feat: implement distributed caching

server/utils/cache.ts

@@ -0,0 +1,79 @@
+import Redis from 'ioredis';
+import type { H3Event } from 'h3';
+
+let cacher: Cacher | null = null;
+
+export type Cacher = {
+	set<T>(key: string, val: T, cacheAgeMs?: number): Promise<void>;
+	get<T>(key: string): Promise<T | null>;
+};
+
+function createCacher(event: H3Event): Cacher {
+	const config = useRuntimeConfig(event);
+	if (config.redisUrl) {
+		const redis = new Redis(config.redisUrl);
+		const prefix = `pn:website:cache`;
+		return {
+			async get(key) {
+				try {
+					const result = await redis.get(`${prefix}:${key}`);
+					if (result) {
+						return JSON.parse(result);
+					}
+				} catch {
+					// Catch connection & serialisation errors
+				}
+				return null;
+			},
+			async set(key, val, cacheAgeMs) {
+				try {
+					const fullKey = `${prefix}:${key}`;
+					await redis.set(fullKey, JSON.stringify(val));
+					if (cacheAgeMs) {
+						await redis.expire(fullKey, Math.round(cacheAgeMs / 1000));
+					}
+				} catch {
+					// Catch connection & serialisation errors
+				}
+			}
+		};
+	}
+
+	// Memory cacher
+	const store = new Map<string, { expiresAt: Date | null; value: string }>();
+	return {
+		async get(key) {
+			try {
+				const result = store.get(key);
+				if (result) {
+					if (result.expiresAt && result.expiresAt < new Date()) {
+						store.delete(key);
+						return null; // Expired
+					}
+					return JSON.parse(result.value);
+				}
+			} catch {
+				// catch Serialisation errors
+			}
+			return null;
+		},
+		async set(key, val, cacheAgeMs) {
+			try {
+				store.set(key, {
+					expiresAt: cacheAgeMs ? new Date(Date.now() + cacheAgeMs) : null,
+					value: JSON.stringify(val)
+				});
+			} catch {
+				// Catch serialisation errors
+			}
+		}
+	};
+}
+
+export function useCacher(event: H3Event): Cacher | null {
+	if (!cacher) {
+		cacher = createCacher(event);
+	}
+
+	return cacher;
+}