RFR: 8329674: JvmtiEnvThreadState::reset_current_location function should use JvmtiHandshake

[Leonid Mesnik]

On Thu, 4 Apr 2024 15:28:41 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

> The internal JVM TI JvmtiHandshake and JvmtiUnitedHandshakeClosure classes were introduced in the JDK 22 to unify/simplify the JVM TI functions supporting implementation of the virtual threads. This enhancement is to refactor the JVM TI internal functions JvmtiEnvThreadState::reset_current_location on the base of JvmtiHandshake and JvmtiUnitedHandshakeClosure classes.
> 
> Testing:
>  - Ran mach5 tiers 1-6

The fix looks good.
It would be better to either rename doit methods to something more specific or even to move code into do_thread and do_vthread. 
And make do_vthread like

void do_vthread(Handle target_h) {
    if (_target_jt != nullptr) {
      do_thread(_target_jt);
    } else {
     <  code for unmounted >
    }
  }

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Marked as reviewed by lmesnik (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18630#pullrequestreview-1990029643