retry: allow modification of options in retry listener

doc/plugins.markdown

@@ -122,6 +122,24 @@ Emitted when a retry has been scheduled.
 
 Possible reasons are `connect`, `codes` or `validate` and for reason `connect` the `response` is `null`.
 
+**Example: modify request options**
+
+```js
+var hosts = [
+  'ww1.example.com',
+  'ww2.example.com',
+  'ww3.example.com'
+];
+
+call.on('retry', function(options, response, reason) {
+  if (hosts.length > 0) {
+    options.request.host = hosts.shift();
+  } else {
+    call.abort();
+  }
+});
+```
+
 [back to top](#table-of-contents)
 
 ## timeout

lib/plugins/retry.js

@@ -89,11 +89,9 @@ RetryPlugin.prototype._retry = function(call, options) {
 
 RetryPlugin.prototype._interceptError = function(call, options, err) {
   if (err.syscall === 'connect') {
-    // TODO: try to auto-correct the config
-    // TODO: alternate protocols, hosts and/or ports
     options.retry.limit = options.retry.limit - 1;
-    this._retry(call);
     call.emit('retry', options, null, 'connect', err.code);
+    this._retry(call, options);
   } else {
     call.__emit('error', err);
   }
@@ -117,8 +115,8 @@ RetryPlugin.prototype._interceptResponse = function(call, options, response) {
 
   function finish() {
     retry.limit = retry.limit - 1;
-    self._retry(call);
     call.emit('retry', options, response, reason, code);
+    self._retry(call, options);
   }
 
   // check if buffer plugin already handled the response body

test/test-http-retry.js

@@ -111,6 +111,49 @@ suite('http:retry', function() {
     }).end();
   });
 
+
+  test('modify request', function(done) {
+    onrequest = function(request, response) {
+      var host = request.headers.host;
+
+      if (host === '127.0.0.1:' + common.port) {
+        response.writeHead(503);
+        response.end();
+
+      } else if (host === 'localhost:' + common.port) {
+        response.writeHead(200);
+        response.end();
+      }
+    };
+
+    var retries = 0;
+
+    rail.call({
+      port: common.port
+    }, function(response) {
+      assert.strictEqual(response.statusCode, 200);
+      assert.strictEqual(retries, 1);
+
+      response.on('readable', function() {
+        response.read();
+      });
+
+      response.on('end', function() {
+        done();
+      });
+
+    }).on('retry', function(options, response, reason) {
+      ++retries;
+
+      assert(options.retry);
+      assert.strictEqual(response.statusCode, 503);
+      assert.strictEqual(reason, 'codes');
+
+      options.request.host = 'localhost';
+    }).end();
+  });
+
+
   suiteTeardown(function(done) {
     server.close(done);
   });