RFR 8054494: Remove sun.misc.Unsafe.monitorEnter, monitorExit and tryMonitorEnter

[Paul Sandoz]

On Jan 12, 2015, at 11:33 AM, Filipp Zhinkin <filipp.zhinkin at gmail.com> wrote:
> So that leaves just hotspot/test/compiler/testlibrary/rtm/BusyLock.java using tryMonitorEnter and monitorExit:
> 
>   66             if (WB.tryMonitorEnter(monitor)) {
>   67                 try {
>   68                     barrier.await();
>   69                     Thread.sleep(timeout);
>   70                 } finally {
>   71                     WB.monitorExit(monitor);
>   72                 }
>   73             } else {
>   74                 throw new RuntimeException("Monitor should be entered by " +
>   75                                            "::run() first.");
>   76             }
> 
> Could we replace that with:
> 
>   if (!WB.isMonitorHeld(monitor)) {
>     synchronized(monitor) {
>         ...
>     }
>   } else {
>     ...
>   }
> 
> ?
> 
> If so we would no longer require any updates to white box and i could also remove ObjectSynchronizer::jni_try_enter method. Plus jdk/test/java/lang/ProcessBuilder/Basic.java could be updated to use WB.isMonitorHeld method.
> 
> Filipp, I noticed you provided the fix for JDK-8050486 so perhaps you may know if BusyLock can be updated as suggested.
> 
> It could be updated to use synchronized-block instead of Unsafe/WB, see attached diff.
> 

Thanks! I was unsure if the use of UNSAFE.tryMonitorEnter was a key part of the test or just some extra defence. I will update as you suggest (plus add you as a contributor), and remove the additional methods i added to WB.

Paul.