From a492b3071c7adc9d6999551c8a8425426ed1ead0 Mon Sep 17 00:00:00 2001
From: Andrew Thornton <art27@cantab.net>
Date: Mon, 23 Dec 2019 10:29:36 +0000
Subject: [PATCH] Prevent deadlock during early shutdown of issue indexer

---
 modules/indexer/issues/indexer.go | 45 +++++++++++++++++++++++++------
 1 file changed, 37 insertions(+), 8 deletions(-)

diff --git a/modules/indexer/issues/indexer.go b/modules/indexer/issues/indexer.go
index 8f0593acff..8676561cf1 100644
--- a/modules/indexer/issues/indexer.go
+++ b/modules/indexer/issues/indexer.go
@@ -6,6 +6,7 @@ package issues
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"sync"
 	"time"
@@ -51,9 +52,10 @@ type Indexer interface {
 }
 
 type indexerHolder struct {
-	indexer Indexer
-	mutex   sync.RWMutex
-	cond    *sync.Cond
+	indexer   Indexer
+	mutex     sync.RWMutex
+	cond      *sync.Cond
+	cancelled bool
 }
 
 func newIndexerHolder() *indexerHolder {
@@ -62,6 +64,13 @@ func newIndexerHolder() *indexerHolder {
 	return h
 }
 
+func (h *indexerHolder) cancel() {
+	h.mutex.Lock()
+	defer h.mutex.Unlock()
+	h.cancelled = true
+	h.cond.Broadcast()
+}
+
 func (h *indexerHolder) set(indexer Indexer) {
 	h.mutex.Lock()
 	defer h.mutex.Unlock()
@@ -72,7 +81,7 @@ func (h *indexerHolder) set(indexer Indexer) {
 func (h *indexerHolder) get() Indexer {
 	h.mutex.RLock()
 	defer h.mutex.RUnlock()
-	if h.indexer == nil {
+	if h.indexer == nil && !h.cancelled {
 		h.cond.Wait()
 	}
 	return h.indexer
@@ -93,6 +102,12 @@ func InitIssueIndexer(syncReindex bool) {
 	switch setting.Indexer.IssueType {
 	case "bleve":
 		handler := func(data ...queue.Data) {
+			indexer := holder.get()
+			if indexer == nil {
+				log.Error("Unable to get indexer!")
+				return
+			}
+
 			iData := make([]*IndexerData, 0, setting.Indexer.IssueQueueBatchNumber)
 			for _, datum := range data {
 				indexerData, ok := datum.(*IndexerData)
@@ -102,12 +117,12 @@ func InitIssueIndexer(syncReindex bool) {
 				}
 				log.Trace("IndexerData Process: %d %v %t", indexerData.ID, indexerData.IDs, indexerData.IsDelete)
 				if indexerData.IsDelete {
-					_ = holder.get().Delete(indexerData.IDs...)
+					_ = indexer.Delete(indexerData.IDs...)
 					continue
 				}
 				iData = append(iData, indexerData)
 			}
-			if err := holder.get().Index(iData); err != nil {
+			if err := indexer.Index(iData); err != nil {
 				log.Error("Error whilst indexing: %v Error: %v", iData, err)
 			}
 		}
@@ -132,6 +147,7 @@ func InitIssueIndexer(syncReindex bool) {
 				issueIndexer := NewBleveIndexer(setting.Indexer.IssuePath)
 				exist, err := issueIndexer.Init()
 				if err != nil {
+					holder.cancel()
 					log.Fatal("Unable to initialize Bleve Issue Indexer: %v", err)
 				}
 				populate = !exist
@@ -153,6 +169,7 @@ func InitIssueIndexer(syncReindex bool) {
 			issueIndexer := &DBIndexer{}
 			holder.set(issueIndexer)
 		default:
+			holder.cancel()
 			log.Fatal("Unknown issue indexer type: %s", setting.Indexer.IssueType)
 		}
 
@@ -168,10 +185,14 @@ func InitIssueIndexer(syncReindex bool) {
 			}
 		}
 		waitChannel <- time.Since(start)
+		close(waitChannel)
 	}()
 
 	if syncReindex {
-		<-waitChannel
+		select {
+		case <-waitChannel:
+		case <-graceful.GetManager().IsShutdown():
+		}
 	} else if setting.Indexer.StartupTimeout > 0 {
 		go func() {
 			timeout := setting.Indexer.StartupTimeout
@@ -181,6 +202,8 @@ func InitIssueIndexer(syncReindex bool) {
 			select {
 			case duration := <-waitChannel:
 				log.Info("Issue Indexer Initialization took %v", duration)
+			case <-graceful.GetManager().IsShutdown():
+				log.Warn("Shutdown occurred before issue index initialisation was complete")
 			case <-time.After(timeout):
 				if shutdownable, ok := issueIndexerQueue.(queue.Shutdownable); ok {
 					shutdownable.Terminate()
@@ -293,7 +316,13 @@ func DeleteRepoIssueIndexer(repo *models.Repository) {
 // SearchIssuesByKeyword search issue ids by keywords and repo id
 func SearchIssuesByKeyword(repoIDs []int64, keyword string) ([]int64, error) {
 	var issueIDs []int64
-	res, err := holder.get().Search(keyword, repoIDs, 1000, 0)
+	indexer := holder.get()
+
+	if indexer == nil {
+		log.Error("Unable to get indexer!")
+		return nil, fmt.Errorf("unable to get issue indexer")
+	}
+	res, err := indexer.Search(keyword, repoIDs, 1000, 0)
 	if err != nil {
 		return nil, err
 	}