RFR: 8321931: memory_swap_current_in_bytes reports 0 as "unlimited" [v9]

[Gerard Ziemski]

> We make a distinction between 0 for a limit vs non-limit cgroup values.
> 
> For all values (limit or non-limit), 0 simply means 0.
> 
> Output before from `jcmd PID VM.info`:
> 
> 
> container (cgroup) information:
> container_type: cgroupv2
> cpu_cpuset_cpus: not supported
> cpu_memory_nodes: not supported
> active_processor_count: 8
> cpu_quota: not supported
> cpu_period: not supported
> cpu_shares: not supported
> memory_limit_in_bytes: unlimited
> memory_and_swap_limit_in_bytes: unlimited
> memory_soft_limit_in_bytes: unlimited
> memory_usage_in_bytes: 11129120 k
> memory_max_usage_in_bytes: not supported
> memory_swap_current_in_bytes: unlimited
> memory_swap_max_limit_in_bytes: unlimited
> maximum number of tasks: 18963
> current number of tasks: 33
> 
> 
> Output now from `jcmd PID VM.info`:
> 
> 
> container (cgroup) information:
> container_type: cgroupv2
> cpu_cpuset_cpus: not supported
> cpu_memory_nodes: not supported
> active_processor_count: 8
> cpu_quota: not supported
> cpu_period: not supported
> cpu_shares: not supported
> memory_limit_in_bytes: unlimited
> memory_and_swap_limit_in_bytes: unlimited
> memory_soft_limit_in_bytes: unlimited
> memory_usage_in_bytes: 4962584 k
> memory_max_usage_in_bytes: not supported
> memory_swap_current_in_bytes: 0
> memory_swap_max_limit_in_bytes: unlimited
> maximum number of tasks: 18963
> current number of tasks: 33
> 
> In this example `memory_swap_current_in_bytes` should be printed as equal to 0, not "unlimited".

Gerard Ziemski 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 16 additional commits since the last revision:

 - need to pass in argument
 - Merge remote-tracking branch 'upstream/master' into JDK-8321931
 - Merge remote-tracking branch 'upstream/master' into JDK-8321931
 - jerboaa feedback
 - whitespace
 - fix how we check
 - whitespace
 - remove the check, we have a dedicated test for it
 - fix comment
 - relax syntax check for 0
 - ... and 6 more: https://git.openjdk.org/jdk/compare/10cfed61...078a79b6

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17314/files
  - new: https://git.openjdk.org/jdk/pull/17314/files/9833820b..078a79b6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17314&range=08
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17314&range=07-08

  Stats: 62084 lines in 2277 files changed: 33422 ins; 13637 del; 15025 mod
  Patch: https://git.openjdk.org/jdk/pull/17314.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17314/head:pull/17314

PR: https://git.openjdk.org/jdk/pull/17314