From 8f1d3f677bab74eae3e61cb1d609511698f0a268 Mon Sep 17 00:00:00 2001
From: Roman Zavodskikh <roman.zavodskikh@zalando.de>
Date: Wed, 4 Oct 2023 11:45:32 +0200
Subject: [PATCH] Get inflight requests number from endpointregistry instead of
 endpoint metrics

Signed-off-by: Roman Zavodskikh <roman.zavodskikh@zalando.de>
---
 loadbalancer/algorithm.go      | 12 ++++++------
 loadbalancer/algorithm_test.go |  6 ++++++
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/loadbalancer/algorithm.go b/loadbalancer/algorithm.go
index 6972239e18..df599f2fbd 100644
--- a/loadbalancer/algorithm.go
+++ b/loadbalancer/algorithm.go
@@ -267,7 +267,7 @@ func computeLoadAverage(ctx *routing.LBContext) float64 {
 	sum := 1.0 // add 1 to include the request that just arrived
 	endpoints := ctx.Route.LBEndpoints
 	for _, v := range endpoints {
-		sum += float64(v.Metrics.GetInflightRequests())
+		sum += float64(ctx.Registry.GetMetrics(v.Host).InflightRequests())
 	}
 	return sum / float64(len(endpoints))
 }
@@ -284,10 +284,10 @@ func (ch *consistentHash) boundedLoadSearch(key string, balanceFactor float64, c
 		if skipEndpoint(endpointIndex) {
 			continue
 		}
-		load := ctx.Route.LBEndpoints[endpointIndex].Metrics.GetInflightRequests()
+		load := ctx.Registry.GetMetrics(ctx.Route.LBEndpoints[endpointIndex].Host).InflightRequests()
 		// We know there must be an endpoint whose load <= average load.
 		// Since targetLoad >= average load (balancerFactor >= 1), there must also be an endpoint with load <= targetLoad.
-		if load <= int(targetLoad) {
+		if load <= int64(targetLoad) {
 			break
 		}
 		ringIndex = (ringIndex + 1) % ch.Len()
@@ -369,7 +369,7 @@ func (p *powerOfRandomNChoices) Apply(ctx *routing.LBContext) routing.LBEndpoint
 	for i := 1; i < p.numberOfChoices; i++ {
 		ce := ctx.Route.LBEndpoints[p.rnd.Intn(ne)]
 
-		if p.getScore(ce) > p.getScore(best) {
+		if p.getScore(ctx, ce) > p.getScore(ctx, best) {
 			best = ce
 		}
 	}
@@ -377,9 +377,9 @@ func (p *powerOfRandomNChoices) Apply(ctx *routing.LBContext) routing.LBEndpoint
 }
 
 // getScore returns negative value of inflightrequests count.
-func (p *powerOfRandomNChoices) getScore(e routing.LBEndpoint) int {
+func (p *powerOfRandomNChoices) getScore(ctx *routing.LBContext, e routing.LBEndpoint) int64 {
 	// endpoints with higher inflight request should have lower score
-	return -e.Metrics.GetInflightRequests()
+	return -ctx.Registry.GetMetrics(e.Host).InflightRequests()
 }
 
 type (
diff --git a/loadbalancer/algorithm_test.go b/loadbalancer/algorithm_test.go
index ca684ebc71..f5ec402bd2 100644
--- a/loadbalancer/algorithm_test.go
+++ b/loadbalancer/algorithm_test.go
@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/zalando/skipper/eskip"
 	"github.com/zalando/skipper/net"
 	"github.com/zalando/skipper/routing"
@@ -404,6 +405,11 @@ func TestConsistentHashBoundedLoadDistribution(t *testing.T) {
 		ifr0 := route.LBEndpoints[0].Metrics.GetInflightRequests()
 		ifr1 := route.LBEndpoints[1].Metrics.GetInflightRequests()
 		ifr2 := route.LBEndpoints[2].Metrics.GetInflightRequests()
+
+		assert.Equal(t, int64(ifr0), ctx.Registry.GetMetrics(route.LBEndpoints[0].Host).InflightRequests())
+		assert.Equal(t, int64(ifr1), ctx.Registry.GetMetrics(route.LBEndpoints[1].Host).InflightRequests())
+		assert.Equal(t, int64(ifr2), ctx.Registry.GetMetrics(route.LBEndpoints[2].Host).InflightRequests())
+
 		avg := float64(ifr0+ifr1+ifr2) / 3.0
 		limit := int(avg*balanceFactor) + 1
 		if ifr0 > limit || ifr1 > limit || ifr2 > limit {