From fa3b8040ebfedc721a538476be28a6217f1dec56 Mon Sep 17 00:00:00 2001 From: Aleksandar Prokopec Date: Thu, 7 Feb 2013 15:52:40 -0800 Subject: SI-6961 no structural sharing in list serialization Revert list serialization back to what it was in 2.9.x and before. Partial revert of a6fcd70b60 e234978dfd, which fixed SI-5374. The ListBuffer part of the fix remains in place. --- src/library/scala/collection/immutable/List.scala | 33 +++------- test/files/run/t5374.check | 6 -- test/files/run/t5374.scala | 76 ----------------------- 3 files changed, 9 insertions(+), 106 deletions(-) delete mode 100644 test/files/run/t5374.check delete mode 100644 test/files/run/t5374.scala diff --git a/src/library/scala/collection/immutable/List.scala b/src/library/scala/collection/immutable/List.scala index 55ac3995e9..9765e7c52f 100644 --- a/src/library/scala/collection/immutable/List.scala +++ b/src/library/scala/collection/immutable/List.scala @@ -55,6 +55,12 @@ import java.io._ * val shorter = mainList.tail // costs nothing as it uses the same 2::1::Nil instances as mainList * }}} * + * @note The functional list is characterized by persistence and structural sharing, thus offering considerable + * performance and space consumption benefits in some scenarios if used correctly. + * However, note that objects having multiple references into the same functional list (that is, + * objects that rely on structural sharing), will be serialized and deserialized with multiple lists, one for + * each reference to it. I.e. structural sharing is lost after serialization/deserialization. + * * @author Martin Odersky and others * @version 2.8 * @since 1.0 @@ -352,25 +358,8 @@ final case class ::[B](private var hd: B, private[scala] var tl: List[B]) extend override def tail : List[B] = tl override def isEmpty: Boolean = false - private def writeObject(out: ObjectOutputStream) { - out.writeObject(ListSerializeStart) // needed to differentiate with the legacy `::` serialization - out.writeObject(this.hd) - out.writeObject(this.tl) - } - private def readObject(in: ObjectInputStream) { - val obj = in.readObject() - if (obj == ListSerializeStart) { - this.hd = in.readObject().asInstanceOf[B] - this.tl = in.readObject().asInstanceOf[List[B]] - } else oldReadObject(in, obj) - } - - /* The oldReadObject method exists here for compatibility reasons. - * :: objects used to be serialized by serializing all the elements to - * the output stream directly, but this was broken (see SI-5374). - */ - private def oldReadObject(in: ObjectInputStream, firstObject: AnyRef) { + val firstObject = in.readObject() hd = firstObject.asInstanceOf[B] assert(hd != ListSerializeEnd) var current: ::[B] = this @@ -378,14 +367,14 @@ final case class ::[B](private var hd: B, private[scala] var tl: List[B]) extend case ListSerializeEnd => current.tl = Nil return - case a : Any => + case a => val list : ::[B] = new ::(a.asInstanceOf[B], Nil) current.tl = list current = list } } - private def oldWriteObject(out: ObjectOutputStream) { + private def writeObject(out: ObjectOutputStream) { var xs: List[B] = this while (!xs.isEmpty) { out.writeObject(xs.head); xs = xs.tail } out.writeObject(ListSerializeEnd) @@ -653,10 +642,6 @@ object List extends SeqFactory[List] { } } -/** Only used for list serialization */ -@SerialVersionUID(0L - 8287891243975527522L) -private[scala] case object ListSerializeStart - /** Only used for list serialization */ @SerialVersionUID(0L - 8476791151975527571L) private[scala] case