PathTimeTable/DB: Improve performance by removing usage of regex in hot places

This cuts execution time on my workstation from about 85 seconds for an
--update-cache adding one archive to roughly 62 seconds. Measured
totally unscientifically by simply running the full application instead
of isolating the code, but it makes sense that regexes are slower so
I'll take it.

Signed-off-by: Florian Pritz <bluewind@xinu.at>

1 files changed, 10 insertions, 6 deletions

diff --git a/lib/App/BorgRestore/PathTimeTable/DB.pm b/lib/App/BorgRestore/PathTimeTable/DB.pm
index 1a24999..b0c0bb8 100644
--- a/lib/App/BorgRestore/PathTimeTable/DB.pm
+++ b/lib/App/BorgRestore/PathTimeTable/DB.pm
@@ -43,15 +43,19 @@ method set_archive_id($archive_id) {
 method add_path($path, $time) {
 	$self->{stats}->{total_paths}++;
 	my $old_cache_path = $self->{current_path_in_cache};
-	while ($old_cache_path =~ m#/#) {
-		unless ($path =~ m#^\Q$old_cache_path\E/#) {
-			delete $self->{cache}->{$old_cache_path};
+	while ((my $slash_index = rindex($old_cache_path, "/")) != -1) {
+		$self->{stats}->{cache_invalidation_loop_iterations}++;
+		if ($old_cache_path eq substr($path, 0, length($old_cache_path))) {
+			# keep the cache content for the part of the path that stays the same
+			last;
 		}
-		$old_cache_path =~ s|/[^/]*$||;
+		delete $self->{cache}->{$old_cache_path};
+		# strip last part of path
+		$old_cache_path = substr($old_cache_path, 0, $slash_index);
 	}
 
 	my $full_path = $path;
-	while ($path =~ m#/#) {
+	while ((my $slash_index = rindex($path, "/")) != -1) {
 		$self->_add_path_to_db($self->{archive_id}, $path, $time);
 		my $cached = $self->{cache}->{$path};
 		if ($path ne $full_path && (!defined $cached || $cached < $time)) {
@@ -60,7 +64,7 @@ method add_path($path, $time) {
 			#$log->tracef("Setting cache time for path '%s' to %d", $path, $time);
 			$self->{cache}->{$path} = $time;
 		}
-		$path =~ s|/[^/]*$||;
+		$path = substr($path, 0, $slash_index);
 	}
 	$self->_add_path_to_db($self->{archive_id}, $path, $time) unless $path eq ".";
 	my $cached = $self->{cache}->{$path};