Re: 回复: 回复: 回复: Avoid Native Pin when use Continuation direclty with reflection invoke(Internet mail)

[Alan Bateman]

On 12/11/2020 10:55, kalinshi(施慧) wrote:
>
> Thank! I checked early discussion and the situation is quite same with us.
>
> There are JLA.getCarrierThreadLocal/setCarrierThreadLocal interfaces. 
> They can be access with --add-exports options and access carrier 
> thread’s thread locals..
>
> Will loom keep these interfaces?
>
It's way too fragile to depend on this as they may change or be removed 
at any time.

If I understand your mail correctly then I think you are looking for 
something like this:

     class Context {
         static final Map<Thread, Context> map = new ConcurrentHashMap<>();
         static Context get() {
             Thread thread = Thread.currentThread();
             return map.computeIfAbsent(thread, k -> new Context());
         }
         void share(Thread thread) {
             map.put(thread, this);
         }
         void unshare(Thread thread) {
             map.remove(thread);
         }
     }

     // custom scheduler with one underlying carrier thread

     ExecutorService pool = Executors.newFixedThreadPool(1);

     Executor scheduler = task -> {
         Thread vthread = ((Thread.VirtualThreadTask) task).thread();
         pool.execute(() -> {
             Context ctxt = Context.get();
             ctxt.share(vthread);
             try {
                 task.run();
             } finally {
                 ctxt.unshare(vthread);
             }
         });
     };

This uses the "hooks" I mentioned in the previous mail to run code in 
the context of the carrier thread before/after the virtual thread task 
runs. In this case, it "shares" a Context object owned by the carrier 
thread so that it is accessible to the virtual thread. Does this help 
with your use-case?

-Alan