fix: prevent buffer reuse in async mode for Put method

If the mode is async, we need to copy request Blob to prevent
fasthttp from reusing the buffer since we are going to
use the buffer in a separate goroutine beyond the scope
of the current request.

Author: rhnvrm

fastcache.go

@@ -77,7 +77,9 @@ type Item struct {
 	ContentType string
 	Compression string
 	ETag        string
-	Blob        []byte
+	// If the Blob is used beyond the scope of the request, it should be copied.
+	// Such as when the cache is written asynchronously.
+	Blob []byte
 }
 
 // Store represents a backend data store where bytes are cached. Individual

stores/goredis/redis.go

@@ -169,6 +169,14 @@ type putReq struct {
 // Put sets a value to given session but stored only on commit
 func (s *Store) Put(namespace, group, uri string, b fastcache.Item, ttl time.Duration) error {
 	if s.config.Async {
+		// In async mode, we need to copy b.Blob to prevent fasthttp from reusing
+		// the buffer, as we will use the buffer in a separate goroutine beyond
+		// the scope of the current request.
+		blobCopy := make([]byte, len(b.Blob))
+		copy(blobCopy, b.Blob)
+		b.Blob = blobCopy
+
+		// Send the put request to the async buffer channel.
 		s.putBuf <- putReq{namespace, group, uri, b, ttl}
 		return nil
 	}