object ListSerializeEnd diff --git a/test/files/run/t5374.check b/test/files/run/t5374.check deleted file mode 100644 index 6be88d77ec..0000000000 --- a/test/files/run/t5374.check +++ /dev/null @@ -1,6 +0,0 @@ -ListBuffer(1, 2, 3, 1) -ListBuffer(1, 2, 3, 1) -ListBuffer() -List(1, 2, 3, 4, 5) -List(1, 2, 3) -ok \ No newline at end of file diff --git a/test/files/run/t5374.scala b/test/files/run/t5374.scala deleted file mode 100644 index 9b1671e795..0000000000 --- a/test/files/run/t5374.scala +++ /dev/null @@ -1,76 +0,0 @@ - - - -import collection.mutable.ListBuffer -import java.io._ - - - -object Test { - - def main(args: Array[String]) { - ticketExample() - emptyListBuffer() - list() - legacyList() - objectWithMultipleLists() - } - - def inAndOut[T <: AnyRef](obj: T): T = { - val baos = new ByteArrayOutputStream - val oos = new ObjectOutputStream(baos) - oos.writeObject( obj ) - val bais = new ByteArrayInputStream( baos.toByteArray ) - val ois = new ObjectInputStream(bais) - ois.readObject.asInstanceOf[T] - } - - def ticketExample() { - val lb = inAndOut(ListBuffer(1, 2, 3)) - val lb2 = ListBuffer[Int]() ++= lb - - lb2 ++= List(1) - lb ++= List(1) - println(lb) - println(lb2) - } - - def emptyListBuffer() { - val lb = inAndOut(ListBuffer[Int]()) - - println(lb) - } - - def list() { - val l = inAndOut(List(1, 2, 3, 4, 5)) - - println(l) - } - - // this byte array corresponds to what List(1, 2, 3) used to be serialized to prior to this fix - val listBytes = Array[Byte](-84, -19, 0, 5, 115, 114, 0, 39, 115, 99, 97, 108, 97, 46, 99, 111, 108, 108, 101, 99, 116, 105, 111, 110, 46, 105, 109, 109, 117, 116, 97, 98, 108, 101, 46, 36, 99, 111, 108, 111, 110, 36, 99, 111, 108, 111, 110, -118, 92, 99, 91, -10, -40, -7, 109, 3, 0, 2, 76, 0, 43, 115, 99, 97, 108, 97, 36, 99, 111, 108, 108, 101, 99, 116, 105, 111, 110, 36, 105, 109, 109, 117, 116, 97, 98, 108, 101, 36, 36, 99, 111, 108, 111, 110, 36, 99, 111, 108, 111, 110, 36, 36, 104, 100, 116, 0, 18, 76, 106, 97, 118, 97, 47, 108, 97, 110, 103, 47, 79, 98, 106, 101, 99, 116, 59, 76, 0, 2, 116, 108, 116, 0, 33, 76, 115, 99, 97, 108, 97, 47, 99, 111, 108, 108, 101, 99, 116, 105, 111, 110, 47, 105, 109, 109, 117, 116, 97, 98, 108, 101, 47, 76, 105, 115, 116, 59, 120, 112, 115, 114, 0, 17, 106, 97, 118, 97, 46, 108, 97, 110, 103, 46, 73, 110, 116, 101, 103, 101, 114, 18, -30, -96, -92, -9, -127, -121, 56, 2, 0, 1, 73, 0, 5, 118, 97, 108, 117, 101, 120, 114, 0, 16, 106, 97, 118, 97, 46, 108, 97, 110, 103, 46, 78, 117, 109, 98, 101, 114, -122, -84, -107, 29, 11, -108, -32, -117, 2, 0, 0, 120, 112, 0, 0, 0, 1, 115, 113, 0, 126, 0, 4, 0, 0, 0, 2, 115, 113, 0, 126, 0, 4, 0, 0, 0, 3, 115, 114, 0, 44, 115, 99, 97, 108, 97, 46, 99, 111, 108, 108, 101, 99, 116, 105, 111, 110, 46, 105, 109, 109, 117, 116, 97, 98, 108, 101, 46, 76, 105, 115, 116, 83, 101, 114, 105, 97, 108, 105, 122, 101, 69, 110, 100, 36, -118, 92, 99, 91, -9, 83, 11, 109, 2, 0, 0, 120, 112, 120) - - def legacyList() { - val bais = new ByteArrayInputStream(listBytes) - val ois = new ObjectInputStream(bais) - val l = ois.readObject() - - println(l) - } - - class Foo extends Serializable { - val head = List(1, 2, 3) - val last = head.tail.tail - def structuralSharing: Boolean = head.tail.tail eq last - - assert(structuralSharing) - } - - def objectWithMultipleLists() { - val foo = inAndOut(new Foo) - - if (foo.structuralSharing) println("ok") - else println("no structural sharing") - } - -} -- cgit v1.2.3