Question

我目前有一种方法可以根据Future[String]更新Redis表。

  def update(key: String, timeStamp: Long, jsonStringF: Future[String], redisClient: RedisClient) = {

    jsonStringF.map { jsonString =>
      val historyKey = "history." + key
      val tempKey = "temp." + key

      val tran = redisClient.transaction()
      tran.zadd(historyKey, (timeStamp, jsonString))
      tran.del(tempKey)
      val f = tran.exec()
      f.onComplete {
        case Success(suc) => dlogger.info(s"Updated $historyKey and deleted $tempKey successfully ....")
        case Failure(ex) => dlogger.warn(s"Error updating tables", ex)
      }
    }
  }

现在我有两个Future[String]（jsonStringF1和jsonStringF2），我想更新两个不同的表格。

  def update(key: String, timeStamp: Long, jsonStringF1: Future[String], jsonStringF2: Future[String], redisClient: RedisClient) = {
 ....

}

我想在"another." + key中使用String更新另一个表格jsonStringF2）。我怎样才能做到这一点？

更新：以下代码是否正确？

  def update(tableKey: String, timeStamp: Long,  jsonStringF1: Future[String], jsonStringF2: Future[String], redisClient: RedisClient) =
  {

    for {
      a <- jsonStringF1
      t <- jsonStringF2

      historyKey = "history." + tableKey
      anotherKey = "another." + tableKey + 

      tempKey = "temp." + tableKey
      tran = redisClient.transaction()
      _ = tran.zadd(historyKey, (timeStamp, a))
      _ = tran.zadd(anotherKey, (timeStamp, t))
      _ = tran.del(tempKey)
      f = tran.exec()
    } yield ()
  }

Answer 1

您可以使用for收集多个期货：

val f1: Future[String] = ...
val f2: Future[String] = ...

for {
  a <- f1
  b <- f2
} {
  // Code to execute when both f1 and f2 complete
  // a and b are available here
}

Answer 2

您可以使用进行循环，如您所述

def update(tableKey: String, timeStamp: Long,  jsonStringF1: Future[String], jsonStringF2:Future[String], redisClient: RedisClient) = {
    for {
        a <- jsonStringF1
        t <- jsonStringF2
    } yield {
        val historyKey = "history." + tableKey
        val anotherKey = "another." + tableKey

        val tran = redisClient.transaction()
        tran.zadd(historyKey, (timeStamp, a))
        tran.zadd(anotherKey, (timeStamp, t))
        tran.del(tempKey)
        tran.exec()
    }
}

作为 for 的替代方法，您还可以使用scala / async（https://github.com/scala/async）并编写代码，如下所示

def update(tableKey: String, timeStamp: Long,  jsonStringF1: Future[String], jsonStringF2:Future[String], redisClient: RedisClient) = {
    async {
        val a = await(jsonStringF1)
        val t = await(jsonStringF2)

        val historyKey = "history." + tableKey
        val anotherKey = "another." + tableKey

        val tran = redisClient.transaction()
        tran.zadd(historyKey, (timeStamp, a))
        tran.zadd(anotherKey, (timeStamp, t))
        tran.del(tempKey)
        tran.exec()
    }
}

哪个也是非阻塞的。由于

异步块被编译为单个匿名类，而不是a 为每个生成器所需的每个闭包分开匿名类。

Answer 3

由于您只有2个期货，您可以压缩它们：

def update(tableKey: String, timeStamp: Long,  jsonStringF1: Future[String], jsonStringF2:Future[String], redisClient: RedisClient) = {

    val jsons = jsonStringF1.zip(jsonStringF2)
    jsons map {
      case (a, t) => 
        val historyKey = "history." + tableKey
        val anotherKey = "another." + tableKey

        val tran = redisClient.transaction()
        tran.zadd(historyKey, (timeStamp, a))
        tran.zadd(anotherKey, (timeStamp, t))
        tran.del(tempKey)
        tran.exec()
    }
}

处理Scala中的多个期货

3 个答案: