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author | Jason Zaugg <jzaugg@gmail.com> | 2015-05-12 15:28:35 +1000 |
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committer | Jason Zaugg <jzaugg@gmail.com> | 2015-05-17 19:30:10 +1000 |
commit | afa2ff9f76123ab982dc5bb2f1110bb58e75c68c (patch) | |
tree | 90f720ed31e91d64beaa3031de7394fd545c27ea /test/files/run/lambda-serialization.scala | |
parent | 6ad9b44b27ede70ec723204bd80361d60f448c1a (diff) | |
download | scala-afa2ff9f76123ab982dc5bb2f1110bb58e75c68c.tar.gz scala-afa2ff9f76123ab982dc5bb2f1110bb58e75c68c.tar.bz2 scala-afa2ff9f76123ab982dc5bb2f1110bb58e75c68c.zip |
[indylambda] Support lambda {de}serialization
To support serialization, we use the alternative lambda metafactory
that lets us specify that our anonymous functions should extend the
marker interface `scala.Serializable`. They will also have a
`writeObject` method added that implements the serialization proxy
pattern using `j.l.invoke.SerializedLamba`.
To support deserialization, we synthesize a `$deserializeLamba$`
method in each class with lambdas. This will be called reflectively by
`SerializedLambda#readResolve`. This method in turn delegates to
`LambdaDeserializer`, currently defined [1] in `scala-java8-compat`,
that uses `LambdaMetafactory` to spin up the anonymous class and
instantiate it with the deserialized environment.
Note: `LambdaDeserializer` can reuses the anonymous class on subsequent
deserializations of a given lambda, in the same spirit as an
invokedynamic call site only spins up the class on the first time
it is run. But first we'll need to host a cache in a static field
of each lambda hosting class. This is noted as a TODO and a failing
test, and will be updated in the next commit.
`LambdaDeserializer` will be moved into our standard library in
the 2.12.x branch, where we can introduce dependencies on the
Java 8 standard library.
The enclosed test cases must be manually run with indylambda enabled.
Once we enable indylambda by default on 2.12.x, the test will
actually test the new feature.
```
% echo $INDYLAMBDA
-Ydelambdafy:method -Ybackend:GenBCode -target:jvm-1.8 -classpath .:scala-java8-compat_2.11-0.5.0-SNAPSHOT.jar
% qscala $INDYLAMBDA -e "println((() => 42).getClass)"
class Main$$anon$1$$Lambda$1/1183231938
% qscala $INDYLAMBDA -e "assert(classOf[scala.Serializable].isInstance(() => 42))"
% qscalac $INDYLAMBDA test/files/run/lambda-serialization.scala && qscala $INDYLAMBDA Test
```
This commit contains a few minor refactorings to the code that
generates the invokedynamic instruction to use more meaningful
names and to reuse Java signature generation code in ASM rather
than the DIY approach.
[1] https://github.com/scala/scala-java8-compat/pull/37
Diffstat (limited to 'test/files/run/lambda-serialization.scala')
-rw-r--r-- | test/files/run/lambda-serialization.scala | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/test/files/run/lambda-serialization.scala b/test/files/run/lambda-serialization.scala new file mode 100644 index 0000000000..46b26d7c5e --- /dev/null +++ b/test/files/run/lambda-serialization.scala @@ -0,0 +1,35 @@ +import java.io.{ByteArrayInputStream, ObjectInputStream, ObjectOutputStream, ByteArrayOutputStream} + +object Test { + def main(args: Array[String]): Unit = { + roundTrip + } + + def roundTrip(): Unit = { + val c = new Capture("Capture") + val lambda = (p: Param) => ("a", p, c) + val reconstituted1 = serializeDeserialize(lambda).asInstanceOf[Object => Any] + val p = new Param + assert(reconstituted1.apply(p) == ("a", p, c)) + val reconstituted2 = serializeDeserialize(lambda).asInstanceOf[Object => Any] + assert(reconstituted1.getClass == reconstituted2.getClass) + + val reconstituted3 = serializeDeserialize(reconstituted1) + assert(reconstituted3.apply(p) == ("a", p, c)) + + val specializedLambda = (p: Int) => List(p, c).length + assert(serializeDeserialize(specializedLambda).apply(42) == 2) + assert(serializeDeserialize(serializeDeserialize(specializedLambda)).apply(42) == 2) + } + + def serializeDeserialize[T <: AnyRef](obj: T) = { + val buffer = new ByteArrayOutputStream + val out = new ObjectOutputStream(buffer) + out.writeObject(obj) + val in = new ObjectInputStream(new ByteArrayInputStream(buffer.toByteArray)) + in.readObject.asInstanceOf[T] + } +} + +case class Capture(s: String) extends Serializable +class Param |