Re: [Xen-devel] [OSSTEST PATCH 07/11] cri-getconfig: Provide debugging for get_psql_cmd

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Fri, 2015-12-04 at 19:35 +0000, Ian Jackson wrote:
> This allows us to execute only the first <some number> SQL
> invocations.ÂÂThe first non-executed one is dumped, instead, by having
> get_psql_command print a rune involving ./mg-debug-fail (which the
> caller will then execute).
> 
> The locking makes things work roughly-correctly if get_psql_cmd is run
> in multiple processes at once: it is not defined exactly which
> invocations get which counter values, but they will all work properly
> and get exactly one counter value each.
> 
> If set -x is in force, turn it off for get_psql_cmd: our perl rune is
> uninteresting to see repeated ad infinitum in debugging output.

I should probably know this, but what is the scope of the set +x here? Is
it confined to get_psql_cmd or will callers find things going surprisingly
quiet?

Experimentally I think it is the latter, which is a shame. Maybe just wrap
the set+perl in ()s ?

> 
> Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> ---
> Âcri-getconfig |ÂÂÂ16 ++++++++++++++++
> Â1 file changed, 16 insertions(+)
> 
> diff --git a/cri-getconfig b/cri-getconfig
> index 48528b5..a357d86 100644
> --- a/cri-getconfig
> +++ b/cri-getconfig
> @@ -41,6 +41,22 @@ getrepos() {
> Â}
> Â
> Âget_psql_cmd () {
> +     # To use this:
> +     #ÂÂon each test run, rm -f t.psql-counter
> +     #ÂÂand set OSSTEST_PSQL_ONLY_DO to an integer
> +     if [ "x$OSSTEST_PSQL_ONLY_DO" != x ]; then
> +             local f=t.psql-counter
> +             psql_counter=$( with-lock-ex -w $f.lock bash -ec '
> +                     psql_counter=$(cat '$f' || echo 0)
> +                     echo $(( $psql_counter + 1 )) >'$f'.tmp
> +                     mv -f '$f'.tmp '$f'
> +                     echo $psql_counter' )
> +             if ! [ $psql_counter -lt $OSSTEST_PSQL_ONLY_DO ]; then
> +                     printf './mg-debug-fail '
> +             fi
> +     fi
> +
> +     set +x
> Â     perl -we '
> Â     use Osstest;
> Â     use Osstest::Executive;

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