通过Kotlin Lambda到Corda Flow的类星体NPE

将一个lambda传递给CollectSignaturesFlow Quasar时,会以无提示方式崩溃,并且无法继续处理。 问题是与others.map { initiateFlow(it as Party) }.toSet() 。 将其移到外部并将其设置为局部variables可以解决问题。

有什么可以或不可以用Quasar序列化的已知问题?

 @InitiatingFlow @StartableByRPC class IOUIssueFlow(val state: IOUState) : FlowLogic() { @Suspendable override fun call(): SignedTransaction { val txCommand = Command( IOUContract.Commands.Issue(), state.participants.map { it.owningKey }) val builder = TransactionBuilder(serviceHub.networkMapCache.notaryIdentities.first()) .withItems( StateAndContract( state, IOUContract.IOU_CONTRACT_ID), txCommand) builder.verify(serviceHub) val others = state.participants - ourIdentity return subFlow( FinalityFlow( subFlow( CollectSignaturesFlow( serviceHub.signInitialTransaction(builder), others.map { initiateFlow(it as Party) }.toSet())))) } } 

代码将无限期地运行,并产生这个警告:

 [WARN ] 16:38:13,655 [Mock network] (FlowStateMachineImpl.kt:127) flow.[49f2ebbd-be62-462d-af87-24f5ae40c7d6].run - Terminated by unexpected exception java.lang.NullPointerException: null at net.corda.node.services.statemachine.FlowStateMachineImpl.suspend(FlowStateMachineImpl.kt:468) ~[corda-node-1.0.0.jar:?] at net.corda.node.services.statemachine.FlowStateMachineImpl.sendInternal(FlowStateMachineImpl.kt:332) ~[corda-node-1.0.0.jar:?] at net.corda.node.services.statemachine.FlowStateMachineImpl.initiateSession(FlowStateMachineImpl.kt:396) ~[corda-node-1.0.0.jar:?] at net.corda.node.services.statemachine.FlowStateMachineImpl.sendAndReceive(FlowStateMachineImpl.kt:200) ~[corda-node-1.0.0.jar:?] at net.corda.core.internal.FlowStateMachine$DefaultImpls.sendAndReceive$default(FlowStateMachine.kt:27) ~[corda-core-1.0.0.jar:?] at net.corda.node.services.statemachine.FlowSessionImpl.sendAndReceive(FlowSessionImpl.kt:25) ~[corda-node-1.0.0.jar:?] at net.corda.core.flows.DataVendingFlow.sendPayloadAndReceiveDataRequest(SendTransactionFlow.kt:70) ~[corda-core-1.0.0.jar:?] at net.corda.core.flows.DataVendingFlow.call(SendTransactionFlow.kt:48) ~[corda-core-1.0.0.jar:?] at net.corda.core.flows.DataVendingFlow.call(SendTransactionFlow.kt:31) ~[corda-core-1.0.0.jar:?] at net.corda.core.flows.FlowLogic.subFlow(FlowLogic.kt:212) ~[corda-core-1.0.0.jar:?] at net.corda.core.flows.CollectSignatureFlow.call(CollectSignaturesFlow.kt:140) ~[corda-core-1.0.0.jar:?] at net.corda.core.flows.CollectSignatureFlow.call(CollectSignaturesFlow.kt:134) ~[corda-core-1.0.0.jar:?] at net.corda.core.flows.FlowLogic.subFlow(FlowLogic.kt:212) ~[corda-core-1.0.0.jar:?] at net.corda.core.flows.CollectSignaturesFlow.call(CollectSignaturesFlow.kt:113) ~[corda-core-1.0.0.jar:?] at net.corda.core.flows.CollectSignaturesFlow.call(CollectSignaturesFlow.kt:64) ~[corda-core-1.0.0.jar:?] at net.corda.core.flows.FlowLogic.subFlow(FlowLogic.kt:212) ~[corda-core-1.0.0.jar:?] at net.corda.training.flow.IOUIssueFlow.call(IOUIssueFlow.kt:39) ~[classes/:?] at net.corda.training.flow.IOUIssueFlow.call(IOUIssueFlow.kt:22) ~[classes/:?] at net.corda.node.services.statemachine.FlowStateMachineImpl.run(FlowStateMachineImpl.kt:112) [corda-node-1.0.0.jar:?] at net.corda.node.services.statemachine.FlowStateMachineImpl.run(FlowStateMachineImpl.kt:40) [corda-node-1.0.0.jar:?] at co.paralleluniverse.fibers.Fiber.run1(Fiber.java:1092) [quasar-core-0.7.9-jdk8.jar:0.7.9] at co.paralleluniverse.fibers.Fiber.exec(Fiber.java:788) [quasar-core-0.7.9-jdk8.jar:0.7.9] at co.paralleluniverse.fibers.RunnableFiberTask.doExec(RunnableFiberTask.java:100) [quasar-core-0.7.9-jdk8.jar:0.7.9] at co.paralleluniverse.fibers.RunnableFiberTask.run(RunnableFiberTask.java:91) [quasar-core-0.7.9-jdk8.jar:0.7.9] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_151] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_151] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [?:1.8.0_151] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [?:1.8.0_151] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_151] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_151] at net.corda.node.utilities.AffinityExecutor$ServiceAffinityExecutor$1$thread$1.run(AffinityExecutor.kt:69) [corda-node-1.0.0.jar:?] [WARN ] 16:38:13,670 [Mock network] (StateMachineManager.kt:93) flow.[49f2ebbd-be62-462d-af87-24f5ae40c7d6].uncaughtException - Caught exception from flow java.lang.IllegalStateException: No transaction in context 

问题是lambda捕获整个堆栈的引用。 如果此时尝试暂停流程,它将尝试通过lambda序列化整个堆栈,流程的暂停将失败。

解决的办法是创建一个局部variables,或者在函数内部使用lambda。 当函数返回时,lambda将从堆栈中被丢弃,所以暂停时不会有问题。