1. 问题概述

在使用Akka Typed时，我们可能遇到需要将MDC（Mapped Diagnostic Context）信息添加到Actor日志中的情况。但是，如果子Actor发生异常，它的MDC信息将不会被正确处理。

2. 解决方法

为了解决这个问题，我们可以在Actor的SupervisorStrategy中重写handleChildTerminated()方法，将子Actor的MDC信息传递给父Actor。

下面是一个示例代码：

class MyActor extends AbstractBehavior[String](context) {

  private val log = LoggerFactory.getLogger(classOf[MyActor])

  override def onMessage(msg: String): Behavior[String] = {
    log.info("Received message: {}", msg)
    this
  }

  override def onSignal: PartialFunction[Signal, Behavior[String]] = {
    case PostStop =>
      log.info("MyActor stopped")
      this
  }

}

class ParentActor extends AbstractBehavior[String](context) {

  private val log = LoggerFactory.getLogger(classOf[ParentActor])

  private val childMdc = new ConcurrentHashMap[String, String]()

  override def onMessage(msg: String): Behavior[String] = {
    val childActor = context.spawnAnonymous(MyActor())
    context.watch(childActor)

    childMdc.put("message", msg)

    Behaviors.supervise(childActor)
      .onFailure[Exception](SupervisorStrategy.restartWithBackoff(
        minBackoff = 3.seconds,
        maxBackoff = 30.seconds,
        randomFactor = 0.2
      ).withLogger(new ChildFailedLogger(childMdc, log)))
      .asInstanceOf[Behavior[String]]
  }

  override def onSignal: PartialFunction[Signal, Behavior[String]] = {
    case PostStop =>
      log.info("ParentActor stopped")
      this
  }

}

class ChildFailedLogger(childMdc: ConcurrentHashMap[String, String], log: Logger) extends Logger {

  override def getName: String = log.getName

  override def isTraceEnabled: Boolean = log.isTraceEnabled

  override def trace(msg: String): Unit = log.trace(msg)

  override def trace(format: String, arg: Any): Unit = log.trace(format, arg)

  override