RFR: 8238761: Asynchronous handshakes [v5]

[Robbin Ehn]

On Wed, 23 Sep 2020 02:45:27 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Robbin Ehn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update after Coleen
>
> src/hotspot/share/runtime/handshake.hpp line 78:
> 
>> 76:   FilterQueue<HandshakeOperation*> _queue;
>> 77:   Mutex   _lock;
>> 78:   Thread* _active_handshaker;
> 
> To be clear, the _handshakee is the always the target JavaThread, while the _active_handshaker, is the thread that is
> actually executing the handshake operation (ie do_thread). If so can you add comments on these declarations to clarify
> that. Thanks.

Fixed

> src/hotspot/share/runtime/handshake.hpp line 90:
> 
>> 88:   void add_operation(HandshakeOperation* op);
>> 89:   HandshakeOperation* pop_for_self();
>> 90:   HandshakeOperation* pop_for_processor();
> 
> What is "processor" in this context - the active handshaker? Can we not introduce yet another piece of terminology
> here. We should have consistency of naming when it comes to "self" and others. ie. we have
> pop_for_self()
> 
> but
> 
> has_operation()
> 
> rather than
> 
> has_operation_for_self()
> 
> If we made the "self" case explicit then we could leave the not-self case implicit e.g.
> 
> pop_for_self();  // Called by handshakee only
> pop();  // Called by handshaker or VMThread
> has_operation_for_self(); // Is there an operation that can be executed by the handshakee itself
> has_operation();           // Is there an operation that can be executed by the handshaker or VMThread
> We can then stop using "processor" in other places as well.

Fixing

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PR: https://git.openjdk.java.net/jdk/pull/151