perf/aggregate: implement codespeed JSON output

Codespeed (https://github.com/tobami/codespeed/) is an open source
project that can be used to track how some software performs over
time. It stores performance test results in a database and can show
nice graphs and charts on a web interface.

As it can be interesting to use Codespeed to see how Git performance
evolves over time and releases, let's implement a Codespeed output
in "perf/aggregate.perl".

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/perf/aggregate.perl

@@ -3,6 +3,7 @@
 use lib '../../perl/blib/lib';
 use strict;
 use warnings;
+use JSON;
 use Git;
 
 sub get_times {
@@ -35,10 +36,15 @@ sub format_times {
 	return $out;
 }
 
-my (@dirs, %dirnames, %dirabbrevs, %prefixes, @tests);
+my (@dirs, %dirnames, %dirabbrevs, %prefixes, @tests, $codespeed);
 while (scalar @ARGV) {
 	my $arg = $ARGV[0];
 	my $dir;
+	if ($arg eq "--codespeed") {
+		$codespeed = 1;
+		shift @ARGV;
+		next;
+	}
 	last if -f $arg or $arg eq "--";
 	if (! -d $arg) {
 		my $rev = Git::command_oneline(qw(rev-parse --verify), $arg);
@@ -70,8 +76,10 @@ if (not @tests) {
 }
 
 my $resultsdir = "test-results";
+my $results_section = "";
 if (exists $ENV{GIT_PERF_SUBSECTION} and $ENV{GIT_PERF_SUBSECTION} ne "") {
 	$resultsdir .= "/" . $ENV{GIT_PERF_SUBSECTION};
+	$results_section = $ENV{GIT_PERF_SUBSECTION};
 }
 
 my @subtests;
@@ -174,6 +182,58 @@ sub print_default_results {
 	}
 }
 
+sub print_codespeed_results {
+	my ($results_section) = @_;
+
+	my $project = "Git";
+
+	my $executable = `uname -s -m`;
+	chomp $executable;
+
+	if ($results_section ne "") {
+		$executable .= ", " . $results_section;
+	}
+
+	my $environment;
+	if (exists $ENV{GIT_PERF_REPO_NAME} and $ENV{GIT_PERF_REPO_NAME} ne "") {
+		$environment = $ENV{GIT_PERF_REPO_NAME};
+	} elsif (exists $ENV{GIT_TEST_INSTALLED} and $ENV{GIT_TEST_INSTALLED} ne "") {
+		$environment = $ENV{GIT_TEST_INSTALLED};
+		$environment =~ s|/bin-wrappers$||;
+	} else {
+		$environment = `uname -r`;
+		chomp $environment;
+	}
+
+	my @data;
+
+	for my $t (@subtests) {
+		for my $d (@dirs) {
+			my $commitid = $prefixes{$d};
+			$commitid =~ s/^build_//;
+			$commitid =~ s/\.$//;
+			my ($result_value, $u, $s) = get_times("$resultsdir/$prefixes{$d}$t.times");
+
+			my %vals = (
+				"commitid" => $commitid,
+				"project" => $project,
+				"branch" => $dirnames{$d},
+				"executable" => $executable,
+				"benchmark" => $shorttests{$t} . " " . read_descr("$resultsdir/$t.descr"),
+				"environment" => $environment,
+				"result_value" => $result_value,
+			    );
+			push @data, \%vals;
+		}
+	}
+
+	print to_json(\@data, {utf8 => 1, pretty => 1}), "\n";
+}
+
 binmode STDOUT, ":utf8" or die "PANIC on binmode: $!";
 
-print_default_results();
+if ($codespeed) {
+	print_codespeed_results($results_section);
+} else {
+	print_default_results();
+}