From 92180bc793e60c9aa5c33e4e146e8485db45ec9f Mon Sep 17 00:00:00 2001
From: Klaus Post <klauspost@gmail.com>
Date: Wed, 21 Feb 2024 12:27:35 -0800
Subject: [PATCH] Add array recycling safety (#19103)

Nil entries when recycling arrays.
---
 cmd/metrics-v2.go       | 10 +++++-----
 cmd/peer-rest-server.go | 24 ++++++++++++++++--------
 internal/grid/types.go  |  4 +++-
 3 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/cmd/metrics-v2.go b/cmd/metrics-v2.go
index 971bfd4d9..f14fc2d0d 100644
--- a/cmd/metrics-v2.go
+++ b/cmd/metrics-v2.go
@@ -420,14 +420,14 @@ func (g *MetricsGroup) RegisterRead(read func(ctx context.Context) []Metric) {
 	})
 }
 
-func (m *Metric) copyMetric() Metric {
+func (m *Metric) clone() Metric {
 	metric := Metric{
 		Description:          m.Description,
 		Value:                m.Value,
 		HistogramBucketLabel: m.HistogramBucketLabel,
-		StaticLabels:         make(map[string]string),
-		VariableLabels:       make(map[string]string),
-		Histogram:            make(map[string]uint64),
+		StaticLabels:         make(map[string]string, len(m.StaticLabels)),
+		VariableLabels:       make(map[string]string, len(m.VariableLabels)),
+		Histogram:            make(map[string]uint64, len(m.Histogram)),
 	}
 	for k, v := range m.StaticLabels {
 		metric.StaticLabels[k] = v
@@ -453,7 +453,7 @@ func (g *MetricsGroup) Get() (metrics []Metric) {
 
 	metrics = make([]Metric, 0, len(m))
 	for i := range m {
-		metrics = append(metrics, m[i].copyMetric())
+		metrics = append(metrics, m[i].clone())
 	}
 	return metrics
 }
diff --git a/cmd/peer-rest-server.go b/cmd/peer-rest-server.go
index fb05f8b3e..6738d9237 100644
--- a/cmd/peer-rest-server.go
+++ b/cmd/peer-rest-server.go
@@ -1007,21 +1007,29 @@ func (s *peerRESTServer) GetBandwidth(params *grid.URLValues) (*bandwidth.Bucket
 
 // GetPeerMetrics gets the metrics to be federated across peers.
 func (s *peerRESTServer) GetPeerMetrics(_ *grid.MSS) (*grid.Array[*Metric], *grid.RemoteErr) {
-	m := ReportMetrics(context.Background(), peerMetricsGroups)
-	res := make([]*Metric, 0, len(m))
-	for m := range m {
+	res := make([]*Metric, 0, len(peerMetricsGroups))
+	populateAndPublish(peerMetricsGroups, func(m Metric) bool {
+		if m.VariableLabels == nil {
+			m.VariableLabels = make(map[string]string, 1)
+		}
+		m.VariableLabels[serverName] = globalLocalNodeName
 		res = append(res, &m)
-	}
+		return true
+	})
 	return aoMetricsGroup.NewWith(res), nil
 }
 
 // GetPeerBucketMetrics gets the metrics to be federated across peers.
 func (s *peerRESTServer) GetPeerBucketMetrics(_ *grid.MSS) (*grid.Array[*Metric], *grid.RemoteErr) {
-	m := ReportMetrics(context.Background(), bucketPeerMetricsGroups)
-	res := make([]*Metric, 0, len(m))
-	for m := range m {
+	res := make([]*Metric, 0, len(bucketPeerMetricsGroups))
+	populateAndPublish(bucketPeerMetricsGroups, func(m Metric) bool {
+		if m.VariableLabels == nil {
+			m.VariableLabels = make(map[string]string, 1)
+		}
+		m.VariableLabels[serverName] = globalLocalNodeName
 		res = append(res, &m)
-	}
+		return true
+	})
 	return aoMetricsGroup.NewWith(res), nil
 }
 
diff --git a/internal/grid/types.go b/internal/grid/types.go
index 0d579c1c2..f60f29d24 100644
--- a/internal/grid/types.go
+++ b/internal/grid/types.go
@@ -595,8 +595,10 @@ func (p *ArrayOf[T]) newA(sz uint32) []T {
 }
 
 func (p *ArrayOf[T]) putA(v []T) {
-	for _, t := range v {
+	var zero T // nil
+	for i, t := range v {
 		p.ePool.Put(t)
+		v[i] = zero
 	}
 	if v != nil {
 		v = v[:0]