Implementing Aspect-Oriented Programming

@Aspect @Component
public class LoggingAspect {
    @Around("@annotation(Loggable)")
    public Object log(ProceedingJoinPoint pjp) throws Throwable {
        var sig = pjp.getSignature().toShortString();
        log.debug("--> {} args={}", sig, Arrays.toString(pjp.getArgs()));
        long t0 = System.nanoTime();
        try {
            Object out = pjp.proceed();
            log.debug("<-- {} ({} ms)", sig, (System.nanoTime() - t0)/1_000_000);
            return out;
        } catch (Throwable ex) {
            log.warn("xx-- {} threw {}", sig, ex.toString());
            throw ex;
        }
    }
}

@Around("@annotation(io.micrometer.core.annotation.Timed)")
public Object timed(ProceedingJoinPoint pjp) throws Throwable {
    return Timer.builder("method.timer")
        .tag("method", pjp.getSignature().toShortString())
        .register(meterRegistry)
        .recordCallable(() -> {
            try { return pjp.proceed(); } catch (Throwable t) { throw new RuntimeException(t); }
        });
}

@Around("@annotation(audit)")
public Object audit(ProceedingJoinPoint pjp, Auditable audit) throws Throwable {
    var actor = SecurityContextHolder.getContext().getAuthentication().getName();
    try {
        Object out = pjp.proceed();
        auditLog.write(actor, audit.action(), "SUCCESS", pjp.getArgs());
        return out;
    } catch (Throwable t) {
        auditLog.write(actor, audit.action(), "FAILURE", pjp.getArgs());
        throw t;
    }
}

@AfterThrowing(pointcut = "execution(* com.acme.api..*(..))", throwing = "ex")
public void onError(JoinPoint jp, Throwable ex) {
    metrics.counter("errors", "method", jp.getSignature().toShortString()).increment();
}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface RateLimited {
    String key() default "";
    int permitsPerSecond() default 10;
}