130 lines
2.6 KiB
TypeScript
130 lines
2.6 KiB
TypeScript
type CacheOptions = {
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/**
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* The time the cached object will be valid for
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*/
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ttl?: number;
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/**
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* How often to check for expired objects
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*/
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checkInterval?: number;
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/**
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* Enable debug messages
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*/
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debug?: boolean;
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};
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type CachedObject = {
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/**
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* The cached object
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*/
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value: any;
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/**
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* The timestamp the object was cached
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*/
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timestamp: number;
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};
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export class SSRCache {
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/**
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* The time the cached object will be valid for
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* @private
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*/
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private readonly ttl: number | undefined;
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/**
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* How often to check for expired objects
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* @private
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*/
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private readonly checkInterval: number | undefined;
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/**
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* Enable debug messages
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* @private
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*/
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private readonly debug: boolean;
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/**
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* The objects that have been cached
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* @private
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*/
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private cache = new Map<string, CachedObject>();
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constructor({ ttl, checkInterval, debug }: CacheOptions) {
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this.ttl = ttl;
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this.checkInterval = checkInterval || this.ttl ? 1000 * 60 : undefined; // 1 minute
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this.debug = debug || false;
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if (this.ttl !== undefined && this.checkInterval !== undefined) {
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setInterval(() => {
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for (const [key, value] of this.cache.entries()) {
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if (value.timestamp + this.ttl! > Date.now()) {
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continue;
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}
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this.remove(key);
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}
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}, this.checkInterval);
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}
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}
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/**
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* Gets an object from the cache
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*
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* @param key the cache key for the object
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*/
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public get<T>(key: string): T | undefined {
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const cachedObject = this.cache.get(key);
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if (cachedObject === undefined) {
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if (this.debug) {
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console.log(`Cache miss for key: ${key}`);
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}
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return undefined;
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}
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if (this.debug) {
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console.log(`Retrieved ${key} from cache, value: ${JSON.stringify(cachedObject)}`);
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}
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return cachedObject.value as T;
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}
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/**
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* Sets an object in the cache
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*
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* @param key the cache key
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* @param value the object
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*/
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public set<T>(key: string, value: T): void {
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this.cache.set(key, {
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value,
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timestamp: Date.now(),
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});
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if (this.debug) {
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console.log(`Inserted ${key} into cache, value: ${JSON.stringify(value)}`);
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}
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}
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/**
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* Checks if an object is in the cache
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*
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* @param key the cache key
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*/
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public has(key: string): boolean {
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return this.cache.has(key);
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}
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/**
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* Removes an object from the cache
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*
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* @param key the cache key
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*/
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public remove(key: string): void {
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this.cache.delete(key);
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if (this.debug) {
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console.log(`Removed ${key} from cache`);
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}
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}
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}
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