[go] all: use strings.Builder instead of bytes.Buffer where appropriate
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Brad Fitzpatrick (Gerrit)
Mar 26, 2018, 3:00:24 AM3/26/18
to Ian Lance Taylor, Andrew Bonventre, goph...@pubsubhelper.golang.org, Brad Fitzpatrick, golang-co...@googlegroups.com
Brad Fitzpatrick would like Ian Lance Taylor and Andrew Bonventre to review this change.
all: use strings.Builder instead of bytes.Buffer where appropriate
I grepped for "bytes.Buffer" and "buf.String" and mostly ignored test
files. I skipped a few on purpose and probably missed a few others,
but otherwise I think this should be most of them.
Updates #18990
Change-Id: I5a6ae4296b87b416d8da02d7bfaf981d8cc14774
---
M src/archive/tar/writer.go
M src/cmd/cover/html.go
M src/expvar/expvar.go
M src/go/types/methodset.go
M src/mime/encodedword.go
M src/mime/mediatype.go
M src/net/http/cookie.go
M src/net/http/httptest/server.go
M src/net/mail/message.go
M src/net/url/url.go
M src/regexp/onepass.go
M src/regexp/syntax/parse_test.go
M src/regexp/syntax/prog.go
M src/regexp/syntax/regexp.go
M src/testing/example.go
M src/testing/testing.go
16 files changed, 56 insertions(+), 86 deletions(-)
diff --git a/src/archive/tar/writer.go b/src/archive/tar/writer.go
index d6f6931..e80498d 100644
--- a/src/archive/tar/writer.go
+++ b/src/archive/tar/writer.go
@@ -5,7 +5,6 @@
package tar
import (
- "bytes"
"fmt"
"io"
"path"
@@ -176,7 +175,7 @@
sort.Strings(keys)
// Write each record to a buffer.
- var buf bytes.Buffer
+ var buf strings.Builder
for _, k := range keys {
rec, err := formatPAXRecord(k, paxHdrs[k])
if err != nil {
diff --git a/src/cmd/cover/html.go b/src/cmd/cover/html.go
index 04dc76f..2179728 100644
--- a/src/cmd/cover/html.go
+++ b/src/cmd/cover/html.go
@@ -15,6 +15,7 @@
"math"
"os"
"path/filepath"
+ "strings"
)
// htmlOutput reads the profile data from profile and generates an HTML
@@ -41,7 +42,7 @@
if err != nil {
return fmt.Errorf("can't read %q: %v", fn, err)
}
- var buf bytes.Buffer
+ var buf strings.Builder
err = htmlGen(&buf, src, profile.Boundaries(src))
if err != nil {
return err
diff --git a/src/expvar/expvar.go b/src/expvar/expvar.go
index 8290e0b..174873a 100644
--- a/src/expvar/expvar.go
+++ b/src/expvar/expvar.go
@@ -22,7 +22,6 @@
package expvar
import (
- "bytes"
"encoding/json"
"fmt"
"log"
@@ -32,6 +31,7 @@
"runtime"
"sort"
"strconv"
+ "strings"
"sync"
"sync/atomic"
)
@@ -111,7 +111,7 @@
}
func (v *Map) String() string {
- var b bytes.Buffer
+ var b strings.Builder
fmt.Fprintf(&b, "{")
first := true
v.Do(func(kv KeyValue) {
diff --git a/src/go/types/methodset.go b/src/go/types/methodset.go
index 2a8b1c2..52048d4 100644
--- a/src/go/types/methodset.go
+++ b/src/go/types/methodset.go
@@ -7,9 +7,9 @@
package types
import (
- "bytes"
"fmt"
"sort"
+ "strings"
)
// A MethodSet is an ordered set of concrete or abstract (interface) methods;
@@ -24,7 +24,7 @@
return "MethodSet {}"
}
- var buf bytes.Buffer
+ var buf strings.Builder
fmt.Fprintln(&buf, "MethodSet {")
for _, f := range s.list {
fmt.Fprintf(&buf, "\t%s\n", f)
diff --git a/src/mime/encodedword.go b/src/mime/encodedword.go
index 99eb432..d73c8f4 100644
--- a/src/mime/encodedword.go
+++ b/src/mime/encodedword.go
@@ -11,7 +11,6 @@
"fmt"
"io"
"strings"
- "sync"
"unicode"
"unicode/utf8"
)
@@ -51,16 +50,15 @@
// encodeWord encodes a string into an encoded-word.
