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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.serializer
import java.io.{EOFException, InputStream, OutputStream}
import java.nio.ByteBuffer
import com.esotericsoftware.kryo.{Kryo, KryoException}
import com.esotericsoftware.kryo.io.{Input => KryoInput, Output => KryoOutput}
import com.esotericsoftware.kryo.serializers.{JavaSerializer => KryoJavaSerializer}
import com.twitter.chill.{AllScalaRegistrar, EmptyScalaKryoInstantiator}
import org.apache.spark._
import org.apache.spark.broadcast.HttpBroadcast
import org.apache.spark.scheduler.MapStatus
import org.apache.spark.storage._
import org.apache.spark.storage.{GetBlock, GotBlock, PutBlock}
/**
* A Spark serializer that uses the [[https://code.google.com/p/kryo/ Kryo serialization library]].
*
* Note that this serializer is not guaranteed to be wire-compatible across different versions of
* Spark. It is intended to be used to serialize/de-serialize data within a single
* Spark application.
*/
class KryoSerializer(conf: SparkConf)
extends org.apache.spark.serializer.Serializer
with Logging
with Serializable {
private val bufferSize = conf.getInt("spark.kryoserializer.buffer.mb", 2) * 1024 * 1024
private val referenceTracking = conf.getBoolean("spark.kryo.referenceTracking", true)
private val registrator = conf.getOption("spark.kryo.registrator")
def newKryoOutput() = new KryoOutput(bufferSize)
def newKryo(): Kryo = {
val instantiator = new EmptyScalaKryoInstantiator
val kryo = instantiator.newKryo()
val classLoader = Thread.currentThread.getContextClassLoader
// Allow disabling Kryo reference tracking if user knows their object graphs don't have loops.
// Do this before we invoke the user registrator so the user registrator can override this.
kryo.setReferences(referenceTracking)
for (cls <- KryoSerializer.toRegister) kryo.register(cls)
// Allow sending SerializableWritable
kryo.register(classOf[SerializableWritable[_]], new KryoJavaSerializer())
kryo.register(classOf[HttpBroadcast[_]], new KryoJavaSerializer())
// Allow the user to register their own classes by setting spark.kryo.registrator
try {
for (regCls <- registrator) {
logDebug("Running user registrator: " + regCls)
val reg = Class.forName(regCls, true, classLoader).newInstance()
.asInstanceOf[KryoRegistrator]
reg.registerClasses(kryo)
}
} catch {
case e: Exception => logError("Failed to run spark.kryo.registrator", e)
}
// Register Chill's classes; we do this after our ranges and the user's own classes to let
// our code override the generic serialziers in Chill for things like Seq
new AllScalaRegistrar().apply(kryo)
kryo.setClassLoader(classLoader)
kryo
}
def newInstance(): SerializerInstance = {
new KryoSerializerInstance(this)
}
}
private[spark]
class KryoSerializationStream(kryo: Kryo, outStream: OutputStream) extends SerializationStream {
val output = new KryoOutput(outStream)
def writeObject[T](t: T): SerializationStream = {
kryo.writeClassAndObject(output, t)
this
}
def flush() { output.flush() }
def close() { output.close() }
}
private[spark]
class KryoDeserializationStream(kryo: Kryo, inStream: InputStream) extends DeserializationStream {
val input = new KryoInput(inStream)
def readObject[T](): T = {
try {
kryo.readClassAndObject(input).asInstanceOf[T]
} catch {
// DeserializationStream uses the EOF exception to indicate stopping condition.
case e: KryoException if e.getMessage.toLowerCase.contains("buffer underflow") =>
throw new EOFException
}
}
def close() {
// Kryo's Input automatically closes the input stream it is using.
input.close()
}
}
private[spark] class KryoSerializerInstance(ks: KryoSerializer) extends SerializerInstance {
val kryo = ks.newKryo()
// Make these lazy vals to avoid creating a buffer unless we use them
lazy val output = ks.newKryoOutput()
lazy val input = new KryoInput()
def serialize[T](t: T): ByteBuffer = {
output.clear()
kryo.writeClassAndObject(output, t)
ByteBuffer.wrap(output.toBytes)
}
def deserialize[T](bytes: ByteBuffer): T = {
input.setBuffer(bytes.array)
kryo.readClassAndObject(input).asInstanceOf[T]
}
def deserialize[T](bytes: ByteBuffer, loader: ClassLoader): T = {
val oldClassLoader = kryo.getClassLoader
kryo.setClassLoader(loader)
input.setBuffer(bytes.array)
val obj = kryo.readClassAndObject(input).asInstanceOf[T]
kryo.setClassLoader(oldClassLoader)
obj
}
def serializeStream(s: OutputStream): SerializationStream = {
new KryoSerializationStream(kryo, s)
}
def deserializeStream(s: InputStream): DeserializationStream = {
new KryoDeserializationStream(kryo, s)
}
}
/**
* Interface implemented by clients to register their classes with Kryo when using Kryo
* serialization.
*/
trait KryoRegistrator {
def registerClasses(kryo: Kryo)
}
private[serializer] object KryoSerializer {
// Commonly used classes.
private val toRegister: Seq[Class[_]] = Seq(
ByteBuffer.allocate(1).getClass,
classOf[StorageLevel],
classOf[PutBlock],
classOf[GotBlock],
classOf[GetBlock],
classOf[MapStatus],
classOf[BlockManagerId],
classOf[Array[Byte]],
(1 to 10).getClass,
(1 until 10).getClass,
(1L to 10L).getClass,
(1L until 10L).getClass
)
}
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