Improve performance of tree rendering in repositories with lots of items

Rails is slow to generate paths dynamically especially when called
hundreds/thousands of times. Also, rendering many partials hundreds
of times can be slower. This change reduces the number of partials
rendered and introduces two fast path methods to speed up path
generation.

app/helpers/icons_helper.rb

@@ -109,6 +109,8 @@ module IconsHelper
   def file_type_icon_class(type, mode, name)
     if type == 'folder'
       icon_class = 'folder'
+    elsif type == 'archive'
+      icon_class = 'archive'
     elsif mode == '120000'
       icon_class = 'share'
     else

app/helpers/tree_helper.rb

@@ -31,11 +31,21 @@ module TreeHelper
   # mode - File unix mode
   # name - File name
   def tree_icon(type, mode, name)
-    icon("#{file_type_icon_class(type, mode, name)} fw")
+    icon([file_type_icon_class(type, mode, name), 'fw'])
   end
 
-  def tree_hex_class(content)
-    "file_#{hexdigest(content.name)}"
+  # Using Rails `*_path` methods can be slow, especially when generating
+  # many paths, as with a repository tree that has thousands of items.
+  def fast_project_blob_path(project, blob_path)
+    Addressable::URI.escape(
+      File.join(relative_url_root, project.path_with_namespace, 'blob', blob_path)
+    )
+  end
+
+  def fast_project_tree_path(project, tree_path)
+    Addressable::URI.escape(
+      File.join(relative_url_root, project.path_with_namespace, 'tree', tree_path)
+    )
   end
 
   # Simple shortcut to File.join
@@ -142,4 +152,8 @@ module TreeHelper
   def selected_branch
     @branch_name || tree_edit_branch
   end
+
+  def relative_url_root
+    Gitlab.config.gitlab.relative_url_root.presence || '/'
+  end
 end

app/views/projects/tree/_blob_item.html.haml

@@ -1,12 +0,0 @@
-- is_lfs_blob = @lfs_blob_ids.include?(blob_item.id)
-%tr{ class: "tree-item #{tree_hex_class(blob_item)}" }
-  %td.tree-item-file-name
-    = tree_icon(type, blob_item.mode, blob_item.name)
-    - file_name = blob_item.name
-    = link_to project_blob_path(@project, tree_join(@id || @commit.id, blob_item.name)), class: 'str-truncated', title: file_name do
-      %span= file_name
-    - if is_lfs_blob
-      %span.badge.label-lfs.prepend-left-5 LFS
-  %td.d-none.d-sm-table-cell.tree-commit
-  %td.tree-time-ago.cgray.text-right
-    = render 'projects/tree/spinner'

app/views/projects/tree/_spinner.html.haml

@@ -1,3 +0,0 @@
-%span.log_loading.hide
-  %i.fa.fa-spinner.fa-spin
-  Loading commit data...

app/views/projects/tree/_submodule_item.html.haml

@@ -1,6 +0,0 @@
-%tr.tree-item
-  %td.tree-item-file-name
-    %i.fa.fa-archive.fa-fw
-    = submodule_link(submodule_item, @ref)
-  %td
-  %td.d-none.d-sm-table-cell

app/views/projects/tree/_tree_item.html.haml

@@ -1,9 +0,0 @@
-%tr{ class: "tree-item #{tree_hex_class(tree_item)}" }
-  %td.tree-item-file-name
-    = tree_icon(type, tree_item.mode, tree_item.name)
-    - path = flatten_tree(@path, tree_item)
-    = link_to project_tree_path(@project, tree_join(@id || @commit.id, path)), class: 'str-truncated', title: path do
-      %span= path
-  %td.d-none.d-sm-table-cell.tree-commit
-  %td.tree-time-ago.text-right
-    = render 'projects/tree/spinner'

