Add delay strategy

README.md

@@ -113,6 +113,28 @@ request({
 });
 ```
 
+## How to define your own delay strategy
+
+```
+/**
+ * @param  {Null | Object} err
+ * @param  {Object} response
+ * @return {Number} number of milliseconds to delay
+ */
+function myDelayStrategy(err, response, body){
+  // set delay of retry to a random number between 500 and 3500 ms
+  return Math.floor(Math.random() * (3500 - 500 + 1) + 500);
+}
+
+request({
+  url: 'https://api.domain.com/v1/a/b'
+  json:true,
+  delayStrategy: myDelayStrategy // delayStrategy is called 1 less times than the maxAttempts set
+}, function(err, response, body){
+  // this callback will only be called when the request succeeded or after maxAttempts or on error
+});
+```
+
 ## Modifying `request` options
 
 You can use the `defaults` method to provide default options like so:

index.js

@@ -62,6 +62,7 @@ function Request(options, f, retryConfig) {
    * @type {Function} (err, response) -> Boolean
    */
   this.retryStrategy = _.isFunction(options.retryStrategy) ? options.retryStrategy : RetryStrategies.HTTPOrNetworkError;
+  this.delayStrategy = _.isFunction(options.delayStrategy) ? options.delayStrategy : function() { return this.retryDelay; };
 
   this._timeout = null;
   this._req = null;
@@ -99,7 +100,7 @@ Request.prototype._tryUntilFail = function () {
       response.attempts = this.attempts;
     }
     if (this.retryStrategy(err, response, body) && this.maxAttempts > 0) {
-      this._timeout = setTimeout(this._tryUntilFail.bind(this), this.retryDelay);
+      this._timeout = setTimeout(this._tryUntilFail.bind(this), this.delayStrategy.call(this, err, response, body));
       return;
     }
 

package.json

@@ -11,6 +11,10 @@
     {
       "name": "juliendangers",
       "email": "[email protected]"
+    },
+    {
+      "name": "Osbert Orr",
+      "email": "[email protected]"
     }
   ],
   "repository": {
@@ -41,6 +45,7 @@
     "nock": "^8.0.0",
     "q": "~1.4.1",
     "rsvp": "^3.2.1",
+    "sinon": "1.17.5",
     "updtr": "^0.2.1"
   }
 }

test/attempts.test.js

@@ -2,6 +2,7 @@
 
 var request = require('../');
 var t = require('chai').assert;
+var sinon = require('sinon');
 
 describe('Request attempts', function () {
   it('should show 1 attempt after a successful call', function (done) {
@@ -23,4 +24,23 @@ describe('Request attempts', function () {
       done();
     });
   });
+
+  it('should call delay strategy 2 times after some retries', function (done) {
+    var mockDelayStrategy = sinon.stub().returns(500);
+    var startTime = process.hrtime();
+    request({
+      url: 'http://www.filltext.com/?rows=1&err=500', // return a 500 status
+      maxAttempts: 3,
+      retryDelay: 1000000, // Set to large delay to prove it will not be used
+      delayStrategy: mockDelayStrategy
+    }, function (err, response, body) {
+      var endTime = process.hrtime(startTime); // process.hrtime returns an array [seconds, nanoseconds]
+      var timeDiff = endTime[0] * 1000 + endTime[1]/1000000;
+
+      t.isAtLeast(timeDiff, 1000, 'delayStrategy\'s return value was not used or was used incorrectly');
+      t.isTrue(mockDelayStrategy.calledTwice, 'mockDelayStrategy was called an incorrect amount of times'); // reason it's called 2 and not 3 times is because there is no delay for the first call
+      done();
+    });
+  });
 });
+