Re: [PATCH] fsmonitor: query watchman with right valid json

[Son Luong Ngoc <sluongng@gmail.com>]

Hi Ævar,

On Tue, Jun 7, 2022 at 10:42 AM Ævar Arnfjörð Bjarmason
<avarab@gmail.com> wrote:
>
>
> On Tue, Jun 07 2022, Son Luong Ngoc wrote:
>
> > In rare circumstances where the current git index does not carry the
> > last_update_token, the fsmonitor v2 hook will be invoked with an
> > empty string which would caused the final rendered json to be invalid.
> >
> >   ["query", "/path/to/my/git/repository/", {
> >           "since": ,
> >           "fields": ["name"],
> >           "expression": ["not", ["dirname", ".git"]]
> >   }]
> >
> > Which will left user with the following error message
> >
> >   > git status
> >   failed to parse command from stdin: line 2, column 13, position 67: unexpected token near ','
> >   Watchman: command returned no output.
> >   Falling back to scanning...
> >
> > Hide the "since" field in json query when "last_update_token" is empty.
> >
> > Signed-off-by: Son Luong Ngoc <sluongng@gmail.com>
> > ---
> >  templates/hooks--fsmonitor-watchman.sample | 21 +++++++++++++--------
> >  1 file changed, 13 insertions(+), 8 deletions(-)
> >
> > diff --git a/templates/hooks--fsmonitor-watchman.sample b/templates/hooks--fsmonitor-watchman.sample
> > index 14ed0aa42d..b4ee86dfc4 100755
> > --- a/templates/hooks--fsmonitor-watchman.sample
> > +++ b/templates/hooks--fsmonitor-watchman.sample
> > @@ -79,6 +79,12 @@ sub watchman_query {
> >       or die "open2() failed: $!\n" .
> >       "Falling back to scanning...\n";
> >
> > +     my $query = <<" END";
> > +             ["query", "$git_work_tree", {
> > +                     "fields": ["name"],
> > +                     "expression": ["not", ["dirname", ".git"]]
> > +             }]
> > +     END
>
> Wouldn't a more minimal & obvious patch here be....
>
> >       # In the query expression below we're asking for names of files that
> >       # changed since $last_update_token but not from the .git folder.
> >       #
> > @@ -87,15 +93,14 @@ sub watchman_query {
> >       # output to file names only. Then we're using the "expression" term to
> >       # further constrain the results.
> >       if (substr($last_update_token, 0, 1) eq "c") {
> > -             $last_update_token = "\"$last_update_token\"";
>
> To just change this to be:
>
>         # same as now:
>         $last_update_token = "\"$last_update_token\"";
>         $last_update_line = qq["since": $last_update_token,];
>
> Of course having declared the new $last_update_line variable earlier, then:
>

Yup, I think this is a sensible suggestion.
I will fixup and send a V2 shortly.

> > +             $query = <<"            END";
> > +                     ["query", "$git_work_tree", {
> > +                             "since": "$last_update_token",
> > +                             "fields": ["name"],
> > +                             "expression": ["not", ["dirname", ".git"]]
> > +                     }]
> > +             END
> >       }
> > -     my $query = <<" END";
> > -             ["query", "$git_work_tree", {
> > -                     "since": $last_update_token,
>
> Just change this line to:
>
>         $last_update_line
>
> I.e. you don't need to duplicate the whole query just to omit/include a
> single line in it, or am I missing something?
>
> (This suggestion *would* include a redundant line, but I'm assuming
> JSON/watchman deals with that just fine...).

I think we can remove that redundant line by adding '\n' before
$last_update_line.
I will be including this into the next version.

Thanks,
Son Luong.