RFR: 8262910: Cleanup THREAD/TRAPS/naming and typing issues in ObjectMonitor and related code

[Patricio Chilano Mateo]

On Wed, 3 Mar 2021 05:15:48 GMT, David Holmes <dholmes at openjdk.org> wrote:

> ObjectMonitors can only be used by JavaThreads (modulo some interactions with hashcodes and deflation) but we use "Thread*" almost everywhere mainly due to use of TRAPS (and TRAPS will itself use JavaThread once JDK-8252685 is done). Also some uses of TRAPS in the API's are wrong as, for example, monitor entry can never throw an exception.
> 
> So this cleanup tackles:
> - remove incorrect use of TRAPS
> - change "Thread*" to "JavaThread*" where applicable
> - don't use THREAD for things not related to exception processing
> - standardise the naming so that we have "JavaThread* current" rather a mix if Self/THREAD/jt etc.
> - remove unnecessary as_Java_thread() conversions
> - other misc cleanup I noticed in some functions
> 
> The cleanup is predominantly in objectMonitor.* and synchronizer.* but with a fan out to the users of those APIs. No attempt is made to cleanup the callers beyond ensuring we have a suitable JavaThread reference for the calls. 
> 
> Thanks,
> David

Hi David,

Changes look good to me.

Thanks,
Patricio

src/hotspot/share/runtime/objectMonitor.hpp line 306:

> 304: 
> 305:   bool      enter(JavaThread* current);
> 306:   void      exit(bool not_suspended, TRAPS);

Shouldn't we also remove use of TRAPS for exit()? In case of unbalanced locking we don't throw IMSE, only just assert.

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Marked as reviewed by pchilanomate (Committer).

PR: https://git.openjdk.java.net/jdk/pull/2802