#2018 able to sync now for mirrors

- Refactor code to use sync.UniqueQueue
- Closes #3509

modules/context/repo.go

@@ -216,7 +216,7 @@ func RepoAssignment(args ...bool) macaron.Handler {
 		ctx.Data["HasAccess"] = true
 
 		if repo.IsMirror {
-			ctx.Repo.Mirror, err = models.GetMirror(repo.ID)
+			ctx.Repo.Mirror, err = models.GetMirrorByRepoID(repo.ID)
 			if err != nil {
 				ctx.Handle(500, "GetMirror", err)
 				return

modules/setting/setting.go

@@ -113,6 +113,7 @@ var (
 		AnsiCharset            string
 		ForcePrivate           bool
 		MaxCreationLimit       int
+		MirrorQueueLength      int
 		PullRequestQueueLength int
 		PreferredLicenses      []string