fix: Retry on failed network calls

Author: Abhi591

CHANGELOG.md

@@ -5,6 +5,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.70.0] - 2024-07-18
+### Fix
+- Retry on failed network calls
+
 ## [1.69.0] - 2024-06-06
 ### Fix
 - Unsupported URL in React native env

dist/vwo-javascript-sdk.js

@@ -71,8 +71,11 @@ const HttpHandlerUtil = {
   },
 
   sendPostCall: function(url, postData, queryParams, authToken, callback, customHeaders = {}) {
+    let retry = 0;
+    const maxRetries = 5;
+    const delay = 1000;
     postData = JSON.stringify(postData);
-    customHeaders['Content-Length'] = postData.length;
+    customHeaders['Content-Length'] = Buffer.byteLength(postData);
     const options = {
       method: 'POST',
       hostname: url.host,
@@ -84,31 +87,63 @@ const HttpHandlerUtil = {
     if (authToken) {
       options.headers.Authorization = authToken;
     } else {
-      // what should be the user-agent here?
+      // Set the user-agent here
       options.headers['User-Agent'] = Constants.SDK_NAME;
     }
 
     if (url.port) {
       options.port = url.port;
     }
 
-    const req = https.request(options, res => {
-      let rawData = ''; // eslint-disable-line no-unused-vars
-      res.setEncoding('utf8');
-      res.on('data', function(chunk) {
-        rawData += chunk;
-      });
-      res.on('end', function() {
-        callback(null, res, rawData);
+    const sendRequest = retries => {
+      const req = https.request(options, res => {
+        let rawData = '';
+        res.setEncoding('utf8');
+        res.on('data', function(chunk) {
+          rawData += chunk;
+        });
+        res.on('end', function() {
+          if (res.statusCode >= 200 && res.statusCode < 300) {
+            callback(null, res, rawData);
+          } else {
+            if (retries < maxRetries) {
+              logger.log(
+                LogLevelEnum.ERROR,
+                `Retrying request... Attempt ${retries + 1} of ${maxRetries} due to status code: ${res.statusCode}`
+              );
+              setTimeout(() => sendRequest(retries + 1), delay * (retries + 1)); // Exponential backoff
+            } else {
+              logger.log(
+                LogLevelEnum.ERROR,
+                `Request failed after ${maxRetries} attempts with status code: ${res.statusCode}`
+              );
+              callback(
+                new Error(`Request failed after ${maxRetries} attempts with status code: ${res.statusCode}`),
+                res,
+                rawData
+              );
+            }
+          }
+        });
       });
-    });
 
-    req.on('error', e => {
-      callback(e, null);
-    });
+      req.on('error', e => {
+        if (retries < maxRetries) {
+          logger.log(
+            LogLevelEnum.ERROR,
+            `Retrying request due to error... Attempt ${retries + 1} of ${maxRetries}. Error: ${e.message}`
+          );
+          setTimeout(() => sendRequest(retries + 1), delay * (retries + 1)); // Exponential backoff
+        } else {
+          logger.log(LogLevelEnum.ERROR, `Request failed after ${maxRetries} attempts due to error: ${e.message}`);
+          callback(e, null);
+        }
+      });
 
-    req.write(postData);
-    req.end();
+      req.write(postData);
+      req.end();
+    };
+    sendRequest(retry);
   }
 };
 

dist/vwo-javascript-sdk.js.map

@@ -75,7 +75,13 @@ const XhrUtil = {
   },
 
   // send request function definition (to allow for retries)
-  sendRequest: function(xhr, retries, maxRetries, delay, logger, customHeaders, payload, method, url, resolve, reject) {
+  sendRequest: function(retries, maxRetries, logger, customHeaders, payload, method, url, resolve, reject) {
+    let delay = 1000 * (retries + 1);
+    let xhr = new XMLHttpRequest();
+
+    // Configure timeout
+    xhr.timeout = 5000; // Set timeout to 5 seconds (5000 ms)
+
     // onload event
     xhr.onload = () => {
       // retry if error and less than max retries
@@ -84,40 +90,53 @@ const XhrUtil = {
           retries++;
 
           // log retried times
-          logger.log(LogLevelEnum.ERROR, 'Retrying with Status Code :' + xhr.status);
-          logger.log(LogLevelEnum.ERROR, 'Retrying with Response :' + xhr.responseText);
+          logger.log(
+            LogLevelEnum.ERROR,
+            `Retrying with Status Code : ${xhr.status}, and Response : ${xhr.responseText}`
+          );
 
           // call send request again, after delay
           setTimeout(() => {
-            this.sendRequest(
-              xhr,
-              retries,
-              maxRetries,
-              delay,
-              logger,
-              customHeaders,
-              payload,
-              method,
-              url,
-              resolve,
-              reject
-            );
+            this.sendRequest(retries, maxRetries, logger, customHeaders, payload, method, url, resolve, reject);
           }, delay);
         } else {
           // log errors with status (clean up later)
-          logger.log(LogLevelEnum.ERROR, 'Request failed with Status Code :' + xhr.status);
-          logger.log(LogLevelEnum.ERROR, 'Request failed with Response :' + xhr.responseText);
+          logger.log(
+            LogLevelEnum.ERROR,
+            `Request failed with Status Code : ${xhr.status} and Response : ${xhr.responseText}`
+          );
           reject(`Got Error: ${xhr.statusText} and Status Code: ${xhr.status}`);
         }
       } else {
         // resolve the promise if all well
-        resolve();
+        resolve(xhr.responseText);
       }
     };
 
     // onerror event
     xhr.onerror = () => {
-      reject(`Error: ${xhr.statusText}, Status Code: ${xhr.status}`);
+      if (retries < maxRetries) {
+        retries++;
+        logger.log(LogLevelEnum.ERROR, 'Retrying due to network error');
+        setTimeout(() => {
+          this.sendRequest(retries, maxRetries, logger, customHeaders, payload, method, url, resolve, reject);
+        }, delay);
+      } else {
+        reject(`Network error: ${xhr.statusText}, Status Code: ${xhr.status}`);
+      }
+    };
+
+    // ontimeout event
+    xhr.ontimeout = () => {
+      if (retries < maxRetries) {
+        retries++;
+        logger.log(LogLevelEnum.ERROR, 'Retrying due to timeout');
+        setTimeout(() => {
+          this.sendRequest(retries, maxRetries, logger, customHeaders, payload, method, url, resolve, reject);
+        }, delay);
+      } else {
+        reject(`Timeout error: ${xhr.statusText}, Status Code: ${xhr.status}`);
+      }
     };
 
     // open connection and add headers if any, and then send
@@ -154,10 +173,9 @@ const XhrUtil = {
       // retry params
       let retries = 0;
       let maxRetries = 5;
-      let delay = 1000;
 
       // send request
-      this.sendRequest(xhr, retries, maxRetries, delay, logger, customHeaders, payload, method, url, resolve, reject);
+      this.sendRequest(retries, maxRetries, logger, customHeaders, payload, method, url, resolve, reject);
     }
   },