Support reflogs (#22451)

This PR adds support for reflogs on all repositories. It does this by
adding a global configuration entry.

Implements #14865

---------

Signed-off-by: Philip Peterson <philip.c.peterson@gmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

modules/git/git.go

@@ -201,6 +201,23 @@ func InitFull(ctx context.Context) (err error) {
 	return syncGitConfig()
 }
 
+func enableReflogs() error {
+	if err := configSet("core.logAllRefUpdates", "true"); err != nil {
+		return err
+	}
+	err := configSet("gc.reflogExpire", fmt.Sprintf("%d", setting.Git.Reflog.Expiration))
+	return err
+}
+
+func disableReflogs() error {
+	if err := configUnsetAll("core.logAllRefUpdates", "true"); err != nil {
+		return err
+	} else if err := configUnsetAll("gc.reflogExpire", ""); err != nil {
+		return err
+	}
+	return nil
+}
+
 // syncGitConfig only modifies gitconfig, won't change global variables (otherwise there will be data-race problem)
 func syncGitConfig() (err error) {
 	if err = os.MkdirAll(HomeDir(), os.ModePerm); err != nil {
@@ -224,6 +241,16 @@ func syncGitConfig() (err error) {
 		return err
 	}
 
+	if setting.Git.Reflog.Enabled {
+		if err := enableReflogs(); err != nil {
+			return err
+		}
+	} else {
+		if err := disableReflogs(); err != nil {
+			return err
+		}
+	}
+
 	if CheckGitVersionAtLeast("2.10") == nil {
 		if err := configSet("receive.advertisePushOptions", "true"); err != nil {
 			return err

modules/setting/git.go

@@ -12,9 +12,13 @@ import (
 
 // Git settings
 var Git = struct {
-	Path                      string
-	HomePath                  string
-	DisableDiffHighlight      bool
+	Path                 string
+	HomePath             string
+	DisableDiffHighlight bool
+	Reflog               struct {
+		Enabled    bool
+		Expiration int
+	} `ini:"git.reflog"`
 	MaxGitDiffLines           int
 	MaxGitDiffLineCharacters  int
 	MaxGitDiffFiles           int
@@ -37,6 +41,13 @@ var Git = struct {
 		GC      int `ini:"GC"`
 	} `ini:"git.timeout"`
 }{
+	Reflog: struct {
+		Enabled    bool
+		Expiration int
+	}{
+		Enabled:    true,
+		Expiration: 90,
+	},
 	DisableDiffHighlight:      false,
 	MaxGitDiffLines:           1000,
 	MaxGitDiffLineCharacters:  5000,