Specify explicitly whether a blob viewer should be loaded asynchronously

app/controllers/concerns/renders_blob.rb

@@ -14,7 +14,7 @@ module RendersBlob
     return render_404 unless viewer
 
     render json: {
-      html: view_to_html_string("projects/blob/_viewer", viewer: viewer, load_asynchronously: false)
+      html: view_to_html_string("projects/blob/_viewer", viewer: viewer, load_async: false)
     }
   end
 

app/models/blob_viewer/base.rb

@@ -2,11 +2,11 @@ module BlobViewer
   class Base
     PARTIAL_PATH_PREFIX = 'projects/blob/viewers'.freeze
 
-    class_attribute :partial_name, :loading_partial_name, :type, :extensions, :file_types, :client_side, :binary, :switcher_icon, :switcher_title, :max_size, :absolute_max_size
+    class_attribute :partial_name, :loading_partial_name, :type, :extensions, :file_types, :load_async, :binary, :switcher_icon, :switcher_title, :max_size, :absolute_max_size
 
     self.loading_partial_name = 'loading'
 
-    delegate :partial_path, :loading_partial_path, :rich?, :simple?, :client_side?, :server_side?, :text?, :binary?, to: :class
+    delegate :partial_path, :loading_partial_path, :rich?, :simple?, :text?, :binary?, to: :class
 
     attr_reader :blob
     attr_accessor :override_max_size
@@ -35,12 +35,8 @@ module BlobViewer
       type == :auxiliary
     end
 
-    def self.client_side?
-      client_side
-    end
-
-    def self.server_side?
-      !client_side?
+    def self.load_async?
+      load_async
     end
 
     def self.binary?
@@ -59,6 +55,10 @@ module BlobViewer
       false
     end
 
+    def load_async?
+      self.class.load_async? && render_error.nil?
+    end
+
     def too_large?
       max_size && blob.raw_size > max_size
     end
@@ -83,17 +83,7 @@ module BlobViewer
     # binary from `blob_raw_url` and does its own format validation and error
     # rendering, especially for potentially large binary formats.
     def render_error
-      return @render_error if defined?(@render_error)
-
-      @render_error =
-        if server_side_but_stored_externally?
-          # Files that are not stored in the repository, like LFS files and
-          # build artifacts, can only be rendered using a client-side viewer,
-          # since we do not want to read large amounts of data into memory on the
-          # server side. Client-side viewers use JS and can fetch the file from
-          # `blob_raw_url` using AJAX.
-          :server_side_but_stored_externally
-        elsif override_max_size ? absolutely_too_large? : too_large?
+      if override_max_size ? absolutely_too_large? : too_large?
         :too_large
       end
     end
@@ -101,11 +91,5 @@ module BlobViewer
     def prepare!
       # To be overridden by subclasses
     end
-
-    private
-
-    def server_side_but_stored_externally?
-      server_side? && blob.stored_externally?
-    end
   end
 end

app/models/blob_viewer/client_side.rb

@@ -3,7 +3,7 @@ module BlobViewer
     extend ActiveSupport::Concern
 
     included do
-      self.client_side = true
+      self.load_async = false
       self.max_size = 10.megabytes
       self.absolute_max_size = 50.megabytes
     end

app/models/blob_viewer/download.rb

 module BlobViewer
   class Download < Base
     include Simple
-    # We treat the Download viewer as if it renders the content client-side,
-    # so that it doesn't attempt to load the entire blob contents and is
-    # rendered synchronously instead of loaded asynchronously.
-    include ClientSide
+    include Static
 
     self.partial_name = 'download'
     self.binary = true
-
-    # We can always render the Download viewer, even if the blob is in LFS or too large.
-    def render_error
-      nil
-    end
   end
 end

app/models/blob_viewer/license.rb

 module BlobViewer
   class License < Base
-    # We treat the License viewer as if it renders the content client-side,
-    # so that it doesn't attempt to load the entire blob contents and is
-    # rendered synchronously instead of loaded asynchronously.
-    include ClientSide
     include Auxiliary
+    include Static
 
     self.partial_name = 'license'
     self.file_types = %i(license)

app/models/blob_viewer/server_side.rb

@@ -3,7 +3,7 @@ module BlobViewer
     extend ActiveSupport::Concern
 
     included do
-      self.client_side = false
+      self.load_async = true
       self.max_size = 2.megabytes
       self.absolute_max_size = 5.megabytes
     end
@@ -13,5 +13,18 @@ module BlobViewer
         blob.load_all_data!(blob.project.repository)
       end
     end
+
+    def render_error
+      if blob.stored_externally?
+        # Files that are not stored in the repository, like LFS files and
+        # build artifacts, can only be rendered using a client-side viewer,
+        # since we do not want to read large amounts of data into memory on the
+        # server side. Client-side viewers use JS and can fetch the file from
+        # `blob_raw_url` using AJAX.
+        return :server_side_but_stored_externally
+      end
+
+      super
+    end
   end
 end

