rainbow-lru-cache
v0.0.4
Published
## How to use LRUCache
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Cache library
How to use LRUCache
import { LRUCache } from './index'
(async () => {
const cache = new LRUCache<string>(); // by default use new Map() as storage and 100 of capacity
await cache.set('1', 'Hello1'); // the item 1 is added and is set as top
await cache.set('2', 'Hello2'); // the item 2 is added and is set as top
await cache.set('3', 'Hello3'); // the item 3 is added and is set as top
await cache.set('4', 'Hello4'); // the item 4 is added and is set as top
await cache.set('5', 'Hello5'); // the item 5 is added and is set as top
await cache.set('6', 'Hello6'); // the item 6 is added and is set as top
await cache.get('2'); // the item 2 is used and then is set as top
})()
How to use LRUCache specifying a storage memory and capacity
import { LRUCache, IStorage, memoize } from './index'
class InMemoryStorage implements IStorage {
private __data: Record<string, string | undefined>;
constructor(){
this.__data = {};
}
delete(key: string): boolean {
return delete this.__data[key];
}
get(key: string): string | undefined {
return this.__data[key];
}
set(key: string, value: string): void {
this.__data[key]=value;
}
}
(async () => {
const cacheStorage = new InMemoryStorage();
const cache = new LRUCache<string>(cacheStorage, 5);
await cache.set('1', 'Hello1'); // the item 1 is added and is set as top
await cache.set('2', 'Hello2'); // the item 2 is added and is set as top
await cache.set('3', 'Hello3'); // the item 3 is added and is set as top
await cache.set('4', 'Hello4'); // the item 4 is added and is set as top
await cache.set('5', 'Hello5'); // the item 5 is added and is set as top
await cache.set('6', 'Hello6'); // the item 6 is added and is set as top, the item 1 is deleted
await cache.get('2'); // the item 2 is used and then is set as top
await cache.set('7', 'Hello7'); // the item 7 is added and is set as top the item 3 is deleted
// await cache.print();
const array = [];
for await (const [key, value] of cache){
array.push(key);
}
console.log(
array.reduce(
((acc: string, current: string) => {
return `${acc} > ${current}`
}) as any
)
)
})()
How to use memoize with cache
import {LRUCache, IStorage, memoize } from './index'
class InMemoryStorage implements IStorage {
private __data: Record<string, string | undefined>;
constructor(){
this.__data = {};
}
delete(key: string): boolean {
return delete this.__data[key];
}
get(key: string): string | undefined {
return this.__data[key];
}
set(key: string, value: string): void {
this.__data[key]=value;
}
}
const sleep = (time: number)=>new Promise(resolve => setTimeout(resolve, time))
const expensiveCalculation = async (arg1: number, arg2: number) => {
await sleep(2000);
return arg1 + arg2;
}
(async () => {
const cacheStorage = new InMemoryStorage();
const cache = new LRUCache<string>(cacheStorage, 3);
const expensiveCalculationMemoized = memoize({
func: expensiveCalculation,
cache,
});
console.log(await expensiveCalculationMemoized(1, 2)); // calling expensiveCalculation and caching the result
console.log(await expensiveCalculationMemoized(1, 2)); // using cached result
console.log(await expensiveCalculationMemoized(1, 3)); // calling expensiveCalculation and caching the result
console.log(await expensiveCalculationMemoized(1, 3)); // using cached result
console.log(await expensiveCalculationMemoized(1, 4)); // calling expensiveCalculation and caching the result
console.log(await expensiveCalculationMemoized(1, 4)); // using cached result
console.log(await expensiveCalculationMemoized(1, 5)); // calling expensiveCalculation and caching the result, key [1, 2] is removed from cache
console.log(await expensiveCalculationMemoized(1, 5)); // using cached result
console.log(await expensiveCalculationMemoized(1, 2)); // calling expensiveCalculation and caching the result again
console.log(await expensiveCalculationMemoized(1, 2)); // using cached result
})()
How to use logger with memoize
const expensiveCalculationMemoized = memoize({
func: expensiveCalculation,
cache,
logger: {
cacheUsed: () => console.log('CACHE USED'),
funcCalled: () => console.log('FUNCTION CALLED'),
error: err => console.error(err)
}
});