[TINKERPOP-1230] Serialising lambdas for RemoteGraph

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Done
• Affects Version/s: 3.1.1-incubating
• Fix Version/s: 3.2.2
• Component/s: driver, server
• Assignee: Marko A. Rodriguez
• Reporter: Michael Pollmeier
• Created: 21/Mar/16 21:33
• Updated: 01/Sep/16 18:09
• Resolved: 27/Aug/16 11:22

Description

I just made an attempt to serialise lambdas and send them via the RemoteGraph. I didn't quite get there, but wanted to share my findings:

• it's possible to serialise lambdas on the jvm by just extending `Serializable`:
  http://stackoverflow.com/questions/22807912/how-to-serialize-a-lambda/22808112#22808112

• sending a normal predicate doesn't work (this is a Scala REPL but it should be pretty easy to convert this to java/groovy)
  val g = RemoteGraph.open("conf/remote-graph.properties").traversal()
  val pred1 = new java.util.function.Predicate[Traverser[Vertex]] { def test(v: Traverser[Vertex]) = true }

  g.V().filter(pred1).toList
  // java.lang.RuntimeException: java.io.NotSerializableException: $anon$1
  // on server: nothing

• simply adding Serializable let's us send it over the wire, but the server doesn't deserialise it
  val pred2 = new java.util.function.Predicate[Traverser[Vertex]] with Serializable { def test(v: Traverser[Vertex]) = true }

  g.V().filter(pred2).toList
  // on server: [WARN] OpExecutorHandler - Could not deserialize the Traversal instance
  org.apache.tinkerpop.gremlin.server.op.OpProcessorException: Could not deserialize the Traversal instance
  at org.apache.tinkerpop.gremlin.server.op.traversal.TraversalOpProcessor.iterateOp(TraversalOpProcessor.java:135)
  at org.apache.tinkerpop.gremlin.server.handler.OpExecutorHandler.channelRead0(OpExecutorHandler.java:68)
  // on client: org.apache.tinkerpop.gremlin.driver.exception.ResponseException: $anon$1

Issue Links

• is related to: TINKERPOP-1278 Implement Gremlin-Python and general purpose language variant test infrastructure
• relates to: TINKERPOP-575 Implement RemoteGraph