app/models/blob_viewer/static.rb

+module BlobViewer
+  module Static
+    extend ActiveSupport::Concern
+
+    included do
+      self.load_async = false
+    end
+
+    # We can always render a static viewer, even if the blob is too large.
+    def render_error
+      nil
+    end
+  end
+end

app/views/projects/blob/_viewer.html.haml

 - hidden = local_assigns.fetch(:hidden, false)
 - render_error = viewer.render_error
-- load_asynchronously = local_assigns.fetch(:load_asynchronously, viewer.server_side?) && render_error.nil?
+- load_async = local_assigns.fetch(:load_async, viewer.load_async?)
 
-- viewer_url = local_assigns.fetch(:viewer_url) { url_for(params.merge(viewer: viewer.type, format: :json)) } if load_asynchronously
+- viewer_url = local_assigns.fetch(:viewer_url) { url_for(params.merge(viewer: viewer.type, format: :json)) } if load_async
 .blob-viewer{ data: { type: viewer.type, url: viewer_url }, class: ('hidden' if hidden) }
-  - if load_asynchronously
+  - if load_async
     = render viewer.loading_partial_path, viewer: viewer
   - elsif render_error
     = render 'projects/blob/render_error', viewer: viewer

spec/helpers/blob_helper_spec.rb

@@ -116,10 +116,11 @@ describe BlobHelper do
 
     let(:viewer_class) do
       Class.new(BlobViewer::Base) do
+        include BlobViewer::ServerSide
+
         self.max_size = 1.megabyte
         self.absolute_max_size = 5.megabytes
         self.type = :rich
-        self.client_side = false
       end
     end
 

spec/models/blob_viewer/base_spec.rb

@@ -7,11 +7,12 @@ describe BlobViewer::Base, model: true do
 
   let(:viewer_class) do
     Class.new(described_class) do
+      include BlobViewer::ServerSide
+
       self.extensions = %w(pdf)
       self.binary = true
       self.max_size = 1.megabyte
       self.absolute_max_size = 5.megabytes
-      self.client_side = false
     end
   end
 
@@ -38,7 +39,7 @@ describe BlobViewer::Base, model: true do
 
     context 'when the file type is supported' do
       before do
-        viewer_class.file_type = :license
+        viewer_class.file_types = %i(license)
         viewer_class.binary = false
       end
 
@@ -172,19 +173,5 @@ describe BlobViewer::Base, model: true do
         end
       end
     end
-
-    context 'when the viewer is server side but the blob is stored externally' do
-      let(:project) { build(:empty_project, lfs_enabled: true) }
-
-      let(:blob) { fake_blob(path: 'file.pdf', lfs: true) }
-
-      before do
-        allow(Gitlab.config.lfs).to receive(:enabled).and_return(true)
-      end
-
-      it 'return :server_side_but_stored_externally' do
-        expect(viewer.render_error).to eq(:server_side_but_stored_externally)
-      end
-    end
   end
 end

spec/models/blob_viewer/server_side_spec.rb

@@ -22,4 +22,20 @@ describe BlobViewer::ServerSide, model: true do
       subject.prepare!
     end
   end
+
+  describe '#render_error' do
+    context 'when the blob is stored externally' do
+      let(:project) { build(:empty_project, lfs_enabled: true) }
+
+      let(:blob) { fake_blob(path: 'file.pdf', lfs: true) }
+
+      before do
+        allow(Gitlab.config.lfs).to receive(:enabled).and_return(true)
+      end
+
+      it 'return :server_side_but_stored_externally' do
+        expect(subject.render_error).to eq(:server_side_but_stored_externally)
+      end
+    end
+  end
 end

spec/views/projects/blob/_viewer.html.haml_spec.rb

@@ -12,7 +12,7 @@ describe 'projects/blob/_viewer.html.haml', :view do
       self.partial_name = 'text'
       self.max_size = 1.megabyte
       self.absolute_max_size = 5.megabytes
-      self.client_side = false
+      self.load_async = true
     end
   end
 
@@ -35,9 +35,9 @@ describe 'projects/blob/_viewer.html.haml', :view do
     render partial: 'projects/blob/viewer', locals: { viewer: viewer }
   end
 
-  context 'when the viewer is server side' do
+  context 'when the viewer is loaded asynchronously' do
     before do
-      viewer_class.client_side = false
+      viewer_class.load_async = true
     end
 
     context 'when there is no render error' do
@@ -65,9 +65,9 @@ describe 'projects/blob/_viewer.html.haml', :view do
     end
   end
 
-  context 'when the viewer is client side' do
+  context 'when the viewer is loaded synchronously' do
     before do
-      viewer_class.client_side = true
+      viewer_class.load_async = false
     end
 
     context 'when there is no render error' do