java - TinkerPop Gremlin How to serialize Predicate passed in Until 步骤

Question

我有一个遍历，我需要重复遍历直到找不到更多新边。在 gremlin console/groovy 中，我通过传递一个始终返回 false 的 lambda 来实现这一点。

g.V(7).
  repeat(out().not(hasLabel('region', 'business')).simplePath()).
  until(outE().count().is(0)).
  repeat(both().not(hasLabel('region', 'business')).dedup()).
  emit().until{t -> false}.
  where(hasLabel('account'))

当我从 Java 应用程序尝试相同的方法并连接到 AWS Neptune 实例时，我收到一个异常，指出无法将命令发送到服务器 ...

GraphTraversal t =
    g.V(uid).union(__.identity(),
        __.repeat(__.out().not(__.hasLabel("region", "business")).simplePath()).
            until(__.outE().limit(1).count().is(0)).
            repeat(__.both().not(__.hasLabel("region", "business")).simplePath()).
            until(x -> false).emit(__.hasLabel("account")));

我明白，我需要将 Java Lambda 和 Predicates 注册为可序列化的，但无法弄清楚语法。另外，如何使用“serializer”将它添加到我的集群构建器中？

完整的堆栈跟踪:

Exception in thread "main" io.netty.handler.codec.EncoderException:org.apache.tinkerpop.gremlin.driver.exception.ResponseException: Anerror occurred during serialization of this request [RequestMessage{,requestId=28cd3e32-306a-457e-a6d2-2dc5bc9797d8, op='bytecode',processor='traversal', args={gremlin=[[], [V(A_639008103873),union([[], [identity()]], [[], [repeat([[], [out(), not([[],[hasLabel(region, business)]]), simplePath()]]), until([[], [outE(),limit(1), count(), is(0)]]), repeat([[], [both(), not([[],[hasLabel(region, business)]]), simplePath()]]),until(org.saswata.Main$$Lambda$34/1735507635@6110020d), emit([[],[hasLabel(aws_account)]])]])]], aliases={g=g}}}] - it could not besent to the server - Reason:org.apache.tinkerpop.gremlin.driver.ser.SerializationException:java.lang.IllegalArgumentException: Class is not registered:org.saswata.Main$$Lambda$34/1735507635 Note: To register this classuse: kryo.register(org.saswata.Main$$Lambda$34/1735507635.class); atio.netty.handler.codec.MessageToMessageEncoder.write(MessageToMessageEncoder.java:106)atio.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)atio.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730)atio.netty.channel.AbstractChannelHandlerContext.access$1900(AbstractChannelHandlerContext.java:38)atio.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.write(AbstractChannelHandlerContext.java:1081)atio.netty.channel.AbstractChannelHandlerContext$WriteAndFlushTask.write(AbstractChannelHandlerContext.java:1128)atio.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.run(AbstractChannelHandlerContext.java:1070)atio.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)atio.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404)at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:465) atio.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)at java.lang.Thread.run(Thread.java:748) Caused by:org.apache.tinkerpop.gremlin.driver.exception.ResponseException: Anerror occurred during serialization of this request [RequestMessage{,requestId=28cd3e32-306a-457e-a6d2-2dc5bc9797d8, op='bytecode',processor='traversal', args={gremlin=[[], [V(A_639008103873),union([[], [identity()]], [[], [repeat([[], [out(), not([[],[hasLabel(region, business)]]), simplePath()]]), until([[], [outE(),limit(1), count(), is(0)]]), repeat([[], [both(), not([[],[hasLabel(region, business)]]), simplePath()]]),until(org.saswata.Main$$Lambda$34/1735507635@6110020d), emit([[],[hasLabel(aws_account)]])]])]], aliases={g=g}}}] - it could not besent to the server - Reason:org.apache.tinkerpop.gremlin.driver.ser.SerializationException:java.lang.IllegalArgumentException: Class is not registered:org.saswata.Main$$Lambda$34/1735507635 Note: To register this classuse: kryo.register(org.saswata.Main$$Lambda$34/1735507635.class); atorg.apache.tinkerpop.gremlin.driver.handler.WebSocketGremlinRequestEncoder.encode(WebSocketGremlinRequestEncoder.java:63)atorg.apache.tinkerpop.gremlin.driver.handler.WebSocketGremlinRequestEncoder.encode(WebSocketGremlinRequestEncoder.java:40)atio.netty.handler.codec.MessageToMessageEncoder.write(MessageToMessageEncoder.java:88)... 11 more

与此同时，我使用 hack 来检查 until 参数中是否存在标签 hasLabel('fake')

Answer 1

如你所见HERE Neptune 不支持 lambdas 步骤。所以你不能使用这种类型的语法。

同样在您的用例中，您根本不需要 until 步骤。如果你不使用它，repeat步骤将继续，直到它到达一个空的遍历。

示例:https://gremlify.com/8es7aelrr4n