Github user vanzin commented on a diff in the pull request:
https://github.com/apache/spark/pull/6457#discussion_r35347758
--- Diff: core/src/main/scala/org/apache/spark/rpc/netty/Inbox.scala ---
@@ -0,0 +1,258 @@
+/*
+ * 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.concurrent.ConcurrentLinkedQueue
+
+import scala.util.control.NonFatal
+
+import org.apache.spark.{SparkException, Logging}
+import org.apache.spark.rpc.{ThreadSafeRpcEndpoint, RpcAddress,
RpcEndpoint}
+
+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
+
+private[netty] abstract class Inbox(
+ val endpointRef: NettyRpcEndpointRef, val endpoint: RpcEndpoint)
extends Logging {
+
+ protected val messages = new ConcurrentLinkedQueue[InboxMessage]()
+
+ /**
+ * Process stored messages. Return `true` if the `Inbox` is already
stopped, and the caller will
+ * release all resources used by the `Inbox`.
+ */
+ def process(dispatcher: Dispatcher): Boolean
+
+ def post(message: InboxMessage): Unit
+
+ protected def onDrop(message: Any): Unit = {
+ logWarning(s"Drop ${message} because $endpointRef is stopped")
+ }
+
+ def stop(): Unit
+
+ protected def safelyCall(endpoint: RpcEndpoint)(action: => Unit): Unit =
{
+ try {
+ action
+ } catch {
+ case NonFatal(e) => {
+ try {
+ endpoint.onError(e)
+ } catch {
+ case NonFatal(e) => logError(s"Ignore error: ${e.getMessage}", e)
+ }
+ }
+ }
+ }
+
+ def isEmpty: Boolean = messages.isEmpty
+
+}
+
+/**
+ * A inbox that stores messages for an [[RpcEndpoint]] and posts messages
to it thread-safely.
+ * @param endpointRef
+ * @param endpoint
+ */
+private[netty] class ThreadSafeInbox(
+ endpointRef: NettyRpcEndpointRef,
+ override val endpoint: ThreadSafeRpcEndpoint) extends
Inbox(endpointRef, endpoint) {
+
+ private val _endpoint = endpoint.asInstanceOf[ThreadSafeRpcEndpoint]
+
+ // protected by "this"
+ private var stopped = false
+
+ // OnStart should be the first message to process
+ messages.add(OnStart)
+
+ override def process(dispatcher: Dispatcher): Boolean = {
+ var exit = false
+ var message = messages.poll()
+ while (message != null) {
+ 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.asInstanceOf[ThreadSafeRpcEndpoint].onStart()
+ }
+ case OnStop =>
+ dispatcher.unregisterRpcEndpoint(endpointRef.name)
+ _endpoint.onStop()
+ assert(isEmpty, "OnStop should be the last message")
+ exit = true
+ case Associated(remoteAddress) =>
+ endpoint.onConnected(remoteAddress)
+ case Disassociated(remoteAddress) =>
+ endpoint.onDisconnected(remoteAddress)
+ case AssociationError(cause, remoteAddress) =>
+ endpoint.onNetworkError(cause, remoteAddress)
+ }
+ }
+ message = messages.poll()
+ }
+ exit
+ }
+
+ override 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()
+ }
+ }
+
+ override def stop(): Unit = synchronized {
+ // The following codes should be in `synchronized` so that we can make
sure "OnStop" is the last
+ // message
+ if (!stopped) {
+ stopped = true
+ messages.add(OnStop)
+ }
+ }
+}
+
+/**
+ * A inbox that stores messages for an [[RpcEndpoint]] and posts messages
to it concurrently.
+ * @param endpointRef
+ * @param endpoint
+ */
+private[netty] class ConcurrentInbox(
--- End diff --
So I'm reading this code and I'm starting to think that you don't need two
inboxes. The thread-safety guarantees for endpoints are not a result of this
inbox being "thread-safe" in some way, but because the message dispatcher makes
sure only one thread is dispatching messages for a `ThreadSafeEndpoint` at a
time.
I think you could get away with a single inbox implementation for both
cases, and leave the "single thread dispatching" semantics to the `MessageLoop`
class. For example, you could have an `AtomicBoolean` for each thread-safe
endpoint that could be used as cheap locks.
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