refactor: modernize the code by new features provided by golang stand… (#3963)

refactor: modernize the code by new features provided by golang standard library

Signed-off-by: chlins <chlins.zhang@gmail.com>

client/daemon/peer/peertask_manager_test.go

@@ -875,7 +875,7 @@ func (ts *testSpec) runConductorTest(assert *testifyassert.Assertions, require *
 		}
 	}
 
-	for i := 0; i < ptcCount; i++ {
+	for i := range ptcCount {
 		request := &schedulerv1.PeerTaskRequest{
 			Url:      ts.url,
 			UrlMeta:  urlMeta,
@@ -920,7 +920,7 @@ func (ts *testSpec) runConductorTest(assert *testifyassert.Assertions, require *
 	}
 	assert.True(success, "task should success")
 
-	for i := 0; i < 3; i++ {
+	for range 3 {
 		ptm.runningPeerTasks.Range(func(key, value any) bool {
 			noRunningTask = false
 			return false

client/daemon/peer/peertask_reuse.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"maps"
 	"os"
 	"strings"
 	"time"
@@ -323,9 +324,7 @@ func (ptm *peerTaskManager) tryReuseStreamPeerTask(ctx context.Context, taskID s
 	attr[headers.ContentLength] = fmt.Sprintf("%d", length)
 
 	if exa != nil {
-		for k, v := range exa.Header {
+		maps.Copy(attr, exa.Header)
-			attr[k] = v
-		}
 	}
 
 	if reuseRange != nil {

client/daemon/peer/peertask_stream.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"maps"
 
 	"github.com/go-http-utils/headers"
 	"go.opentelemetry.io/otel/trace"
@@ -177,9 +178,7 @@ func (s *streamTask) Start(ctx context.Context) (io.ReadCloser, map[string]strin
 			return nil, attr, err
 		}
 		if exa != nil {
-			for k, v := range exa.Header {
+			maps.Copy(attr, exa.Header)
-				attr[k] = v
-			}
 		}
 		rc, err := s.peerTaskConductor.StorageManager.ReadAllPieces(
 			ctx,
@@ -197,9 +196,7 @@ func (s *streamTask) Start(ctx context.Context) (io.ReadCloser, map[string]strin
 			return nil, attr, err
 		}
 		if exa != nil {
-			for k, v := range exa.Header {
+			maps.Copy(attr, exa.Header)
-				attr[k] = v
-			}
 		}
 	}
 
@@ -373,9 +370,7 @@ pieceReady:
 		return nil, attr, err
 	}
 	if exa != nil {
-		for k, v := range exa.Header {
+		maps.Copy(attr, exa.Header)
-			attr[k] = v
-		}
 	}
 
 	attr[headers.ContentLength] = fmt.Sprintf("%d", s.peerTaskConductor.GetContentLength()-s.skipBytes)

client/daemon/peer/peertask_stream_resume_test.go

@@ -107,9 +107,7 @@ func (i *intervalSleepReader) Read(p []byte) (n int, err error) {
 		return 0, io.EOF
 	}
 	end := i.offset + i.size
-	if end > len(i.data) {
+	end = min(end, len(i.data))
-		end = len(i.data)
-	}
 
 	n = copy(p, i.data[i.offset:end])
 	time.Sleep(i.interval)

client/daemon/peer/piece_dispatcher_test.go

@@ -66,9 +66,9 @@ func (pc *pieceTestManager) Run() {
 	// producer
 	go func() {
 		slice := make([]*DownloadPieceRequest, 0)
-		for i := 0; i < 4; i++ {
+		for range 4 {
 			for _, peer := range pc.peers {
-				for j := 0; j < pc.pieceNum; j++ {
+				for j := range pc.pieceNum {
 					slice = append(slice, &DownloadPieceRequest{
 						piece:  &commonv1.PieceInfo{PieceNum: int32(j)},
 						DstPid: peer.id,

client/daemon/peer/piece_manager.go

@@ -902,9 +902,7 @@ func newPieceGroup(i int32, reminderPieces int32, startPieceNum int32, minPieceC
 	// calculate piece group first and last range byte with parsedRange.Start
 	startByte := int64(start) * int64(pieceSize)
 	endByte := int64(end+1)*int64(pieceSize) - 1
-	if endByte > parsedRange.Length-1 {
+	endByte = min(endByte, parsedRange.Length-1)
-		endByte = parsedRange.Length - 1
-	}
 
