How to ensure Spring Cloud Stream Listener to wait to process messages until Application is fully initialized on Start? - spring-boot

Question

With Spring Cloud Stream Kafka app, how can we ensure that the stream listener waits to process messages until some dependency tasks (reference data population, e.g.) are done? Below app fails to process messages because messages are delivered too early. How can we guarantee this kind of ordering within a Spring Boot App?
#Service
public class ApplicationStartupService implements ApplicationRunner {
private final FooReferenceDataService fooReferenceDataService;
#Override
public void run(ApplicationArguments args) throws Exception {
fooReferenceDataService.loadData();
}
}
#EnableBinding(MyBinding.class)
public class MyFooStreamProcessor {
#Autowired FooService fooService;
#StreamListener("my-input")
public void process(KStream<String, Foo> input) {
input.foreach((k,v)-> {
// !!! this fails to save
// messages are delivered too early before foo reference data got loaded into database
fooService.save(v);
});
}
}
spring-cloud-stream: 2.1.0.RELEASE
spring-boot: 2.1.2.RELEASE
I found this is not available in spring cloud stream as of May 15, 2018.
Kafka - Delay binding until complex service initialisation has completed
Do we have a plan/timeline when this is supported?

Answer 1

In the mean time, I achieved what I wanted by using #Ordered and ApplicationRunner. It's messy but works. Basically, stream listener will wait until other works are done.
#Service
#Order(1)
public class ApplicationStartupService implements ApplicationRunner {
private final FooReferenceDataService fooReferenceDataService;
#Override
public void run(ApplicationArguments args) throws Exception {
fooReferenceDataService.loadData();
}
}
#EnableBinding(MyBinding.class)
#Order(2)
public class MyFooStreamProcessor implements ApplicationRunner {
#Autowired FooService fooService;
private final AtomicBoolean ready = new AtomicBoolean(false);
#StreamListener("my-input")
public void process(KStream<String, Foo> input) {
input.foreach((k,v)-> {
while (ready.get() == false) {
try {
log.info("sleeping for other dependent components to finish initialization");
Thread.sleep(10000);
} catch (InterruptedException e) {
log.info("woke up");
}
}
fooService.save(v);
});
}
#Override
public void run(ApplicationArguments args) throws Exception {
ready.set(true);
}
}