RFR: 8339289: Parameter size mismatch between client and VM sides of the Attach API - Windows

[Serguei Spitsyn]

On Fri, 30 Aug 2024 00:07:50 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

> The fix improves Attch API protocol and implements updated protocol on windows; shared code is ready to implement updated protocol support on other platforms.
> More detailed explanations on the 1st comment.
> 
> Testing: tier1,tier2,tier3,tier4,hs-tier5-svc
>   manually tested backward compatibility (old tools can attach to current VMs, current tools can attach to older VMs) on Windows with jdk21u and jdk8u.

This is nice fix, thank you for doing this!
I still need one more pass on the Windows `AttachListener` part and hope to complete it early next week.

src/hotspot/share/services/attachListener.cpp line 649:

> 647: 
> 648:   return true;
> 649: }

Nit: This function is too big. I'd suggest to split it to make more readable. For example, the lines 596-648 can be moved to new function which is called by the `AttachOperation::read_request()'.

src/jdk.attach/windows/classes/sun/tools/attach/VirtualMachineImpl.java line 46:

> 44: 
> 45:     private volatile long hProcess;     // handle to the process
> 46:     private int ver = VERSION_1;        // updated by detectVersion on attach

Nit: The comment is not fully accurate as the result returned by the `detectVersion()` is stored in this private field by the `VirtualMachineImpl` constructor.

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PR Review: https://git.openjdk.org/jdk/pull/20782#pullrequestreview-2363889264
PR Review Comment: https://git.openjdk.org/jdk/pull/20782#discussion_r1797683041
PR Review Comment: https://git.openjdk.org/jdk/pull/20782#discussion_r1797678822