On Sun, Jan 15, 2023 at 12:27 AM Mike Frysinger <vap...@gentoo.org> wrote: > On 14 Jan 2023 21:27, Jacob Bachmeyer wrote: > > Mike Frysinger wrote: > > > --- a/lib/Automake/FileUtils.pm > > > +++ b/lib/Automake/FileUtils.pm > > > @@ -42,6 +42,11 @@ use Exporter; > > > use File::stat; > > > use IO::File; > > > > > > +# Perl's builtin stat does not provide sub-second resolution. Use > > > Time::HiRes > > > +# if it's available instead. Hopefully one day perl will update. > > > +# https://github.com/Perl/perl5/issues/17900 > > > +my $have_time_hires = eval { require Time::HiRes; }; > > > + > > > use Automake::Channels; > > > use Automake::ChannelDefs; > > > > > > @@ -115,10 +120,18 @@ sub mtime ($) > > > return 0 > > > if $file eq '-' || ! -f $file; > > > > > > - my $stat = stat ($file) > > > - or fatal "cannot stat $file: $!"; > > > - > > > - return $stat->mtime; > > > + if ($have_time_hires) > > > + { > > > + my @stat = Time::HiRes::stat ($file) > > > + or fatal "cannot stat $file: $!"; > > > + return $stat[9]; > > > + } > > > + else > > > + { > > > + my $stat = stat ($file) > > > + or fatal "cannot stat $file: $!"; > > > + return $stat->mtime; > > > + } > > > } > > > > If you change that variable to a constant, you can eliminate the runtime > > overhead entirely, since Perl optimizes if(1) and if(0) and folds > > constants at compile time. > > > > Something like: > > > > use constant HAVE_Time_HiRes => eval { require Time::HiRes; }; > > > > Then: > > > > if (HAVE_Time_HiRes) > > ... > > > > If you do this, Perl will inline the block actually used and elide the > > branch at runtime. This is generally useful for any test that can only > > go one way in a specific run of the program. > > thanks, i'll integrate that idea. i'm by no means a perl programmer.
Thanks, Mike. It looks like this has been resolved slightly differently by a recent change from Paul Eggert, so I'm closing this.
