stop onebox rapid fire

app/assets/javascripts/discourse/models/onebox.js.coffee

@@ -13,17 +13,26 @@ Discourse.Onebox = (->
     null
 
   lookupCache = (url) ->
-    localCache[url]
+    cached = localCache[url]
+    if cached && cached.then # its a promise
+      null
+    else
+      cached
 
   lookup = (url, refresh, callback) ->
-    cached = lookupCache(url) unless refresh
+    cached = localCache[url]
+    cached = null if refresh && cached && !cached.then
     if cached
-      callback(cached)
+      if cached.then
+        cached.then(callback(lookupCache(url)))
+      else
+        callback(cached)
       return false
     else
-      $.get "/onebox", url: url, refresh: refresh, (html) ->
+      cache(url, $.get "/onebox", url: url, refresh: refresh, (html) ->
         cache(url,html)
         callback(html)
+      )
       return true
 
   load = (e, refresh=false) ->

spec/javascripts/onebox.js.coffee

@@ -0,0 +1,14 @@
+describe "Discourse.Onebox", ->
+
+  beforeEach ->
+    spyOn($, 'ajax').andCallThrough()
+
+  it "Stops rapid calls with cache true", ->
+    Discourse.Onebox.lookup('http://bla.com', true, (c) -> c)
+    Discourse.Onebox.lookup('http://bla.com', true, (c) -> c)
+    expect($.ajax.calls.length).toBe(1)
+
+  it "Stops rapid calls with cache false", ->
+    Discourse.Onebox.lookup('http://bla.com/a', false, (c) -> c)
+    Discourse.Onebox.lookup('http://bla.com/a', false, (c) -> c)
+    expect($.ajax.calls.length).toBe(1)