RFR: 8287007: [cgroups] Consistently use stringStream throughout parsing code [v2]

[Severin Gehwolf]

On Wed, 8 Jun 2022 07:13:30 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Severin Gehwolf has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:
>> 
>>  - Merge branch 'master' into jdk-8287007-string-stream
>>  - Add cgroups v2 java test
>>  - use stringStream in cgroups v2
>>  - Add gtest for cgroups v2 code path
>>    
>>    Also fixes the bug when cgroup path is '/'.
>>  - 8287007: [cgroups] Consistently use stringStream throughout parsing code
>>  - 8287007: [cgroups] Consistently use stringStream throughout parsing code
>
> src/hotspot/os/linux/cgroupV1Subsystem_linux.cpp line 54:
> 
>> 52:       } else {
>> 53:         char *p = strstr(cgroup_path, _root);
>> 54:         if (p != NULL && p == cgroup_path) {
> 
> I think this change should be done in a separate bug, because it will cause the `if` block to be executed. Previously the `if` block is never executed (unless `cgroup_path == _root` ??, but then it will just set `_path` to the same string as `_mount_point`) -- so we don't even know if this change of behavior might do something harmful.

OK. Then this will remain to be dead code and I'll remove the corresponding test case in the new `gtests` too (as they'd otherwise fail in contrast to the Java code).

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PR: https://git.openjdk.java.net/jdk/pull/8969