Function cachedPosthogQuery

apps/web/src/lib/posthog-query.ts:65–106

(schema: z.ZodType<Output[]>)

const MEMORY_CACHE_TTL_MS = 60 * 60 * 1000; // 1 hour

export function cachedPosthogQuery<Output>(schema: z.ZodType<Output[]>) {
  const parse = (name: string, raw: unknown): Output[] => {
    const result = schema.safeParse(raw);
    if (!result.success) {
      throw new Error(`${name} parse failed: ${z.prettifyError(result.error)}`);
    }
    return result.data;
  };

  const memoryCache = new Map<string, { value: Output[]; at: number }>();

  return async (name: string, query: string): Promise<Output[]> => {
    const memoryCached = memoryCache.get(name);
    if (memoryCached && Date.now() - memoryCached.at < MEMORY_CACHE_TTL_MS) {
      return memoryCached.value;
    }

    const key = posthogQueryRedisKey(name);

    const cached = await redisClient.get<string>(key);
    if (cached !== null) {
      const data = parse(name, JSON.parse(cached));
      memoryCache.set(name, { value: data, at: Date.now() });
      return data;
    }

    const startTime = performance.now();
    const response = await posthogQuery(name, query);
    if (response.status !== 'ok') {
      throw new Error(`${name} query failed: ${JSON.stringify(response.error, undefined, 2)}`);
    }
    const data = parse(name, response.body.results);
    console.debug(
      `[cachedPosthogQuery] ${name} returned ${data.length} rows in ${performance.now() - startTime}ms`
    );

    await redisClient.set(key, JSON.stringify(response.body.results), { ex: CACHE_TTL_SECONDS });
    memoryCache.set(name, { value: data, at: Date.now() });

    return data;
  };
}