Merge branch 'cache-raw-2' into 'master'

Set cache headers for raw blobs

This changes allows browsers and (in the case of public projects)
proxy caches to cache raw Git blob responses.

See merge request !3113

app/controllers/projects/avatars_controller.rb

@@ -7,6 +7,9 @@ class Projects::AvatarsController < Projects::ApplicationController
     @blob = @repository.blob_at_branch('master', @project.avatar_in_git)
     if @blob
       headers['X-Content-Type-Options'] = 'nosniff'
+
+      return if cached_blob?
+
       headers.store(*Gitlab::Workhorse.send_git_blob(@repository, @blob))
       headers['Content-Disposition'] = 'inline'
       headers['Content-Type'] = safe_content_type(@blob)

app/controllers/projects/raw_controller.rb

@@ -13,6 +13,8 @@ class Projects::RawController < Projects::ApplicationController
     if @blob
       headers['X-Content-Type-Options'] = 'nosniff'
 
+      return if cached_blob?
+
       if @blob.lfs_pointer?
         send_lfs_object
       else

app/helpers/blob_helper.rb

@@ -152,4 +152,25 @@ module BlobHelper
       'application/octet-stream'
     end
   end
+
+  def cached_blob?
+    stale = stale?(etag: @blob.id) # The #stale? method sets cache headers.
+
+    # Because we are opionated we set the cache headers ourselves.
+    response.cache_control[:public] = @project.public?
+
+    if @ref && @commit && @ref == @commit.id
+      # This is a link to a commit by its commit SHA. That means that the blob
+      # is immutable. The only reason to invalidate the cache is if the commit
+      # was deleted or if the user lost access to the repository.
+      response.cache_control[:max_age] = Blob::CACHE_TIME_IMMUTABLE
+    else
+      # A branch or tag points at this blob. That means that the expected blob
+      # value may change over time.
+      response.cache_control[:max_age] = Blob::CACHE_TIME
+    end
+
+    response.etag = @blob.id
+    !stale
+  end
 end

app/models/blob.rb

 # Blob is a Rails-specific wrapper around Gitlab::Git::Blob objects
 class Blob < SimpleDelegator
+  CACHE_TIME = 60 # Cache raw blobs referred to by a (mutable) ref for 1 minute
+  CACHE_TIME_IMMUTABLE = 3600 # Cache blobs referred to by an immutable reference for 1 hour
+
   # Wrap a Gitlab::Git::Blob object, or return nil when given nil
   #
   # This method prevents the decorated object from evaluating to "truthy" when

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

@@ -6,4 +6,4 @@
     - blob = sanitize_svg(blob)
     %img{src: "data:#{blob.mime_type};base64,#{Base64.encode64(blob.data)}"}
   - else
-    %img{src: namespace_project_raw_path(@project.namespace, @project, @id)}
+    %img{src: namespace_project_raw_path(@project.namespace, @project, tree_join(@commit.id, blob.path))}