Exception with Spring Framework 5.2 merged annotations mechanism

[sdeleuze]

Spring Fu native image builds are broken (with GraalVM RC14 and RC15 so it is not a regression unlike what I wrote in the original report). It seems it comes from the new merged annotation subsystem that was introduced as part of Spring Framework 5.2 M1 which SubstrateVM seems not supporting.

The error can be observed when running the native image of our basic jafu-reactive-minimal sample and generates this stack trace:

Exception in thread "main" java.util.NoSuchElementException: No attribute named 'value' present in merged annotation org.springframework.core.annotation.Order
	at org.springframework.core.annotation.AbstractMergedAnnotation.getRequiredAttributeValue(AbstractMergedAnnotation.java:198)
	at org.springframework.core.annotation.AbstractMergedAnnotation.getInt(AbstractMergedAnnotation.java:90)
	at org.springframework.core.annotation.OrderUtils.findOrder(OrderUtils.java:113)
	at org.springframework.core.annotation.OrderUtils.getOrderFromAnnotations(OrderUtils.java:104)
	at org.springframework.core.annotation.AnnotationAwareOrderComparator.findOrderFromAnnotation(AnnotationAwareOrderComparator.java:75)
	at org.springframework.core.annotation.AnnotationAwareOrderComparator.findOrder(AnnotationAwareOrderComparator.java:68)
	at org.springframework.core.OrderComparator.getOrder(OrderComparator.java:124)
	at org.springframework.core.OrderComparator.getOrder(OrderComparator.java:112)
	at org.springframework.core.OrderComparator.doCompare(OrderComparator.java:81)
	at org.springframework.core.OrderComparator.compare(OrderComparator.java:68)
	at java.util.TimSort.binarySort(TimSort.java:296)
	at java.util.TimSort.sort(TimSort.java:221)
	at java.util.Arrays.sort(Arrays.java:1512)
	at java.util.ArrayList.sort(ArrayList.java:1462)
	at org.springframework.core.annotation.AnnotationAwareOrderComparator.sort(AnnotationAwareOrderComparator.java:111)
	at org.springframework.boot.SpringApplication.getSpringFactoriesInstances(SpringApplication.java:438)
	at org.springframework.boot.SpringApplication.getSpringFactoriesInstances(SpringApplication.java:427)
	at org.springframework.boot.SpringApplication.<init>(SpringApplication.java:273)
	at org.springframework.boot.SpringApplication.<init>(SpringApplication.java:252)
	at org.springframework.fu.jafu.JafuApplication$1.<init>(JafuApplication.java:73)
	at org.springframework.fu.jafu.JafuApplication.run(JafuApplication.java:73)
	at org.springframework.fu.jafu.JafuApplication.run(JafuApplication.java:60)
	at com.sample.Application.main(Application.java:30)

To reproduce:

git clone https://github.com/spring-projects/spring-fu.git
./gradlew clean build publishToMavenLocal
cd samples/jafu-reactive-minimal/
./build.sh
./com.sample.application

[cstancu]

@sdeleuze how does spring access the value attribute for annotations. Is it via reflection? I quickly looked in the implementation of AbstractMergedAnnotation.getAttributeValue but couldn't immediately figure it out.

[philwebb]

@cstancu It's usually via reflection, but there's an additional layer of indirection so that we can use the same API against different underlying data structures. The TypeMappedAnnotation class has the following member variable:

 BiFunction<Method, Object, Object> valueExtractor;

Most of the time, this will be a method reference to ReflectionUtils::invokeMethod which ultimately calls Method.invoke. My guess is this extra indirection means GraalVM doesn't realize that there is a reflective call going on.

[cstancu]

@philwebb the indirection that you mention above is not the problem. After some debugging I found that you are calling annotationType.getDeclaredMethods() where the annotationType comes from a call to annotation.annotationType(), so it looks like you need to register the annotation interface methods for reflection, at least for those annotations whose internals you expect to access via reflection. By adding this reflection configuration this problem goes away:

{
    "name": "org.springframework.core.annotation.Order",
    "allDeclaredMethods": true
}

To automate registering annotation interface methods for reflection you can write a Feature to detect all annotation interfaces that need reflective access.

However, now I hit #1135. I will work on that next.

[cstancu]

FYI #1135 is now fixed.