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mirror of https://github.com/golang/go synced 2024-11-26 04:07:59 -07:00

fmt: speed up 10-20%

The check for Stringer etc. can only fire if the test is not a builtin, so avoid
the expensive check if we know there's no chance.
Also put in a fast path for pad, which saves a more modest amount.

benchmark                      old ns/op    new ns/op    delta
BenchmarkSprintfEmpty                148          152   +2.70%
BenchmarkSprintfString               585          497  -15.04%
BenchmarkSprintfInt                  441          396  -10.20%
BenchmarkSprintfIntInt               718          603  -16.02%
BenchmarkSprintfPrefixedInt          676          621   -8.14%
BenchmarkSprintfFloat               1003          953   -4.99%
BenchmarkManyArgs                   2945         2312  -21.49%
BenchmarkScanInts                1704152      1734441   +1.78%
BenchmarkScanRecursiveInt        1837397      1828920   -0.46%

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6245068
This commit is contained in:
Rob Pike 2012-05-29 15:08:08 -07:00
parent d61707f490
commit 53bc19442d
3 changed files with 20 additions and 12 deletions

View File

@ -527,6 +527,14 @@ func BenchmarkSprintfFloat(b *testing.B) {
} }
} }
func BenchmarkManyArgs(b *testing.B) {
var buf bytes.Buffer
for i := 0; i < b.N; i++ {
buf.Reset()
Fprintf(&buf, "%2d/%2d/%2d %d:%d:%d %s %s\n", 3, 4, 5, 11, 12, 13, "hello", "world")
}
}
var mallocBuf bytes.Buffer var mallocBuf bytes.Buffer
var mallocTest = []struct { var mallocTest = []struct {

View File

@ -110,11 +110,11 @@ func (f *fmt) writePadding(n int, padding []byte) {
// Append b to f.buf, padded on left (w > 0) or right (w < 0 or f.minus) // Append b to f.buf, padded on left (w > 0) or right (w < 0 or f.minus)
// clear flags afterwards. // clear flags afterwards.
func (f *fmt) pad(b []byte) { func (f *fmt) pad(b []byte) {
var padding []byte if !f.widPresent || f.wid == 0 {
var left, right int f.buf.Write(b)
if f.widPresent && f.wid != 0 { return
padding, left, right = f.computePadding(len(b))
} }
padding, left, right := f.computePadding(len(b))
if left > 0 { if left > 0 {
f.writePadding(left, padding) f.writePadding(left, padding)
} }
@ -127,11 +127,11 @@ func (f *fmt) pad(b []byte) {
// append s to buf, padded on left (w > 0) or right (w < 0 or f.minus). // append s to buf, padded on left (w > 0) or right (w < 0 or f.minus).
// clear flags afterwards. // clear flags afterwards.
func (f *fmt) padString(s string) { func (f *fmt) padString(s string) {
var padding []byte if !f.widPresent || f.wid == 0 {
var left, right int f.buf.WriteString(s)
if f.widPresent && f.wid != 0 { return
padding, left, right = f.computePadding(utf8.RuneCountInString(s))
} }
padding, left, right := f.computePadding(utf8.RuneCountInString(s))
if left > 0 { if left > 0 {
f.writePadding(left, padding) f.writePadding(left, padding)
} }

View File

@ -734,10 +734,6 @@ func (p *pp) printField(field interface{}, verb rune, plus, goSyntax bool, depth
return false return false
} }
if wasString, handled := p.handleMethods(verb, plus, goSyntax, depth); handled {
return wasString
}
// Some types can be done without reflection. // Some types can be done without reflection.
switch f := field.(type) { switch f := field.(type) {
case bool: case bool:
@ -779,6 +775,10 @@ func (p *pp) printField(field interface{}, verb rune, plus, goSyntax bool, depth
p.fmtBytes(f, verb, goSyntax, depth) p.fmtBytes(f, verb, goSyntax, depth)
wasString = verb == 's' wasString = verb == 's'
default: default:
// If the type is not simple, it might have methods.
if wasString, handled := p.handleMethods(verb, plus, goSyntax, depth); handled {
return wasString
}
// Need to use reflection // Need to use reflection
return p.printReflectValue(reflect.ValueOf(field), verb, plus, goSyntax, depth) return p.printReflectValue(reflect.ValueOf(field), verb, plus, goSyntax, depth)
} }