Concurrency Control for CDI (Interceptor and ReentrantReadWriteLock example)

Lock.java

@Inherited
@InterceptorBinding
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD,ElementType.TYPE})
public @interface Lock {
  LockType value() default LockType.WRITE;
}

LockInterceptor.java

@Lock
@Interceptor
public class LockInterceptor {
 
  private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock(true);
 
  @AroundInvoke
  public Object concurrencyControl(InvocationContext ctx) throws Exception {
    Lock lockAnnotation = ctx.getMethod().getAnnotation(Lock.class);
     
    if (lockAnnotation == null) {
      lockAnnotation = ctx.getTarget().getClass().getAnnotation(Lock.class);
    }
 
    Object returnValue = null;
    switch (lockAnnotation.value()) {
      case WRITE:
        ReentrantReadWriteLock.WriteLock writeLock = lock.writeLock();
        try {
          writeLock.lock();
          returnValue = ctx.proceed();
        } finally {
          writeLock.unlock();
        }
        break;
      case READ:
        ReentrantReadWriteLock.ReadLock readLock = lock.readLock();
        try {
          readLock.lock();
          returnValue = ctx.proceed();
        } finally {
          readLock.unlock();
        }
        break;
    }
    return returnValue;
  }
}

MyAppScopedBean_Example1.java

@Lock
@ApplicationScoped
public class MyAppScopedBean {
     
  @Lock(LockType.READ)
  public int threadSafeOperation() {
    ...
  }
 
  public void threadUnsafeOperation() {
    ...
  }
}

OtherAppScopedBean.java

@ApplicationScoped
public class OtherAppScopedBean {
     
  public int threadSafeOperation() {
    ...
  }
   
  @Lock
  public void threadUnsafeOperation() {
    ...
  }
}

More informations, http://www.knitelius.com/2016/01/25/concurrency-control-for-cdi/