1 files changed, 71 insertions, 0 deletions
diff --git a/lib/gitlab/composer/cache.rb b/lib/gitlab/composer/cache.rb
new file mode 100644
index 00000000000..1f404d63047
--- /dev/null
+++ b/lib/gitlab/composer/cache.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+require 'tempfile'
+
+module Gitlab
+  module Composer
+    class Cache
+      def initialize(project:, name:, last_page_sha: nil)
+        @project = project
+        @name = name
+        @last_page_sha = last_page_sha
+      end
+
+      def execute
+        Packages::Composer::Metadatum.transaction do # rubocop: disable CodeReuse/ActiveRecord
+          # make sure we lock these records at the start
+          locked_package_metadata
+
+          if locked_package_metadata.any?
+            mark_pages_for_delete(shas_to_delete)
+
+            create_cache_page!
+
+            # assign the newest page SHA to the packages
+            locked_package_metadata.update_all(version_cache_sha: version_index.sha)
+          elsif @last_page_sha
+            mark_pages_for_delete([@last_page_sha])
+          end
+        end
+      end
+
+      private
+
+      def mark_pages_for_delete(shas)
+        Packages::Composer::CacheFile
+          .with_namespace(@project.namespace)
+          .with_sha(shas)
+          .update_all(delete_at: 1.day.from_now)
+      end
+
+      def create_cache_page!
+        Packages::Composer::CacheFile
+          .safe_find_or_create_by!(namespace_id: @project.namespace_id, file_sha256: version_index.sha) do |cache_file|
+            cache_file.file = CarrierWaveStringFile.new(version_index.to_json)
+          end
+      end
+
+      def version_index
+        @version_index ||= ::Gitlab::Composer::VersionIndex.new(siblings)
+      end
+
+      def siblings
+        @siblings ||= locked_package_metadata.map(&:package)
+      end
+
+      # find all metadata of the package versions and lock it for update
+      def locked_package_metadata
+        @locked_package_metadata ||= Packages::Composer::Metadatum
+          .for_package(@name, @project.id)
+          .locked_for_update
+      end
+
+      def shas_to_delete
+        locked_package_metadata
+          .map(&:version_cache_sha)
+          .reject { |sha| sha == version_index.sha }
+          .compact
+      end
+    end
+  end
+end