⚡️ perf(ctx.Range): reduce allocations (#2705)

* perf(ctx.Range): reduce allocations

strings.Split was causing extra allocations where using
strings.IndexByte can suffice. ALso switch from strconv.Atoi because it
causes an allocation when parsing a non-integer, which is common for
Ranges.

* chore: fix lint

ctx.go

@@ -115,10 +115,13 @@ func (t *TLSHandler) GetClientInfo(info *tls.ClientHelloInfo) (*tls.Certificate,
 // Range data for c.Range
 type Range struct {
 	Type   string
-	Ranges []struct {
-		Start int
-		End   int
-	}
+	Ranges []RangeSet
+}
+
+// RangeSet represents a single content range from a request.
+type RangeSet struct {
+	Start int
+	End   int
 }
 
 // Cookie data for c.Cookie
@@ -1392,25 +1395,44 @@ var (
 
 // Range returns a struct containing the type and a slice of ranges.
 func (c *Ctx) Range(size int) (Range, error) {
-	var rangeData Range
+	var (
+		rangeData Range
+		ranges    string
+	)
 	rangeStr := c.Get(HeaderRange)
-	if rangeStr == "" || !strings.Contains(rangeStr, "=") {
-		return rangeData, ErrRangeMalformed
-	}
-	data := strings.Split(rangeStr, "=")
-	const expectedDataParts = 2
-	if len(data) != expectedDataParts {
+
+	i := strings.IndexByte(rangeStr, '=')
+	if i == -1 || strings.Contains(rangeStr[i+1:], "=") {
 		return rangeData, ErrRangeMalformed
 	}
-	rangeData.Type = data[0]
-	arr := strings.Split(data[1], ",")
-	for i := 0; i < len(arr); i++ {
-		item := strings.Split(arr[i], "-")
-		if len(item) == 1 {
+	rangeData.Type = rangeStr[:i]
+	ranges = rangeStr[i+1:]
+
+	var (
+		singleRange string
+		moreRanges  = ranges
+	)
+	for moreRanges != "" {
+		singleRange = moreRanges
+		if i := strings.IndexByte(moreRanges, ','); i >= 0 {
+			singleRange = moreRanges[:i]
+			moreRanges = moreRanges[i+1:]
+		} else {
+			moreRanges = ""
+		}
+
+		var (
+			startStr, endStr string
+			i                int
+		)
+		if i = strings.IndexByte(singleRange, '-'); i == -1 {
 			return rangeData, ErrRangeMalformed
 		}
-		start, startErr := strconv.Atoi(item[0])
-		end, endErr := strconv.Atoi(item[1])
+		startStr = singleRange[:i]
+		endStr = singleRange[i+1:]
+
+		start, startErr := fasthttp.ParseUint(utils.UnsafeBytes(startStr))
+		end, endErr := fasthttp.ParseUint(utils.UnsafeBytes(endStr))
 		if startErr != nil { // -nnn
 			start = size - end
 			end = size - 1

ctx_test.go

@@ -2521,39 +2521,67 @@ func Test_Ctx_Range(t *testing.T) {
 	c := app.AcquireCtx(&fasthttp.RequestCtx{})
 	defer app.ReleaseCtx(c)
 
-	var (
-		result Range
-		err    error
-	)
-
-	_, err = c.Range(1000)
-	utils.AssertEqual(t, true, err != nil)
-
-	c.Request().Header.Set(HeaderRange, "bytes=500")
-	_, err = c.Range(1000)
-	utils.AssertEqual(t, true, err != nil)
+	testRange := func(header string, ranges ...RangeSet) {
+		c.Request().Header.Set(HeaderRange, header)
+		result, err := c.Range(1000)
+		if len(ranges) == 0 {
+			utils.AssertEqual(t, true, err != nil)
+		} else {
+			utils.AssertEqual(t, "bytes", result.Type)
+			utils.AssertEqual(t, true, err == nil)
+		}
+		utils.AssertEqual(t, len(ranges), len(result.Ranges))
+		for i := range ranges {
+			utils.AssertEqual(t, ranges[i], result.Ranges[i])
+		}
+	}
 
-	c.Request().Header.Set(HeaderRange, "bytes=500=")
-	_, err = c.Range(1000)
-	utils.AssertEqual(t, true, err != nil)
+	testRange("bytes=500")
+	testRange("bytes=")
+	testRange("bytes=500=")
+	testRange("bytes=500-300")
+	testRange("bytes=a-700", RangeSet{300, 999})
+	testRange("bytes=500-b", RangeSet{500, 999})
+	testRange("bytes=500-1000", RangeSet{500, 999})
+	testRange("bytes=500-700", RangeSet{500, 700})
+	testRange("bytes=0-0,2-1000", RangeSet{0, 0}, RangeSet{2, 999})
+	testRange("bytes=0-99,450-549,-100", RangeSet{0, 99}, RangeSet{450, 549}, RangeSet{900, 999})
+	testRange("bytes=500-700,601-999", RangeSet{500, 700}, RangeSet{601, 999})
+}
 
-	c.Request().Header.Set(HeaderRange, "bytes=500-300")
-	_, err = c.Range(1000)
-	utils.AssertEqual(t, true, err != nil)
+// go test -v -run=^$ -bench=Benchmark_Ctx_Range -benchmem -count=4
+func Benchmark_Ctx_Range(b *testing.B) {
+	app := New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{})
+	defer app.ReleaseCtx(c)
 
-	testRange := func(header string, start, end int) {
-		c.Request().Header.Set(HeaderRange, header)
-		result, err = c.Range(1000)
-		utils.AssertEqual(t, nil, err)
-		utils.AssertEqual(t, "bytes", result.Type)
-		utils.AssertEqual(t, start, result.Ranges[0].Start)
-		utils.AssertEqual(t, end, result.Ranges[0].End)
+	testCases := []struct {
+		str   string
+		start int
+		end   int
+	}{
+		{"bytes=-700", 300, 999},
+		{"bytes=500-", 500, 999},
+		{"bytes=500-1000", 500, 999},
+		{"bytes=0-700,800-1000", 0, 700},
+	}
+
+	for _, tc := range testCases {
+		b.Run(tc.str, func(b *testing.B) {
+			c.Request().Header.Set(HeaderRange, tc.str)
+			var (
+				result Range
+				err    error
+			)
+			for n := 0; n < b.N; n++ {
+				result, err = c.Range(1000)
+			}
+			utils.AssertEqual(b, nil, err)
+			utils.AssertEqual(b, "bytes", result.Type)
+			utils.AssertEqual(b, tc.start, result.Ranges[0].Start)
+			utils.AssertEqual(b, tc.end, result.Ranges[0].End)
+		})
 	}
-
-	testRange("bytes=a-700", 300, 999)
-	testRange("bytes=500-b", 500, 999)
-	testRange("bytes=500-1000", 500, 999)
-	testRange("bytes=500-700", 500, 700)
 }
 
 // go test -run Test_Ctx_Route