 	// adjust by range start
 	startByte += parsedRange.Start
@@ -935,7 +933,7 @@ func (pm *pieceManager) concurrentDownloadSourceByPiece(
 
 	downloadedPieceCount := atomic.NewInt32(startPieceNum)
 
-	for i := 0; i < con; i++ {
+	for i := range con {
 		go func(i int) {
 			for {
 				select {

client/daemon/pex/peer_exchange_test.go

@@ -365,7 +365,7 @@ func setupMembers(assert *assert.Assertions, memberCount int) []*peerExchange {
 	ports, err := freeport.GetFreePorts(2 * memberCount)
 	assert.Nil(err)
 
-	for i := 0; i < memberCount; i++ {
+	for i := range memberCount {
 		rpcPort, gossipPort := ports[2*i], ports[2*i+1]
 		testMembers = append(testMembers, &testMember{
 			idx:        i,
@@ -378,7 +378,7 @@ func setupMembers(assert *assert.Assertions, memberCount int) []*peerExchange {
 		})
 	}
 
-	for i := 0; i < memberCount; i++ {
+	for i := range memberCount {
 		peerExchangeServers = append(peerExchangeServers, setupMember(assert, testMembers[i], members))
 	}
 	return peerExchangeServers

client/daemon/rpcserver/rpcserver.go

@@ -573,7 +573,7 @@ func (s *server) startDownloadWorkers(
 	lock := sync.Mutex{}
 	sender := &sequentialResultSender{realSender: stream}
 
-	for i := 0; i < s.recursiveConcurrent; i++ {
+	for i := range s.recursiveConcurrent {
 		go func(i int) {
 			logKV := []any{
 				"recursiveDownloader", fmt.Sprintf("%d", i),

client/daemon/storage/local_storage_test.go

@@ -163,9 +163,7 @@ func TestLocalTaskStore_PutAndGetPiece(t *testing.T) {
 			for i := 0; i*pieceSize < len(testBytes); i++ {
 				start := i * pieceSize
 				end := start + pieceSize
-				if end > len(testBytes) {
+				end = min(end, len(testBytes))
-					end = len(testBytes)
-				}
 				pieces = append(pieces, struct {
 					index int
 					start int

client/daemon/storage/storage_manager.go

@@ -29,6 +29,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"slices"
 	"sort"
 	"strings"
 	"sync"
@@ -726,11 +727,9 @@ func (s *storageManager) ReloadPersistentTask(gcCallback GCCallback) {
 	done := make(chan struct{})
 
 	reloadGoroutineCount := s.storeOption.ReloadGoroutineCount
-	if count < reloadGoroutineCount {
+	reloadGoroutineCount = min(reloadGoroutineCount, count)
-		reloadGoroutineCount = count
-	}
 
-	for i := 0; i < reloadGoroutineCount; i++ {
+	for range reloadGoroutineCount {
 		go func() {
 			for {
 				select {
@@ -981,7 +980,7 @@ func (s *storageManager) TryGC() (bool, error) {
 		// remove reclaimed task in markedTasks
 		for i, k := range markedTasks {
 			if k.TaskID == key.TaskID && k.PeerID == key.PeerID {
-				markedTasks = append(markedTasks[:i], markedTasks[i+1:]...)
+				markedTasks = slices.Delete(markedTasks, i, i+1)
 				break
 			}
 		}

pkg/cache/cache_test.go

@@ -533,9 +533,9 @@ func benchmarkCacheGetConcurrent(b *testing.B, exp time.Duration) {
 	each := b.N / workers
 	wg.Add(workers)
 	b.StartTimer()
-	for i := 0; i < workers; i++ {
+	for range workers {
 		go func() {
-			for j := 0; j < each; j++ {
+			for range each {
 				tc.Get(v1)
 			}
 			wg.Done()
@@ -555,9 +555,9 @@ func BenchmarkRWMutexMapGetConcurrent(b *testing.B) {
 	each := b.N / workers
 	wg.Add(workers)
 	b.StartTimer()
-	for i := 0; i < workers; i++ {
+	for range workers {
 		go func() {
-			for j := 0; j < each; j++ {
+			for range each {
 				mu.RLock()
 				_, _ = m[v1]
 				mu.RUnlock()
@@ -584,7 +584,7 @@ func benchmarkCacheGetManyConcurrent(b *testing.B, exp time.Duration) {
 	n := 10000
 	tc := New(exp, 0)
 	keys := make([]string, n)
-	for i := 0; i < n; i++ {
+	for i := range n {
 		k := v1 + strconv.Itoa(i)
 		keys[i] = k
 		tc.Set(k, v2, DefaultExpiration)
@@ -594,7 +594,7 @@ func benchmarkCacheGetManyConcurrent(b *testing.B, exp time.Duration) {
 	wg.Add(n)
 	for _, v := range keys {
 		go func(k string) {
-			for j := 0; j < each; j++ {
+			for range each {
 				tc.Get(k)
 			}
 			wg.Done()

