fix: race condition

.github/workflows/run-tests.yml

@@ -0,0 +1,32 @@
+name: run-tests
+
+on:
+  push:
+    branches:
+      - main
+
+  pull_request:
+    branches:
+      - main
+
+jobs:
+
+  run-tests:
+
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+
+    steps:
+
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
+      - name: Setup Go
+        uses: actions/setup-go@v6
+        with:
+          go-version: stable
+
+      - name: Run tests
+        run: go test -v ./...

go.mod

@@ -1,3 +1,3 @@
 module netexp
 
-go 1.21.4
+go 1.25

main.go

@@ -6,13 +6,14 @@ import (
 	"net/http"
 	"netexp/netdev"
 	"netexp/pipeline"
+	"netexp/rcu"
 	"os"
 	"time"
 )
 
 var (
 	version = "0.3.8"
-	metrics []byte
+	metrics rcu.RCU[[]byte]
 	listen  string
 	getver  bool
 )
@@ -45,7 +46,7 @@ func serve() {
 	})
 
 	http.HandleFunc("/metrics", func(w http.ResponseWriter, r *http.Request) {
-		w.Write(metrics)
+		w.Write(*metrics.Load())
 	})
 
 	go func() {
@@ -72,7 +73,9 @@ func gather() {
 			panic(fmt.Errorf("could not get traffic: %w", err))
 		}
 
-		metrics = p.Step(recv, trns)
+		buf := p.Step(recv, trns)
+
+		metrics.Store(&buf)
 
 		time.Sleep(time.Second)
 	}

pipeline/pipeline.go

@@ -2,7 +2,6 @@ package pipeline
 
 import (
 	"fmt"
-	"netexp/math"
 	"netexp/series"
 )
 
@@ -53,8 +52,8 @@ func (p *Pipeline) Step(recv, trns int64) []byte {
 	for _, r := range p.ranges {
 		// Check if there exists enough sample data for the current duration range 'r'
 		if p.trns_series.Length() >= r+1 {
-			trns_rate := math.Rate(p.trns_series.Samples, r+1)
-			recv_rate := math.Rate(p.recv_series.Samples, r+1)
+			trns_rate := series.Rate(p.trns_series.Samples, r+1)
+			recv_rate := series.Rate(p.recv_series.Samples, r+1)
 
 			p.trns_rates_series[r].Record(trns_rate)
 			p.recv_rates_series[r].Record(recv_rate)
@@ -69,8 +68,8 @@ func (p *Pipeline) Step(recv, trns int64) []byte {
 			if m > r && p.trns_rates_series[r].Length() >= m {
 				trns_name := fmt.Sprintf("netexp_transmit_rate_%ds_max_%ds_bps", r, m)
 				recv_name := fmt.Sprintf("netexp_receive_rate_%ds_max_%ds_bps", r, m)
-				register(trns_name, math.Max(p.trns_rates_series[r].Samples, m))
-				register(recv_name, math.Max(p.recv_rates_series[r].Samples, m))
+				register(trns_name, series.Max(p.trns_rates_series[r].Samples, m))
+				register(recv_name, series.Max(p.recv_rates_series[r].Samples, m))
 			}
 		}
 	}

rcu/rcu.go

@@ -0,0 +1,15 @@
+package rcu
+
+import "sync/atomic"
+
+type RCU[T any] struct {
+	p atomic.Pointer[T]
+}
+
+func (r *RCU[T]) Store(t *T) {
+	r.p.Store(t)
+}
+
+func (r *RCU[T]) Load() *T {
+	return r.p.Load()
+}

math/math.go → series/math.go

@@ -1,4 +1,4 @@
-package math
+package series
 
 func Max(series []int64, head int) int64 {
 	var max int64

math/math_test.go → series/math_test.go

@@ -1,7 +1,7 @@
-package math_test
+package series_test
 
 import (
-	"netexp/math"
+	"netexp/series"
 	"strconv"
 	"testing"
 )
@@ -20,7 +20,7 @@ func TestMax(t *testing.T) {
 
 	for i, tc := range tests {
 		t.Run(strconv.Itoa(i), func(t *testing.T) {
-			got := math.Max(tc.series, tc.head)
+			got := series.Max(tc.series, tc.head)
 			if got != tc.want {
 				t.Errorf("incorrect max; got %d want %d", got, tc.want)
 			}
@@ -42,7 +42,7 @@ func TestRate(t *testing.T) {
 
 	for i, tc := range tests {
 		t.Run(strconv.Itoa(i), func(t *testing.T) {
-			got := math.Rate(tc.series, tc.head)
+			got := series.Rate(tc.series, tc.head)
 			if got != tc.want {
 				t.Errorf("incorrect rate; got %d want %d", got, tc.want)
 			}