調用了Thread.sleep演員

Question

裏面我有一個功能重試基本上看起來像這樣（簡化）：

object SomeObject { 
def retry[T](n: Int)(fn: => T): Option[T] = { 
    val res = try { 
     Some(fn) 
    } catch { 
     case _: Exception => None 
    } 

    res match { 
     case Some(x) => Some(x) 
     case None => 
     if (n > 1) 
      //make it sleep for a little while 
      retry(n - 1)(fn) 
     else None 
    } 
    } 
} 

我需要做的嘗試之間的一些暫停。據我所知，這是不能接受的調用Thread.sleep(123)演員裏面：

class MyActor extends Actor { 
    //...... 
    def someFunc = { 
    Thread.sleep(456) // it's not acceptable in an actor, there is another way to do it 
    } 

} 

很顯然，我不知道客戶是否會使用SomeObject.retry演員裏面：

class MyActor extends Actor { 
    //...... 
    def someFunc = { 
    SomeObject.retry(5)(someRequestToServer) // ops, SomeObject.retry uses Thread.sleep! 
    } 

} 

所以，如果我只是補充：

res match { 
     case Some(x) => Some(x) 
     case None => 
     if (n > 1) 
      //make it sleep for a little while 
      Thread.sleep(123) // ops, what if it's being called inside an actor by a client?! 
      retry(n - 1)(fn) 
     else None 
    } 
    } 

它不會是明智的，會嗎？如果不是，我該怎麼辦？

Answer 1

是的，調用Thread.sleep是一個壞主意，因爲在actor系統中線程通常是Actors之間共享的有限資源。你不希望一個Actor調用sleep並且從其他Actor中竊取一個Thread。

您應該做的是使用Scheduler（請參閱docs）讓您的演員在將來某個時間向其自身發送消息以重試。要做到這一點，你會如果你使用SomeObject.try外的演員來移動重試碼出SomeObject進入Actor

class MyActor extends Actor { 

    import context.system.dispatcher 

    def receive = { 
    case DoIt(retries) if retries > 0 => 
     SomeObject.attempt(someRequestToServer) match { 
     case Some(x) => ... 
     case None => 
      context.system.scheduler.scheduleOnce(5.seconds, self, DoIt(retries - 1)) 
     } 
    } 

} 

然後系統

def attempt(retries: Int) = { 
    SomeObject.attempt(someRequestToServer) match { 
    case Some(x) => ... 
    case None if retries > 0 => { 
     Thread.sleep(123) 
     attempt(retries - 1) 
    } 
    } 
} 

其中SomeObject.attempt是：

object SomeObject { 
    def attempt[T](fn: => T): Option[T] = 
    try { 
     Some(fn) 
    } catch { 
     case _: Exception => None 
    } 
}