968f75f6af
closures. This enables using Kryo as the closure serializer.
223 lines
7.3 KiB
Scala
223 lines
7.3 KiB
Scala
package spark
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import java.io._
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import java.nio.ByteBuffer
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import java.nio.channels.Channels
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import scala.collection.immutable
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import scala.collection.mutable
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import com.esotericsoftware.kryo._
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import com.esotericsoftware.kryo.{Serializer => KSerializer}
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import com.esotericsoftware.kryo.serialize.ClassSerializer
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import de.javakaffee.kryoserializers.KryoReflectionFactorySupport
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/**
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* Zig-zag encoder used to write object sizes to serialization streams.
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* Based on Kryo's integer encoder.
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*/
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object ZigZag {
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def writeInt(n: Int, out: OutputStream) {
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var value = n
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if ((value & ~0x7F) == 0) {
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out.write(value)
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return
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}
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out.write(((value & 0x7F) | 0x80))
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value >>>= 7
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if ((value & ~0x7F) == 0) {
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out.write(value)
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return
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}
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out.write(((value & 0x7F) | 0x80))
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value >>>= 7
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if ((value & ~0x7F) == 0) {
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out.write(value)
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return
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}
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out.write(((value & 0x7F) | 0x80))
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value >>>= 7
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if ((value & ~0x7F) == 0) {
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out.write(value)
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return
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}
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out.write(((value & 0x7F) | 0x80))
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value >>>= 7
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out.write(value)
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}
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def readInt(in: InputStream): Int = {
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var offset = 0
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var result = 0
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while (offset < 32) {
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val b = in.read()
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if (b == -1) {
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throw new EOFException("End of stream")
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}
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result |= ((b & 0x7F) << offset)
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if ((b & 0x80) == 0) {
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return result
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}
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offset += 7
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}
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throw new SparkException("Malformed zigzag-encoded integer")
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}
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}
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class KryoSerializationStream(kryo: Kryo, buf: ByteBuffer, out: OutputStream)
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extends SerializationStream {
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val channel = Channels.newChannel(out)
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def writeObject[T](t: T) {
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kryo.writeClassAndObject(buf, t)
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ZigZag.writeInt(buf.position(), out)
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buf.flip()
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channel.write(buf)
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buf.clear()
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}
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def flush() { out.flush() }
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def close() { out.close() }
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}
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class KryoDeserializationStream(buf: ObjectBuffer, in: InputStream)
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extends DeserializationStream {
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def readObject[T](): T = {
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val len = ZigZag.readInt(in)
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buf.readClassAndObject(in, len).asInstanceOf[T]
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}
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def close() { in.close() }
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}
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class KryoSerializerInstance(ks: KryoSerializer) extends SerializerInstance {
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val buf = ks.threadBuf.get()
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def serialize[T](t: T): Array[Byte] = {
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buf.writeClassAndObject(t)
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}
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def deserialize[T](bytes: Array[Byte]): T = {
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buf.readClassAndObject(bytes).asInstanceOf[T]
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}
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def deserialize[T](bytes: Array[Byte], loader: ClassLoader): T = {
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val oldClassLoader = ks.kryo.getClassLoader
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ks.kryo.setClassLoader(loader)
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val obj = buf.readClassAndObject(bytes).asInstanceOf[T]
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ks.kryo.setClassLoader(oldClassLoader)
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obj
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}
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def outputStream(s: OutputStream): SerializationStream = {
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new KryoSerializationStream(ks.kryo, ks.threadByteBuf.get(), s)
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}
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def inputStream(s: InputStream): DeserializationStream = {
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new KryoDeserializationStream(buf, s)
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}
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}
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// Used by clients to register their own classes
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trait KryoRegistrator {
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def registerClasses(kryo: Kryo): Unit
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}
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class KryoSerializer extends Serializer with Logging {
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val kryo = createKryo()
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val bufferSize =
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System.getProperty("spark.kryoserializer.buffer.mb", "2").toInt * 1024 * 1024
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val threadBuf = new ThreadLocal[ObjectBuffer] {
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override def initialValue = new ObjectBuffer(kryo, bufferSize)
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}
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val threadByteBuf = new ThreadLocal[ByteBuffer] {
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override def initialValue = ByteBuffer.allocate(bufferSize)
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}
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def createKryo(): Kryo = {
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// This is used so we can serialize/deserialize objects without a zero-arg
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// constructor.
