[ROCKETMQ-259] Too many reflection calls when decode remoting command header

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0.0-incubating, 4.1.0-incubating
• Fix Version/s: 4.2.0
• Component/s: rocketmq-remoting
• Assignee: Xinyu Zhou
• Reporter: Xinyu Zhou
• Created: 10/Aug/17 09:36
• Updated: 09/Oct/17 06:49
• Resolved: 09/Oct/17 06:49

Description

Each field in a CommandCustomHeader will be checked to ensure some key fields aren't null when decode RemotingCommand header. This process will cause a reflection call, and current code has a cache mechanism, but it doesn't work.

Annotation annotation = getNotNullAnnotation(field);
if (annotation != null) {
    throw new RemotingCommandException("the custom field <" + fieldName + "> is null");
}

private Annotation getNotNullAnnotation(Field field) {
        Annotation annotation = NOT_NULL_ANNOTATION_CACHE.get(field);

        if (annotation == null) { 
            annotation = field.getAnnotation(CFNotNull.class); //[1]
            synchronized (NOT_NULL_ANNOTATION_CACHE) {
                NOT_NULL_ANNOTATION_CACHE.put(field, annotation);
            }
        }
        return annotation;
    }

[1]. If a field doesn't has CFNotNull annotation, each check will cause a reflection call.