From a89f2eee3e06facd7b9b2cfce35e2c38828b4134 Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Sun, 8 Feb 2015 19:14:15 +0100
Subject: [PATCH] Added caching of image hashes (optional)

---
 gal/Makefile              |  2 +-
 gal/UCW/Gallery.pm        |  1 +
 gal/UCW/Gallery/Hashes.pm | 51 +++++++++++++++++++++++++++++++++++++++
 gal/bin/gal-scan          | 13 +++++-----
 4 files changed, 59 insertions(+), 8 deletions(-)
 create mode 100644 gal/UCW/Gallery/Hashes.pm

diff --git a/gal/Makefile b/gal/Makefile
index fcab413..5c6a23b 100644
--- a/gal/Makefile
+++ b/gal/Makefile
@@ -1,7 +1,7 @@
 $(eval $(dir-setup))
 
 $(call lib-copy, UCW/Gallery.pm)
-$(call lib-copy, $(addprefix UCW/Gallery/, Web.pm Archive.pm))
+$(call lib-copy, $(addprefix UCW/Gallery/, Web.pm HashCache.pm Archive.pm))
 $(call lib-copy, $(addprefix UCW/Gallery/Web/, Plain.pm NrtBlue.pm HighSlide.pm))
 
 $(call copy, $(addprefix nrt-blue/,back.png bot.png left.png next.png prev.png right.png top.png style.css))
diff --git a/gal/UCW/Gallery.pm b/gal/UCW/Gallery.pm
index c5d5c9b..1e7bba3 100644
--- a/gal/UCW/Gallery.pm
+++ b/gal/UCW/Gallery.pm
@@ -32,6 +32,7 @@ sub new($) {
 		ThumbFormats => [ "114x94" ],	# Built-in themes use the first size,
 						# but more can be generated
 		CacheExif => 0,			# Cache selected EXIF meta-data
+		CacheHashes => 1,		# Let gal-scan cache file hashes
 
 		# Titles and navigation
 		Title => 'An Unnamed Gallery',
diff --git a/gal/UCW/Gallery/Hashes.pm b/gal/UCW/Gallery/Hashes.pm
new file mode 100644
index 0000000..d0414e9
--- /dev/null
+++ b/gal/UCW/Gallery/Hashes.pm
@@ -0,0 +1,51 @@
+# Simple Photo Gallery: Image Hashes
+# (c) 2015 Martin Mares <mj@ucw.cz>
+
+package UCW::Gallery::Hashes;
+
+use strict;
+use warnings;
+
+use File::stat ();
+use Digest::SHA;
+
+sub new {
+	my ($class, $gal) = @_;
+	my $self = { gal => $gal };
+
+	if ($gal->get('CacheHashes') && -f 'gallery.cache') {
+		print "Loading gallery.cache\n";
+		$self->{cache} = $gal->read_meta('gallery.cache');
+	} else {
+		$self->{cache} = {};
+	}
+
+	return bless $self, $class;
+}
+
+sub write {
+	my ($self) = @_;
+	my $gal = $self->{gal};
+	if ($gal->get('CacheHashes')) {
+		print "Writing gallery.cache\n";
+		$gal->write_meta('gallery.cache', $self->{cache});
+	}
+}
+
+sub hash_image {
+	my ($self, $path) = @_;
+	my $cache = $self->{cache};
+
+	my $st = File::stat::stat($path) or die "Cannot access $path: $!\n";
+	my $key_text = join(":", $path, $st->dev, $st->ino, $st->mtime);
+	my $key = Digest::SHA->sha1_base64($key_text);
+
+	if (!exists $cache->{$key}) {
+		my $sha = Digest::SHA->new(1);
+		$sha->addfile($path) or die "Cannot hash $path\n";
+		$cache->{$key} = substr($sha->hexdigest, 0, 16);
+	}
+	return $cache->{$key};
+}
+
+42;
diff --git a/gal/bin/gal-scan b/gal/bin/gal-scan
index a1f5e5b..4424cc3 100755
--- a/gal/bin/gal-scan
+++ b/gal/bin/gal-scan
@@ -1,14 +1,14 @@
 #!/usr/bin/perl
 # UCW Gallery: Scan images and generate image list
-# (c) 2004--2012 Martin Mares <mj@ucw.cz>
+# (c) 2004--2015 Martin Mares <mj@ucw.cz>
 
 use strict;
 use warnings;
 
 use UCW::Gallery;
+use UCW::Gallery::Hashes;
 use File::Spec;
 use Image::EXIF;
-use Digest::SHA;
 use Getopt::Long;
 
 if (@ARGV && $ARGV[0] eq '--help') {
@@ -60,6 +60,8 @@ if ($update) {
 	}
 }
 
+my $hashes = UCW::Gallery::Hashes->new($gal);
+
 print "Scanning photos\n";
 my @images = ();
 foreach my $src (@source) {
@@ -75,11 +77,7 @@ foreach my $src (@source) {
 	my $path = File::Spec->rel2abs($name, $gal->get('OrigDir'));
 	-f $path or die "Cannot find $path\n";
 
-	if (!defined $src->{id}) {
-		my $sha = Digest::SHA->new(1);
-		$sha->addfile($path) or die "Cannot hash $path\n";
-		$src->{id} = substr($sha->hexdigest, 0, 16);
-	}
+	$src->{id} = $hashes->hash_image($path);
 	print " id=", $src->{id};
 
 	if (!defined $src->{orientation} || $src->{orientation} eq '-') {
@@ -141,3 +139,4 @@ if (!$update) {
 
 $gal->write_list('gallery.list', \@images);
 print "Written gallery.list (", (scalar @images), " items)\n";
+$hashes->write;
-- 
2.39.2