RFR: 8268855: Cleanup name handling in the Thread class and subclasses

[Coleen Phillimore]

On Wed, 23 Jun 2021 06:21:43 GMT, David Holmes <dholmes at openjdk.org> wrote:

> Please review this small cleanup item.
> 
> We can simplify and cleanup up name() management:
> 
> - make name() return "const char *" and only cast away constness at API boundaries when essential
> - add type_name() so that we can avoid code like "if (t->is_VM_Thread()) print("VMThread");
> - Rename JavaThread::get_thread_name() to name() (no need for the extra indirection)
> 
> There are a couple of minor changes to the appearance of some internal threads in the hs_err log e.g.
> 
>   0x000055af03e5b1b0 WatcherThread [stack: 0x00007f685df00000,0x00007f685e000000] [id=15952]
> 
> is now:
> 
>   0x000055af03e5b1b0 WatcherThread "VM Periodic Task Thread" [stack: 0x00007f685df00000,0x00007f685e000000] [id=15952]
> 
> but this shouldn't affect anything and makes things more consistent.
> 
> Notes: 
> 
> 1. While "override" is the ideal style when declaring overriding methods it has to be applied to all virtual methods in a class. So unless "override" is already used in a class, I did not start using it. I have filed a separate RFE to convert the Thread classes to use "override" consistently.
> 2.  While there is no need to redeclare a virtual method as "virtual" I kept to the existing style in those classes where changes were made.
> 3. I did not override type_name() for all the JavaThread subclasses as it seemed unnecessary, but happy to hear other views on this.
> 
> Testing (in progress):
>  - All builds in tiers 1-5
>  - GHA
>  - tiers 1-3 as a sanity test
> 
> Thanks,
> David

This looks good.

-------------

Marked as reviewed by coleenp (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/4569