[jboss-dev-forums] [Design of AOP on JBoss (Aspects/JBoss)] - Re: AOPConstructorJoinpoint and methodHasSubInstanceMetaData

[kabir.khan@jboss.com]

BTW looking at ReflectionUtils.findMethod() it relies on exceptions:

  |    public static Method findMethod(Class<?> clazz, String name, Class<?>... parameterTypes)
  |    {
  |       if (clazz == null)
  |          return null;
  | 
  |       try
  |       {
  |          return clazz.getDeclaredMethod(name, parameterTypes);
  |       }
  |       catch(Exception ignored)
  |       {
  |       }
  |       return findMethod(clazz.getSuperclass(), name, parameterTypes);
  |    }
  | 

Since exceptions are expensive to create, I threw together a small benchmark

  | public class TestFindMethods
  | {
  |    
  |    public static void main(String[] args)
  |    {
  |       Class<?> clazz = ArrayList.class;
  |       //Use the name of one of the last methods from the base class, but with non-matching params
  |       //(The method is called java.util.AbstractCollection.retainAll(Collection<?>))
  |       String name = "retainAll";
  |       Class<?>[] params = new Class<?>[] {Integer.class};
  |       
  |       long get = 0;
  |       long iterate = 0;
  |       for (int i = 0 ; i < 10000000 ; i++)
  |       {
  |          long start1 = System.currentTimeMillis();
  |          Method m1 = getDeclaredMethod(clazz, name, params);
  |          get += (System.currentTimeMillis() - start1);
  | 
  |          long start2 = System.currentTimeMillis();
  |          Method m2 = iterateDeclaredMethods(clazz, name, params);
  |          iterate += (System.currentTimeMillis() - start2);
  |       }
  |       
  |       System.out.println("Get took " + get);
  |       System.out.println("Iterate took " + iterate);
  |    }
  |    
  |    private static Method getDeclaredMethod(Class clazz, String name, Class<?>[] params)
  |    {
  |       try
  |       {
  |          return clazz.getDeclaredMethod(name, params);
  |       }
  |       catch(Exception e)
  |       {
  |          
  |       }
  |       clazz = clazz.getSuperclass();
  |       if (clazz != null)
  |       {
  |          return getDeclaredMethod(clazz, name, params);
  |       }
  |       return null;
  |    }
  |    
  |    private static Method iterateDeclaredMethods(Class<?> clazz, String name, Class<?>[] params)
  |    {
  |       Method[] methods = clazz.getDeclaredMethods();
  |       for (int i = 0 ; i < methods.length ; i++)
  |       {
  |          if (name.equals(methods.getName()))
  |          {
  |             Class<?>[] myparams = methods.getParameterTypes();
  |             if (myparams.length == params.length)
  |             {
  |                for (int j = 0 ; j < myparams.length ; j++)
  |                {
  |                   if (params[j] != myparams[j])
  |                   {
  |                      break;
  |                   }
  |                   return methods;
  |                }
  |             }
  |          }
  |       }
  |       clazz = clazz.getSuperclass();
  |       if (clazz != null)
  |       {
  |          return iterateDeclaredMethods(clazz, name, params);
  |       }
  |       return null;
  |    } 
  | }
  | 

Running it I get:

  | Get took 179658
  | Iterate took 112402
  | 
Of course if we get rid of the cause of not finding these methods then this becomes less relevant.



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