1 files changed, 48 insertions, 19 deletions

diff --git a/app/models/repository.rb b/app/models/repository.rb
index cb7aba89020..d29d2a83708 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -1,6 +1,18 @@
 require 'securerandom'
 
 class Repository
+  REF_MERGE_REQUEST = 'merge-requests'.freeze
+  REF_KEEP_AROUND = 'keep-around'.freeze
+  REF_ENVIRONMENTS = 'environments'.freeze
+
+  RESERVED_REFS_NAMES = %W[
+    heads
+    tags
+    #{REF_ENVIRONMENTS}
+    #{REF_KEEP_AROUND}
+    #{REF_ENVIRONMENTS}
+  ].freeze
+
   include Gitlab::ShellAdapter
   include RepositoryMirroring
 
@@ -60,6 +72,10 @@ class Repository
     @project = project
   end
 
+  def ==(other)
+    @disk_path == other.disk_path
+  end
+
   def raw_repository
     return nil unless full_path
 
@@ -75,6 +91,10 @@ class Repository
     )
   end
 
+  def inspect
+    "#<#{self.class.name}:#{@disk_path}>"
+  end
+
   #
   # Git repository can contains some hidden refs like:
   #   /refs/notes/*
@@ -234,10 +254,10 @@ class Repository
     begin
       write_ref(keep_around_ref_name(sha), sha)
     rescue Rugged::ReferenceError => ex
-      Rails.logger.error "Unable to create keep-around reference for repository #{path}: #{ex}"
+      Rails.logger.error "Unable to create #{REF_KEEP_AROUND} reference for repository #{path}: #{ex}"
     rescue Rugged::OSError => ex
       raise unless ex.message =~ /Failed to create locked file/ && ex.message =~ /File exists/
-      Rails.logger.error "Unable to create keep-around reference for repository #{path}: #{ex}"
+      Rails.logger.error "Unable to create #{REF_KEEP_AROUND} reference for repository #{path}: #{ex}"
     end
   end
 
@@ -992,25 +1012,22 @@ class Repository
   end
 
   def with_repo_branch_commit(start_repository, start_branch_name)
-    return yield(nil) if start_repository.empty_repo?
+    return yield nil if start_repository.empty_repo?
 
-    branch_name_or_sha =
-      if start_repository == self
-        start_branch_name
-      else
-        tmp_ref = fetch_ref(
-          start_repository.path_to_repo,
-          "#{Gitlab::Git::BRANCH_REF_PREFIX}#{start_branch_name}",
-          "refs/tmp/#{SecureRandom.hex}/head"
-        )
+    if start_repository == self
+      yield commit(start_branch_name)
+    else
+      sha = start_repository.commit(start_branch_name).sha
 
-        start_repository.commit(start_branch_name).sha
+      if branch_commit = commit(sha)
+        yield branch_commit
+      else
+        with_repo_tmp_commit(
+          start_repository, start_branch_name, sha) do |tmp_commit|
+          yield tmp_commit
+        end
       end
-
-    yield(commit(branch_name_or_sha))
-
-  ensure
-    rugged.references.delete(tmp_ref) if tmp_ref
+    end
   end
 
   def add_remote(name, url)
@@ -1159,7 +1176,7 @@ class Repository
   end
 
   def keep_around_ref_name(sha)
-    "refs/keep-around/#{sha}"
+    "refs/#{REF_KEEP_AROUND}/#{sha}"
   end
 
   def repository_event(event, tags = {})
@@ -1219,4 +1236,16 @@ class Repository
       .commits_by_message(query, revision: ref, path: path, limit: limit, offset: offset)
       .map { |c| commit(c) }
   end
+
+  def with_repo_tmp_commit(start_repository, start_branch_name, sha)
+    tmp_ref = fetch_ref(
+      start_repository.path_to_repo,
+      "#{Gitlab::Git::BRANCH_REF_PREFIX}#{start_branch_name}",
+      "refs/tmp/#{SecureRandom.hex}/head"
+    )
+
+    yield commit(sha)
+  ensure
+    delete_refs(tmp_ref) if tmp_ref
+  end
 end