From d04a98e723555c5cd21dde6834b42c0297850e42 Mon Sep 17 00:00:00 2001
From: Jens Kraemer <jk@jkraemer.net>
Date: Tue, 11 Dec 2018 14:48:13 +0800
Subject: [PATCH 1/2] allows re-use of thumbnails for identical attachments

- changes the thumbnail file naming scheme to
  digest_filesize_size.thumb.
---
 app/models/attachment.rb     |  2 +-
 test/unit/attachment_test.rb | 24 +++++++++++++++++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/app/models/attachment.rb b/app/models/attachment.rb
index cc9b5f930..fd4931eaf 100644
--- a/app/models/attachment.rb
+++ b/app/models/attachment.rb
@@ -216,7 +216,7 @@ class Attachment < ActiveRecord::Base
         size = Setting.thumbnails_size.to_i
       end
       size = 100 unless size > 0
-      target = File.join(self.class.thumbnails_storage_path, "#{id}_#{digest}_#{size}.thumb")
+      target = File.join(self.class.thumbnails_storage_path, "#{digest}_#{filesize}_#{size}.thumb")
 
       begin
         Redmine::Thumbnail.generate(self.diskfile, target, size)
diff --git a/test/unit/attachment_test.rb b/test/unit/attachment_test.rb
index 2bee67ed2..c89ed5631 100644
--- a/test/unit/attachment_test.rb
+++ b/test/unit/attachment_test.rb
@@ -429,11 +429,33 @@ class AttachmentTest < ActiveSupport::TestCase
 
       assert_difference "Dir.glob(File.join(Attachment.thumbnails_storage_path, '*.thumb')).size" do
         thumbnail = attachment.thumbnail
-        assert_equal "16_8e0294de2441577c529f170b6fb8f638_100.thumb", File.basename(thumbnail)
+        assert_equal "8e0294de2441577c529f170b6fb8f638_2654_100.thumb", File.basename(thumbnail)
         assert File.exists?(thumbnail)
       end
     end
 
+    def test_should_reuse_thumbnail
+      a = Attachment.create!(
+        :container => Issue.find(1),
+        :file => uploaded_test_file("2010/11/101123161450_testfile_1.png", "image/png"),
+        :author => User.find(1)
+      )
+      a_thumb = b_thumb = nil
+      assert_difference "Dir.glob(File.join(Attachment.thumbnails_storage_path, '*.thumb')).size" do
+        a_thumb = a.thumbnail
+      end
+
+      b = Attachment.create!(
+        :container => Issue.find(2),
+        :file => uploaded_test_file("2010/11/101123161450_testfile_1.png", "image/png"),
+        :author => User.find(1)
+      )
+      assert_no_difference "Dir.glob(File.join(Attachment.thumbnails_storage_path, '*.thumb')).size" do
+        b_thumb = b.thumbnail
+      end
+      assert_equal a_thumb, b_thumb
+    end
+
     def test_thumbnail_should_return_nil_if_generation_fails
       Redmine::Thumbnail.expects(:generate).raises(SystemCallError, 'Something went wrong')
       set_fixtures_attachments_directory
-- 
2.11.0