RFR: 8344892: beans/finder/MethodFinder.findMethod incorrectly returns null

[Alexander Zvegintsev]

On Fri, 28 Feb 2025 14:41:41 GMT, Alexander Zvegintsev <azvegint at openjdk.org> wrote:

> During the [JDK-8344891 Remove uses of sun.misc.ReflectUtil in java.desktop](https://bugs.openjdk.org/browse/JDK-8344891) it was discovered that `beans/finder/MethodFinder.findMethod' incorrectly returned null if a signature was not in the cache and added it to the cache if it was already there:
> 
> 
> Method method = CACHE.get(signature);
> return (method == null) ? method : CACHE.create(signature);
> 
> This resulted in a [significant drop in performance](https://bugs.openjdk.org/browse/JDK-8350573).
> 
> ----
> 
> Before ReflectUtil was removed, it worked by coincidence:
> 
> 
> Method method = CACHE.get(signature);
> return (method == null) || isPackageAccessible(method.getDeclaringClass()) ? method : CACHE.create(signature);
> 
> 
> 
> 
> 1. `Cache#get` non-obviously creates a value in Cache, this in turn allowed us to avoid the NPE in the `(method == null) || isPackageAccessible(method.getDeclaringClass())` condition
> 
> 
> https://github.com/openjdk/jdk/blob/d6c4be672f6348f8ed985416ed90d0447f5d5bb3/src/java.desktop/share/classes/com/sun/beans/util/Cache.java#L120-L126
> 
> 2. `isPackageAccessible(method.getDeclaringClass())` was evaluated as true
> 
> This is how we previously returned the cached value.
> 
> ---
> 
> So the solution is obvious:
> 
> 
> Method method = CACHE.get(signature);
> return (method != null) ? method : CACHE.create(signature);
> 
> 
> Testing is green.

src/java.desktop/share/classes/com/sun/beans/finder/MethodFinder.java line 81:

> 79:         try {
> 80:             Method method = CACHE.get(signature);
> 81:             return (method != null) ? method : CACHE.create(signature);

This can be simplified to the `return CACHE.get(signature)`, since we know that the implementation creates the value in the get method:

https://github.com/openjdk/jdk/blob/d6c4be672f6348f8ed985416ed90d0447f5d5bb3/src/java.desktop/share/classes/com/sun/beans/util/Cache.java#L120-L126

However, I am not a fan of this solution as it is implementation dependent and this behavior is not documented.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/23845#discussion_r1975538624