reactive @Transactional fails with java.lang.IllegalStateException: block()/blockFirst()/blockLast() are blocking

From #1524.

The underlying issue is that TransactionInterceptor is being called instead of CouchbaseTransactionInterceptor. And it should be calling executeReactive() instead of execute().

@Service
class ScheduleService(
    private val reactiveOperations: ReactiveCouchbaseOperations
) {
    @Transactional
    fun saveScheduleWithTransaction(schedule: Schedule): Mono<Schedule> {
        return reactiveOperations.insertById(Schedule::class.java).one(schedule)
    }
}

java.lang.IllegalStateException: block()/blockFirst()/blockLast() are blocking, which is not supported in thread reactor-http-nio-3
	at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:83) ~[reactor-core-3.5.0-M4.jar:3.5.0-M4]
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	*__checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain]
	*__checkpoint ⇢ HTTP POST "/schedule" [ExceptionHandlingWebHandler]
Original Stack Trace:
		at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:83) ~[reactor-core-3.5.0-M4.jar:3.5.0-M4]
		at reactor.core.publisher.Mono.block(Mono.java:1675) ~[reactor-core-3.5.0-M4.jar:3.5.0-M4]
		at org.springframework.data.couchbase.transaction.CouchbaseCallbackTransactionManager.handlePropagation(CouchbaseCallbackTransactionManager.java:191) ~[spring-data-couchbase-5.0.0-M5.jar:5.0.0-M5]
		at org.springframework.data.couchbase.transaction.CouchbaseCallbackTransactionManager.execute(CouchbaseCallbackTransactionManager.java:76) ~[spring-data-couchbase-5.0.0-M5.jar:5.0.0-M5]
		at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:417) ~[spring-tx-6.0.0-M5.jar:6.0.0-M5]
		at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-6.0.0-M5.jar:6.0.0-M5]
		at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184) ~[spring-aop-6.0.0-M5.jar:6.0.0-M5]
		at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) ~[spring-aop-6.0.0-M5.jar:6.0.0-M5]
		at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708) ~[spring-aop-6.0.0-M5.jar:6.0.0-M5]
		at com.rbleuse.spring.reactive.couchbase.service.ScheduleService$$EnhancerBySpringCGLIB$$f091fb23.saveScheduleWithTransaction(<generated>) ~[main/:na]
		at com.rbleuse.spring.reactive.couchbase.handler.ScheduleHandler.createSchedule(ScheduleHandler.kt:20) ~[main/:na]

[mikereiche]

 		at org.springframework.data.couchbase.transaction.CouchbaseCallbackTransactionManager.handlePropagation(CouchbaseCallbackTransactionManager.java:191) ~[spring-data-couchbase-5.0.0-M5.jar:5.0.0-M5]
		at org.springframework.data.couchbase.transaction.CouchbaseCallbackTransactionManager.lambda$executeReactive$0(CouchbaseCallbackTransactionManager.java:91) ~[spring-data-couchbase-5.0.0-M5.jar:5.0.0-M5]

Ok - I can fix this.

[rbleuse]

Sorry for the issues with block(). We do the testing in java as below, and it’s not in a non-blocking thread.

@GetMapping("/hello")
public Mono<ResponseEntity<String>> hello(@RequestParam(value = "name", defaultValue = "World") String name) {
	return Mono
			.just(new ResponseEntity<>(userService.insertReactive().block().toString(), HttpStatusCode.valueOf(200)));
}

I didn’t notice earlier, but may I know why there’s a block when we want a Mono as result in this endpoint ? Doesn’t it work with a non blocking process ? Something like (didn’t try)

@GetMapping("/hello")
public Mono<ResponseEntity<String>> hello(@RequestParam(value = "name", defaultValue = "World") String name) {
       return userService.insertReactive().map(value -> new ResponseEntity<>(value.toString(), HttpStatusCode.valueOf(200)));
}