RFR: 8283044: Use asynchronous handshakes to deliver asynchronous exceptions [v4]

[Robbin Ehn]

On Mon, 28 Mar 2022 02:40:38 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Thanks for confirming.
>
> Aside: as the handshake filtering mechanism is growing this doesn't look like a scalable approach to dealing with filters - we can't keep adding hardwired filter functions and new parameters to get_op_for_self and its callers. get_op_for_self should be taking a filtering object which in turn is used by queue.peek() to determine what can be returned. Perhaps a use for C++ lambdas?

My original thought was to have the filter in the specific handshake:

class MyHandshake : public HandshakeClosure {
public:
  MyHandshake(Handle throwable) : HandshakeClosure("MyHandshake") {}
  void do_thread(Thread* thr) {}
  bool executeable_for_context(JavaThreadState from, JavaThreadState to, ...) {
  	return to == _thread_in_Java;
  }
};


This would keep what and when together.

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PR: https://git.openjdk.java.net/jdk/pull/7930