func (e WordEncoder) encodeWord(charset, s string) string {
- buf := getBuffer()
- defer putBuffer(buf)
+ var buf strings.Builder
- e.openWord(buf, charset)
+ e.openWord(&buf, charset)
if e == BEncoding {
- e.bEncode(buf, charset, s)
+ e.bEncode(&buf, charset, s)
} else {
- e.qEncode(buf, charset, s)
+ e.qEncode(&buf, charset, s)
}
- closeWord(buf)
+ closeWord(&buf)
return buf.String()
}
@@ -77,7 +75,7 @@
var maxBase64Len = base64.StdEncoding.DecodedLen(maxContentLen)
// bEncode encodes s using base64 encoding and writes it to buf.
-func (e WordEncoder) bEncode(buf *bytes.Buffer, charset, s string) {
+func (e WordEncoder) bEncode(buf *strings.Builder, charset, s string) {
w := base64.NewEncoder(base64.StdEncoding, buf)
// If the charset is not UTF-8 or if the content is short, do not bother
// splitting the encoded-word.
@@ -109,7 +107,7 @@
// qEncode encodes s using Q encoding and writes it to buf. It splits the
// encoded-words when necessary.
-func (e WordEncoder) qEncode(buf *bytes.Buffer, charset, s string) {
+func (e WordEncoder) qEncode(buf *strings.Builder, charset, s string) {
// We only split encoded-words when the charset is UTF-8.
if !isUTF8(charset) {
writeQString(buf, s)
@@ -139,7 +137,7 @@
}
// writeQString encodes s using Q encoding and writes it to buf.
-func writeQString(buf *bytes.Buffer, s string) {
+func writeQString(buf *strings.Builder, s string) {
for i := 0; i < len(s); i++ {
switch b := s[i]; {
case b == ' ':
@@ -155,7 +153,7 @@
}
// openWord writes the beginning of an encoded-word into buf.
-func (e WordEncoder) openWord(buf *bytes.Buffer, charset string) {
+func (e WordEncoder) openWord(buf *strings.Builder, charset string) {
buf.WriteString("=?")
buf.WriteString(charset)
buf.WriteByte('?')
@@ -164,12 +162,12 @@
}
// closeWord writes the end of an encoded-word into buf.
-func closeWord(buf *bytes.Buffer) {
+func closeWord(buf *strings.Builder) {
buf.WriteString("?=")
}
// splitWord closes the current encoded-word and opens a new one.
