Update for review

rootfs/etc/nginx/lua/balancer/ewma.lua

@@ -176,7 +176,6 @@ function _M.balance(self)
 
   if #peers > 1 then
     local k = (#peers < PICK_SET_SIZE) and #peers or PICK_SET_SIZE
-    local peer_copy = util.deepcopy(peers)
 
     local tried_endpoints
     if not ngx.ctx.balancer_ewma_tried_endpoints then
@@ -187,7 +186,7 @@ function _M.balance(self)
     end
 
     local filtered_peers
-    for _, peer in ipairs(peer_copy) do
+    for _, peer in ipairs(peers) do
       if not tried_endpoints[get_upstream_name(peer)] then
         if not filtered_peers then
           filtered_peers = {}
@@ -198,7 +197,7 @@ function _M.balance(self)
 
     if not filtered_peers then
       ngx.log(ngx.WARN, "all endpoints have been retried")
-      filtered_peers = peer_copy
+      filtered_peers = util.deepcopy(peers)
     end
 
     if #filtered_peers > 1 then

rootfs/etc/nginx/lua/test/balancer/ewma_test.lua

@@ -106,6 +106,7 @@ describe("Balancer ewma", function()
       -- even though 10.10.10.1:8080 has a lower ewma score
       -- algorithm picks 10.10.10.3:8080 because its decayed score is even lower
       assert.equal("10.10.10.3:8080", peer)
+      assert.equal(true, ngx.ctx.balancer_ewma_tried_endpoints["10.10.10.3:8080"])
       assert.are.equals(0.16240233988393523723, ngx.var.balancer_ewma_score)
     end)
 
@@ -114,8 +115,12 @@ describe("Balancer ewma", function()
       table.remove(two_endpoints_backend.endpoints, 2)
       local two_endpoints_instance = balancer_ewma:new(two_endpoints_backend)
 
+      ngx.ctx.balancer_ewma_tried_endpoints = {
+        ["10.10.10.3:8080"] = true,
+      }
       local peer = two_endpoints_instance:balance()
       assert.equal("10.10.10.1:8080", peer)
+      assert.equal(true, ngx.ctx.balancer_ewma_tried_endpoints["10.10.10.1:8080"])
     end)
 
     it("all the endpoints are tried, pick the one with lowest score", function()
@@ -123,6 +128,10 @@ describe("Balancer ewma", function()
       table.remove(two_endpoints_backend.endpoints, 2)
       local two_endpoints_instance = balancer_ewma:new(two_endpoints_backend)
 
+      ngx.ctx.balancer_ewma_tried_endpoints = {
+        ["10.10.10.1:8080"] = true,
+        ["10.10.10.3:8080"] = true,
+      }
       local peer = two_endpoints_instance:balance()
       assert.equal("10.10.10.3:8080", peer)
     end)