Add NewTransaction and AreKeysInSameSlot.

Author: Feng Zhou

cluster.go

@@ -1423,6 +1423,16 @@ func (c *ClusterClient) cmdsMoved(
 	return nil
 }
 
+// NewTransation returns a transaction, the related slot is determined by key.
+func (c *ClusterClient) NewTransation(ctx context.Context, key string) (*Tx, error) {
+	slot := hashtag.Slot(key)
+	node, err := c.slotMasterNode(ctx, slot)
+	if err != nil {
+		return nil, err
+	}
+	return node.Client.newTx(ctx), nil
+}
+
 func (c *ClusterClient) Watch(ctx context.Context, fn func(*Tx) error, keys ...string) error {
 	if len(keys) == 0 {
 		return fmt.Errorf("redis: Watch requires at least one key")

redis.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/go-redis/redis/v8/internal"
+	"github.com/go-redis/redis/v8/internal/hashtag"
 	"github.com/go-redis/redis/v8/internal/pool"
 	"github.com/go-redis/redis/v8/internal/proto"
 	"go.opentelemetry.io/otel/label"
@@ -790,3 +791,16 @@ func (c *Conn) TxPipeline() Pipeliner {
 	pipe.init()
 	return &pipe
 }
+
+func AreKeysInSameSlot(keys ...string) bool {
+	if len(keys) == 0 {
+		return true
+	}
+	slot := hashtag.Slot(keys[0])
+	for _, key := range keys[1:] {
+		if hashtag.Slot(key) != slot {
+			return false
+		}
+	}
+	return true
+}