Github user zsxwing commented on a diff in the pull request:
https://github.com/apache/spark/pull/6457#discussion_r39752618
--- Diff: core/src/main/scala/org/apache/spark/rpc/netty/Inbox.scala ---
@@ -0,0 +1,229 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.rpc.netty
+
+import java.util.LinkedList
+import javax.annotation.concurrent.GuardedBy
+
+import scala.util.control.NonFatal
+
+import org.apache.spark.{Logging, SparkException}
+import org.apache.spark.rpc.{RpcAddress, RpcEndpoint,
ThreadSafeRpcEndpoint}
+
+private[netty] sealed trait InboxMessage
+
+private[netty] case class ContentMessage(
+ senderAddress: RpcAddress,
+ content: Any,
+ needReply: Boolean,
+ context: NettyRpcCallContext) extends InboxMessage
+
+/**
+ * A message type that will be posted to all registered [[RpcEndpoint]]
+ */
+private[netty] sealed trait BroadcastMessage extends InboxMessage
+
+private[netty] case object OnStart extends InboxMessage
+
+private[netty] case object OnStop extends InboxMessage
+
+private[netty] case class Associated(remoteAddress: RpcAddress) extends
BroadcastMessage
+
+/**
+ * A broadcast message that indicates
+ */
+private[netty] case class Disassociated(remoteAddress: RpcAddress) extends
BroadcastMessage
+
+/**
+ * A broadcast message that indicates a network error
+ */
+private[netty] case class AssociationError(cause: Throwable,
remoteAddress: RpcAddress)
+ extends BroadcastMessage
+
+/**
+ * A inbox that stores messages for an [[RpcEndpoint]] and posts messages
to it thread-safely.
+ * @param endpointRef
+ * @param endpoint
+ */
+private[netty] class Inbox(
+ val endpointRef: NettyRpcEndpointRef,
+ val endpoint: RpcEndpoint) extends Logging {
+
+ private val supportConcurrent =
!endpoint.isInstanceOf[ThreadSafeRpcEndpoint]
+
+ @GuardedBy("this")
+ protected val messages = new LinkedList[InboxMessage]()
+
+ @GuardedBy("this")
+ private var stopped = false
+
+ @GuardedBy("this")
+ private var enableConcurrent = false
+
+ @GuardedBy("this")
+ private var workerCount = 0
+
+ // OnStart should be the first message to process
+ synchronized {
+ messages.add(OnStart)
+ }
+
+ def process(dispatcher: Dispatcher): Boolean = {
+ var message: InboxMessage = null
+ synchronized {
+ if (!enableConcurrent && workerCount != 0) {
+ return false
+ }
+ message = messages.poll()
+ if (message != null) {
+ workerCount += 1
+ } else {
+ return false
+ }
+ }
+ var skipFinally = false
+ try {
+ while (true) {
+ safelyCall(endpoint) {
+ message match {
+ case ContentMessage(_sender, content, needReply, context) =>
+ val pf: PartialFunction[Any, Unit] =
+ if (needReply) {
+ endpoint.receiveAndReply(context)
+ } else {
+ endpoint.receive
+ }
+ try {
+ pf.applyOrElse[Any, Unit](content, { msg =>
+ throw new SparkException(s"Unmatched message $message
from ${_sender}")
+ })
+ if (!needReply) {
+ context.finish()
+ }
+ } catch {
+ case NonFatal(e) =>
+ if (needReply) {
+ // If the sender asks a reply, we should send the
error back to the sender
+ context.sendFailure(e)
+ } else {
+ context.finish()
+ throw e
+ }
+ }
+
+ case OnStart => {
+ endpoint.onStart()
+ if (supportConcurrent) {
+ synchronized {
+ enableConcurrent = true
+ }
+ }
+ }
+ case OnStop =>
+ dispatcher.removeRpcEndpointRef(endpoint)
+ endpoint.onStop()
+ assert(isEmpty, "OnStop should be the last message")
+ return true
+ case Associated(remoteAddress) =>
+ endpoint.onConnected(remoteAddress)
+ case Disassociated(remoteAddress) =>
+ endpoint.onDisconnected(remoteAddress)
+ case AssociationError(cause, remoteAddress) =>
+ endpoint.onNetworkError(cause, remoteAddress)
+ }
+ }
+
+ synchronized {
+ // "enableConcurrent" will be set to false after `onStop` is
called, so we should check it
+ // every time.
+ if (!enableConcurrent && workerCount != 1) {
+ // If we are not the only one worker, exit
+ skipFinally = true
+ workerCount -= 1
+ return false
+ }
+ message = messages.poll()
+ if (message == null) {
+ skipFinally = true
+ workerCount -= 1
+ return false
+ }
+ }
+ }
+ return false
+ } finally {
+ if (!skipFinally) {
+ // Reset `workerCount` if some exception is thrown.
+ synchronized {
+ workerCount -= 1
+ }
+ }
+ }
+ }
+
+ def post(message: InboxMessage): Unit = {
+ val dropped =
+ synchronized {
+ if (stopped) {
+ // We already put "OnStop" into "messages", so we should drop
further messages
+ true
+ } else {
+ messages.add(message)
+ false
+ }
+ }
+ if (dropped) {
+ onDrop()
+ }
+ }
+
+ def stop(): Unit = synchronized {
+ // The following codes should be in `synchronized` so that we can make
sure "OnStop" is the last
+ // message
+ if (!stopped) {
+ // We should disable concurrent here. Then when RpcEndpoint.onStop
is called, it's the only
+ // thread that is processing messages. So `RpcEndpoint.onStop` can
release its resources
+ // safely.
+ enableConcurrent = false
+ stopped = true
+ messages.add(OnStop)
+ // Note: The concurrent events in messages will be processed one by
one.
+ }
+ }
+
+ protected def onDrop(message: Any): Unit = {
+ logWarning(s"Drop ${message} because $endpointRef is stopped")
+ }
+
+ def isEmpty: Boolean = messages.isEmpty
+
+ protected def safelyCall(endpoint: RpcEndpoint)(action: => Unit): Unit =
{
--- End diff --
I prefer to keep this method. I feel `process` is a bit long.
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