From: Mischa POSLAWSKY <perl@shiar.org>
Date: Sat, 7 Sep 2019 17:32:07 +0000 (+0200)
Subject: order incoming values before interval
X-Git-Tag: v1.04~2
X-Git-Url: http://git.shiar.nl/barcat.git/commitdiff_plain/cdad4c9fc575cb94974ae27e451aed47fc072710

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 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;