[PATCH v2] virProcessGetStatInfo: add a comment describing why we can not report error

[Ani Sinha]

ping ...

On Fri, 21 Jan 2022, Ani Sinha wrote:

> virProcessGetStatInfo() currently is unable to report error conditions because
> that breaks libvirt's public best effort APIs. We add a comment in the function
> to indicate this. Adding comment here prevents others from going down the path
> of reporting error conditions in this functions in the future. It also reminds
> us that at some point in the future we need to fix the code so that this
> limitations no longer exists.
>
> Please also see commit
> 105dace22cc7 ("Revert "report error when virProcessGetStatInfo() is unable to parse data"")
>
> Signed-off-by: Ani Sinha <ani at anisinha.ca>
> ---
>  src/util/virprocess.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/src/util/virprocess.c b/src/util/virprocess.c
> index b559a4257e..9422829b8b 100644
> --- a/src/util/virprocess.c
> +++ b/src/util/virprocess.c
> @@ -1784,6 +1784,12 @@ virProcessGetStatInfo(unsigned long long *cpuTime,
>          virStrToLong_ullp(proc_stat[VIR_PROCESS_STAT_STIME], NULL, 10, &systime) < 0 ||
>          virStrToLong_l(proc_stat[VIR_PROCESS_STAT_RSS], NULL, 10, &rss) < 0 ||
>          virStrToLong_i(proc_stat[VIR_PROCESS_STAT_PROCESSOR], NULL, 10, &cpu) < 0) {
> +        /* This function can not report error at present. Reporting error here
> +         * causes some of libvirt's best effort public APIs to fail. This
> +         * resuts in external API behavior change. Until we can fix this in
> +         * a way so that public API behavior remains unchanged, we can only
> +         * write a warning log here.
> +         */
>          VIR_WARN("cannot parse process status data");
>      }
>
> --
> 2.25.1
>
>