, and if not found, calls the provided function to compute the value and store it in cache before returning it. Here are the options:

export type GetOrSetFunctionOptions = {
    	ttl?: number | string;
    	cacheErrors?: boolean;
    	throwErrors?: boolean;
    };

Here is an example of how to use the getOrSet method:

import { Cacheable } from 'cacheable';
    const cache = new Cacheable();
    // Use getOrSet to fetch user data
    const function_ = async () => Math.random() * 100;
    const value = await getOrSet('randomValue', function_, { ttl: '1h', cache });
    console.log(value); // e.g. 42.123456789

You can also use a function to compute the key for the function:

import { Cacheable, GetOrSetOptions } from 'cacheable';
    const cache = new Cacheable();
    
    // Function to generate a key based on options
    const generateKey = (options?: GetOrSetOptions) => {
      return `custom_key_:${options?.cacheId || 'default'}`;
    };
    
    const function_ = async () => Math.random() * 100;
    const value = await getOrSet(generateKey(), function_, { ttl: '1h', cache });

How to Contribute

You can contribute by forking the repo and submitting a pull request. Please make sure to add tests and update the documentation. To learn more about how to contribute go to our main README https://github.com/jaredwray/cacheable. This will talk about how to Open a Pull Request, Ask a Question, or Post an Issue.

License and Copyright

MIT © Jared Wray