Theo's Typesafe Cult•11mo ago

How does vercel run my code? Is my cache code working as intended?

You can use something for a long time yet not know what you're working with. I just came to a realization that something I am doing may not be correct:

type Object = {
    //some data
};

const CACHE_DURATION = 60 * 60 * 1000;
let cache: { timestamp: number; data: Object[] } | null = null;

export async function getObjects() {
  const currentTime = Date.now();

  if (cache && currentTime - cache.timestamp < CACHE_DURATION)
    return cache.data;

  const objects = await new Promise<Object[]>((resolve, reject) => {
    https.get("https://example.com/", (res: IncomingMessage) => {
      let data = "";

      res.on("data", (chunk: string) => {
        data += chunk;
      });

      res.on("end", () => {
        const root = parse(data);
        const servers = root.querySelectorAll("tr.server-list__row");

        const objects: Object[] = [];

        servers.forEach((server) => {
          const data = server.querySelector("foo");
          objects.push({
              //data
          });
        });

        objects.sort();

        resolve(objects);
      });

      res.on("error", (error: Error) => {
        reject(
          new TRPCError({
            code: "INTERNAL_SERVER_ERROR",
            message: error.message,
          })
        );
      });
    });
  });

  cache = { timestamp: currentTime, data: worlds };
  return objects;
}

export const someRouter = createTRPCRouter({
  list: protectedProcedure.query(async () => {
      return await getObjects();
  }),
});

type Object = {
    //some data
};

const CACHE_DURATION = 60 * 60 * 1000;
let cache: { timestamp: number; data: Object[] } | null = null;

export async function getObjects() {
  const currentTime = Date.now();

  if (cache && currentTime - cache.timestamp < CACHE_DURATION)
    return cache.data;

  const objects = await new Promise<Object[]>((resolve, reject) => {
    https.get("https://example.com/", (res: IncomingMessage) => {
      let data = "";

      res.on("data", (chunk: string) => {
        data += chunk;
      });

      res.on("end", () => {
        const root = parse(data);
        const servers = root.querySelectorAll("tr.server-list__row");

        const objects: Object[] = [];

        servers.forEach((server) => {
          const data = server.querySelector("foo");
          objects.push({
              //data
          });
        });

        objects.sort();

        resolve(objects);
      });

      res.on("error", (error: Error) => {
        reject(
          new TRPCError({
            code: "INTERNAL_SERVER_ERROR",
            message: error.message,
          })
        );
      });
    });
  });

  cache = { timestamp: currentTime, data: worlds };
  return objects;
}

export const someRouter = createTRPCRouter({
  list: protectedProcedure.query(async () => {
      return await getObjects();
  }),
});

This is one of my routers. It fetches data from an external source. The goal is to cache this data so I don't have to fetch it each time my clients send a request. But I am starting to understand that serverless stuff doesn't work that way... I am using T3 and hosting on vercel. Does this code make any sense? Or should I use something like redis for this?

Solution:

I was caching the fetch data in the api route so that clients can request that data from a third party from my api. This should not be done. I used getStaticProps with revalidate to put the data into the page which means no additional request is needed. ```typescript export async function getStaticProps() { const objects = await getObjects(); ...

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1 Reply

Solution

NubeBuster•11mo ago

export async function getStaticProps() {
  const objects = await getObjects();

  return {
    props: {
      objects,
    },
    revalidate: 600,
  };
}

export async function getStaticProps() {
  const objects = await getObjects();

  return {
    props: {
      objects,
    },
    revalidate: 600,
  };
}

This solves the issue and even improves the general logic.

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How does vercel run my code? Is my cache code working as intended?