-func (e WordEncoder) splitWord(buf *bytes.Buffer, charset string) {
+func (e WordEncoder) splitWord(buf *strings.Builder, charset string) {
closeWord(buf)
buf.WriteByte(' ')
e.openWord(buf, charset)
@@ -224,10 +222,9 @@
return "", err
}
- buf := getBuffer()
- defer putBuffer(buf)
+ var buf strings.Builder
- if err := d.convert(buf, charset, content); err != nil {
+ if err := d.convert(&buf, charset, content); err != nil {
return "", err
}
@@ -243,8 +240,7 @@
return header, nil
}
- buf := getBuffer()
- defer putBuffer(buf)
+ var buf strings.Builder
buf.WriteString(header[:i])
header = header[i:]
@@ -296,7 +292,7 @@
buf.WriteString(header[:start])
}
- if err := d.convert(buf, charset, content); err != nil {
+ if err := d.convert(&buf, charset, content); err != nil {
return "", err
}
@@ -322,7 +318,7 @@
}
}
-func (d *WordDecoder) convert(buf *bytes.Buffer, charset string, content []byte) error {
+func (d *WordDecoder) convert(buf *strings.Builder, charset string, content []byte) error {
switch {
case strings.EqualFold("utf-8", charset):
buf.Write(content)
@@ -346,7 +342,7 @@
if err != nil {
return err
}
- if _, err = buf.ReadFrom(r); err != nil {
+ if _, err = io.Copy(buf, r); err != nil {
return err
}
}
@@ -422,21 +418,3 @@
}
return 0, fmt.Errorf("mime: invalid hex byte %#02x", b)
}
-
-var bufPool = sync.Pool{
- New: func() interface{} {
- return new(bytes.Buffer)
- },
-}
-
-func getBuffer() *bytes.Buffer {
- return bufPool.Get().(*bytes.Buffer)
-}
-
-func putBuffer(buf *bytes.Buffer) {
- if buf.Len() > 1024 {
- return
- }
- buf.Reset()
- bufPool.Put(buf)
-}
diff --git a/src/mime/mediatype.go b/src/mime/mediatype.go
index 426d417..ea2bbac 100644
--- a/src/mime/mediatype.go
+++ b/src/mime/mediatype.go
@@ -5,7 +5,6 @@
package mime
import (
- "bytes"
"errors"
"fmt"
"sort"
@@ -19,7 +18,7 @@
// When any of the arguments result in a standard violation then
// FormatMediaType returns the empty string.
func FormatMediaType(t string, param map[string]string) string {
- var b bytes.Buffer
+ var b strings.Builder
if slash := strings.Index(t, "/"); slash == -1 {
if !isToken(t) {
return ""
@@ -167,7 +166,7 @@
// Stitch together any continuations or things with stars
// (i.e. RFC 2231 things with stars: "foo*0" or "foo*")
- var buf bytes.Buffer
+ var buf strings.Builder
for key, pieceMap := range continuation {
singlePartKey := key + "*"
if v, ok := pieceMap[singlePartKey]; ok {
@@ -265,7 +264,7 @@
}
// parse a quoted-string
- buffer := new(bytes.Buffer)
+ buffer := new(strings.Builder)
for i := 1; i < len(v); i++ {
r := v[i]
if r == '"' {
diff --git a/src/net/http/cookie.go b/src/net/http/cookie.go
index 38b1b36..3e80cb6 100644
--- a/src/net/http/cookie.go
+++ b/src/net/http/cookie.go
@@ -5,7 +5,6 @@
package http
import (
- "bytes"
"log"
"net"
"strconv"
@@ -143,7 +142,7 @@
if c == nil || !isCookieNameValid(c.Name) {
return ""
}
- var b bytes.Buffer
+ var b strings.Builder
b.WriteString(sanitizeCookieName(c.Name))
b.WriteRune('=')
b.WriteString(sanitizeCookieValue(c.Value))
@@ -168,17 +167,14 @@
log.Printf("net/http: invalid Cookie.Domain %q; dropping domain attribute", c.Domain)
}
}
+ var buf [len(TimeFormat)]byte
if validCookieExpires(c.Expires) {
b.WriteString("; Expires=")
- b2 := b.Bytes()
- b.Reset()
- b.Write(c.Expires.UTC().AppendFormat(b2, TimeFormat))
+ b.Write(c.Expires.UTC().AppendFormat(buf[:0], TimeFormat))
}
if c.MaxAge > 0 {
b.WriteString("; Max-Age=")
- b2 := b.Bytes()
- b.Reset()
- b.Write(strconv.AppendInt(b2, int64(c.MaxAge), 10))
+ b.Write(strconv.AppendInt(buf[:0], int64(c.MaxAge), 10))
} else if c.MaxAge < 0 {
b.WriteString("; Max-Age=0")
}
diff --git a/src/net/http/httptest/server.go b/src/net/http/httptest/server.go
index 6075397..ebafc99 100644
--- a/src/net/http/httptest/server.go
+++ b/src/net/http/httptest/server.go
@@ -7,7 +7,6 @@
package httptest
import (
- "bytes"
"crypto/tls"
"crypto/x509"
"flag"
@@ -17,6 +16,7 @@
"net/http"
"net/http/internal"
"os"
+ "strings"
"sync"
"time"
)
@@ -224,7 +224,7 @@
func (s *Server) logCloseHangDebugInfo() {
s.mu.Lock()
defer s.mu.Unlock()
- var buf bytes.Buffer
+ var buf strings.Builder
buf.WriteString("httptest.Server blocked in Close after 5 seconds, waiting for connections:\n")
for c, st := range s.conns {
fmt.Fprintf(&buf, " %T %p %v in state %v\n", c, c, c.RemoteAddr(), st)
diff --git a/src/net/mail/message.go b/src/net/mail/message.go
index 4f3184f..5912b90 100644
--- a/src/net/mail/message.go
+++ b/src/net/mail/message.go
@@ -19,7 +19,6 @@
import (
"bufio"
- "bytes"
"errors"
"fmt"
"io"
@@ -735,7 +734,7 @@
// quoteString renders a string as an RFC 5322 quoted-string.
