RFR: 8334254: Cleanup CGroups initialization code

[Johan Sjölen]

On Thu, 13 Jun 2024 18:20:33 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

> Hi,
> 
> Please consider this patch which attempts to improve the code quality of some of the cgroups code, somewhat.
> 
> 1. Get rid of `#define`s and upgrade to a `CG_INFO` enum, with some helpers
> 2. Make some of the code prettier by removing copy-pasted and edited code
> 3. Make `CgroupInfo` RAII, ridding us of the `cleanup` function
> 4. `set_subsystem_path` is **only** used at construction time, only call it at that time and make those functions private. Also remove `virtual`ness, as this is unnecessary now.
> 
> Testing:
> 
> 1. cgroupTest group in gtest.
> 
> Thank you.

@jerboaa 

Hi Severin,

This is a couple of examples of unnecessary complexity that we have in the code. Especially the `set_subsystem_path` function: It's `virtual` and public, yet is always called right after constructing an object.  Make it private, make the constructor call it, make it private, now I no longer have to ask myself a lot of questions when reading the code.

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PR Comment: https://git.openjdk.org/jdk/pull/19709#issuecomment-2166621574