Automatically pause queue if index service is unavailable (#15066)

* Handle keyword search error when issue indexer service is not available

* Implement automatic disabling and resume of code indexer queue

modules/indexer/issues/elastic_search.go

@@ -8,9 +8,12 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net"
 	"strconv"
+	"sync"
 	"time"
 
+	"code.gitea.io/gitea/modules/graceful"
 	"code.gitea.io/gitea/modules/log"
 
 	"github.com/olivere/elastic/v7"
@@ -20,8 +23,12 @@ var _ Indexer = &ElasticSearchIndexer{}
 
 // ElasticSearchIndexer implements Indexer interface
 type ElasticSearchIndexer struct {
-	client      *elastic.Client
-	indexerName string
+	client               *elastic.Client
+	indexerName          string
+	available            bool
+	availabilityCallback func(bool)
+	stopTimer            chan struct{}
+	lock                 sync.RWMutex
 }
 
 type elasticLogger struct {
@@ -56,10 +63,27 @@ func NewElasticSearchIndexer(url, indexerName string) (*ElasticSearchIndexer, er
 		return nil, err
 	}
 
-	return &ElasticSearchIndexer{
+	indexer := &ElasticSearchIndexer{
 		client:      client,
 		indexerName: indexerName,
-	}, nil
+		available:   true,
+		stopTimer:   make(chan struct{}),
+	}
+
+	ticker := time.NewTicker(10 * time.Second)
+	go func() {
+		for {
+			select {
+			case <-ticker.C:
+				indexer.checkAvailability()
+			case <-indexer.stopTimer:
+				ticker.Stop()
+				return
+			}
+		}
+	}()
+
+	return indexer, nil
 }
 
 const (
@@ -93,10 +117,10 @@ const (
 
 // Init will initialize the indexer
 func (b *ElasticSearchIndexer) Init() (bool, error) {
-	ctx := context.Background()
+	ctx := graceful.GetManager().HammerContext()
 	exists, err := b.client.IndexExists(b.indexerName).Do(ctx)
 	if err != nil {
-		return false, err
+		return false, b.checkError(err)
 	}
 
 	if !exists {
@@ -104,7 +128,7 @@ func (b *ElasticSearchIndexer) Init() (bool, error) {
 
 		createIndex, err := b.client.CreateIndex(b.indexerName).BodyString(mapping).Do(ctx)
 		if err != nil {
-			return false, err
+			return false, b.checkError(err)
 		}
 		if !createIndex.Acknowledged {
 			return false, errors.New("init failed")
@@ -115,6 +139,20 @@ func (b *ElasticSearchIndexer) Init() (bool, error) {
 	return true, nil
 }
 
+// SetAvailabilityChangeCallback sets callback that will be triggered when availability changes
+func (b *ElasticSearchIndexer) SetAvailabilityChangeCallback(callback func(bool)) {
+	b.lock.Lock()
+	defer b.lock.Unlock()
+	b.availabilityCallback = callback
+}
+
+// Ping checks if elastic is available
+func (b *ElasticSearchIndexer) Ping() bool {
+	b.lock.RLock()
+	defer b.lock.RUnlock()
+	return b.available
+}
+
 // Index will save the index data
 func (b *ElasticSearchIndexer) Index(issues []*IndexerData) error {
 	if len(issues) == 0 {
@@ -131,8 +169,8 @@ func (b *ElasticSearchIndexer) Index(issues []*IndexerData) error {
 				"content":  issue.Content,
 				"comments": issue.Comments,
 			}).
-			Do(context.Background())
-		return err
+			Do(graceful.GetManager().HammerContext())
+		return b.checkError(err)
 	}
 
 	reqs := make([]elastic.BulkableRequest, 0)
@@ -154,8 +192,8 @@ func (b *ElasticSearchIndexer) Index(issues []*IndexerData) error {
 	_, err := b.client.Bulk().
 		Index(b.indexerName).
 		Add(reqs...).
-		Do(context.Background())
-	return err
+		Do(graceful.GetManager().HammerContext())
+	return b.checkError(err)
 }
 
 // Delete deletes indexes by ids
@@ -166,8 +204,8 @@ func (b *ElasticSearchIndexer) Delete(ids ...int64) error {
 		_, err := b.client.Delete().
 			Index(b.indexerName).
 			Id(fmt.Sprintf("%d", ids[0])).
-			Do(context.Background())
-		return err
+			Do(graceful.GetManager().HammerContext())
+		return b.checkError(err)
 	}
 
 	reqs := make([]elastic.BulkableRequest, 0)
@@ -182,13 +220,13 @@ func (b *ElasticSearchIndexer) Delete(ids ...int64) error {
 	_, err := b.client.Bulk().
 		Index(b.indexerName).
 		Add(reqs...).
-		Do(context.Background())
-	return err
+		Do(graceful.GetManager().HammerContext())
+	return b.checkError(err)
 }
 
 // Search searches for issues by given conditions.
 // Returns the matching issue IDs
-func (b *ElasticSearchIndexer) Search(keyword string, repoIDs []int64, limit, start int) (*SearchResult, error) {
+func (b *ElasticSearchIndexer) Search(ctx context.Context, keyword string, repoIDs []int64, limit, start int) (*SearchResult, error) {
 	kwQuery := elastic.NewMultiMatchQuery(keyword, "title", "content", "comments")
 	query := elastic.NewBoolQuery()
 	query = query.Must(kwQuery)
@@ -205,9 +243,9 @@ func (b *ElasticSearchIndexer) Search(keyword string, repoIDs []int64, limit, st
 		Query(query).
 		Sort("_score", false).
 		From(start).Size(limit).
-		Do(context.Background())
+		Do(ctx)
 	if err != nil {
-		return nil, err
+		return nil, b.checkError(err)
 	}
 
 	hits := make([]Match, 0, limit)
@@ -225,4 +263,51 @@ func (b *ElasticSearchIndexer) Search(keyword string, repoIDs []int64, limit, st
 }
 
 // Close implements indexer
-func (b *ElasticSearchIndexer) Close() {}
+func (b *ElasticSearchIndexer) Close() {
+	select {
+	case <-b.stopTimer:
+	default:
+		close(b.stopTimer)
+	}
+}
+
+func (b *ElasticSearchIndexer) checkError(err error) error {
+	var opErr *net.OpError
+	if !(elastic.IsConnErr(err) || (errors.As(err, &opErr) && (opErr.Op == "dial" || opErr.Op == "read"))) {
+		return err
+	}
+
+	b.setAvailability(false)
+
+	return err
+}
+
+func (b *ElasticSearchIndexer) checkAvailability() {
+	if b.Ping() {
+		return
+	}
+
+	// Request cluster state to check if elastic is available again
+	_, err := b.client.ClusterState().Do(graceful.GetManager().ShutdownContext())
+	if err != nil {
+		b.setAvailability(false)
+		return
+	}
+
+	b.setAvailability(true)
+}
+
+func (b *ElasticSearchIndexer) setAvailability(available bool) {
+	b.lock.Lock()
+	defer b.lock.Unlock()
+
+	if b.available == available {
+		return
+	}
+
+	b.available = available
+	if b.availabilityCallback != nil {
+		// Call the callback from within the lock to ensure that the ordering remains correct
+		b.availabilityCallback(b.available)
+	}
+}