Graceful: Xorm, RepoIndexer, Cron and Others (#9282)

* Change graceful to use a singleton obtained through GetManager instead of a global.
* Graceful: Make TestPullRequests shutdownable
* Graceful: Make the cron tasks graceful
* Graceful: AddTestPullRequest run in graceful ctx
* Graceful: SyncMirrors shutdown
* Graceful: SetDefaultContext for Xorm to be HammerContext
* Avoid starting graceful for migrate commands and checkout
* Graceful: DeliverHooks now can be shutdown
* Fix multiple syncing errors in modules/sync/UniqueQueue &  Make UniqueQueue closable
* Begin the process of making the repo indexer shutdown gracefully

services/mirror/mirror.go

@@ -5,11 +5,14 @@
 package mirror
 
 import (
+	"context"
 	"fmt"
 	"net/url"
 	"strings"
 	"time"
 
+	"code.gitea.io/gitea/modules/graceful"
+
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/cache"
 	"code.gitea.io/gitea/modules/git"
@@ -294,29 +297,38 @@ func Password(m *models.Mirror) string {
 }
 
 // Update checks and updates mirror repositories.
-func Update() {
+func Update(ctx context.Context) {
 	log.Trace("Doing: Update")
-
 	if err := models.MirrorsIterate(func(idx int, bean interface{}) error {
 		m := bean.(*models.Mirror)
 		if m.Repo == nil {
 			log.Error("Disconnected mirror repository found: %d", m.ID)
 			return nil
 		}
-
-		mirrorQueue.Add(m.RepoID)
-		return nil
+		select {
+		case <-ctx.Done():
+			return fmt.Errorf("Aborted due to shutdown")
+		default:
+			mirrorQueue.Add(m.RepoID)
+			return nil
+		}
 	}); err != nil {
 		log.Error("Update: %v", err)
 	}
 }
 
 // SyncMirrors checks and syncs mirrors.
-// TODO: sync more mirrors at same time.
-func SyncMirrors() {
+// FIXME: graceful: this should be a persistable queue
+func SyncMirrors(ctx context.Context) {
 	// Start listening on new sync requests.
-	for repoID := range mirrorQueue.Queue() {
-		syncMirror(repoID)
+	for {
+		select {
+		case <-ctx.Done():
+			mirrorQueue.Close()
+			return
+		case repoID := <-mirrorQueue.Queue():
+			syncMirror(repoID)
+		}
 	}
 }
 
@@ -416,7 +428,7 @@ func syncMirror(repoID string) {
 
 // InitSyncMirrors initializes a go routine to sync the mirrors
 func InitSyncMirrors() {
-	go SyncMirrors()
+	go graceful.GetManager().RunWithShutdownContext(SyncMirrors)
 }
 
 // StartToMirror adds repoID to mirror queue