Merge branch 'remove-banzai-commit-full-title' into 'master'

Introduce a rendering limit for commit titles

See merge request gitlab-org/gitlab!52904

app/models/commit.rb

@@ -36,7 +36,7 @@ class Commit
   LINK_EXTENSION_PATTERN = /(patch)/.freeze
 
   cache_markdown_field :title, pipeline: :single_line
-  cache_markdown_field :full_title, pipeline: :single_line
+  cache_markdown_field :full_title, pipeline: :single_line, limit: 1.kilobyte
   cache_markdown_field :description, pipeline: :commit_description, limit: 1.megabyte
 
   class << self

changelogs/unreleased/remove-banzai-commit-full-title.yml

+---
+title: Introduce a rendering limit for commit titles
+merge_request: 52904
+author:
+type: performance

doc/administration/instance_limits.md

@@ -127,6 +127,15 @@ It's possible that this limit will be changed to a lower number in the future.
 
 - **Max size:** ~1 million characters / ~1 MB
 
+## Size of commit titles and descriptions
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/292039) in GitLab 13.9
+
+Commits with arbitrarily large messages may be pushed to GitLab, but when
+displaying commits, titles (the first line of the commit message) will be
+limited to 1KiB, and descriptions (the rest of the message) will be limited to
+1MiB.
+
 ## Number of issues in the milestone overview
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/39453) in GitLab 12.10.

lib/banzai/filter/truncate_source_filter.rb

@@ -6,7 +6,9 @@ module Banzai
       def call
         return text unless context.key?(:limit)
 
-        text.truncate_bytes(context[:limit])
+        # Use three dots instead of the ellipsis Unicode character because
+        # some clients show the raw Unicode value in the merge commit.
+        text.truncate_bytes(context[:limit], omission: '...')
       end
     end
   end

spec/lib/banzai/filter/truncate_source_filter_spec.rb

@@ -22,7 +22,7 @@ RSpec.describe Banzai::Filter::TruncateSourceFilter do
 
   it 'truncates UTF-8 text by bytes, on a character boundary' do
     utf8_text = '日本語の文字が大きい'
-    truncated = '日…'
+    truncated = '日...'
 
     expect(filter(utf8_text, limit: truncated.bytesize)).to eq(truncated)
     expect(filter(utf8_text, limit: utf8_text.bytesize)).to eq(utf8_text)

spec/lib/banzai/pipeline/pre_process_pipeline_spec.rb

@@ -30,6 +30,6 @@ RSpec.describe Banzai::Pipeline::PreProcessPipeline do
 
     result = described_class.call(text, limit: 12)
 
-    expect(result[:output]).to eq('foo foo f…')
+    expect(result[:output]).to eq('foo foo f...')
   end
 end

spec/models/commit_spec.rb

@@ -400,6 +400,19 @@ eos
       allow(commit).to receive(:safe_message).and_return(message + "\n" + message)
       expect(commit.full_title).to eq(message)
     end
+
+    it 'truncates html representation if more than 1KiB' do
+      # Commit title is over 2KiB on a single line
+      huge_commit_title = ('panic ' * 350) + 'trailing text'
+
+      allow(commit).to receive(:safe_message).and_return(huge_commit_title)
+
+      commit.refresh_markdown_cache
+      full_title_html = commit.full_title_html
+
+      expect(full_title_html.bytesize).to be < 2.kilobytes
+      expect(full_title_html).not_to include('trailing text')
+    end
   end
 
   describe 'description' do