From cdad4c9fc575cb94974ae27e451aed47fc072710 Mon Sep 17 00:00:00 2001
From: Mischa POSLAWSKY <perl@shiar.org>
Date: Sat, 7 Sep 2019 19:32:07 +0200
Subject: [PATCH] order incoming values before interval
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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)).
---
 barcat | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/barcat b/barcat
index 1114656..4c3cf8a 100755
--- 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;
-- 
2.30.0