Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-11-09 05:01:01 +00:00
Code Issues Projects Releases Packages Wiki Activity

encoding/gob: speed up encoding of arrays and slices

Browse source 
We borrow a trick from the fmt package and avoid reflection
to walk the elements when possible. We could push further with
unsafe (and we may) but this is a good start.
Decode can benefit similarly; it will be done separately.

Use go generate (engen.go) to produce the helper functions
(enc_helpers.go).

benchmark                            old ns/op     new ns/op     delta
BenchmarkEndToEndPipe                6593          6482          -1.68%
BenchmarkEndToEndByteBuffer          3662          3684          +0.60%
BenchmarkEndToEndSliceByteBuffer     350306        351693        +0.40%
BenchmarkComplex128Slice             96347         80045         -16.92%
BenchmarkInt32Slice                  42484         26008         -38.78%
BenchmarkFloat64Slice                51143         36265         -29.09%
BenchmarkStringSlice                 53402         35077         -34.32%

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/156310043
This commit is contained in:
Rob Pike 2014-10-17 09:00:07 -07:00
parent fb173c4185
commit 5e713062b4
4 changed files with 708 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

15
src/encoding/gob/encode.go
View file

@ -2,6 +2,8 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:generate go run encgen.go -output enc_helpers.go
package gob
import (
@ -13,6 +15,8 @@ import (
const uint64Size = 8
type encHelper func(state *encoderState, v reflect.Value) bool
// encoderState is the global execution state of an instance of the encoder.
// Field numbers are delta encoded and always increase. The field
// number is initialized to -1 so 0 comes out as delta(1). A delta of
@ -291,12 +295,15 @@ func (enc *Encoder) encodeStruct(b *bytes.Buffer, engine *encEngine, value refle
}
// encodeArray encodes an array.
func (enc *Encoder) encodeArray(b *bytes.Buffer, value reflect.Value, op encOp, elemIndir int, length int) {
func (enc *Encoder) encodeArray(b *bytes.Buffer, value reflect.Value, op encOp, elemIndir int, length int, helper encHelper) {
state := enc.newEncoderState(b)
defer enc.freeEncoderState(state)
state.fieldnum = -1
state.sendZero = true
state.encodeUint(uint64(length))
if helper != nil && helper(state, value) {
return
}
for i := 0; i < length; i++ {
elem := value.Index(i)
if elemIndir > 0 {
@ -501,19 +508,21 @@ func encOpFor(rt reflect.Type, inProgress map[reflect.Type]*encOp, building map[
}
// Slices have a header; we decode it to find the underlying array.
elemOp, elemIndir := encOpFor(t.Elem(), inProgress, building)
helper := sliceHelper[t.Elem().Kind()]
op = func(i *encInstr, state *encoderState, slice reflect.Value) {
if !state.sendZero && slice.Len() == 0 {
return
}
state.update(i)
state.enc.encodeArray(state.b, slice, *elemOp, elemIndir, slice.Len())
state.enc.encodeArray(state.b, slice, *elemOp, elemIndir, slice.Len(), helper)
}
case reflect.Array:
// True arrays have size in the type.
elemOp, elemIndir := encOpFor(t.Elem(), inProgress, building)
helper := arrayHelper[t.Elem().Kind()]
op = func(i *encInstr, state *encoderState, array reflect.Value) {
state.update(i)
state.enc.encodeArray(state.b, array, *elemOp, elemIndir, array.Len())
state.enc.encodeArray(state.b, array, *elemOp, elemIndir, array.Len(), helper)
}
case reflect.Map:
keyOp, keyIndir := encOpFor(t.Key(), inProgress, building)