net/http: optimize internal cookie functions

- precalculate *Cookie slice in read cookie functions
- readSetCookies: pre-allocs depending on the count of Set-Cookies
- rename success variable to ok; avoid else
- refactor Cookie.String to use less allocations
- remove fmt package and replace with writes to a bytes.Buffer
- add BenchmarkReadSetCookies and BenchmarkReadCookies

name              old time/op    new time/op    delta
CookieString-8      1.42µs ± 2%    0.78µs ± 1%  -45.36%        (p=0.000 n=10+10)
ReadSetCookies-8    3.46µs ± 1%    3.42µs ± 2%   -1.39%        (p=0.001 n=10+10)
ReadCookies-8       5.12µs ± 1%    5.15µs ± 2%     ~           (p=0.393 n=10+10)

name              old alloc/op   new alloc/op   delta
CookieString-8        520B ± 0%      384B ± 0%  -26.15%        (p=0.000 n=10+10)
ReadSetCookies-8      968B ± 0%      960B ± 0%   -0.83%        (p=0.000 n=10+10)
ReadCookies-8       2.01kB ± 0%    2.01kB ± 0%     ~     (all samples are equal)

name              old allocs/op  new allocs/op  delta
CookieString-8        10.0 ± 0%       3.0 ± 0%  -70.00%        (p=0.000 n=10+10)
ReadSetCookies-8      18.0 ± 0%      17.0 ± 0%   -5.56%        (p=0.000 n=10+10)
ReadCookies-8         16.0 ± 0%      16.0 ± 0%     ~     (all samples are equal)

Change-Id: I870670987f10f3e52f9c657cfb8e6eaaa97a6162
Reviewed-on: https://go-review.googlesource.com/27850
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

src/net/http/cookie.go

@@ -6,7 +6,6 @@ package http
 
 import (
 	"bytes"
-	"fmt"
 	"log"
 	"net"
 	"strconv"
@@ -40,7 +39,11 @@ type Cookie struct {
 // readSetCookies parses all "Set-Cookie" values from
 // the header h and returns the successfully parsed Cookies.
 func readSetCookies(h Header) []*Cookie {
-	cookies := []*Cookie{}
+	cookieCount := len(h["Set-Cookie"])
+	if cookieCount == 0 {
+		return []*Cookie{}
+	}
+	cookies := make([]*Cookie, 0, cookieCount)
 	for _, line := range h["Set-Cookie"] {
 		parts := strings.Split(strings.TrimSpace(line), ";")
 		if len(parts) == 1 && parts[0] == "" {
@@ -55,8 +58,8 @@ func readSetCookies(h Header) []*Cookie {
 		if !isCookieNameValid(name) {
 			continue
 		}
-		value, success := parseCookieValue(value, true)
-		if !success {
+		value, ok := parseCookieValue(value, true)
+		if !ok {
 			continue
 		}
 		c := &Cookie{
@@ -75,8 +78,8 @@ func readSetCookies(h Header) []*Cookie {
 				attr, val = attr[:j], attr[j+1:]
 			}
 			lowerAttr := strings.ToLower(attr)
-			val, success = parseCookieValue(val, false)
-			if !success {
+			val, ok = parseCookieValue(val, false)
+			if !ok {
 				c.Unparsed = append(c.Unparsed, parts[i])
 				continue
 			}
@@ -96,10 +99,9 @@ func readSetCookies(h Header) []*Cookie {
 					break
 				}
 				if secs <= 0 {
-					c.MaxAge = -1
-				} else {
-					c.MaxAge = secs
+					secs = -1
 				}
+				c.MaxAge = secs
 				continue
 			case "expires":
 				c.RawExpires = val
@@ -142,9 +144,13 @@ func (c *Cookie) String() string {
 		return ""
 	}
 	var b bytes.Buffer
-	fmt.Fprintf(&b, "%s=%s", sanitizeCookieName(c.Name), sanitizeCookieValue(c.Value))
+	b.WriteString(sanitizeCookieName(c.Name))
+	b.WriteRune('=')
+	b.WriteString(sanitizeCookieValue(c.Value))
+
 	if len(c.Path) > 0 {
-		fmt.Fprintf(&b, "; Path=%s", sanitizeCookiePath(c.Path))
+		b.WriteString("; Path=")
+		b.WriteString(sanitizeCookiePath(c.Path))
 	}
 	if len(c.Domain) > 0 {
 		if validCookieDomain(c.Domain) {
@@ -156,25 +162,31 @@ func (c *Cookie) String() string {
 			if d[0] == '.' {
 				d = d[1:]
 			}
-			fmt.Fprintf(&b, "; Domain=%s", d)
+			b.WriteString("; Domain=")
+			b.WriteString(d)
 		} else {
-			log.Printf("net/http: invalid Cookie.Domain %q; dropping domain attribute",
-				c.Domain)
+			log.Printf("net/http: invalid Cookie.Domain %q; dropping domain attribute", c.Domain)
 		}
 	}
 	if c.Expires.Unix() > 0 {
-		fmt.Fprintf(&b, "; Expires=%s", c.Expires.UTC().Format(TimeFormat))
+		b.WriteString("; Expires=")
+		b2 := b.Bytes()
+		b.Reset()
+		b.Write(c.Expires.UTC().AppendFormat(b2, TimeFormat))
 	}
 	if c.MaxAge > 0 {
-		fmt.Fprintf(&b, "; Max-Age=%d", c.MaxAge)
+		b.WriteString("; Max-Age=")
+		b2 := b.Bytes()
+		b.Reset()
+		b.Write(strconv.AppendInt(b2, int64(c.MaxAge), 10))
 	} else if c.MaxAge < 0 {
-		fmt.Fprintf(&b, "; Max-Age=0")
+		b.WriteString("; Max-Age=0")
 	}
 	if c.HttpOnly {
-		fmt.Fprintf(&b, "; HttpOnly")
+		b.WriteString("; HttpOnly")
 	}
 	if c.Secure {
-		fmt.Fprintf(&b, "; Secure")
+		b.WriteString("; Secure")
 	}
 	return b.String()
 }
@@ -184,12 +196,12 @@ func (c *Cookie) String() string {
 //
 // if filter isn't empty, only cookies of that name are returned
 func readCookies(h Header, filter string) []*Cookie {
-	cookies := []*Cookie{}
 	lines, ok := h["Cookie"]
 	if !ok {
-		return cookies
+		return []*Cookie{}
 	}
 
