From de96e33698ae70bf791b69a4deadcce34730e807 Mon Sep 17 00:00:00 2001
From: chejinge <chejinge@360.cn>
Date: Thu, 18 Dec 2025 18:44:54 +0800
Subject: [PATCH] =?UTF-8?q?fix:proxy=E5=B4=A9=E6=BA=83?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 codis/pkg/proxy/forward.go | 67 ++++++++++++++++++++++++++++++++------
 1 file changed, 57 insertions(+), 10 deletions(-)

diff --git a/codis/pkg/proxy/forward.go b/codis/pkg/proxy/forward.go
index 4ccb929974..52756cc9e3 100644
--- a/codis/pkg/proxy/forward.go
+++ b/codis/pkg/proxy/forward.go
@@ -51,14 +51,19 @@ func (d *forwardSync) process(s *Slot, r *Request, hkey []byte) (*BackendConn, e
 	}
 	if s.migrate.bc != nil && len(hkey) != 0 {
 		if err := d.slotsmgrt(s, hkey, r.Database, r.Seed16()); err != nil {
-			log.Debugf("slot-%04d migrate from = %s to %s failed: hash key = '%s', database = %d, error = %s",
+			log.Warnf("slot-%04d migrate from = %s to %s failed: hash key = '%s', database = %d, error = %s",
 				s.id, s.migrate.bc.Addr(), s.backend.bc.Addr(), hkey, r.Database, err)
-			return nil, err
+			// Migration failed, but continue to forward directly to backend instead of returning error
+			log.Warnf("slot-%04d migration failed, forwarding directly to backend", s.id)
 		}
 	}
 	r.Group = &s.refs
 	r.Group.Add(1)
-	return d.forward2(s, r), nil
+	bc := d.forward2(s, r)
+	if bc == nil {
+		return nil, fmt.Errorf("slot-%04d backend connection unavailable", s.id)
+	}
+	return bc, nil
 }
 
 type forwardSemiAsync struct {
@@ -114,9 +119,11 @@ func (d *forwardSemiAsync) process(s *Slot, r *Request, hkey []byte) (_ *Backend
 		resp, moved, err := d.slotsmgrtExecWrapper(s, hkey, r.Database, r.Seed16(), r.Multi)
 		switch {
 		case err != nil:
-			log.Debugf("slot-%04d migrate from = %s to %s failed: hash key = '%s', error = %s",
+			log.Warnf("slot-%04d migrate from = %s to %s failed: hash key = '%s', error = %s",
 				s.id, s.migrate.bc.Addr(), s.backend.bc.Addr(), hkey, err)
-			return nil, false, err
+			// Migration failed, but continue to forward directly to backend instead of returning error
+			log.Warnf("slot-%04d migration failed in semi-async mode, forwarding directly to backend", s.id)
+			// Fall through to use backend connection
 		case !moved:
 			switch {
 			case resp != nil:
@@ -128,13 +135,30 @@ func (d *forwardSemiAsync) process(s *Slot, r *Request, hkey []byte) (_ *Backend
 	}
 	r.Group = &s.refs
 	r.Group.Add(1)
-	return d.forward2(s, r), false, nil
+	
+	bc := d.forward2(s, r)
+	if bc == nil {
+		return nil, false, fmt.Errorf("slot-%04d backend connection unavailable", s.id)
+	}
+	return bc, false, nil
 }
 
 type forwardHelper struct {
 }
 
 func (d *forwardHelper) slotsmgrt(s *Slot, hkey []byte, database int32, seed uint) error {
+	// Add nil pointer check for migrate.bc
+	if s.migrate.bc == nil {
+		log.Errorf("slot-%04d migrate connection is nil", s.id)
+		return fmt.Errorf("migrate connection is nil for slot-%04d", s.id)
+	}
+	
+	// Add nil pointer check for backend.bc
+	if s.backend.bc == nil {
+		log.Errorf("slot-%04d backend connection is nil", s.id)
+		return fmt.Errorf("backend connection is nil for slot-%04d", s.id)
+	}
+	
 	m := &Request{}
 	m.Multi = []*redis.Resp{
 		redis.NewBulkBytes([]byte("SLOTSMGRTTAGONE")),
@@ -145,8 +169,13 @@ func (d *forwardHelper) slotsmgrt(s *Slot, hkey []byte, database int32, seed uin
 	}
 	m.Batch = &sync.WaitGroup{}
 
-	s.migrate.bc.BackendConn(database, seed, true, m.OpFlag.IsQuick()).PushBack(m)
-
+	bc := s.migrate.bc.BackendConn(database, seed, true, m.OpFlag.IsQuick())
+	if bc == nil {
+		log.Errorf("slot-%04d failed to get backend connection for migration", s.id)
+		return fmt.Errorf("failed to get backend connection for slot-%04d", s.id)
+	}
+	
+	bc.PushBack(m)
 	m.Batch.Wait()
 
 	if err := m.Err; err != nil {
@@ -167,6 +196,12 @@ func (d *forwardHelper) slotsmgrt(s *Slot, hkey []byte, database int32, seed uin
 }
 
 func (d *forwardHelper) slotsmgrtExecWrapper(s *Slot, hkey []byte, database int32, seed uint, multi []*redis.Resp) (_ *redis.Resp, moved bool, _ error) {
+	// Add nil pointer check for migrate.bc
+	if s.migrate.bc == nil {
+		log.Errorf("slot-%04d migrate connection is nil", s.id)
+		return nil, false, fmt.Errorf("migrate connection is nil for slot-%04d", s.id)
+	}
+	
 	m := &Request{}
 	m.Multi = make([]*redis.Resp, 0, 2+len(multi))
 	m.Multi = append(m.Multi,
@@ -176,8 +211,13 @@ func (d *forwardHelper) slotsmgrtExecWrapper(s *Slot, hkey []byte, database int3
 	m.Multi = append(m.Multi, multi...)
 	m.Batch = &sync.WaitGroup{}
 
-	s.migrate.bc.BackendConn(database, seed, true, m.OpFlag.IsQuick()).PushBack(m)
-
+	bc := s.migrate.bc.BackendConn(database, seed, true, m.OpFlag.IsQuick())
+	if bc == nil {
+		log.Errorf("slot-%04d failed to get backend connection for migration", s.id)
+		return nil, false, fmt.Errorf("failed to get backend connection for slot-%04d", s.id)
+	}
+	
+	bc.PushBack(m)
 	m.Batch.Wait()
 
 	if err := m.Err; err != nil {
@@ -227,6 +267,13 @@ func (d *forwardHelper) forward2(s *Slot, r *Request) *BackendConn {
 			}
 		}
 	}
+	
+	// Add nil pointer check for backend.bc to prevent crash
+	if s.backend.bc == nil {
+		log.Errorf("slot-%04d backend connection is nil", s.id)
+		return nil
+	}
+	
 	//  fix:https://github.com/OpenAtomFoundation/pika/issues/2174
 	return s.backend.bc.BackendConn(database, uint(s.id), true, r.OpFlag.IsQuick())
 }