Rotate slaves

Author: TimWeils

lib/resty/redis/connector.lua

@@ -39,6 +39,7 @@ redis.add_commands("sentinel")
 local get_master = require("resty.redis.sentinel").get_master
 local get_slaves = require("resty.redis.sentinel").get_slaves
 
+local slave_rr_counter = 0
 
 -- A metatable which prevents undefined fields from being created / accessed
 local fixed_field_metatable = {
@@ -262,6 +263,19 @@ function _M.connect(self, params)
 end
 
 
+local function rotate_slaves(slaves)
+    local rotated_slaves = {}
+    local local_rr_counter = (slave_rr_counter + 1) % #slaves
+    slave_rr_counter = local_rr_counter
+
+    for i, _ in ipairs(slaves) do
+        local_rr_counter = (local_rr_counter % #slaves) + 1
+        rotated_slaves[i] = slaves[local_rr_counter]
+    end
+
+    return rotated_slaves
+end
+
 local function sort_by_localhost(a, b)
     if a.host == "127.0.0.1" and b.host ~= "127.0.0.1" then
         return true
@@ -319,6 +333,7 @@ function _M.connect_via_sentinel(self, params)
 
         sentnl:set_keepalive()
 
+        slaves = rotate_slaves(slaves)
         -- Put any slaves on 127.0.0.1 at the front
         tbl_sort(slaves, sort_by_localhost)