pkg/container/ring/queue_test.go

@@ -74,7 +74,7 @@ func TestSequence(t *testing.T) {
 				}
 			}()
 			var values []int
-			for i := 0; i < len(tc.values); i++ {
+			for range len(tc.values) {
 				val, ok := q.Dequeue()
 				assert.True(ok, "dequeue should be ok")
 				values = append(values, *val)
@@ -139,7 +139,7 @@ func TestRandom(t *testing.T) {
 				}
 			}()
 			var values []int
-			for i := 0; i < len(tc.values); i++ {
+			for range len(tc.values) {
 				val, ok := q.Dequeue()
 				assert.True(ok, "dequeue should be ok")
 				values = append(values, *val)
@@ -158,7 +158,7 @@ func TestRandom(t *testing.T) {
 func benchmarkRandom(b *testing.B, exponent int, input, output int) {
 	queue := NewRandom[int](exponent)
 	done := false
-	for i := 0; i < input; i++ {
+	for i := range input {
 		go func(i int) {
 			for {
 				if done {

pkg/container/set/safe_set_test.go

@@ -70,7 +70,7 @@ func TestSafeSetAdd_Concurrent(t *testing.T) {
 
 	var wg sync.WaitGroup
 	wg.Add(len(nums))
-	for i := 0; i < len(nums); i++ {
+	for i := range len(nums) {
 		go func(i int) {
 			s.Add(i)
 			wg.Done()
@@ -238,7 +238,7 @@ func TestSafeSetLen_Concurrent(t *testing.T) {
 	wg.Add(1)
 	go func() {
 		elems := s.Len()
-		for i := 0; i < N; i++ {
+		for range N {
 			newElems := s.Len()
 			if newElems < elems {
 				t.Errorf("Len shrunk from %v to %v", elems, newElems)
@@ -247,7 +247,7 @@ func TestSafeSetLen_Concurrent(t *testing.T) {
 		wg.Done()
 	}()
 
-	for i := 0; i < N; i++ {
+	for range N {
 		s.Add(rand.Int())
 	}
 	wg.Wait()
@@ -302,7 +302,7 @@ func TestSafeSetValues_Concurrent(t *testing.T) {
 	wg.Add(1)
 	go func() {
 		elems := s.Values()
-		for i := 0; i < N; i++ {
+		for range N {
 			newElems := s.Values()
 			if len(newElems) < len(elems) {
 				t.Errorf("Values shrunk from %v to %v", elems, newElems)
@@ -311,7 +311,7 @@ func TestSafeSetValues_Concurrent(t *testing.T) {
 		wg.Done()
 	}()
 
-	for i := 0; i < N; i++ {
+	for i := range N {
 		s.Add(i)
 	}
 	wg.Wait()
@@ -359,7 +359,7 @@ func TestSafeSetClear_Concurrent(t *testing.T) {
 
 	var wg sync.WaitGroup
 	wg.Add(len(nums))
-	for i := 0; i < len(nums); i++ {
+	for i := range len(nums) {
 		go func(i int) {
 			s.Add(i)
 			s.Clear()

pkg/retry/retry.go

@@ -33,7 +33,7 @@ func Run(ctx context.Context,
 		cancel bool
 		cause  error
 	)
-	for i := 0; i < maxAttempts; i++ {
+	for i := range maxAttempts {
 		if i > 0 {
 			time.Sleep(math.RandBackoffSeconds(initBackoff, maxBackoff, 2.0, i))
 		}

pkg/slices/slices.go

@@ -16,6 +16,8 @@
 
 package slices
 
+import "slices"
+
 // Contains returns true if elements is present in a collection.
 func Contains[T comparable](s []T, els ...T) bool {
 	ss := make(map[T]struct{}, len(s))
@@ -63,7 +65,7 @@ func RemoveDuplicates[T comparable](s []T) []T {
 
 // Remove removes an element from a collection.
 func Remove[T comparable](s []T, i int) []T {
-	return append(s[:i], s[i+1:]...)
+	return slices.Delete(s, i, i+1)
 }
 
 // Reverse reverses elements in a collection.

