From 063393987ad5010fac0dc88b1237d3de9694ed44 Mon Sep 17 00:00:00 2001
From: "T. Thyer" <tthyer@users.noreply.github.com>
Date: Wed, 7 Mar 2018 02:23:38 -0800
Subject: [PATCH] Add option to balance load between master node and replica
 nodes (#729)

* Add option to balance load between master node and replica nodes
---
 cluster.go | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/cluster.go b/cluster.go
index ba562cf1..319f1e2c 100644
--- a/cluster.go
+++ b/cluster.go
@@ -34,6 +34,8 @@ type ClusterOptions struct {
 	ReadOnly bool
 	// Allows routing read-only commands to the closest master or slave node.
 	RouteByLatency bool
+	// Allows routing read-only commands to the random master or slave node.
+	RouteRandomly bool
 
 	// Following options are copied from Options struct.
 
@@ -473,6 +475,12 @@ func (c *clusterState) slotClosestNode(slot int) (*clusterNode, error) {
 	return node, nil
 }
 
+func (c *clusterState) slotRandomNode(slot int) *clusterNode {
+	nodes := c.slotNodes(slot)
+	n := rand.Intn(len(nodes))
+	return nodes[n]
+}
+
 func (c *clusterState) slotNodes(slot int) []*clusterNode {
 	if slot >= 0 && slot < len(c.slots) {
 		return c.slots[slot]
@@ -639,6 +647,11 @@ func (c *ClusterClient) cmdSlotAndNode(cmd Cmder) (int, *clusterNode, error) {
 			return slot, node, err
 		}
 
+		if c.opt.RouteRandomly {
+			node := state.slotRandomNode(slot)
+			return slot, node, nil
+		}
+
 		node, err := state.slotSlaveNode(slot)
 		return slot, node, err
 	}