如何在处理速率限制时异步发送 HTTP 请求? [英] How can I send HTTP Requests asynchronously while handling rate-limits?

问题描述

免责声明:我是 sttp 和 Monix，这是我尝试了解更多关于这些库的尝试.我的目标是通过 HTTP GET 请求从给定的 API 获取数据(客户端)->解析 JSON 响应 ->将此信息写入数据库.我的问题仅与第一部分有关.我的目标是以异步(希望是快速的)方式运行 get 请求，同时有办法避免或处理速率限制.

Disclaimer: I am new to sttp and Monix, and that is my attempt to learn more about these libraries. My goal is to fetch data (client-side) from a given API via HTTP GET requests -> parse JSON responses -> write this information to a database. My question pertains to the first part only. My objective is to run get requests in an asynchronous (hopefully fast) way while having a way to either avoid or handle rate limits.

以下是我已经尝试过的片段，似乎适用于单个请求:

Below is a snippet of what I have already tried, and seems to work for a single request:

package com.github.client

import io.circe.{Decoder, HCursor}
import sttp.client._
import sttp.client.circe._
import sttp.client.asynchttpclient.monix._
import monix.eval.Task

object SO extends App {

  case class Bla(paging: Int)

  implicit val dataDecoder: Decoder[Bla] = (hCursor: HCursor) => {
    for {
      next_page <- hCursor.downField("foo").downArray.downField("bar").as[Int]
    } yield Bla(next_page)
  }

  val postTask = AsyncHttpClientMonixBackend().flatMap { implicit backend =>
    val r = basicRequest
      .get(uri"https://foo.bar.io/v1/baz")
      .header("accept", "application/json")
      .header("Authorization", "hushh!")
      .response(asJson[Bla])

    r.send() // How can I instead of operating on a single request, operate on multiple
      .flatMap { response =>
        Task(response.body)
      }
      .guarantee(backend.close())
  } 

  import monix.execution.Scheduler.Implicits.global

  postTask.runSyncUnsafe() match {
    case Left(error) => println(s"Error when executing request: $error")
    case Right(data) => println(data)
  }
}

我的问题:

1. 如何通过使用 Monix 处理多个 GET 请求(而不是单个请求)，同时保持代码异步和可组合
2. 如何避免或处理由 api 服务器强加的命中率限制

顺便说一句，如果支持速率限制目标，我在使用另一个后端方面也很灵活.

On a side note, I am also flexible in terms of using another back-end if that will support the rate limiting objective.

推荐答案

你可以像这样使用 monix.reactive.Observable

You can use monix.reactive.Observable like this

  Observable.repeatEval(postTask) // we generate infinite observable of the task
    .throttle(1.second, 3) // set throttling
    .mapParallelOrderedF(2)(_.runToFuture) // set execution parallelism and execute tasks
    .subscribe() // start the pipline
  
  
  while (true) {}

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