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/*
* 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.api.r
import java.io.{DataOutputStream, File, FileOutputStream, IOException}
import java.net.{InetAddress, InetSocketAddress, ServerSocket}
import java.util.concurrent.TimeUnit
import io.netty.bootstrap.ServerBootstrap
import io.netty.channel.{ChannelFuture, ChannelInitializer, ChannelOption, EventLoopGroup}
import io.netty.channel.nio.NioEventLoopGroup
import io.netty.channel.socket.SocketChannel
import io.netty.channel.socket.nio.NioServerSocketChannel
import io.netty.handler.codec.LengthFieldBasedFrameDecoder
import io.netty.handler.codec.bytes.{ByteArrayDecoder, ByteArrayEncoder}
import io.netty.handler.timeout.ReadTimeoutHandler
import org.apache.spark.SparkConf
import org.apache.spark.internal.Logging
/**
* Netty-based backend server that is used to communicate between R and Java.
*/
private[spark] class RBackend {
private[this] var channelFuture: ChannelFuture = null
private[this] var bootstrap: ServerBootstrap = null
private[this] var bossGroup: EventLoopGroup = null
def init(): Int = {
val conf = new SparkConf()
val backendConnectionTimeout = conf.getInt(
"spark.r.backendConnectionTimeout", SparkRDefaults.DEFAULT_CONNECTION_TIMEOUT)
bossGroup = new NioEventLoopGroup(
conf.getInt("spark.r.numRBackendThreads", SparkRDefaults.DEFAULT_NUM_RBACKEND_THREADS))
val workerGroup = bossGroup
val handler = new RBackendHandler(this)
bootstrap = new ServerBootstrap()
.group(bossGroup, workerGroup)
.channel(classOf[NioServerSocketChannel])
bootstrap.childHandler(new ChannelInitializer[SocketChannel]() {
def initChannel(ch: SocketChannel): Unit = {
ch.pipeline()
.addLast("encoder", new ByteArrayEncoder())
.addLast("frameDecoder",
// maxFrameLength = 2G
// lengthFieldOffset = 0
// lengthFieldLength = 4
// lengthAdjustment = 0
// initialBytesToStrip = 4, i.e. strip out the length field itself
new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4))
.addLast("decoder", new ByteArrayDecoder())
.addLast("readTimeoutHandler", new ReadTimeoutHandler(backendConnectionTimeout))
.addLast("handler", handler)
}
})
channelFuture = bootstrap.bind(new InetSocketAddress("localhost", 0))
channelFuture.syncUninterruptibly()
channelFuture.channel().localAddress().asInstanceOf[InetSocketAddress].getPort()
}
def run(): Unit = {
channelFuture.channel.closeFuture().syncUninterruptibly()
}
def close(): Unit = {
if (channelFuture != null) {
// close is a local operation and should finish within milliseconds; timeout just to be safe
channelFuture.channel().close().awaitUninterruptibly(10, TimeUnit.SECONDS)
channelFuture = null
}
if (bootstrap != null && bootstrap.group() != null) {
bootstrap.group().shutdownGracefully()
}
if (bootstrap != null && bootstrap.childGroup() != null) {
bootstrap.childGroup().shutdownGracefully()
}
bootstrap = null
}
}
private[spark] object RBackend extends Logging {
initializeLogIfNecessary(true)
def main(args: Array[String]): Unit = {
if (args.length < 1) {
// scalastyle:off println
System.err.println("Usage: RBackend <tempFilePath>")
// scalastyle:on println
System.exit(-1)
}
val sparkRBackend = new RBackend()
try {
// bind to random port
val boundPort = sparkRBackend.init()
val serverSocket = new ServerSocket(0, 1, InetAddress.getByName("localhost"))
val listenPort = serverSocket.getLocalPort()
// Connection timeout is set by socket client. To make it configurable we will pass the
// timeout value to client inside the temp file
val conf = new SparkConf()
val backendConnectionTimeout = conf.getInt(
"spark.r.backendConnectionTimeout", SparkRDefaults.DEFAULT_CONNECTION_TIMEOUT)
// tell the R process via temporary file
val path = args(0)
val f = new File(path + ".tmp")
val dos = new DataOutputStream(new FileOutputStream(f))
dos.writeInt(boundPort)
dos.writeInt(listenPort)
SerDe.writeString(dos, RUtils.rPackages.getOrElse(""))
dos.writeInt(backendConnectionTimeout)
dos.close()
f.renameTo(new File(path))
// wait for the end of stdin, then exit
new Thread("wait for socket to close") {
setDaemon(true)
override def run(): Unit = {
// any un-catched exception will also shutdown JVM
val buf = new Array[Byte](1024)
// shutdown JVM if R does not connect back in 10 seconds
serverSocket.setSoTimeout(10000)
try {
val inSocket = serverSocket.accept()
serverSocket.close()
// wait for the end of socket, closed if R process die
inSocket.getInputStream().read(buf)
} finally {
sparkRBackend.close()
System.exit(0)
}
}
}.start()
sparkRBackend.run()
} catch {
case e: IOException =>
logError("Server shutting down: failed with exception ", e)
sparkRBackend.close()
System.exit(1)
}
System.exit(0)
}
}
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