Merge branch 'ff_port_from_ee' into 'master'

Move Fast-Forward Merge to CE

See merge request gitlab-org/gitlab-ce!14272

3 files changed, 55 insertions, 0 deletions

diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index 8d9a30397a9..e85b83daf9e 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -524,6 +524,14 @@ class MergeRequest < ActiveRecord::Base
     true
   end
 
+  def ff_merge_possible?
+    project.repository.ancestor?(target_branch_sha, diff_head_sha)
+  end
+
+  def should_be_rebased?
+    project.ff_merge_must_be_possible? && !ff_merge_possible?
+  end
+
   def can_cancel_merge_when_pipeline_succeeds?(current_user)
     can_be_merged_by?(current_user) || self.author == current_user
   end
diff --git a/app/models/project.rb b/app/models/project.rb
index 44d1190cc5b..952e9e22b28 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -1566,6 +1566,34 @@ class Project < ActiveRecord::Base
     persisted? && path_changed?
   end
 
+  def merge_method
+    if self.merge_requests_ff_only_enabled
+      :ff
+    elsif self.merge_requests_rebase_enabled
+      :rebase_merge
+    else
+      :merge
+    end
+  end
+
+  def merge_method=(method)
+    case method.to_s
+    when "ff"
+      self.merge_requests_ff_only_enabled = true
+      self.merge_requests_rebase_enabled = true
+    when "rebase_merge"
+      self.merge_requests_ff_only_enabled = false
+      self.merge_requests_rebase_enabled = true
+    when "merge"
+      self.merge_requests_ff_only_enabled = false
+      self.merge_requests_rebase_enabled = false
+    end
+  end
+
+  def ff_merge_must_be_possible?
+    self.merge_requests_ff_only_enabled || self.merge_requests_rebase_enabled
+  end
+
   def migrate_to_hashed_storage!
     return if hashed_storage?
 
diff --git a/app/models/repository.rb b/app/models/repository.rb
index a0f57f1e54d..d47dc9a05cd 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -850,6 +850,25 @@ class Repository
     end
   end
 
+  def ff_merge(user, source, target_branch, merge_request: nil)
+    our_commit = rugged.branches[target_branch].target
+    their_commit =
+      if source.is_a?(Gitlab::Git::Commit)
+        source.raw_commit
+      else
+        rugged.lookup(source)
+      end
+
+    raise 'Invalid merge target' if our_commit.nil?
+    raise 'Invalid merge source' if their_commit.nil?
+
+    with_branch(user, target_branch) do |start_commit|
+      merge_request&.update(in_progress_merge_commit_sha: their_commit.oid)
+
+      their_commit.oid
+    end
+  end
+
   def revert(
     user, commit, branch_name, message,
     start_branch_name: nil, start_project: project)