Refactor compare logic for MR. Use satellites only for forks for better performance

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

2 files changed, 33 insertions, 6 deletions

diff --git a/app/services/compare_service.rb b/app/services/compare_service.rb
new file mode 100644
index 00000000000..e4c3bb1507d
--- /dev/null
+++ b/app/services/compare_service.rb
@@ -0,0 +1,28 @@
+# Compare 2 branches for one repo or between repositories
+# and return Gitlab::CompareResult object that responds to commits and diffs
+class CompareService
+  def execute(current_user, source_project, source_branch, target_project, target_branch)
+    # Try to compare branches to get commits list and diffs
+    #
+    # Note: Use satellite only when need to compare between to repos
+    # because satellites are slower then operations on bare repo
+    if target_project == source_project
+      Gitlab::CompareResult.new(
+        Gitlab::Git::Compare.new(
+          target_project.repository.raw_repository,
+          target_branch,
+          source_branch,
+          10000
+        )
+      )
+    else
+      Gitlab::Satellite::CompareAction.new(
+        current_user,
+        target_project,
+        target_branch,
+        source_project,
+        source_branch
+      ).result
+    end
+  end
+end
diff --git a/app/services/merge_requests/build_service.rb b/app/services/merge_requests/build_service.rb
index 81dd8887395..1475973e543 100644
--- a/app/services/merge_requests/build_service.rb
+++ b/app/services/merge_requests/build_service.rb
@@ -19,16 +19,15 @@ module MergeRequests
       # Generate suggested MR title based on source branch name
       merge_request.title = merge_request.source_branch.titleize.humanize
 
-      # Try to compare branches to get commits list and diffs
-      compare_action = Gitlab::Satellite::CompareAction.new(
+      compare_result = CompareService.new.execute(
         current_user,
+        merge_request.source_project,
+        merge_request.source_branch,
         merge_request.target_project,
         merge_request.target_branch,
-        merge_request.source_project,
-        merge_request.source_branch
       )
 
-      commits = compare_action.commits
+      commits = compare_result.commits
 
       # At this point we decide if merge request can be created
       # If we have at least one commit to merge -> creation allowed
@@ -38,7 +37,7 @@ module MergeRequests
         merge_request.compare_failed = false
 
         # Try to collect diff for merge request.
-        diffs = compare_action.diffs
+        diffs = compare_result.diffs
 
         if diffs.present?
           merge_request.compare_diffs = diffs