PathTimeTable/DB: Add cache to reduce number of DB calls

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

1 files changed, 51 insertions, 2 deletions

diff --git a/lib/App/BorgRestore/PathTimeTable/DB.pm b/lib/App/BorgRestore/PathTimeTable/DB.pm
index ac9969e..5d07ebc 100644
--- a/lib/App/BorgRestore/PathTimeTable/DB.pm
+++ b/lib/App/BorgRestore/PathTimeTable/DB.pm
@@ -3,6 +3,7 @@ use strict;
 use warnings;
 
 use Function::Parameters;
+use Log::Any qw($log);
 
 =head1 NAME
 
@@ -13,6 +14,13 @@ App::BorgRestore::PathTimeTable::DB - Directly write new archive data to the dat
 This is used by L<App::BorgRestore> to add new archive data into the database.
 Data is written to the database directly and existing data is updated where necessary.
 
+For performance reasons this class keeps an internal cache so that the database
+is only contacted when necessary. Depending on the distribution of modification
+times of files and directories, the effectiveness of this cache can vary. The
+cache also assumes that the path are sorted so that all files from one
+directory are added, before files from another. If a path from a different
+directory is added, the previous cache is invalidated.
+
 =cut
 
 method new($class: $deps = {}) {
@@ -23,6 +31,9 @@ method new_no_defaults($class: $deps = {}) {
 	my $self = {};
 	bless $self, $class;
 	$self->{deps} = $deps;
+	$self->{cache} = {};
+	$self->{current_path_in_cache} = "";
+	$self->{stats} = {};
 	return $self;
 }
 
@@ -31,15 +42,53 @@ 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};
+		}
+		$old_cache_path =~ s|/[^/]*$||;
+	}
+
+	my $full_path = $path;
 	while ($path =~ m#/#) {
-		$self->{deps}->{db}->update_path_if_greater($self->{archive_id}, $path, $time);
+		$self->_add_path_to_db($self->{archive_id}, $path, $time);
+		my $cached = $self->{cache}->{$path};
+		if ($path ne $full_path && (!defined $cached || $cached < $time)) {
+			# logging statements are commented since they incur a performance
+			# overhead because they are called very often. Uncomment when necessary
+			#$log->tracef("Setting cache time for path '%s' to %d", $path, $time);
+			$self->{cache}->{$path} = $time;
+		}
 		$path =~ s|/[^/]*$||;
 	}
-	$self->{deps}->{db}->update_path_if_greater($self->{archive_id}, $path, $time) unless $path eq ".";
+	$self->_add_path_to_db($self->{archive_id}, $path, $time) unless $path eq ".";
+	my $cached = $self->{cache}->{$path};
+	if ($path ne $full_path && (!defined $cached || $cached < $time)) {
+		#$log->tracef("Setting cache time for path '%s' to %d", $path, $time);
+		$self->{cache}->{$path} = $time;
+	}
+	$self->{current_path_in_cache} = $full_path;
+}
+
+method _add_path_to_db($archive_id, $path,$time) {
+	my $cached = $self->{cache}->{$path};
+	$self->{stats}->{total_potential_calls_to_db_class}++;
+	if (!defined $cached || $cached < $time) {
+		#$log->tracef("Updating DB for path '%s' with time %d", $path, $time);
+		$self->{stats}->{real_calls_to_db_class}++;
+		$self->{deps}->{db}->update_path_if_greater($archive_id, $path, $time);
+	} else {
+		#$log->tracef("Skipping DB update for path '%s' because (cached) DB time is %d and file time is %d which is lower", $path, $cached, $time);
+	}
 }
 
 
 method save_nodes() {
+	for my $key (keys %{$self->{stats}}) {
+		$log->debugf("Performance counter %s = %s", $key, $self->{stats}->{$key});
+	}
 	# do nothing because we already write everything to the DB directly
 }