+	cookies := []*Cookie{}
 	for _, line := range lines {
 		parts := strings.Split(strings.TrimSpace(line), ";")
 		if len(parts) == 1 && parts[0] == "" {
@@ -212,8 +224,8 @@ func readCookies(h Header, filter string) []*Cookie {
 			if filter != "" && filter != name {
 				continue
 			}
-			val, success := parseCookieValue(val, true)
-			if !success {
+			val, ok := parseCookieValue(val, true)
+			if !ok {
 				continue
 			}
 			cookies = append(cookies, &Cookie{Name: name, Value: val})

src/net/http/cookie_test.go

@@ -426,3 +426,92 @@ func TestCookieSanitizePath(t *testing.T) {
 		t.Errorf("Expected substring %q in log output. Got:\n%s", sub, got)
 	}
 }
+
+func BenchmarkCookieString(b *testing.B) {
+	const wantCookieString = `cookie-9=i3e01nf61b6t23bvfmplnanol3; Path=/restricted/; Domain=example.com; Expires=Tue, 10 Nov 2009 23:00:00 GMT; Max-Age=3600`
+	c := &Cookie{
+		Name:    "cookie-9",
+		Value:   "i3e01nf61b6t23bvfmplnanol3",
+		Expires: time.Unix(1257894000, 0),
+		Path:    "/restricted/",
+		Domain:  ".example.com",
+		MaxAge:  3600,
+	}
+	var benchmarkCookieString string
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		benchmarkCookieString = c.String()
+	}
+	if have, want := benchmarkCookieString, wantCookieString; have != want {
+		b.Fatalf("Have: %v Want: %v", have, want)
+	}
+}
+
+func BenchmarkReadSetCookies(b *testing.B) {
+	header := Header{
+		"Set-Cookie": {
+			"NID=99=YsDT5i3E-CXax-; expires=Wed, 23-Nov-2011 01:05:03 GMT; path=/; domain=.google.ch; HttpOnly",
+			".ASPXAUTH=7E3AA; expires=Wed, 07-Mar-2012 14:25:06 GMT; path=/; HttpOnly",
+		},
+	}
+	wantCookies := []*Cookie{
+		{
+			Name:       "NID",
+			Value:      "99=YsDT5i3E-CXax-",
+			Path:       "/",
+			Domain:     ".google.ch",
+			HttpOnly:   true,
+			Expires:    time.Date(2011, 11, 23, 1, 5, 3, 0, time.UTC),
+			RawExpires: "Wed, 23-Nov-2011 01:05:03 GMT",
+			Raw:        "NID=99=YsDT5i3E-CXax-; expires=Wed, 23-Nov-2011 01:05:03 GMT; path=/; domain=.google.ch; HttpOnly",
+		},
+		{
+			Name:       ".ASPXAUTH",
+			Value:      "7E3AA",
+			Path:       "/",
+			Expires:    time.Date(2012, 3, 7, 14, 25, 6, 0, time.UTC),
+			RawExpires: "Wed, 07-Mar-2012 14:25:06 GMT",
+			HttpOnly:   true,
+			Raw:        ".ASPXAUTH=7E3AA; expires=Wed, 07-Mar-2012 14:25:06 GMT; path=/; HttpOnly",
+		},
+	}
+	var c []*Cookie
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c = readSetCookies(header)
+	}
+	if !reflect.DeepEqual(c, wantCookies) {
+		b.Fatalf("readSetCookies:\nhave: %s\nwant: %s\n", toJSON(c), toJSON(wantCookies))
+	}
+}
+
+func BenchmarkReadCookies(b *testing.B) {
+	header := Header{
+		"Cookie": {
