Delete non-latest merge request diff files upon diffs reload

4 files changed, 66 insertions, 17 deletions

diff --git a/app/services/merge_requests/delete_non_latest_diffs_service.rb b/app/services/merge_requests/delete_non_latest_diffs_service.rb
new file mode 100644
index 00000000000..40079b21189
--- /dev/null
+++ b/app/services/merge_requests/delete_non_latest_diffs_service.rb
@@ -0,0 +1,18 @@
+module MergeRequests
+  class DeleteNonLatestDiffsService
+    BATCH_SIZE = 10
+
+    def initialize(merge_request)
+      @merge_request = merge_request
+    end
+
+    def execute
+      diffs = @merge_request.non_latest_diffs.with_files
+
+      diffs.each_batch(of: BATCH_SIZE) do |relation, index|
+        ids = relation.pluck(:id).map { |id| [id] }
+        DeleteDiffFilesWorker.bulk_perform_in(index * 5.minutes, ids)
+      end
+    end
+  end
+end
diff --git a/app/services/merge_requests/merge_request_diff_cache_service.rb b/app/services/merge_requests/merge_request_diff_cache_service.rb
deleted file mode 100644
index 10aa9ae609c..00000000000
--- a/app/services/merge_requests/merge_request_diff_cache_service.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-module MergeRequests
-  class MergeRequestDiffCacheService
-    def execute(merge_request, new_diff)
-      # Executing the iteration we cache all the highlighted diff information
-      merge_request.diffs.diff_files.to_a
-
-      # Remove cache for all diffs on this MR. Do not use the association on the
-      # model, as that will interfere with other actions happening when
-      # reloading the diff.
-      MergeRequestDiff.where(merge_request: merge_request).each do |merge_request_diff|
-        next if merge_request_diff == new_diff
-
-        merge_request_diff.diffs.clear_cache!
-      end
-    end
-  end
-end
diff --git a/app/services/merge_requests/post_merge_service.rb b/app/services/merge_requests/post_merge_service.rb
index c78e78afcd1..5b160ffba67 100644
--- a/app/services/merge_requests/post_merge_service.rb
+++ b/app/services/merge_requests/post_merge_service.rb
@@ -15,6 +15,7 @@ module MergeRequests
       execute_hooks(merge_request, 'merge')
       invalidate_cache_counts(merge_request, users: merge_request.assignees)
       merge_request.update_project_counter_caches
+      delete_non_latest_diffs(merge_request)
     end
 
     private
@@ -31,6 +32,10 @@ module MergeRequests
       end
     end
 
+    def delete_non_latest_diffs(merge_request)
+      DeleteNonLatestDiffsService.new(merge_request).execute
+    end
+
     def create_merge_event(merge_request, current_user)
       EventCreateService.new.merge_mr(merge_request, current_user)
     end
diff --git a/app/services/merge_requests/reload_diffs_service.rb b/app/services/merge_requests/reload_diffs_service.rb
new file mode 100644
index 00000000000..2ec7b403903
--- /dev/null
+++ b/app/services/merge_requests/reload_diffs_service.rb
@@ -0,0 +1,43 @@
+module MergeRequests
+  class ReloadDiffsService
+    def initialize(merge_request, current_user)
+      @merge_request = merge_request
+      @current_user = current_user
+    end
+
+    def execute
+      old_diff_refs = merge_request.diff_refs
+      new_diff = merge_request.create_merge_request_diff
+
+      clear_cache(new_diff)
+      update_diff_discussion_positions(old_diff_refs)
+    end
+
+    private
+
+    attr_reader :merge_request, :current_user
+
+    def update_diff_discussion_positions(old_diff_refs)
+      new_diff_refs = merge_request.diff_refs
+
+      merge_request.update_diff_discussion_positions(old_diff_refs: old_diff_refs,
+                                                     new_diff_refs: new_diff_refs,
+                                                     current_user: current_user)
+    end
+
+    def clear_cache(new_diff)
+      # Executing the iteration we cache highlighted diffs for each diff file of
+      # MergeRequestDiff.
+      new_diff.diffs_collection.diff_files.to_a
+
+      # Remove cache for all diffs on this MR. Do not use the association on the
+      # model, as that will interfere with other actions happening when
+      # reloading the diff.
+      MergeRequestDiff.where(merge_request: merge_request).each do |merge_request_diff|
+        next if merge_request_diff == new_diff
+
+        merge_request_diff.diffs_collection.clear_cache!
+      end
+    end
+  end
+end