Use BFG object maps to clean projects

1 files changed, 52 insertions, 0 deletions

diff --git a/app/services/projects/cleanup_service.rb b/app/services/projects/cleanup_service.rb
new file mode 100644
index 00000000000..12103ea34b5
--- /dev/null
+++ b/app/services/projects/cleanup_service.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+module Projects
+  # The CleanupService removes data from the project repository following a
+  # BFG rewrite: https://rtyley.github.io/bfg-repo-cleaner/
+  #
+  # Before executing this service, all refs rewritten by BFG should have been
+  # pushed to the repository
+  class CleanupService < BaseService
+    NoUploadError = StandardError.new("Couldn't find uploaded object map")
+
+    include Gitlab::Utils::StrongMemoize
+
+    # Attempt to clean up the project following the push. Warning: this is
+    # destructive!
+    #
+    # path is the path of an upload of a BFG object map file. It contains a line
+    # per rewritten object, with the old and new SHAs space-separated. It can be
+    # used to update or remove content that references the objects that BFG has
+    # altered
+    #
+    # Currently, only the project repository is modified by this service, but we
+    # may wish to modify other data sources in the future.
+    def execute
+      apply_bfg_object_map!
+
+      # Remove older objects that are no longer referenced
+      GitGarbageCollectWorker.new.perform(project.id, :gc)
+
+      # The cache may now be inaccurate, and holding onto it could prevent
+      # bugs assuming the presence of some object from manifesting for some
+      # time. Better to feel the pain immediately.
+      project.repository.expire_all_method_caches
+
+      project.bfg_object_map.remove!
+    end
+
+    private
+
+    def apply_bfg_object_map!
+      raise NoUploadError unless project.bfg_object_map.exists?
+
+      project.bfg_object_map.open do |io|
+        repository_cleaner.apply_bfg_object_map(io)
+      end
+    end
+
+    def repository_cleaner
+      @repository_cleaner ||= Gitlab::Git::RepositoryCleaner.new(repository.raw)
+    end
+  end
+end