+			`de=; client_region=0; rpld1=0:hispeed.ch|20:che|21:zh|22:zurich|23:47.36|24:8.53|; rpld0=1:08|; backplane-channel=newspaper.com:1471; devicetype=0; osfam=0; rplmct=2; s_pers=%20s_vmonthnum%3D1472680800496%2526vn%253D1%7C1472680800496%3B%20s_nr%3D1471686767664-New%7C1474278767664%3B%20s_lv%3D1471686767669%7C1566294767669%3B%20s_lv_s%3DFirst%2520Visit%7C1471688567669%3B%20s_monthinvisit%3Dtrue%7C1471688567677%3B%20gvp_p5%3Dsports%253Ablog%253Aearly-lead%2520-%2520184693%2520-%252020160820%2520-%2520u-s%7C1471688567681%3B%20gvp_p51%3Dwp%2520-%2520sports%7C1471688567684%3B; s_sess=%20s_wp_ep%3Dhomepage%3B%20s._ref%3Dhttps%253A%252F%252Fwww.google.ch%252F%3B%20s_cc%3Dtrue%3B%20s_ppvl%3Dsports%25253Ablog%25253Aearly-lead%252520-%252520184693%252520-%25252020160820%252520-%252520u-lawyer%252C12%252C12%252C502%252C1231%252C502%252C1680%252C1050%252C2%252CP%3B%20s_ppv%3Dsports%25253Ablog%25253Aearly-lead%252520-%252520184693%252520-%25252020160820%252520-%252520u-s-lawyer%252C12%252C12%252C502%252C1231%252C502%252C1680%252C1050%252C2%252CP%3B%20s_dslv%3DFirst%2520Visit%3B%20s_sq%3Dwpninewspapercom%253D%252526pid%25253Dsports%2525253Ablog%2525253Aearly-lead%25252520-%25252520184693%25252520-%2525252020160820%25252520-%25252520u-s%252526pidt%25253D1%252526oid%25253Dhttps%2525253A%2525252F%2525252Fwww.newspaper.com%2525252F%2525253Fnid%2525253Dmenu_nav_homepage%252526ot%25253DA%3B`,
+		},
+	}
+	wantCookies := []*Cookie{
+		{Name: "de", Value: ""},
+		{Name: "client_region", Value: "0"},
+		{Name: "rpld1", Value: "0:hispeed.ch|20:che|21:zh|22:zurich|23:47.36|24:8.53|"},
+		{Name: "rpld0", Value: "1:08|"},
+		{Name: "backplane-channel", Value: "newspaper.com:1471"},
+		{Name: "devicetype", Value: "0"},
+		{Name: "osfam", Value: "0"},
+		{Name: "rplmct", Value: "2"},
+		{Name: "s_pers", Value: "%20s_vmonthnum%3D1472680800496%2526vn%253D1%7C1472680800496%3B%20s_nr%3D1471686767664-New%7C1474278767664%3B%20s_lv%3D1471686767669%7C1566294767669%3B%20s_lv_s%3DFirst%2520Visit%7C1471688567669%3B%20s_monthinvisit%3Dtrue%7C1471688567677%3B%20gvp_p5%3Dsports%253Ablog%253Aearly-lead%2520-%2520184693%2520-%252020160820%2520-%2520u-s%7C1471688567681%3B%20gvp_p51%3Dwp%2520-%2520sports%7C1471688567684%3B"},
+		{Name: "s_sess", Value: "%20s_wp_ep%3Dhomepage%3B%20s._ref%3Dhttps%253A%252F%252Fwww.google.ch%252F%3B%20s_cc%3Dtrue%3B%20s_ppvl%3Dsports%25253Ablog%25253Aearly-lead%252520-%252520184693%252520-%25252020160820%252520-%252520u-lawyer%252C12%252C12%252C502%252C1231%252C502%252C1680%252C1050%252C2%252CP%3B%20s_ppv%3Dsports%25253Ablog%25253Aearly-lead%252520-%252520184693%252520-%25252020160820%252520-%252520u-s-lawyer%252C12%252C12%252C502%252C1231%252C502%252C1680%252C1050%252C2%252CP%3B%20s_dslv%3DFirst%2520Visit%3B%20s_sq%3Dwpninewspapercom%253D%252526pid%25253Dsports%2525253Ablog%2525253Aearly-lead%25252520-%25252520184693%25252520-%2525252020160820%25252520-%25252520u-s%252526pidt%25253D1%252526oid%25253Dhttps%2525253A%2525252F%2525252Fwww.newspaper.com%2525252F%2525253Fnid%2525253Dmenu_nav_homepage%252526ot%25253DA%3B"},
+	}
+	var c []*Cookie
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c = readCookies(header, "")
+	}
+	if !reflect.DeepEqual(c, wantCookies) {
+		b.Fatalf("readCookies:\nhave: %s\nwant: %s\n", toJSON(c), toJSON(wantCookies))
+	}
+}