@thermopylae/lib.cache

High performant and modular cache.

Install

npm install @thermopylae/lib.cache

Usage

Bellow is a simple use case of how this package can be used. It reveals the basic principles of cache usage, such as backend, policies and arguments bundle. For more details, please consult API documentation, as it contains detailed explanation of each cache building block.

import { ObjMap } from '@thermopylae/core.declarations';
import {
    CacheEvent,
    CacheReplacementPolicy,
    EntryPoolCacheBackend,
    HeapGarbageCollector,
    KeysDependenciesEvictionPolicy,
    KeysDependenciesEvictionPolicyArgumentsBundle,
    LRUEvictionPolicy,
    PolicyPerKeyCache,
    PolicyPerKeyCacheArgumentsBundle,
    SlidingExpirationPolicyArgsBundle,
    SlidingProactiveExpirationPolicy
} from '@thermopylae/lib.cache';

/* Define Policy Tags */
const enum PolicyTag {
    SLIDING_EXPIRATION,
    KEYS_DEPENDENCIES,
    LRU
}

/* Define Arguments Bundle */
interface ArgumentsBundle
    extends PolicyPerKeyCacheArgumentsBundle<PolicyTag>,
        SlidingExpirationPolicyArgsBundle,
        KeysDependenciesEvictionPolicyArgumentsBundle<string> {}

/* Build Cache */
const CAPACITY = 1_000;

const backend = new EntryPoolCacheBackend<string, ObjMap>(CAPACITY);

const policies = new Map<PolicyTag, CacheReplacementPolicy<string, ObjMap, ArgumentsBundle>>([
    [PolicyTag.SLIDING_EXPIRATION, new SlidingProactiveExpirationPolicy<string, ObjMap, ArgumentsBundle>(new HeapGarbageCollector())],
    [PolicyTag.KEYS_DEPENDENCIES, new KeysDependenciesEvictionPolicy<string, ObjMap, ArgumentsBundle>(backend)],
    [PolicyTag.LRU, new LRUEvictionPolicy<string, ObjMap, ArgumentsBundle>(CAPACITY, backend)]
]);

const cache = new PolicyPerKeyCache<string, ObjMap, PolicyTag, ArgumentsBundle>(backend, policies);

/* Attach listeners */
cache.on(CacheEvent.DELETE, (key, value) => {
    console.log(`Key '${key}' having value '${JSON.stringify(value)}' has been deleted/evicted from cache.`);
});

/* Insert keys */
cache.set(
    'user:session:1',
    { token: 'iuj0-9unj8wetyu' },
    {
        timeSpan: 10_000,
        policies: [PolicyTag.SLIDING_EXPIRATION]
    }
);

cache.set(
    'user:profile:0igk9g9',
    { name: 'John' },
    {
        dependents: ['user:session:1'],
        throwOnDependencyNotFound: true,
        policies: [PolicyTag.KEYS_DEPENDENCIES]
    }
);

cache.set(
    'book:1',
    { title: 'JavaScript Data Structures and Algorithms' },
    {
        policies: [PolicyTag.LRU]
    }
);

/* Retrieve key */
console.log(cache.get('user:session:1')); // { token: 'iuj0-9unj8wetyu' }
console.log(cache.has('user:profile:0igk9g9')); // true

/* Explicit delete */
cache.del('book:1'); // Key 'book:1' having value '{ title: 'JavaScript Data Structures and Algorithms' }' has been deleted/evicted from cache.

/* After 10 seconds will evict user session and cascade evict user profile */
// Key 'user:session:1' having value '{ token: 'iuj0-9unj8wetyu' }' has been deleted/evicted from cache.
// Key 'user:profile:0igk9g9' having value '{ name: 'John' }' has been deleted/evicted from cache.

API Reference

API documentation is available here.

It can also be generated by issuing the following commands:

git clone [e-mail]:marinrusu1997/thermopylae.git
cd thermopylae
yarn install
yarn workspace @thermopylae/lib.cache run doc

Author

👤 Rusu Marin

• GitHub: @marinrusu1997
• Email: [e-mail]
• LinkedIn: @marinrusu1997

📝 License

Copyright © 2021 Rusu Marin.
This project is MIT licensed.