Merge branch '204891-enable-gathering-metrics-of-blob-truncation' into 'master'

Begin collecting blob truncation metrics

See merge request gitlab-org/gitlab!25464

lib/gitlab/git/blob.rb

@@ -124,11 +124,12 @@ module Gitlab
           self.__send__("#{key}=", options[key.to_sym]) # rubocop:disable GitlabSecurity/PublicSend
         end
 
-        record_metric_blob_size
-
         # Retain the actual size before it is encoded
         @loaded_size = @data.bytesize if @data
         @loaded_all_data = @loaded_size == size
+
+        record_metric_blob_size
+        record_metric_truncated(truncated?)
       end
 
       def binary_in_repo?
@@ -210,6 +211,14 @@ module Gitlab
         self.class.gitlab_blob_size.observe({}, size)
       end
 
+      def record_metric_truncated(bool)
+        if bool
+          self.class.gitlab_blob_truncated_true.increment
+        else
+          self.class.gitlab_blob_truncated_false.increment
+        end
+      end
+
       def has_lfs_version_key?
         !empty? && text_in_repo? && data.start_with?("version https://git-lfs.github.com/spec")
       end

spec/lib/gitlab/git/blob_spec.rb

@@ -22,7 +22,23 @@ describe Gitlab::Git::Blob, :seed_helper do
     it 'records blob size' do
       expect(described_class).to receive(:gitlab_blob_size).and_call_original
 
-      Gitlab::Git::Blob.new(name: 'test', size: 1234)
+      Gitlab::Git::Blob.new(name: 'test', size: 4, data: 'abcd')
+    end
+
+    context 'when untruncated' do
+      it 'attempts to record gitlab_blob_truncated_false' do
+        expect(described_class).to receive(:gitlab_blob_truncated_false).and_call_original
+
+        Gitlab::Git::Blob.new(name: 'test', size: 4, data: 'abcd')
+      end
+    end
+
+    context 'when truncated' do
+      it 'attempts to record gitlab_blob_truncated_true' do
+        expect(described_class).to receive(:gitlab_blob_truncated_true).and_call_original
+
+        Gitlab::Git::Blob.new(name: 'test', size: 40, data: 'abcd')
+      end
     end
   end