twitter-server: Move admin http server to netty4

Problem / Solution

We want to slowly move to Netty4 and the admin server is a good
candidate to port over. Note, a non-jdk zlib codec isn't provided
transitively in Netty4. If you override the zlib codec via the flag
`-Dio.netty.noJdkZlib{Encoder,Decoder}=true`, you must furnish the
`com.jcraft.jzlib` dependency.

RB_ID=868328

project/Build.scala

@@ -107,7 +107,7 @@ object TwitterServer extends Build {
     name := "twitter-server",
     libraryDependencies ++= Seq(
       finagle("core"),
-      finagle("http"),
+      finagle("netty4-http"),
       finagle("toggle"),
       finagle("zipkin-core"),
       util("app"),

src/main/scala/BUILD

@@ -11,6 +11,8 @@ scala_library(name='scala',
     '3rdparty/jvm/com/fasterxml/jackson/core:jackson-databind',
     '3rdparty/jvm/com/fasterxml/jackson/module:jackson-module-scala',
     '3rdparty/jvm/org/scala-lang/modules:scala-xml',
+    'finagle/finagle-core',
+    'finagle/finagle-netty4-http',
     'finagle/finagle-toggle',
     'finagle/finagle-zipkin',
     'finagle/finagle-zipkin-core',

src/main/scala/com/twitter/server/AdminHttpServer.scala

@@ -1,13 +1,14 @@
 package com.twitter.server
 
 import com.twitter.app.App
-import com.twitter.finagle.{Http, ListeningServer, NullServer, Service, param}
 import com.twitter.finagle.client.ClientRegistry
 import com.twitter.finagle.filter.ServerAdmissionControl
 import com.twitter.finagle.http.{HttpMuxer, Request, Response}
+import com.twitter.finagle.netty4.http.exp.Netty4Impl
 import com.twitter.finagle.server.ServerRegistry
 import com.twitter.finagle.stats.NullStatsReceiver
 import com.twitter.finagle.tracing.NullTracer
+import com.twitter.finagle.{Http, ListeningServer, NullServer, Service, param}
 import com.twitter.server.util.HttpUtils
 import com.twitter.server.view.{IndexView, NotFoundView}
 import com.twitter.util.registry.Library
@@ -187,6 +188,7 @@ trait AdminHttpServer { self: App =>
     }
     log.info(s"Serving admin http on ${adminPort()}")
     adminHttpServer = Http.server
+      .configured(Netty4Impl)
       .configured(param.Stats(NullStatsReceiver))
       .configured(param.Tracer(NullTracer))
       .configured(param.Monitor(loggingMonitor))

src/main/scala/com/twitter/server/ShadowAdminServer.scala

@@ -3,21 +3,15 @@ package com.twitter.server
 import com.twitter.app.App
 import com.twitter.concurrent.NamedPoolThreadFactory
 import com.twitter.finagle.http.{HttpMuxer, HttpMuxHandler}
-import com.twitter.finagle.netty3.Netty3Listener
+import com.twitter.finagle.netty4
+import com.twitter.finagle.netty4.http.exp.Netty4Impl
 import com.twitter.finagle.stats.NullStatsReceiver
 import com.twitter.finagle.tracing.NullTracer
 import com.twitter.finagle.util.LoadService
 import com.twitter.finagle.{Http, ListeningServer, NullServer, param}
+import io.netty.channel.nio.NioEventLoopGroup
 import java.net.InetSocketAddress
-import java.util.concurrent.Executors
 import java.util.logging.Logger
-import org.jboss.netty.channel.ServerChannelFactory
-import org.jboss.netty.channel.socket.nio.{NioWorkerPool, NioServerSocketChannelFactory}
-
-private object ShadowAdminServer {
-  val Executor = Executors.newCachedThreadPool(
-    new NamedPoolThreadFactory("twitter-server/netty3", true /*daemon*/))
-}
 
 /**
  * An admin http server which serves requests outside the default
@@ -31,14 +25,11 @@ private object ShadowAdminServer {
  * are an accurate proxy of server health.
  */
 trait ShadowAdminServer { self: App with AdminHttpServer =>
-  import ShadowAdminServer._
 
   @volatile protected var shadowHttpServer: ListeningServer = NullServer
   val shadowAdminPort = flag("shadow.admin.port", new InetSocketAddress(defaultHttpPort+1),
     "Shadow admin http server port")
 
-  def shadowWorkerPool: NioWorkerPool = new NioWorkerPool(Executor, 1)
-
   premain {
     val log = Logger.getLogger(getClass.getName)
     log.info(s"Serving BlackBox http server on port ${shadowAdminPort().getPort}")
@@ -54,15 +45,14 @@ trait ShadowAdminServer { self: App with AdminHttpServer =>
       case (muxer, h) => muxer.withHandler(h.pattern, h)
     }
 
-    val channelFactory: ServerChannelFactory =
-      new NioServerSocketChannelFactory(Executor, shadowWorkerPool) {
-        override def releaseExternalResources() = () // no-op
-      }
+    val shadowEventLoop = new NioEventLoopGroup(1 /*nThreads*/ ,
+      new NamedPoolThreadFactory("twitter-server/netty", makeDaemons = true))
 
     shadowHttpServer = Http.server
       .configured(param.Stats(NullStatsReceiver))
+      .configured(Netty4Impl)
       .configured(param.Tracer(NullTracer))
-      .configured(Netty3Listener.ChannelFactory(channelFactory))
+      .configured(netty4.param.WorkerPool(shadowEventLoop))
       .serve(shadowAdminPort(), muxer)
     closeOnExit(shadowHttpServer)
   }