vendor: update bigcache

(cherry picked from commit 37e5a908e7)

vendor/github.com/allegro/bigcache/shard.go

@@ -32,7 +32,7 @@ func (s *cacheShard) get(key string, hashedKey uint64) ([]byte, error) {
 	if itemIndex == 0 {
 		s.lock.RUnlock()
 		s.miss()
-		return nil, notFound(key)
+		return nil, ErrEntryNotFound
 	}
 
 	wrappedEntry, err := s.entries.Get(int(itemIndex))
@@ -47,11 +47,12 @@ func (s *cacheShard) get(key string, hashedKey uint64) ([]byte, error) {
 		}
 		s.lock.RUnlock()
 		s.collision()
-		return nil, notFound(key)
+		return nil, ErrEntryNotFound
 	}
+	entry := readEntry(wrappedEntry)
 	s.lock.RUnlock()
 	s.hit()
-	return readEntry(wrappedEntry), nil
+	return entry, nil
 }
 
 func (s *cacheShard) set(key string, hashedKey uint64, entry []byte) error {
@@ -85,17 +86,17 @@ func (s *cacheShard) set(key string, hashedKey uint64, entry []byte) error {
 }
 
 func (s *cacheShard) del(key string, hashedKey uint64) error {
+	// Optimistic pre-check using only readlock
 	s.lock.RLock()
 	itemIndex := s.hashmap[hashedKey]
 
 	if itemIndex == 0 {
 		s.lock.RUnlock()
 		s.delmiss()
-		return notFound(key)
+		return ErrEntryNotFound
 	}
 
-	wrappedEntry, err := s.entries.Get(int(itemIndex))
-	if err != nil {
+	if err := s.entries.CheckGet(int(itemIndex)); err != nil {
 		s.lock.RUnlock()
 		s.delmiss()
 		return err
@@ -104,6 +105,23 @@ func (s *cacheShard) del(key string, hashedKey uint64) error {
 
 	s.lock.Lock()
 	{
+		// After obtaining the writelock, we need to read the same again,
+		// since the data delivered earlier may be stale now
+		itemIndex = s.hashmap[hashedKey]
+
+		if itemIndex == 0 {
+			s.lock.Unlock()
+			s.delmiss()
+			return ErrEntryNotFound
+		}
+
+		wrappedEntry, err := s.entries.Get(int(itemIndex))
+		if err != nil {
+			s.lock.Unlock()
+			s.delmiss()
+			return err
+		}
+
 		delete(s.hashmap, hashedKey)
 		s.onRemove(wrappedEntry, Deleted)
 		resetKeyFromEntry(wrappedEntry)
@@ -136,17 +154,22 @@ func (s *cacheShard) cleanUp(currentTimestamp uint64) {
 }
 
 func (s *cacheShard) getOldestEntry() ([]byte, error) {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
 	return s.entries.Peek()
 }
 
 func (s *cacheShard) getEntry(index int) ([]byte, error) {
-	return s.entries.Get(index)
+	s.lock.RLock()
+	entry, err := s.entries.Get(index)
+	s.lock.RUnlock()
+
+	return entry, err
 }
 
 func (s *cacheShard) copyKeys() (keys []uint32, next int) {
-	keys = make([]uint32, len(s.hashmap))
-
 	s.lock.RLock()
+	keys = make([]uint32, len(s.hashmap))
 
 	for _, index := range s.hashmap {
 		keys[next] = index