RxJS：每秒发送 x 个请求

Question

我有函数createEvent() 向谷歌日历发送请求。

Google 日历的 API 要求我每秒最多发送 5 个请求。

如果我拨打createEvent() 100 次，它将淹没谷歌日历并且我的请求被拒绝。如果可能的话，我希望 createEvent() 包含将请求限制为每秒 5 次所需的逻辑。

我尽量避免，

calendar.addEventToQueue(eventData);
calendar.addEventToQueue(eventData);
calendar.addEventToQueue(eventData);
cleandar.submitEvents();

而只是

calendar.createEvent(eventData);
calendar.createEvent(eventData);
calendar.createEvent(eventData);

Answer 1

我想我不久前在rate limiting 上给出了这个答案。

你可以用 RxJS 做到这一点：

//This would be replaced by whatever your event source was
//I just made it a button click in this case
var source = Rx.Observable.fromEvent($button, 'click')

  //Captures either all the events for one second for a max of 5 events
  //Projects each set into an Observable
  .windowWithTimeOrCount(1000, 5)

  //Only the first window in a single second gets propagated
  //The others will be dropped
  .throttleFirst(1000)

  //Flatten the sequence by concatenating all the windows
  .concatAll()

  //Build the event body now *after* we have done filtering
  .flatMap(function() { 
    //The calendar request api supports promises which are 
    //handled implicitly in Rx by operators like flatMap. As a result
    //this will automatically wait until it receives a response.
    return gapi.client.calendar.events.insert(/*event body*/);
  });

//Process the response
source.subscribe(
  function(response) { console.log('Event successfully created!'); });