Support rebuilding issue indexer manually (#26546)

Provide a way to rebuild issue indexer manually.

So if the indexer get outdated because of some bugs like #26539, we can
rebuild it.

<img width="1104" alt="image"
src="https://github.com/go-gitea/gitea/assets/9418365/ac242e29-6f04-47ca-b3d0-801a796448d3">

Co-authored-by: Giteabot <teabot@gitea.io>

3 files changed, 28 insertions, 7 deletions

diff --git a/modules/indexer/issues/indexer.go b/modules/indexer/issues/indexer.go
index 42279cbddb..6619949104 100644
--- a/modules/indexer/issues/indexer.go
+++ b/modules/indexer/issues/indexer.go
@@ -5,6 +5,7 @@ package issues
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"runtime/pprof"
 	"sync/atomic"
@@ -202,11 +203,16 @@ func getIssueIndexerQueueHandler(ctx context.Context) func(items ...*IndexerMeta
 func populateIssueIndexer(ctx context.Context) {
 	ctx, _, finished := process.GetManager().AddTypedContext(ctx, "Service: PopulateIssueIndexer", process.SystemProcessType, true)
 	defer finished()
+	if err := PopulateIssueIndexer(ctx, true); err != nil {
+		log.Error("Issue indexer population failed: %v", err)
+	}
+}
+
+func PopulateIssueIndexer(ctx context.Context, keepRetrying bool) error {
 	for page := 1; ; page++ {
 		select {
 		case <-ctx.Done():
-			log.Warn("Issue Indexer population shutdown before completion")
-			return
+			return fmt.Errorf("shutdown before completion: %w", ctx.Err())
 		default:
 		}
 		repos, _, err := repo_model.SearchRepositoryByName(ctx, &repo_model.SearchRepoOptions{
@@ -221,20 +227,22 @@ func populateIssueIndexer(ctx context.Context) {
 		}
 		if len(repos) == 0 {
 			log.Debug("Issue Indexer population complete")
-			return
+			return nil
 		}
 
 		for _, repo := range repos {
 			for {
 				select {
 				case <-ctx.Done():
-					log.Info("Issue Indexer population shutdown before completion")
-					return
+					return fmt.Errorf("shutdown before completion: %w", ctx.Err())
 				default:
 				}
 				if err := updateRepoIndexer(ctx, repo.ID); err != nil {
-					log.Warn("Retry to populate issue indexer for repo %d: %v", repo.ID, err)
-					continue
+					if keepRetrying && ctx.Err() == nil {
+						log.Warn("Retry to populate issue indexer for repo %d: %v", repo.ID, err)
+						continue
+					}
+					return fmt.Errorf("populate issue indexer for repo %d: %v", repo.ID, err)
 				}
 				break
 			}
diff --git a/options/locale/locale_en-US.ini b/options/locale/locale_en-US.ini
index cbafef9d5b..0bfe1eac75 100644
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@@ -2752,6 +2752,7 @@ dashboard.stop_zombie_tasks = Stop zombie tasks
 dashboard.stop_endless_tasks = Stop endless tasks
 dashboard.cancel_abandoned_jobs = Cancel abandoned jobs
 dashboard.sync_branch.started = Branches Sync started
+dashboard.rebuild_issue_indexer = Rebuild issue indexer
 
 users.user_manage_panel = User Account Management
 users.new_account = Create User Account
diff --git a/services/cron/tasks_extended.go b/services/cron/tasks_extended.go
index acf2d3373c..48ea87df7f 100644
--- a/services/cron/tasks_extended.go
+++ b/services/cron/tasks_extended.go
@@ -13,6 +13,7 @@ import (
 	"code.gitea.io/gitea/models/system"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/git"
+	issue_indexer "code.gitea.io/gitea/modules/indexer/issues"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/updatechecker"
 	repo_service "code.gitea.io/gitea/services/repository"
@@ -213,6 +214,16 @@ func registerGCLFS() {
 	})
 }
 
+func registerRebuildIssueIndexer() {
+	RegisterTaskFatal("rebuild_issue_indexer", &BaseConfig{
+		Enabled:    false,
+		RunAtStart: false,
+		Schedule:   "@annually",
+	}, func(ctx context.Context, _ *user_model.User, config Config) error {
+		return issue_indexer.PopulateIssueIndexer(ctx, false)
+	})
+}
+
 func initExtendedTasks() {
 	registerDeleteInactiveUsers()
 	registerDeleteRepositoryArchives()
@@ -227,4 +238,5 @@ func initExtendedTasks() {
 	registerUpdateGiteaChecker()
 	registerDeleteOldSystemNotices()
 	registerGCLFS()
+	registerRebuildIssueIndexer()
 }