app/views/projects/tree/_tree_row.html.haml

@@ -1,6 +1,27 @@
-- if tree_row.type == :tree
-  = render partial: 'projects/tree/tree_item', object: tree_row, as: 'tree_item', locals: { type: 'folder' }
-- elsif tree_row.type == :blob
-  = render partial: 'projects/tree/blob_item', object: tree_row, as: 'blob_item', locals: { type: 'file' }
-- elsif tree_row.type == :commit
-  = render partial: 'projects/tree/submodule_item', object: tree_row, as: 'submodule_item'
+- tree_row_name = tree_row.name
+- tree_row_type = tree_row.type
+
+%tr{ class: "tree-item file_#{hexdigest(tree_row_name)}" }
+  %td.tree-item-file-name
+    - if tree_row_type == :tree
+      = tree_icon('folder', tree_row.mode, tree_row.name)
+      - path = flatten_tree(@path, tree_row)
+      %a.str-truncated{ href: fast_project_tree_path(@project, tree_join(@id || @commit.id, path)), title: path }
+        %span= path
+
+    - elsif tree_row_type == :blob
+      = tree_icon('file', tree_row.mode, tree_row_name)
+      %a.str-truncated{ href: fast_project_blob_path(@project, tree_join(@id || @commit.id, tree_row_name)), title: tree_row_name }
+        %span= tree_row_name
+      - if @lfs_blob_ids.include?(tree_row.id)
+        %span.badge.label-lfs.prepend-left-5 LFS
+
+    - elsif tree_row_type == :commit
+      = tree_icon('archive', tree_row.mode, tree_row.name)
+      = submodule_link(tree_row, @ref)
+
+  %td.d-none.d-sm-table-cell.tree-commit
+  %td.tree-time-ago.text-right
+    %span.log_loading.hide
+      %i.fa.fa-spinner.fa-spin
+      Loading commit data...

changelogs/unreleased/fast_project_blob_path.yml

@@ -0,0 +1,5 @@
+---
+title: Improve performance of tree rendering in repositories with lots of items
+merge_request:
+author:
+type: performance

spec/helpers/tree_helper_spec.rb

@@ -3,7 +3,7 @@ require 'spec_helper'
 describe TreeHelper do
   let(:project) { create(:project, :repository) }
   let(:repository) { project.repository }
-  let(:sha) { 'ce369011c189f62c815f5971d096b26759bab0d1' }
+  let(:sha) { 'c1c67abbaf91f624347bb3ae96eabe3a1b742478' }
 
   describe '.render_tree' do
     before do
@@ -32,6 +32,49 @@ describe TreeHelper do
     end
   end
 
+  describe '.fast_project_blob_path' do
+    it 'generates the same path as project_blob_path' do
+      blob_path = repository.tree(sha, 'with space').entries.first.path
+      fast_path = fast_project_blob_path(project, blob_path)
+      std_path  = project_blob_path(project, blob_path)
+
+      expect(fast_path).to eq(std_path)
+    end
+
+    it 'generates the same path with encoded file names' do
+      tree = repository.tree(sha, 'encoding')
+      blob_path = tree.entries.find { |entry| entry.path == 'encoding/テスト.txt' }.path
+      fast_path = fast_project_blob_path(project, blob_path)
+      std_path  = project_blob_path(project, blob_path)
+
+      expect(fast_path).to eq(std_path)
+    end
+
+    it 'respects a configured relative URL' do
+      allow(Gitlab.config.gitlab).to receive(:relative_url_root).and_return('/gitlab/root')
+      blob_path = repository.tree(sha, '').entries.first.path
+      fast_path = fast_project_blob_path(project, blob_path)
+
+      expect(fast_path).to start_with('/gitlab/root')
+    end
+  end
+
+  describe '.fast_project_tree_path' do
+    let(:tree_path) { repository.tree(sha, 'with space').path }
+    let(:fast_path) { fast_project_tree_path(project, tree_path) }
+    let(:std_path) { project_tree_path(project, tree_path) }
+
+    it 'generates the same path as project_tree_path' do
+      expect(fast_path).to eq(std_path)
+    end
+
+    it 'respects a configured relative URL' do
+      allow(Gitlab.config.gitlab).to receive(:relative_url_root).and_return('/gitlab/root')
+
+      expect(fast_path).to start_with('/gitlab/root')
+    end
+  end
+
   describe 'flatten_tree' do
     let(:tree) { repository.tree(sha, 'files') }
     let(:root_path) { 'files' }

spec/views/projects/tree/_tree_row.html.haml_spec.rb

@@ -1,6 +1,6 @@
 require 'spec_helper'
 
-describe 'projects/tree/_blob_item' do
+describe 'projects/tree/_tree_row' do
   let(:project) { create(:project, :repository) }
   let(:repository) { project.repository }
   let(:blob_item) { Gitlab::Git::Tree.where(repository, SeedRepo::Commit::ID, 'files/ruby').first }
@@ -31,10 +31,7 @@ describe 'projects/tree/_blob_item' do
     end
   end
 
-  def render_partial(blob_item)
-    render partial: 'projects/tree/blob_item', locals: {
-      blob_item: blob_item,
-      type: 'blob'
-    }
+  def render_partial(items)
+    render partial: 'projects/tree/tree_row', collection: [items].flatten
   end
 end