func quoteString(s string) string {
- var buf bytes.Buffer
+ var buf strings.Builder
buf.WriteByte('"')
for _, r := range s {
if isQtext(r) || isWSP(r) {
diff --git a/src/net/url/url.go b/src/net/url/url.go
index cc6c5e2..4a81514 100644
--- a/src/net/url/url.go
+++ b/src/net/url/url.go
@@ -11,7 +11,6 @@
// contain references to issue numbers with details.
import (
- "bytes"
"errors"
"fmt"
"sort"
@@ -737,7 +736,7 @@
// - if u.RawQuery is empty, ?query is omitted.
// - if u.Fragment is empty, #fragment is omitted.
func (u *URL) String() string {
- var buf bytes.Buffer
+ var buf strings.Builder
if u.Scheme != "" {
buf.WriteString(u.Scheme)
buf.WriteByte(':')
@@ -878,7 +877,7 @@
if v == nil {
return ""
}
- var buf bytes.Buffer
+ var buf strings.Builder
keys := make([]string, 0, len(v))
for k := range v {
keys = append(keys, k)
@@ -886,12 +885,13 @@
sort.Strings(keys)
for _, k := range keys {
vs := v[k]
- prefix := QueryEscape(k) + "="
+ keyEscaped := QueryEscape(k)
for _, v := range vs {
if buf.Len() > 0 {
buf.WriteByte('&')
}
- buf.WriteString(prefix)
+ buf.WriteString(keyEscaped)
+ buf.WriteByte('=')
buf.WriteString(QueryEscape(v))
}
}
diff --git a/src/regexp/onepass.go b/src/regexp/onepass.go
index 3ceb461..125be59 100644
--- a/src/regexp/onepass.go
+++ b/src/regexp/onepass.go
@@ -5,9 +5,9 @@
package regexp
import (
- "bytes"
"regexp/syntax"
"sort"
+ "strings"
"unicode"
)
@@ -54,7 +54,7 @@
}
// Have prefix; gather characters.
- var buf bytes.Buffer
+ var buf strings.Builder
for iop(i) == syntax.InstRune && len(i.Rune) == 1 && syntax.Flags(i.Arg)&syntax.FoldCase == 0 {
buf.WriteRune(i.Rune[0])
pc, i = i.Out, &p.Inst[i.Out]
diff --git a/src/regexp/syntax/parse_test.go b/src/regexp/syntax/parse_test.go
index dd6529f..fe3d251 100644
--- a/src/regexp/syntax/parse_test.go
+++ b/src/regexp/syntax/parse_test.go
@@ -5,8 +5,8 @@
package syntax
import (
- "bytes"
"fmt"
+ "strings"
"testing"
"unicode"
)
@@ -282,7 +282,7 @@
// dump prints a string representation of the regexp showing
// the structure explicitly.
func dump(re *Regexp) string {
- var b bytes.Buffer
+ var b strings.Builder
dumpRegexp(&b, re)
return b.String()
}
@@ -312,7 +312,7 @@
// dumpRegexp writes an encoding of the syntax tree for the regexp re to b.
// It is used during testing to distinguish between parses that might print
// the same using re's String method.
