order incoming values before interval

If Tie::Array::Sorted is available, use it to insert input in order instead
of recalculating on every interval.  Assumes frequent refreshes of thousands
of lines, in which case it saves significantly, also slowing down less
exponentially (probably O(l) instead of O(t*l²)).

diff --git a/barcat b/barcat
index 1114656f74c0cab9a0a69eb91f3599ca78ffea26..4c3cf8a763210ae3eb31fb7ecb41a25665da6ac0 100755 (executable)
--- a/barcat
+++ b/barcat
@@ -6,7 +6,7 @@ use List::Util qw( min max sum );
 use open qw( :std :utf8 );
 use experimental qw( lexical_subs );
 
-our $VERSION = '1.03';
+our $VERSION = '1.04';
 
 use Getopt::Long '2.33', qw( :config gnu_getopt );
 sub podexit {
@@ -61,6 +61,8 @@ $opt{units}   = [split //, ' kMGTPEZYyzafpnμm'] if $opt{'human-readable'};
 $opt{anchor} //= qr/\A/;
 $opt{'value-length'} = 6 if $opt{units};
 
+my (@lines, @values, @order);
+
 if (defined $opt{interval}) {
        $opt{interval} ||= 1;
        $SIG{ALRM} = sub {
@@ -68,11 +70,15 @@ if (defined $opt{interval}) {
                alarm $opt{interval};
        };
        alarm $opt{interval};
+
+       eval {
+               require Tie::Array::Sorted;
+               tie @order, 'Tie::Array::Sorted', sub { $_[1] <=> $_[0] };
+       } or warn $@, "Expect slowdown with large datasets!\n";
 }
 
 $SIG{INT} = 'IGNORE';  # continue after assumed eof
 
-my (@lines, @values, @order);
 my $valmatch = qr/$opt{anchor} ( \h* -? [0-9]* \.? [0-9]+ (?: e[+-]?[0-9]+ )? |)/x;
 while (readline) {
        s/\r?\n\z//;
@@ -100,7 +106,7 @@ state $nr = $opt{hidemin} ? $opt{hidemin} - 1 : 0;
 @lines or return;
 @lines > $nr or return unless $opt{hidemin};
 
-@order = sort { $b <=> $a } @order;
+@order = sort { $b <=> $a } @order unless tied @order;
 my $maxval = ($opt{hidemax} ? max grep { length } @values[0 .. $opt{hidemax} - 1] : $order[0]) // 0;
 my $minval = min $order[-1] // (), 0;
 my $lenval = $opt{'value-length'} // max map { length } @order;