1 files changed, 163 insertions, 0 deletions
diff --git a/lib/gitlab/background_migration/prepare_untracked_uploads.rb b/lib/gitlab/background_migration/prepare_untracked_uploads.rb
new file mode 100644
index 00000000000..476c46341ae
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+++ b/lib/gitlab/background_migration/prepare_untracked_uploads.rb
@@ -0,0 +1,163 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module BackgroundMigration
+    # This class finds all non-hashed uploaded file paths and saves them to a
+    # `untracked_files_for_uploads` table.
+    class PrepareUntrackedUploads # rubocop:disable Metrics/ClassLength
+      # For bulk_queue_background_migration_jobs_by_range
+      include Database::MigrationHelpers
+
+      FIND_BATCH_SIZE = 500
+      RELATIVE_UPLOAD_DIR = "uploads".freeze
+      ABSOLUTE_UPLOAD_DIR = "#{CarrierWave.root}/#{RELATIVE_UPLOAD_DIR}".freeze
+      FOLLOW_UP_MIGRATION = 'PopulateUntrackedUploads'.freeze
+      START_WITH_CARRIERWAVE_ROOT_REGEX = %r{\A#{CarrierWave.root}/}
+      EXCLUDED_HASHED_UPLOADS_PATH = "#{ABSOLUTE_UPLOAD_DIR}/@hashed/*".freeze
+      EXCLUDED_TMP_UPLOADS_PATH = "#{ABSOLUTE_UPLOAD_DIR}/tmp/*".freeze
+
+      # This class is used to iterate over batches of
+      # `untracked_files_for_uploads` rows.
+      class UntrackedFile < ActiveRecord::Base
+        include EachBatch
+
+        self.table_name = 'untracked_files_for_uploads'
+      end
+
+      def perform
+        ensure_temporary_tracking_table_exists
+
+        # Since Postgres < 9.5 does not have ON CONFLICT DO NOTHING, and since
+        # doing inserts-if-not-exists without ON CONFLICT DO NOTHING would be
+        # slow, start with an empty table for Postgres < 9.5.
+        # That way we can do bulk inserts at ~30x the speed of individual
+        # inserts (~20 minutes worth of inserts at GitLab.com scale instead of
+        # ~10 hours).
+        # In all other cases, installations will get both bulk inserts and the
+        # ability for these jobs to retry without having to clear and reinsert.
+        clear_untracked_file_paths unless can_bulk_insert_and_ignore_duplicates?
+
+        store_untracked_file_paths
+
+        schedule_populate_untracked_uploads_jobs
+      end
+
+      private
+
+      def ensure_temporary_tracking_table_exists
+        table_name = :untracked_files_for_uploads
+        unless UntrackedFile.connection.table_exists?(table_name)
+          UntrackedFile.connection.create_table table_name do |t|
+            t.string :path, limit: 600, null: false
+            t.index :path, unique: true
+          end
+        end
+      end
+
+      def clear_untracked_file_paths
+        UntrackedFile.delete_all
+      end
+
+      def store_untracked_file_paths
+        return unless Dir.exist?(ABSOLUTE_UPLOAD_DIR)
+
+        each_file_batch(ABSOLUTE_UPLOAD_DIR, FIND_BATCH_SIZE) do |file_paths|
+          insert_file_paths(file_paths)
+        end
+      end
+
+      def each_file_batch(search_dir, batch_size, &block)
+        cmd = build_find_command(search_dir)
+
+        Open3.popen2(*cmd) do |stdin, stdout, status_thread|
+          yield_paths_in_batches(stdout, batch_size, &block)
+
+          raise "Find command failed" unless status_thread.value.success?
+        end
+      end
+
+      def yield_paths_in_batches(stdout, batch_size, &block)
+        paths = []
+
+        stdout.each_line("\0") do |line|
+          paths << line.chomp("\0").sub(START_WITH_CARRIERWAVE_ROOT_REGEX, '')
+
+          if paths.size >= batch_size
+            yield(paths)
+            paths = []
+          end
+        end
+
+        yield(paths)
+      end
+
+      def build_find_command(search_dir)
+        cmd = %W[find -L #{search_dir}
+                 -type f
+                 ! ( -path #{EXCLUDED_HASHED_UPLOADS_PATH} -prune )
+                 ! ( -path #{EXCLUDED_TMP_UPLOADS_PATH} -prune )
+                 -print0]
+
+        ionice = which_ionice
+        cmd = %W[#{ionice} -c Idle] + cmd if ionice
+
+        log_msg = "PrepareUntrackedUploads find command: \"#{cmd.join(' ')}\""
+        Rails.logger.info log_msg
+
+        cmd
+      end
+
+      def which_ionice
+        Gitlab::Utils.which('ionice')
+      rescue StandardError
+        # In this case, returning false is relatively safe,
+        # even though it isn't very nice
+        false
+      end
+
+      def insert_file_paths(file_paths)
+        sql = insert_sql(file_paths)
+
+        ActiveRecord::Base.connection.execute(sql)
+      end
+
+      def insert_sql(file_paths)
+        if postgresql_pre_9_5?
+          "INSERT INTO #{table_columns_and_values_for_insert(file_paths)};"
+        elsif postgresql?
+          "INSERT INTO #{table_columns_and_values_for_insert(file_paths)}"\
+            " ON CONFLICT DO NOTHING;"
+        else # MySQL
+          "INSERT IGNORE INTO"\
+            " #{table_columns_and_values_for_insert(file_paths)};"
+        end
+      end
+
+      def table_columns_and_values_for_insert(file_paths)
+        values = file_paths.map do |file_path|
+          ActiveRecord::Base.send(:sanitize_sql_array, ['(?)', file_path]) # rubocop:disable GitlabSecurity/PublicSend, Metrics/LineLength
+        end.join(', ')
+
+        "#{UntrackedFile.table_name} (path) VALUES #{values}"
+      end
+
+      def postgresql?
+        @postgresql ||= Gitlab::Database.postgresql?
+      end
+
+      def can_bulk_insert_and_ignore_duplicates?
+        !postgresql_pre_9_5?
+      end
+
+      def postgresql_pre_9_5?
+        @postgresql_pre_9_5 ||= postgresql? &&
+          Gitlab::Database.version.to_f < 9.5
+      end
+
+      def schedule_populate_untracked_uploads_jobs
+        bulk_queue_background_migration_jobs_by_range(
+          UntrackedFile, FOLLOW_UP_MIGRATION)
+      end
+    end
+  end
+end