-func dumpRegexp(b *bytes.Buffer, re *Regexp) {
+func dumpRegexp(b *strings.Builder, re *Regexp) {
if int(re.Op) >= len(opNames) || opNames[re.Op] == "" {
fmt.Fprintf(b, "op%d", re.Op)
} else {
diff --git a/src/regexp/syntax/prog.go b/src/regexp/syntax/prog.go
index 36aa653..49a06bb 100644
--- a/src/regexp/syntax/prog.go
+++ b/src/regexp/syntax/prog.go
@@ -5,8 +5,8 @@
package syntax
import (
- "bytes"
"strconv"
+ "strings"
"unicode"
)
@@ -117,7 +117,7 @@
}
func (p *Prog) String() string {
- var b bytes.Buffer
+ var b strings.Builder
dumpProg(&b, p)
return b.String()
}
@@ -153,7 +153,7 @@
}
// Have prefix; gather characters.
- var buf bytes.Buffer
+ var buf strings.Builder
for i.op() == InstRune && len(i.Rune) == 1 && Flags(i.Arg)&FoldCase == 0 {
buf.WriteRune(i.Rune[0])
i = p.skipNop(i.Out)
@@ -267,18 +267,18 @@
}
func (i *Inst) String() string {
- var b bytes.Buffer
+ var b strings.Builder
dumpInst(&b, i)
return b.String()
}
-func bw(b *bytes.Buffer, args ...string) {
+func bw(b *strings.Builder, args ...string) {
for _, s := range args {
b.WriteString(s)
}
}
-func dumpProg(b *bytes.Buffer, p *Prog) {
+func dumpProg(b *strings.Builder, p *Prog) {
for j := range p.Inst {
i := &p.Inst[j]
pc := strconv.Itoa(j)
@@ -298,7 +298,7 @@
return strconv.FormatUint(uint64(i), 10)
}
-func dumpInst(b *bytes.Buffer, i *Inst) {
+func dumpInst(b *strings.Builder, i *Inst) {
switch i.Op {
case InstAlt:
bw(b, "alt -> ", u32(i.Out), ", ", u32(i.Arg))
diff --git a/src/regexp/syntax/regexp.go b/src/regexp/syntax/regexp.go
index 7b703f2..a3f56f8 100644
--- a/src/regexp/syntax/regexp.go
+++ b/src/regexp/syntax/regexp.go
@@ -8,7 +8,6 @@
// In this package, re is always a *Regexp and r is always a rune.
import (
- "bytes"
"strconv"
"strings"
"unicode"
@@ -114,7 +113,7 @@
}
// writeRegexp writes the Perl syntax for the regular expression re to b.
-func writeRegexp(b *bytes.Buffer, re *Regexp) {
+func writeRegexp(b *strings.Builder, re *Regexp) {
switch re.Op {
default:
b.WriteString("<invalid op" + strconv.Itoa(int(re.Op)) + ">")
@@ -245,14 +244,14 @@
}
func (re *Regexp) String() string {
- var b bytes.Buffer
+ var b strings.Builder
writeRegexp(&b, re)
return b.String()
}
const meta = `\.+*?()|[]{}^$`
-func escape(b *bytes.Buffer, r rune, force bool) {
+func escape(b *strings.Builder, r rune, force bool) {
if unicode.IsPrint(r) {
if strings.ContainsRune(meta, r) || force {
b.WriteRune('\\')
diff --git a/src/testing/example.go b/src/testing/example.go
index b995550..f4beb76 100644
--- a/src/testing/example.go
+++ b/src/testing/example.go
@@ -5,7 +5,6 @@
package testing
import (
- "bytes"
"fmt"
"io"
"os"
@@ -72,7 +71,7 @@
os.Stdout = w
outC := make(chan string)
go func() {
- var buf bytes.Buffer
+ var buf strings.Builder
_, err := io.Copy(&buf, r)
r.Close()
if err != nil {
diff --git a/src/testing/testing.go b/src/testing/testing.go
index 27d0de7..7e936f0 100644
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -376,7 +376,7 @@
file = "???"
