Exception caused by suspend lambda of kotlin that implements java.util.function.Consumer #1081
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Have you looked at one of our tests with coroutines? - |
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Hi @olegz , Thanks a lot for your kind reply. The test code you mentioned is written in Java, while I use When comparing these codes, I got some further information. 1. when "Multi argument Kotlin functions are not currently supported" exception occurs The reason of this result is due to isTypeRepresentedByClass(functionType, Function2.class) &&
type.length == 3 &&
CoroutinesUtils.isFlowType(type[0]) &&
CoroutinesUtils.isContinuationUnitType(type[1])Obviously, the third one which checks whether the input patameter is a 2. the problem of using @TestInstance(TestInstance.Lifecycle.PER_CLASS)
class KotlinSuspendFunctionJUnitTest {
private lateinit var context: GenericApplicationContext
private lateinit var catalog: FunctionCatalog
@AfterEach
fun close() {
context.close()
}
@Test
fun typeDiscoveryTests() {
create(arrayOf(KotlinSuspendFlowLambdasConfiguration::class.java))
val functionCatalog = context.getBean(FunctionCatalog::class.java)
val kotlinFunction = functionCatalog.lookup<FunctionInvocationWrapper>("kotlinFunction")
Assertions.assertThat(kotlinFunction.isFunction).isTrue()
Assertions.assertThat(kotlinFunction.inputType.typeName)
.isEqualTo("reactor.core.publisher.Flux<java.lang.String>")
Assertions.assertThat(kotlinFunction.outputType.typeName)
.isEqualTo("reactor.core.publisher.Flux<java.lang.String>")
// The following code runs correctly
val result = kotlinFunction.apply(Flux.just("abcd")) as Flux<String>
StepVerifier.create(result).expectNext("ABCD").verifyComplete()
}
private fun create(types: Array<Class<*>>, vararg props: String) {
context = SpringApplicationBuilder(*types).properties(*props).run() as GenericApplicationContext
catalog = context.getBean(FunctionCatalog::class.java)
}
}As you can see, if using
val result1 = kotlinFunction.apply(flowOf("abcd"))
val result2 = result1 as Flux<String>
StepVerifier.create(result2).expectNext("ABCD").verifyComplete()An exception occurs at the
val result1 = kotlinFunction.apply(Flux.just("abcd"))
val result2 = result1 as Flow<String>An exception occurs on the type cast:
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Describe the bug
According to the docs, a lambda can be used to implement
java.utl.function.Cusumer.However, if calls a suspend method in the body, the lambda must add
suspendkeywords which casuses an exception ofjava.lang.UnsupportedOperationException: Multi argument Kotlin functions are not currently supported.Sample
Suppose I have a
DataRepositoryinterface which extendsCoroutineCrudRepository, hence theDataRepository#savemethod is asuspendmethod (In theCoroutineCrudRepositoryinterface, it issuspend fun <S : T> save(entity: S): T).And the function class is
and it cause the exception
Other tries
If using
kotlinx.coroutines.flow.Flow, a non-suspend methodCoroutineCrudRepository#saveAllcan be used. Therefore, the lambda signature can be changed to(Flow<Data>) -> Unitwhich causes no exceptions in startup.However, if call the function with a message, another exception occurs:
ugly workaound
Calling
suspendmethod in arunBlockingblock that makes the Consumer itself be not in a suspend one.The version of spring-cloud-function is 4.0.5 (spring-cloud 2022.0.4).
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