refactor: refactored retryer logic & handled invalid tokens

Author: anuraghazra

api/index.js

@@ -18,7 +18,7 @@ module.exports = async (req, res) => {
   } = req.query;
   let stats;
 
-  res.setHeader("Cache-Control", "public, max-age=300");
+  res.setHeader("Cache-Control", "public, max-age=1800");
   res.setHeader("Content-Type", "image/svg+xml");
 
   try {

api/pin.js

@@ -15,7 +15,7 @@ module.exports = async (req, res) => {
 
   let repoData;
 
-  res.setHeader("Cache-Control", "public, max-age=300");
+  res.setHeader("Cache-Control", "public, max-age=1800");
   res.setHeader("Content-Type", "image/svg+xml");
 
   try {

src/fetchRepo.js

@@ -1,11 +1,8 @@
 const { request } = require("./utils");
+const retryer = require("./retryer");
 
-async function fetchRepo(username, reponame) {
-  if (!username || !reponame) {
-    throw new Error("Invalid username or reponame");
-  }
-
-  const res = await request(
+const fetcher = (variables, token) => {
+  return request(
     {
       query: `
       fragment RepoInfo on Repository {
@@ -34,15 +31,20 @@ async function fetchRepo(username, reponame) {
         }
       }
     `,
-      variables: {
-        login: username,
-        repo: reponame,
-      },
+      variables,
     },
     {
-      Authorization: `bearer ${process.env.PAT_1}`,
+      Authorization: `bearer ${token}`,
     }
   );
+};
+
+async function fetchRepo(username, reponame) {
+  if (!username || !reponame) {
+    throw new Error("Invalid username or reponame");
+  }
+
+  let res = await retryer(fetcher, { login: username, repo: reponame });
 
   const data = res.data.data;
 

src/fetchStats.js

@@ -1,9 +1,9 @@
 const { request } = require("./utils");
+const retryer = require("./retryer");
 const calculateRank = require("./calculateRank");
 require("dotenv").config();
 
-// creating a fetcher function to reduce duplication
-const fetcher = (username, token) => {
+const fetcher = (variables, token) => {
   return request(
     {
       query: `
@@ -37,43 +37,15 @@ const fetcher = (username, token) => {
         }
       }
       `,
-      variables: { login: username },
+      variables,
     },
     {
-      // set the token
       Authorization: `bearer ${token}`,
     }
   );
 };
 
-async function retryer(username, RETRIES) {
-  try {
-    console.log(`Trying PAT_${RETRIES + 1}`);
-
-    // try to fetch with the first token since RETRIES is 0 index i'm adding +1
-    let response = await fetcher(username, process.env[`PAT_${RETRIES + 1}`]);
-
-    // if rate limit is hit increase the RETRIES and recursively call the retryer
-    // with username, and current RETRIES
-    if (
-      response.data.errors &&
-      response.data.errors[0].type === "RATE_LIMITED"
-    ) {
-      console.log(`PAT_${RETRIES} Failed`);
-      RETRIES++;
-      // directly return from the function
-      return await retryer(username, RETRIES);
-    }
-
-    // finally return the response
-    return response;
-  } catch (err) {
-    console.log(err);
-  }
-}
-
 async function fetchStats(username) {
-  let RETRIES = 0;
   if (!username) throw Error("Invalid username");
 
   const stats = {
@@ -86,7 +58,7 @@ async function fetchStats(username) {
     rank: { level: "C", score: 0 },
   };
 
-  let res = await retryer(username, RETRIES);
+  let res = await retryer(fetcher, { login: username });
 
   if (res.data.errors) {
     console.log(res.data.errors);

src/retryer.js

@@ -0,0 +1,43 @@
+const retryer = async (fetcher, variables, retries = 0) => {
+  if (retries > 7) {
+    throw new Error("Maximum retries exceeded");
+  }
+  try {
+    console.log(`Trying PAT_${retries + 1}`);
+
+    // try to fetch with the first token since RETRIES is 0 index i'm adding +1
+    let response = await fetcher(
+      variables,
+      process.env[`PAT_${retries + 1}`],
+      retries
+    );
+
+    // prettier-ignore
+    const isRateExceeded = response.data.errors && response.data.errors[0].type === "RATE_LIMITED";
+
+    // if rate limit is hit increase the RETRIES and recursively call the retryer
+    // with username, and current RETRIES
+    if (isRateExceeded) {
+      console.log(`PAT_${retries + 1} Failed`);
+      retries++;
+      // directly return from the function
+      return retryer(fetcher, variables, retries);
+    }
+
+    // finally return the response
+    return response;
+  } catch (err) {
+    // prettier-ignore
+    // also checking for bad credentials if any tokens gets invalidated
+    const isBadCredential = err.response.data && err.response.data.message === "Bad credentials";
+
+    if (isBadCredential) {
+      console.log(`PAT_${retries + 1} Failed`);
+      retries++;
+      // directly return from the function
+      return retryer(fetcher, variables, retries);
+    }
+  }
+};
+
+module.exports = retryer;

tests/retryer.test.js

@@ -0,0 +1,50 @@
+require("@testing-library/jest-dom");
+const retryer = require("../src/retryer");
+
+const fetcher = jest.fn((variables, token) => {
+  console.log(variables, token);
+  return new Promise((res, rej) => res({ data: "ok" }));
+});
+
+const fetcherFail = jest.fn(() => {
+  return new Promise((res, rej) =>
+    res({ data: { errors: [{ type: "RATE_LIMITED" }] } })
+  );
+});
+
+const fetcherFailOnSecondTry = jest.fn((_vars, _token, retries) => {
+  return new Promise((res, rej) => {
+    // faking rate limit
+    if (retries < 1) {
+      return res({ data: { errors: [{ type: "RATE_LIMITED" }] } });
+    }
+    return res({ data: "ok" });
+  });
+});
+
+describe("Test Retryer", () => {
+  it("retryer should return value and have zero retries on first try", async () => {
+    let res = await retryer(fetcher, {});
+
+    expect(fetcher).toBeCalledTimes(1);
+    expect(res).toStrictEqual({ data: "ok" });
+  });
+
+  it("retryer should return value and have 2 retries", async () => {
+    let res = await retryer(fetcherFailOnSecondTry, {});
+
+    expect(fetcherFailOnSecondTry).toBeCalledTimes(2);
+    expect(res).toStrictEqual({ data: "ok" });
+  });
+
+  it("retryer should throw error if maximum retries reached", async () => {
+    let res;
+
+    try {
+      res = await retryer(fetcherFail, {});
+    } catch (err) {
+      expect(fetcherFail).toBeCalledTimes(8);
+      expect(err.message).toBe("Maximum retries exceeded");
+    }
+  });
+});