RFR: 8328866: Add raw monitor rank support to the debug agent. [v4]

[Serguei Spitsyn]

On Wed, 8 May 2024 22:10:29 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> In fact, I do not understand why reporting the "rank order" violation is important what "leaf rank order" is violated. I feel that I'm missing something. Let me think on it a little bit.
>
> If the following are all true 
> - you are entering is a leaf monitor
> - the current thread has already entered a leaf monitor
> - the rank of the monitor you are entering is lower than the rank of the monitor already held
> 
> Then you have both a rank order violation and a violation for entering a leaf monitor when you have already entered a leaf monitor. My current implementation will complain about the rank violation (although can easily be made to instead complain about the leaf violation or complain about both). Yours will complain about the leaf violation.  To make yours instead complain about the rank violation, the first loop needs to also check all the leaf monitors. Since the 2nd loop also checks all the leaf monitors (but for a different reason), this means iterating over the leaf monitors twice. Complaining about both violations would also require iterating over the leaf monitors twice.

Okay, thanks.
> Then you have both a rank order violation and a violation for entering a leaf monitor when you have already entered a leaf monitor. 

I kind of disagree with the second part of this statement.
My understanding is that the second loop does a little bit different check:
  "Violation for entering ANY monitor when you have already entered a leaf monitor."
Please, note that `rank` can be any rank including those with conditions:

   rank < FIRST_LEAF_DEBUG_RAW_MONITOR
   rank >= FIRST_LEAF_DEBUG_RAW_MONITOR

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PR Review Comment: https://git.openjdk.org/jdk/pull/19044#discussion_r1594776344