async retry strategy

README.md

@@ -137,6 +137,24 @@ function myRetryStrategy(err, response, body, options){
   }
 }
 
+/**
+ * With an asynchronous retry strategy
+ * @param  {Null | Object} err
+ * @param  {Object} response
+ * @param  {Object} body
+ * @param  {Object} options copy 
+ * @return {Object} mustRetry: {Boolean} true if the request should be retried
+ *                  options: {Object} new options for request
+ */
+async function myRetryStrategy(err, response, body, options){
+  let token = await getNewApiAuthToken();
+  options.headers = {'Authorization': `Bearer ${token}`}
+  return {
+    mustRetry: true,
+    options: options, // retry with new auth token
+  }
+}
+
 request({
   url: 'https://api.domain.com/v1/a/b'
   json:true,

index.js

@@ -121,7 +121,7 @@ Request.prototype._tryUntilFail = function () {
   this.maxAttempts--;
   this.attempts++;
 
-  this._req = Request.request(this.options, function (err, response, body) {
+  this._req = Request.request(this.options, async function (err, response, body) {
     if (response) {
       response.attempts = this.attempts;
     }
@@ -130,7 +130,7 @@ Request.prototype._tryUntilFail = function () {
       err.attempts = this.attempts;
     }
 
-    var mustRetry = this.retryStrategy(err, response, body, _.cloneDeep(this.options));
+    var mustRetry = await Promise.resolve(this.retryStrategy(err, response, body, _.cloneDeep(this.options)));
     if (_.isObject(mustRetry) && _.has(mustRetry, 'mustRetry')) {
       if (_.isObject(mustRetry.options)) {
         this.options = mustRetry.options; //if retryStrategy supposes different request options for retry

test/strategies.test.js

@@ -140,6 +140,25 @@ describe('RetryStrategies', function () {
         done();
       });
     })
+
+    it('should work with an async strategy', function (done) {
+      var strategy = function (err, response, body) {
+        return new Promise(function(resolve, reject) {
+          setTimeout(function () {resolve({mustRetry: false})}, 500);
+        });
+      };
+
+      request({
+        url: 'http://www.filltext.com/?rows=1',
+        maxAttempts: 2,
+        retryDelay: 100,
+        retryStrategy: strategy
+      }, function(err, response, body) {
+        if(err) done(err);
+        t.strictEqual(1, this.attempts); // maxAttempts NOT reached
+        done();
+      });
+    });
   });
 });