Implemented wait in generate function so generation of dynamic routes with ajax calls are not all sceduled simultaneously, possibly flooding the data backend with queries.

Use generate.wait (ms) to stagger route generate calls over time.

Fixes #590.

lib/generate.js

@@ -89,11 +89,28 @@ export default function () {
         this.routes.push(route)
       }
     })
+    var n = 0
+    function timer () {
+      let promise = new Promise(
+        (resolve, reject) => {
+         setTimeout( () => {
+          resolve()
+         }, self.options.generate.wait * n)
+        }
+      )
+      n++
+      return promise
+
+    }
+
     let routes = this.routes
     return co(function * () {
       while (routes.length) {
         yield routes.splice(0, 500).map((route) => {
           return co(function * () {
+            if(self.options.generate.wait) {
+              yield timer()
+            }
             var { html } = yield self.renderRoute(route, { _generate: true })
             html = minify(html, self.options.generate.minify)
             var path = join(route, sep, 'index.html') // /about -> /about/index.html

test/fixtures/basic/nuxt.config.js

@@ -4,6 +4,7 @@ module.exports = {
       '/users/1',
       '/users/2',
       '/users/3'
-    ]
+    ],
+    wait : 1000
   }
 }