pekko/akka-kernel/src/main/scala/akka/kernel/Main.scala

/**
 * Copyright (C) 2009-2010 Typesafe Inc. <http://www.typesafe.com>
 */

package akka.kernel

import akka.actor.ActorSystem
import com.typesafe.config.ConfigFactory
import java.io.File
import java.lang.Boolean.getBoolean
import java.net.{ URL, URLClassLoader }
import java.util.jar.JarFile
import scala.collection.JavaConverters._

trait Bootable {
  def startup(system: ActorSystem): Unit
  def shutdown(system: ActorSystem): Unit
}

object Main {
  val quiet = getBoolean("akka.kernel.quiet")

  def log(s: String) = if (!quiet) println(s)

  def main(args: Array[String]) = {
    log(banner)
    log("Starting Akka...")
    log("Running Akka " + ActorSystem.Version)

    val config = ConfigFactory.load("akka.conf")
    val name = config.getString("akka.kernel.system.name")
    val system = ActorSystem(name, config)
    val classLoader = deployJars(system)

    log("Created actor system '%s'" format name)

    Thread.currentThread.setContextClassLoader(classLoader)

    val bootClasses: Seq[String] = system.settings.config.getStringList("akka.kernel.boot").asScala
    val bootables: Seq[Bootable] = bootClasses map { c ⇒ classLoader.loadClass(c).newInstance.asInstanceOf[Bootable] }

    for (bootable ← bootables) {
      log("Starting up " + bootable.getClass.getName)
      bootable.startup(system)
    }

    addShutdownHook(system, bootables)

    log("Successfully started Akka")
  }

  def deployJars(system: ActorSystem): ClassLoader = {
    if (system.settings.Home.isEmpty) {
      log("Akka home is not defined")
      System.exit(1)
      Thread.currentThread.getContextClassLoader
    } else {
      val home = system.settings.Home.get
      val deploy = new File(home, "deploy")

      if (!deploy.exists) {
        log("No deploy dir found at " + deploy)
        log("Please check that akka home is defined correctly")
        System.exit(1)
      }

      val jars = deploy.listFiles.filter(_.getName.endsWith(".jar"))

      val nestedJars = jars flatMap { jar ⇒
        val jarFile = new JarFile(jar)
        val jarEntries = jarFile.entries.asScala.toArray.filter(_.getName.endsWith(".jar"))
        jarEntries map { entry ⇒ new File("jar:file:%s!/%s" format (jarFile.getName, entry.getName)) }
      }

      val urls = (jars ++ nestedJars) map { _.toURI.toURL }

      urls foreach { url ⇒ log("Deploying " + url) }

      new URLClassLoader(urls, Thread.currentThread.getContextClassLoader)
    }
  }

  def addShutdownHook(system: ActorSystem, bootables: Seq[Bootable]): Unit = {
    Runtime.getRuntime.addShutdownHook(new Thread(new Runnable {
      def run = {
        log("")
        log("Received signal to stop")
        log("Shutting down Akka...")
        for (bootable ← bootables) {
          log("Shutting down " + bootable.getClass.getName)
          bootable.shutdown(system)
        }
        system.stop()
        log("Successfully shut down Akka")
      }
    }))
  }

  def banner = """
==============================================================================

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==============================================================================
"""
}