On Wed, 28 Oct 2020 19:28:36 GMT, Mandy Chung <mch...@openjdk.org> wrote:
>> Hi Mandy and Peter, >> reading your exchanges, i wonder if it's not better to stop trying to add >> more and more features to the already clunky java.lang.reflect.Proxy but >> instead to move to provide the same set of feature but using an >> implementation based on java.lang.invoke.Lookup/MethodHandle. >> >> I propose to introduce a java.lang.invoke.Proxy has a replacement of >> java.lang.reflect.Proxy using j.l.i.MethodHandle instead of j.l.r.Method, >> the equivalent of the InvocationHandler acting as a linker called once per >> the first time a method of the Proxy is called instead of being called each >> time a method is called. >> >> Such proxy >> - has it's security model based on Lookup to define the class, >> so no supplementary restrictions on package/module of the interface >> implemented >> - avoid to mix java.lang.reflect API and java.invoke API >> - is transparent in term of exceptions (ther are propagated without any >> wrapping/unwrapping) >> - can support default methods natively >> - doesn't requires any caching (the user will be responsible to do the >> caching) >> - is more efficient, actually as efficient as the equivalent written code or >> a little more (thanks to @ForceInline) > > Hi Remi, > > I appreciate your proposal to modernize Proxy API. There are several > requests for this enhancement to support default methods in Proxy. Defining > a new `java.lang.invoke.Proxy` is a much bigger project that I can't tell > when the existing users of `java.lang.reflect.Proxy` will be able to get this > default method invocation support. > > I do agree that this API design has many challenges caused by what you listed > above. Well, I believe we are very close to have a consensus: > 1. New `newProxyInstance` factory method takes a handler factory doing the > access check > 2. Update `getInvocationHandler` to throw > `InaccessibleInvocationHandlerException` if access denied to get an > invocation handler associated with the proxy instance > > If this needs more time, I think I will consider to shelf this RFE and come > back to it later (and consider your proposal as well). The trick is that if we know that a class like java.lang.invoke.Proxy may exist, it means that instead of distorting the j.l.r.Proxy API to increase of few percents the performance when calling a default method, you can come with a simpler design in term of API that just add an API point to call a default method. Better performance becoming on the the goals of java.lang.invoke.Proxy. ------------- PR: https://git.openjdk.java.net/jdk/pull/313
