We can avoid a slow regexp capture and instead and rely on
rindex + substr to extract the section from the config file.
Then we use the defined-or-assignment (//=) operator combined
with the documented return value of `push' to ensure @section_order
is unique without repeating a hash lookup.
Finally, we avoid short-lived variables inside the loop and
declare them subroutine-wide to knock a teeny bit of allocation
time.
Combined, these optimizations bring the ~1.22s
PublicInbox::Config->new time down to ~0.98s with 50K inboxes.
sub config_fh_parse ($$$) {
my ($fh, $rs, $fs) = @_;
sub config_fh_parse ($$$) {
my ($fh, $rs, $fs) = @_;
- my %rv;
- my (%section_seen, @section_order);
+ my (%rv, %section_seen, @section_order, $line, $k, $v, $section, $cur);
- while (defined(my $line = <$fh>)) {
+ while (defined($line = <$fh>)) { # performance critical with giant configs
- my ($k, $v) = split($fs, $line, 2);
- my ($section) = ($k =~ /\A(\S+)\.[^\.]+\z/);
- unless (defined $section_seen{$section}) {
- $section_seen{$section} = 1;
- push @section_order, $section;
- }
+ ($k, $v) = split($fs, $line, 2);
+ $section = substr($k, 0, rindex($k, '.'));
+ $section_seen{$section} //= push(@section_order, $section);
- my $cur = $rv{$k};
- if (defined $cur) {
+ if (defined($cur = $rv{$k})) {
if (ref($cur) eq "ARRAY") {
push @$cur, $v;
} else {
if (ref($cur) eq "ARRAY") {
push @$cur, $v;
} else {