line = 1
}
- buf := new(bytes.Buffer)
+ buf := new(strings.Builder)
// Every line is indented at least one tab.
buf.WriteByte('\t')
fmt.Fprintf(buf, "%s:%d: ", file, line)
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Brad Fitzpatrick (Gerrit)
Mar 26, 2018, 3:00:54 AM3/26/18
to Brad Fitzpatrick, goph...@pubsubhelper.golang.org, Ian Lance Taylor, Andrew Bonventre, golang-co...@googlegroups.com
Patch set 1:Run-TryBot +1
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Gobot Gobot (Gerrit)
Mar 26, 2018, 3:01:03 AM3/26/18
to Brad Fitzpatrick, goph...@pubsubhelper.golang.org, Ian Lance Taylor, Andrew Bonventre, golang-co...@googlegroups.com
TryBots beginning. Status page: https://farmer.golang.org/try?commit=09c201a7
Gobot Gobot (Gerrit)
Mar 26, 2018, 3:11:18 AM3/26/18
to Brad Fitzpatrick, goph...@pubsubhelper.golang.org, Ian Lance Taylor, Andrew Bonventre, golang-co...@googlegroups.com
TryBots are happy.
Patch set 1:TryBot-Result +1
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Marvin Stenger (Gerrit)
Mar 26, 2018, 5:37:53 AM3/26/18
to Brad Fitzpatrick, goph...@pubsubhelper.golang.org, Gobot Gobot, Ian Lance Taylor, Andrew Bonventre, golang-co...@googlegroups.com
2 comments:
Patch Set #1, Line 267:
new(strings.Builder)I don't think new() should be needed when using strings.Builder, it is way smaller than bytes.Buffer. Just put it on the stack (if the compiler isn't doing that already).
Patch Set #1, Line 379:
new(strings.Builder)same
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Brad Fitzpatrick (Gerrit)
Mar 26, 2018, 1:11:15 PM3/26/18
to Brad Fitzpatrick, goph...@pubsubhelper.golang.org, Marvin Stenger, Gobot Gobot, Ian Lance Taylor, Andrew Bonventre, golang-co...@googlegroups.com
2 comments:
Patch Set #1, Line 267:
new(strings.Builder)
I don't think new() should be needed when using strings.Builder, it is way smaller than bytes. […]
Whether you use "new" or not doesn't impact whether it's on the stack or heap. I tried to keep the existing code style as much as possible in this CL. This should still be on the stack.
Patch Set #1, Line 379:
new(strings.Builder)same
Likewise.
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Ian Lance Taylor (Gerrit)
Mar 26, 2018, 2:57:49 PM3/26/18
to Brad Fitzpatrick, goph...@pubsubhelper.golang.org, Marvin Stenger, Gobot Gobot, Andrew Bonventre, golang-co...@googlegroups.com
Patch set 1:Code-Review +2
Brad Fitzpatrick (Gerrit)
Mar 26, 2018, 7:05:57 PM3/26/18
to Brad Fitzpatrick, goph...@pubsubhelper.golang.org, golang-...@googlegroups.com, Ian Lance Taylor, Marvin Stenger, Gobot Gobot, Andrew Bonventre, golang-co...@googlegroups.com
Brad Fitzpatrick merged this change.
Approvals:
Ian Lance Taylor: Looks good to me, approved
Brad Fitzpatrick: Run TryBots
Gobot Gobot: TryBots succeeded
all: use strings.Builder instead of bytes.Buffer where appropriate
I grepped for "bytes.Buffer" and "buf.String" and mostly ignored test
files. I skipped a few on purpose and probably missed a few others,
but otherwise I think this should be most of them.
Updates #18990
Change-Id: I5a6ae4296b87b416d8da02d7bfaf981d8cc14774
Reviewed-on: https://go-review.googlesource.com/102479
Run-TryBot: Brad Fitzpatrick <brad...@golang.org>
TryBot-Result: Gobot Gobot <go...@golang.org>
Reviewed-by: Ian Lance Taylor <ia...@golang.org>
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