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val kryo = new KryoReflectionFactorySupport()
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// Register some commonly used classes
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val toRegister: Seq[AnyRef] = Seq(
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// Arrays
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Array(1), Array(1.0), Array(1.0f), Array(1L), Array(""), Array(("", "")),
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Array(new java.lang.Object), Array(1.toByte), Array(true), Array('c'),
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// Specialized Tuple2s
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("", ""), (1, 1), (1.0, 1.0), (1L, 1L),
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(1, 1.0), (1.0, 1), (1L, 1.0), (1.0, 1L), (1, 1L), (1L, 1),
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// Scala collections
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List(1), mutable.ArrayBuffer(1),
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// Options and Either
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Some(1), Left(1), Right(1),
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// Higher-dimensional tuples
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(1, 1, 1), (1, 1, 1, 1), (1, 1, 1, 1, 1)
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)
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for (obj <- toRegister) {
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kryo.register(obj.getClass)
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}
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// Register the following classes for passing closures.
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kryo.register(classOf[Class[_]], new ClassSerializer(kryo))
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kryo.setRegistrationOptional(true)
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// Register some commonly used Scala singleton objects. Because these
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// are singletons, we must return the exact same local object when we
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// deserialize rather than returning a clone as FieldSerializer would.
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class SingletonSerializer(obj: AnyRef) extends KSerializer {
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override def writeObjectData(buf: ByteBuffer, obj: AnyRef) {}
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override def readObjectData[T](buf: ByteBuffer, cls: Class[T]): T = obj.asInstanceOf[T]
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}
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kryo.register(None.getClass, new SingletonSerializer(None))
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kryo.register(Nil.getClass, new SingletonSerializer(Nil))
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// Register maps with a special serializer since they have complex internal structure
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class ScalaMapSerializer(buildMap: Array[(Any, Any)] => scala.collection.Map[Any, Any])
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extends KSerializer {
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override def writeObjectData(buf: ByteBuffer, obj: AnyRef) {
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val map = obj.asInstanceOf[scala.collection.Map[Any, Any]]
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kryo.writeObject(buf, map.size.asInstanceOf[java.lang.Integer])
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for ((k, v) <- map) {
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kryo.writeClassAndObject(buf, k)
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kryo.writeClassAndObject(buf, v)
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}
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}
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override def readObjectData[T](buf: ByteBuffer, cls: Class[T]): T = {
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val size = kryo.readObject(buf, classOf[java.lang.Integer]).intValue
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val elems = new Array[(Any, Any)](size)
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for (i <- 0 until size)
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elems(i) = (kryo.readClassAndObject(buf), kryo.readClassAndObject(buf))
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buildMap(elems).asInstanceOf[T]
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}
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}
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kryo.register(mutable.HashMap().getClass, new ScalaMapSerializer(mutable.HashMap() ++ _))
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// TODO: add support for immutable maps too; this is more annoying because there are many
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// subclasses of immutable.Map for small maps (with <= 4 entries)
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val map1 = Map[Any, Any](1 -> 1)
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val map2 = Map[Any, Any](1 -> 1, 2 -> 2)
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val map3 = Map[Any, Any](1 -> 1, 2 -> 2, 3 -> 3)
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val map4 = Map[Any, Any](1 -> 1, 2 -> 2, 3 -> 3, 4 -> 4)
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val map5 = Map[Any, Any](1 -> 1, 2 -> 2, 3 -> 3, 4 -> 4, 5 -> 5)
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kryo.register(map1.getClass, new ScalaMapSerializer(mutable.HashMap() ++ _ toMap))
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kryo.register(map2.getClass, new ScalaMapSerializer(mutable.HashMap() ++ _ toMap))
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kryo.register(map3.getClass, new ScalaMapSerializer(mutable.HashMap() ++ _ toMap))
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kryo.register(map4.getClass, new ScalaMapSerializer(mutable.HashMap() ++ _ toMap))
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kryo.register(map5.getClass, new ScalaMapSerializer(mutable.HashMap() ++ _ toMap))
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// Allow the user to register their own classes by setting spark.kryo.registrator
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val regCls = System.getProperty("spark.kryo.registrator")
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if (regCls != null) {
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logInfo("Running user registrator: " + regCls)
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val reg = Class.forName(regCls).newInstance().asInstanceOf[KryoRegistrator]
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reg.registerClasses(kryo)
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}
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kryo
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}
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def newInstance(): SerializerInstance = new KryoSerializerInstance(this)
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}
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