Merge pull request #6 from batmat/add-retry-for-support-of-exp-backof…

…f-and-more

Add simplistic exponential backoff retry

README.md

@@ -27,6 +27,8 @@ var options = {
     retry : 2, // will retry the call twice, in case of error.
     verbose_logging : false, // will log errors only, if set to be true, will log all actions
     accepted: [ 400, 404 ] // Accepted HTTP Status codes (will not retry if request response has any of these HTTP Status Code)
+    delay: 2000 // will delay retries by 2000 ms.  The default is 100. 
+    factor: 2 // will multiple the delay by the factor each time a retry is attempted. 
 };
 
 rp(options)

index.js

@@ -10,7 +10,18 @@ class rpRetry {
         }
         const tries = options.retry || 1;
         delete options.retry;
-        const fetchDataWithRetry = tryCount => {
+
+        const delay = options.delay || 100; // default ms delay between retries
+        delete options.delay;
+
+        const factor = options.factor || 1; // If absent, delay will always be the same.
+        delete options.factor;
+
+        if (options.verbose_logging) {
+            logger.info(`calling ${options.uri} with retry ${tries}, initial delay=${delay}, factor=${factor}`);
+        }
+
+        const fetchDataWithRetry = (tryCount, delay) => {
             return requestPromise(options)
                 .then(result => {
                     if (options.verbose_logging) {
@@ -28,12 +39,17 @@ class rpRetry {
                     logger.info(`Encountered error ${err.message} for ${options.method} request to ${options.uri}, retry count ${tryCount}`);
                     tryCount -= 1;
                     if (tryCount) {
-                        return fetchDataWithRetry(tryCount);
+                        return new Promise((resolve, reject) => {
+                            setTimeout(() => {
+                                logger.debug(`waiting for ${delay} ms before next retry for ${options.uri}. Next wait ${delay * factor}`);
+                                resolve(fetchDataWithRetry(tryCount, delay * factor));
+                            }, delay);
+                        });
                     }
                     return Promise.reject(err);
                 });
         };
-        return fetchDataWithRetry(tries);
+        return fetchDataWithRetry(tries, delay);
     }
 
     static _rp(options) {

package.json

@@ -5,7 +5,9 @@
   "main": "index.js",
   "scripts": {
     "test": "node_modules/gulp/bin/gulp.js test",
-    "coveralls": "cat ./coverage/lcov.info | ./node_modules/.bin/coveralls"
+    "coveralls": "cat ./coverage/lcov.info | ./node_modules/.bin/coveralls",
+    "eslint": "eslint test/. index.js",
+    "eslint-fix": "eslint test/. index.js --fix"
   },
   "repository": {
     "type": "git",
@@ -45,6 +47,7 @@
     "chai": "^4.1.2",
     "chai-subset": "^1.6.0",
     "coveralls": "^3.0.0",
+    "eslint": "^5.5.0",
     "gulp": "^3.9.1",
     "gulp-eslint": "^4.0.0",
     "gulp-if": "^2.0.2",

test/index.test.js

@@ -114,6 +114,19 @@ describe('request-promise-retry', function () {
                 expect(data.error).equal(undefined);
             });
     });
+    it('should pass, retry with exponential backoff', () => {
+        // failure should take a bit of time to happen
+        const startTime = new Date();
+        return rp({
+            uri: 'http://adadadadad.com/',
+            method: 'GET',
+            retry: 4,
+            delay: 30,
+            factor: 10 // 0 + 30 + 300 + 3000
+        })
+            .catch(error => {
+                expect(new Date() - startTime).to.be.above(0 + 30 + 300 + 3000);
+    });
     it('should not retry, accepted options enabled', () => {
         return rp(optionsDontRetryAcceptedOptions)
             .catch(data => {