Question

ActorLogging中的DiagnosticActorLogging和Akka特征之间的区别是什么？您应该何时优先于另一个？快速查看docs并不能提供很多指导。

Answer 1

MDC允许您为记录的邮件添加其他上下文。例如，对于日志记录模式%5p %X{user-id} %m%n，在mdc map中插入user-id将替换模板字段%X{user-id}中的值

DiagnosticActorLogging为您提供了对mdc的轻松访问，并负责为actor处理的每条消息设置和清除mdc。请查看aroundReceive特征中的DiagnosticActorLogging方法，以便更好地理解

override protected[akka] def aroundReceive(receive: Actor.Receive, msg: Any): Unit = try {
    log.mdc(mdc(msg))
    super.aroundReceive(receive, msg)
  } finally {
    log.clearMDC()
  }

Answer 2

最简单的解决方法是检查DiagnosticActorLogging来源：

/**
 * Scala API: Mix in DiagnosticActorLogging into your Actor to easily obtain a reference to a logger with MDC support,
 * which is available under the name "log".
 * In the example bellow "the one who knocks" will be available under the key "iam" for using it in the logback pattern.
 *
 * {{{
 * class MyActor extends Actor with DiagnosticActorLogging {
 *
 *   override def mdc(currentMessage: Any): MDC = {
 *     Map("iam", "the one who knocks")
 *   }
 *
 *   def receive = {
 *     case "pigdog" => log.info("We've got yet another pigdog on our hands")
 *   }
 * }
 * }}}
 */
trait DiagnosticActorLogging extends Actor {
  import akka.event.Logging._
  val log = akka.event.Logging(this)
  def mdc(currentMessage: Any): MDC = emptyMDC

  override protected[akka] def aroundReceive(receive: Actor.Receive, msg: Any): Unit = try {
    log.mdc(mdc(msg))
    super.aroundReceive(receive, msg)
  } finally {
    log.clearMDC()
  }
}

基本上，它允许隐式地将一些共享的日志记录数据关联到actor中的每个日志记录调用，而不会明确地添加它们。根据您的应用程序，它可能对主机名，请求ID，客户端ID，jar版本，构建日期，端点等等有用。

何时在Akka中使用DiagnosticActorLogging而不是ActorLogging特征？

2 个答案: