From 01d412e6b93053cff2c47c52fecec3dad7af55e7 Mon Sep 17 00:00:00 2001
From: Benjamin Wang <wachao@vmware.com>
Date: Sun, 22 Oct 2023 09:16:28 +0100
Subject: [PATCH] resolve the data race on accessing tx stats

Refer to https://github.com/etcd-io/bbolt/issues/213

Signed-off-by: Benjamin Wang <wachao@vmware.com>
---
 bucket.go | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/bucket.go b/bucket.go
index 604b138ac..d32252563 100644
--- a/bucket.go
+++ b/bucket.go
@@ -73,7 +73,12 @@ func (b *Bucket) Writable() bool {
 // Do not use a cursor after the transaction is closed.
 func (b *Bucket) Cursor() *Cursor {
 	// Update transaction statistics.
+	// Note that `Cursor()` may be called by multiple readonly
+	// transactions concurrently, so we need to hold the lock
+	// `statlock` when updating the stats.
+	b.tx.db.statlock.Lock()
 	b.tx.stats.CursorCount++
+	b.tx.db.statlock.Unlock()
 
 	// Allocate and return a cursor.
 	return &Cursor{