pkg/source/clients/httpprotocol/http_source_client.go

@@ -21,6 +21,7 @@ import (
 	"io"
 	"net/http"
 	"regexp"
+	"slices"
 	"strconv"
 	"time"
 
@@ -285,10 +286,5 @@ func exportPassThroughHeader(header http.Header) map[string]string {
 }
 
 func detectTemporary(statusCode int) bool {
-	for _, code := range notTemporaryStatusCode {
+	return !slices.Contains(notTemporaryStatusCode, statusCode)
-		if code == statusCode {
-			return false
-		}
-	}
-	return true
 }

pkg/source/source_client.go

@@ -23,6 +23,7 @@ import (
 	"errors"
 	"fmt"
 	"net/url"
+	"slices"
 	"strconv"
 	"strings"
 	"sync"
@@ -78,11 +79,10 @@ func (e UnexpectedStatusCodeError) Got() int {
 // CheckResponseCode returns UnexpectedStatusError if the given response code is not
 // one of the allowed status codes; otherwise nil.
 func CheckResponseCode(respCode int, allowed []int) error {
-	for _, v := range allowed {
+	if slices.Contains(allowed, respCode) {
-		if respCode == v {
 		return nil
 	}
-	}
+
 	return UnexpectedStatusCodeError{allowed, respCode}
 }
 

pkg/strings/strings.go

@@ -17,6 +17,7 @@
 package strings
 
 import (
+	"slices"
 	"strings"
 )
 
@@ -27,13 +28,7 @@ func IsBlank(s string) bool {
 
 // Contains reports whether the string contains the element.
 func Contains(slice []string, ele string) bool {
-	for _, one := range slice {
+	return slices.Contains(slice, ele)
-		if one == ele {
-			return true
-		}
-	}
-
-	return false
 }
 
 // Remove the duplicate elements in the string slice.

scheduler/resource/standard/peer_manager_test.go

@@ -554,7 +554,7 @@ func TestPeerManager_RunGC(t *testing.T) {
 				assert := assert.New(t)
 				peerManager.Store(mockPeer)
 				mockPeer.FSM.SetState(PeerStateSucceeded)
-				for i := 0; i < PeerCountLimitForTask+1; i++ {
+				for range PeerCountLimitForTask + 1 {
 					peer := NewPeer(idgen.PeerIDV1("127.0.0.1"), mockTask, mockHost)
 					mockPeer.Task.StorePeer(peer)
 				}

scheduler/scheduling/evaluator/evaluator_base.go

@@ -192,11 +192,9 @@ func (e *evaluatorBase) calculateMultiElementAffinityScore(dst, src string) floa
 	elementLen = math.Min(len(dstElements), len(srcElements))
 
 	// Maximum element length is 5.
-	if elementLen > maxElementLen {
+	elementLen = min(elementLen, maxElementLen)
-		elementLen = maxElementLen
-	}
 
-	for i := 0; i < elementLen; i++ {
+	for i := range elementLen {
 		if !strings.EqualFold(dstElements[i], srcElements[i]) {
 			break
 		}

scheduler/scheduling/evaluator/evaluator_base_test.go

@@ -993,7 +993,7 @@ func TestEvaluatorBase_IsBadParent(t *testing.T) {
 			totalPieceCount: 1,
 			mock: func(peer *standard.Peer) {
 				peer.FSM.SetState(standard.PeerStateRunning)
-				for i := 0; i < 30; i++ {
+				for i := range 30 {
 					peer.AppendPieceCost(time.Duration(i))
 				}
 				peer.AppendPieceCost(50)
@@ -1009,7 +1009,7 @@ func TestEvaluatorBase_IsBadParent(t *testing.T) {
 			totalPieceCount: 1,
 			mock: func(peer *standard.Peer) {
 				peer.FSM.SetState(standard.PeerStateRunning)
-				for i := 0; i < 30; i++ {
+				for i := range 30 {
 					peer.AppendPieceCost(time.Duration(i))
 				}
 				peer.AppendPieceCost(18)

scheduler/scheduling/scheduling_test.go

@@ -1043,7 +1043,7 @@ func TestScheduling_FindCandidateParents(t *testing.T) {
 			peer := standard.NewPeer(mockPeerID, mockTask, mockHost)
 
