feat: use a new ws implementation thats encapsulated

server/ws/cache.ts

@@ -0,0 +1,126 @@
+import { createHash } from 'node:crypto';
+import { readFile, writeFile } from 'node:fs/promises';
+import { type } from 'arktype';
+import log from '~server/utils/log';
+import mutex from '~server/utils/mutex';
+
+const diskSchema = type({
+	key: 'string',
+	value: 'unknown',
+	expires: 'number?',
+}).array();
+
+// A persistent HashMap with a TTL for each key
+export class TimedCache<V> {
+	private _cache = new Map<string, V>();
+	private _timings = new Map<string, number>();
+
+	// Default TTL is 1 minute
+	private defaultTTL: number;
+	private filePath: string;
+	private writeLock = mutex();
+
+	// Last flush ID is essentially a hash of the flush contents
+	// Prevents unnecessary flushing if nothing has changed
+	private lastFlushId = '';
+
+	constructor(defaultTTL: number, filePath: string) {
+		this.defaultTTL = defaultTTL;
+		this.filePath = filePath;
+
+		// Load the cache from disk and then queue flushes every 10 seconds
+		this.load().then(() => {
+			setInterval(() => this.flush(), 10000);
+		});
+	}
+
+	set(key: string, value: V, ttl: number = this.defaultTTL) {
+		this._cache.set(key, value);
+		this._timings.set(key, Date.now() + ttl);
+	}
+
+	get(key: string) {
+		const value = this._cache.get(key);
+		if (!value) {
+			return;
+		}
+
+		const expires = this._timings.get(key);
+		if (!expires || expires < Date.now()) {
+			this._cache.delete(key);
+			this._timings.delete(key);
+			return;
+		}
+
+		return value;
+	}
+
+	// Map into a Record without any TTLs
+	toJSON() {
+		const result: Record<string, V> = {};
+		for (const [key, value] of this._cache.entries()) {
+			result[key] = value;
+		}
+
+		return result;
+	}
+
+	// WARNING: This function expects that this.filePath is NOT ENOENT
+	private async load() {
+		const data = await readFile(this.filePath, 'utf-8');
+		const cache = () => {
+			try {
+				return JSON.parse(data);
+			} catch (e) {
+				return undefined;
+			}
+		};
+
+		const diskData = cache();
+		if (diskData === undefined) {
+			log.error('CACH', 'Failed to load cache at %s', this.filePath);
+			return;
+		}
+
+		const cacheData = diskSchema(diskData);
+		if (cacheData instanceof type.errors) {
+			log.error('CACH', 'Failed to load cache at %s', this.filePath);
+			log.debug('CACHE', 'Error details: %s', cacheData.toString());
+
+			// Skip loading the cache (it should be overwritten soon)
+			return;
+		}
+
+		for (const { key, value, expires } of diskData) {
+			this._cache.set(key, value);
+			this._timings.set(key, expires);
+		}
+
+		log.info('CACH', 'Loaded cache from %s', this.filePath);
+	}
+
+	private async flush() {
+		this.writeLock.acquire();
+		const data = Array.from(this._cache.entries()).map(([key, value]) => {
+			return { key, value, expires: this._timings.get(key) };
+		});
+
+		if (data.length === 0) {
+			this.writeLock.release();
+			return;
+		}
+
+		// Calculate the hash of the data
+		const dumpData = JSON.stringify(data);
+		const sha = createHash('sha256').update(dumpData).digest('hex');
+		if (sha === this.lastFlushId) {
+			this.writeLock.release();
+			return;
+		}
+
+		await writeFile(this.filePath, dumpData, 'utf-8');
+		this.lastFlushId = sha;
+		this.writeLock.release();
+		log.debug('CACH', 'Flushed cache to %s', this.filePath);
+	}
+}