Simplify crossbuild parallelism

Use a Go errgroup to modernize the parallelism of crossbuild.

Signed-off-by: SuperQ <superq@gmail.com>

Author: SuperQ

cmd/crossbuild.go

@@ -22,11 +22,10 @@ import (
 	"sort"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 
 	kingpin "github.com/alecthomas/kingpin/v2"
-	"go.uber.org/atomic"
+	"golang.org/x/sync/errgroup"
 
 	"github.com/prometheus/promu/util/sh"
 )
@@ -190,19 +189,13 @@ func (pg platformGroup) Build(repoPath string) error {
 	if err != nil {
 		return err
 	}
-	var wg sync.WaitGroup
-	wg.Add(*parallelFlag)
-	atomicErr := atomic.NewError(nil)
+	var g errgroup.Group
 	for p := 0; p < *parallelFlag; p++ {
-		go func(p int) {
-			defer wg.Done()
-			if err := pg.buildThread(repoPath, p); err != nil {
-				atomicErr.Store(err)
-			}
-		}(p)
+		g.Go(func() error {
+			return pg.buildThread(repoPath, p)
+		})
 	}
-	wg.Wait()
-	return atomicErr.Load()
+	return g.Wait()
 }
 
 func (pg platformGroup) buildThread(repoPath string, p int) error {

go.mod

@@ -7,9 +7,9 @@ require (
 	github.com/alecthomas/kingpin/v2 v2.4.0
 	github.com/google/go-github/v25 v25.1.3
 	github.com/prometheus/common v0.67.5
-	go.uber.org/atomic v1.11.0
 	go.yaml.in/yaml/v2 v2.4.4
 	golang.org/x/oauth2 v0.36.0
+	golang.org/x/sync v0.20.0
 )
 
 require (

go.sum

@@ -28,8 +28,6 @@ github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/xhit/go-str2duration/v2 v2.1.0 h1:lxklc02Drh6ynqX+DdPyp5pCKLUQpRT8bp8Ydu2Bstc=
 github.com/xhit/go-str2duration/v2 v2.1.0/go.mod h1:ohY8p+0f07DiV6Em5LKB0s2YpLtXVyJfNt1+BlmyAsU=
-go.uber.org/atomic v1.11.0 h1:ZvwS0R+56ePWxUNi+Atn9dWONBPp/AUETXlHW0DxSjE=
-go.uber.org/atomic v1.11.0/go.mod h1:LUxbIzbOniOlMKjJjyPfpl4v+PKK2cNJn91OQbhoJI0=
 go.yaml.in/yaml/v2 v2.4.4 h1:tuyd0P+2Ont/d6e2rl3be67goVK4R6deVxCUX5vyPaQ=
 go.yaml.in/yaml/v2 v2.4.4/go.mod h1:gMZqIpDtDqOfM0uNfy0SkpRhvUryYH0Z6wdMYcacYXQ=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
@@ -38,6 +36,8 @@ golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAG
 golang.org/x/oauth2 v0.36.0 h1:peZ/1z27fi9hUOFCAZaHyrpWG5lwe0RJEEEeH0ThlIs=
 golang.org/x/oauth2 v0.36.0/go.mod h1:YDBUJMTkDnJS+A4BP4eZBjCqtokkg1hODuPjwiGPO7Q=
 golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
+golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=