 			var mockPeers []*standard.Peer
-			for i := 0; i < 11; i++ {
+			for i := range 11 {
 				mockHost := standard.NewHost(
 					idgen.HostIDV2("127.0.0.1", uuid.New().String(), false), mockRawHost.IP, mockRawHost.Hostname,
 					mockRawHost.Port, mockRawHost.DownloadPort, mockRawHost.Type)
@@ -1361,7 +1361,7 @@ func TestScheduling_FindParentAndCandidateParents(t *testing.T) {
 			peer := standard.NewPeer(mockPeerID, mockTask, mockHost)
 
 			var mockPeers []*standard.Peer
-			for i := 0; i < 11; i++ {
+			for i := range 11 {
 				mockHost := standard.NewHost(
 					idgen.HostIDV2("127.0.0.1", uuid.New().String(), false), mockRawHost.IP, mockRawHost.Hostname,
 					mockRawHost.Port, mockRawHost.DownloadPort, mockRawHost.Type)
@@ -1623,7 +1623,7 @@ func TestScheduling_FindSuccessParent(t *testing.T) {
 			peer := standard.NewPeer(mockPeerID, mockTask, mockHost)
 
 			var mockPeers []*standard.Peer
-			for i := 0; i < 11; i++ {
+			for i := range 11 {
 				mockHost := standard.NewHost(
 					idgen.HostIDV2("127.0.0.1", uuid.New().String(), false), mockRawHost.IP, mockRawHost.Hostname,
 					mockRawHost.Port, mockRawHost.DownloadPort, mockRawHost.Type)

test/e2e/v1/dfget_test.go

@@ -35,7 +35,7 @@ var _ = Describe("Download with dfget and proxy", func() {
 		singleDfgetTest("dfget daemon download should be ok",
 			dragonflyNamespace, "component=dfdaemon",
 			"dragonfly-dfdaemon-", "dfdaemon")
-		for i := 0; i < 3; i++ {
+		for i := range 3 {
 			singleDfgetTest(
 				fmt.Sprintf("dfget daemon proxy-%d should be ok", i),
 				dragonflyE2ENamespace,

test/e2e/v1/e2e_test.go

@@ -40,7 +40,7 @@ func init() {
 
 var _ = AfterSuite(func() {
 	for _, server := range servers {
-		for i := 0; i < server.replicas; i++ {
+		for i := range server.replicas {
 			out, err := util.KubeCtlCommand("-n", server.namespace, "get", "pod", "-l", fmt.Sprintf("component=%s", server.name),
 				"-o", fmt.Sprintf("jsonpath='{.items[%d].metadata.name}'", i)).CombinedOutput()
 			if err != nil {

test/e2e/v1/manager/preheat.go

@@ -47,7 +47,7 @@ var _ = Describe("Preheat with manager", func() {
 	Context("preheat", func() {
 		It("preheat files should be ok", Label("preheat", "file"), func() {
 			seedPeerPods := make([]*util.PodExec, 3)
-			for i := 0; i < 3; i++ {
+			for i := range 3 {
 				seedPeerPods[i] = getSeedPeerExec(i)
 			}
 			fsPod := getFileServerExec()
@@ -110,7 +110,7 @@ var _ = Describe("Preheat with manager", func() {
 			}
 
 			seedPeerPods := make([]*util.PodExec, 3)
-			for i := 0; i < 3; i++ {
+			for i := range 3 {
 				seedPeerPods[i] = getSeedPeerExec(i)
 			}
 			fsPod := getFileServerExec()
@@ -177,7 +177,7 @@ var _ = Describe("Preheat with manager", func() {
 			}
 
 			seedPeerPods := make([]*util.PodExec, 3)
-			for i := 0; i < 3; i++ {
+			for i := range 3 {
 				seedPeerPods[i] = getSeedPeerExec(i)
 			}
 			fsPod := getFileServerExec()
@@ -245,7 +245,7 @@ var _ = Describe("Preheat with manager", func() {
 			}
 
 			seedPeerPods := make([]*util.PodExec, 3)
-			for i := 0; i < 3; i++ {
+			for i := range 3 {
 				seedPeerPods[i] = getSeedPeerExec(i)
 			}
 			fsPod := getFileServerExec()

test/e2e/v2/concurrency_test.go

@@ -57,7 +57,7 @@ var _ = Describe("Download Concurrency", func() {
 			Expect(testFile.GetSha256()).To(Equal(sha256sum))
 
 			seedClientPods := make([]*util.PodExec, 3)
-			for i := 0; i < 3; i++ {
+			for i := range 3 {
 				seedClientPods[i], err = util.SeedClientExec(i)
 				fmt.Println(err)
 				Expect(err).NotTo(HaveOccurred())
@@ -82,7 +82,7 @@ var _ = Describe("Download Concurrency", func() {
 			Expect(testFile.GetSha256()).To(Equal(sha256sum))
 
 			seedClientPods := make([]*util.PodExec, 3)
-			for i := 0; i < 3; i++ {
+			for i := range 3 {
 				seedClientPods[i], err = util.SeedClientExec(i)
 				fmt.Println(err)
 				Expect(err).NotTo(HaveOccurred())

test/e2e/v2/containerd_test.go

@@ -71,7 +71,7 @@ var _ = Describe("Containerd with CRI support", func() {
 
 			time.Sleep(1 * time.Second)
 			seedClientPods := make([]*util.PodExec, 3)
-			for i := 0; i < 3; i++ {
+			for i := range 3 {
 				seedClientPods[i], err = util.SeedClientExec(i)
 				fmt.Println(err)
 				Expect(err).NotTo(HaveOccurred())

test/e2e/v2/util/file.go

@@ -140,9 +140,7 @@ func parseRangeHeader(rangeHeader string, fileSize int64) (start, end int64) {
 		end = fileSize - 1
 		bytes, _ := strconv.ParseInt(parts[1], 10, 64)
 		start = fileSize - bytes
-		if start < 0 {
+		start = max(start, 0)
-			start = 0
-		}
 
 	case parts[1] == "": // N-: from N to end
 		start, _ = strconv.ParseInt(parts[0], 10, 64)

test/tools/no-content-length/main.go

@@ -59,7 +59,7 @@ func (f *fileHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		if err != nil {
 			log.Printf("wrong X-Dragonfly-E2E-Status-Code format %s, error: %s", str, err)
 			w.WriteHeader(http.StatusBadRequest)
-			_, _ = w.Write([]byte(fmt.Sprintf("wrong X-Dragonfly-E2E-Status-Code format")))
+			_, _ = w.Write(fmt.Appendf([]byte{}, "wrong X-Dragonfly-E2E-Status-Code format"))
 			return
 		}
 		w.WriteHeader(code)
@@ -70,12 +70,12 @@ func (f *fileHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		rgs, err := parseRange(s, math.MaxInt)
 		if err != nil {
 			w.WriteHeader(http.StatusBadRequest)
-			_, _ = w.Write([]byte(fmt.Sprintf("wrong range format")))
+			_, _ = w.Write(fmt.Appendf([]byte{}, "wrong range format"))
 			return
 		}
 		if len(rgs) > 1 || len(rgs) == 0 {
 			w.WriteHeader(http.StatusBadRequest)
-			_, _ = w.Write([]byte(fmt.Sprintf("unsupport range format")))
+			_, _ = w.Write(fmt.Appendf([]byte{}, "unsupport range format"))
 			return
 		}
 		rg = &rgs[0]
@@ -89,7 +89,7 @@ func (f *fileHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	filePath := path.Join(f.dir, upath)
 	if !strings.HasPrefix(filePath, f.dir) {
 		w.WriteHeader(http.StatusBadRequest)
-		_, _ = w.Write([]byte(fmt.Sprintf("target is not in correct dir")))
+		_, _ = w.Write(fmt.Appendf([]byte{}, "target is not in correct dir"))
 		return
 	}
 	fileInfo, err := os.Stat(filePath)
@@ -99,19 +99,19 @@ func (f *fileHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		} else {
 			w.WriteHeader(http.StatusInternalServerError)
 		}
-		_, _ = w.Write([]byte(fmt.Sprintf("%s", err)))
+		_, _ = w.Write(fmt.Appendf([]byte{}, "%s", err))
 		return
 	}
 	if fileInfo.IsDir() {
 		// todo list files
 		w.WriteHeader(http.StatusBadRequest)
-		_, _ = w.Write([]byte(fmt.Sprintf("target is dir not file")))
+		_, _ = w.Write(fmt.Appendf([]byte{}, "target is dir not file"))
 		return
 	}
 	file, err := os.Open(filePath)
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
-		_, _ = w.Write([]byte(fmt.Sprintf("%s", err)))
+		_, _ = w.Write(fmt.Appendf([]byte{}, "%s", err))
 		return
 	}
 	defer file.Close()

test/tools/stress/main.go

@@ -102,7 +102,7 @@ func main() {
 	wgCollect.Add(1)
 	go collect(wgCollect, resultCh)
 
-	for i := 0; i < con; i++ {
+	for range con {
 		wgProcess.Add(1)
 		go process(ctx, wgProcess, resultCh)
 	}