fast-path.go.tmpl
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// +build !notfastpath
// Copyright (c) 2012-2018 Ugorji Nwoke. All rights reserved.
// Use of this source code is governed by a MIT license found in the LICENSE file.
// Code generated from fast-path.go.tmpl - DO NOT EDIT.
package codec
// Fast path functions try to create a fast path encode or decode implementation
// for common maps and slices.
//
// We define the functions and register them in this single file
// so as not to pollute the encode.go and decode.go, and create a dependency in there.
// This file can be omitted without causing a build failure.
//
// The advantage of fast paths is:
// - Many calls bypass reflection altogether
//
// Currently support
// - slice of all builtin types (numeric, bool, string, []byte)
// - maps of builtin types to builtin or interface{} type, EXCEPT FOR
// keys of type uintptr, int8/16/32, uint16/32, float32/64, bool, interface{}
// AND values of type type int8/16/32, uint16/32
// This should provide adequate "typical" implementations.
//
// Note that fast track decode functions must handle values for which an address cannot be obtained.
// For example:
// m2 := map[string]int{}
// p2 := []interface{}{m2}
// // decoding into p2 will bomb if fast track functions do not treat like unaddressable.
//
{{/*
fastpathEncMapStringUint64R (called by fastpath...switch)
EncMapStringUint64V (called by codecgen)
fastpathEncSliceBoolR: (called by fastpath...switch) (checks f.ti.mbs and calls one of them below)
EncSliceBoolV (also called by codecgen)
EncAsMapSliceBoolV (delegate when mapbyslice=true)
fastpathDecSliceIntfR (called by fastpath...switch) (calls Y or N below depending on if it can be updated)
DecSliceIntfX (called by codecgen) (calls Y below)
DecSliceIntfY (delegate when slice CAN be updated)
DecSliceIntfN (delegate when slice CANNOT be updated e.g. from array or non-addressable slice)
fastpathDecMap...R (called by fastpath...switch) (calls L or X? below)
DecMap...X (called by codecgen)
DecMap...L (delegated to by both above)
*/ -}}
import (
"reflect"
"sort"
)
const fastpathEnabled = true
const fastpathMapBySliceErrMsg = "mapBySlice requires even slice length, but got %v"
type fastpathT struct {}
var fastpathTV fastpathT
type fastpathE struct {
rtid uintptr
rt reflect.Type
encfn func(*Encoder, *codecFnInfo, reflect.Value)
decfn func(*Decoder, *codecFnInfo, reflect.Value)
}
type fastpathA [{{ .FastpathLen }}]fastpathE
func (x *fastpathA) index(rtid uintptr) int {
// use binary search to grab the index (adapted from sort/search.go)
// Note: we use goto (instead of for loop) so this can be inlined.
// h, i, j := 0, 0, len(x)
var h, i uint
var j = uint(len(x))
LOOP:
if i < j {
h = i + (j-i)/2
if x[h].rtid < rtid {
i = h + 1
} else {
j = h
}
goto LOOP
}
if i < uint(len(x)) && x[i].rtid == rtid {
return int(i)
}
return -1
}
type fastpathAslice []fastpathE
func (x fastpathAslice) Len() int { return len(x) }
func (x fastpathAslice) Less(i, j int) bool { return x[uint(i)].rtid < x[uint(j)].rtid }
func (x fastpathAslice) Swap(i, j int) { x[uint(i)], x[uint(j)] = x[uint(j)], x[uint(i)] }
var fastpathAV fastpathA
// due to possible initialization loop error, make fastpath in an init()
func init() {
var i uint = 0
fn := func(v interface{},
fe func(*Encoder, *codecFnInfo, reflect.Value),
fd func(*Decoder, *codecFnInfo, reflect.Value)) {
xrt := reflect.TypeOf(v)
xptr := rt2id(xrt)
fastpathAV[i] = fastpathE{xptr, xrt, fe, fd}
i++
}
{{/* do not register []uint8 in fast-path */}}
{{range .Values}}{{if not .Primitive}}{{if not .MapKey }}{{if ne .Elem "uint8" -}}
fn([]{{ .Elem }}(nil), (*Encoder).{{ .MethodNamePfx "fastpathEnc" false }}R, (*Decoder).{{ .MethodNamePfx "fastpathDec" false }}R)
{{end}}{{end}}{{end}}{{end}}
{{range .Values}}{{if not .Primitive}}{{if .MapKey -}}
fn(map[{{ .MapKey }}]{{ .Elem }}(nil), (*Encoder).{{ .MethodNamePfx "fastpathEnc" false }}R, (*Decoder).{{ .MethodNamePfx "fastpathDec" false }}R)
{{end}}{{end}}{{end}}
sort.Sort(fastpathAslice(fastpathAV[:]))
}
// -- encode
// -- -- fast path type switch
func fastpathEncodeTypeSwitch(iv interface{}, e *Encoder) bool {
switch v := iv.(type) {
{{range .Values}}{{if not .Primitive}}{{if not .MapKey }}{{if ne .Elem "uint8" -}}
case []{{ .Elem }}:
fastpathTV.{{ .MethodNamePfx "Enc" false }}V(v, e)
case *[]{{ .Elem }}:
if *v == nil {
e.e.EncodeNil()
} else {
fastpathTV.{{ .MethodNamePfx "Enc" false }}V(*v, e)
}
{{end}}{{end}}{{end}}{{end -}}
{{range .Values}}{{if not .Primitive}}{{if .MapKey -}}
case map[{{ .MapKey }}]{{ .Elem }}:
fastpathTV.{{ .MethodNamePfx "Enc" false }}V(v, e)
case *map[{{ .MapKey }}]{{ .Elem }}:
if *v == nil {
e.e.EncodeNil()
} else {
fastpathTV.{{ .MethodNamePfx "Enc" false }}V(*v, e)
}
{{end}}{{end}}{{end -}}
default:
_ = v // workaround https://github.com/golang/go/issues/12927 seen in go1.4
return false
}
return true
}
// -- -- fast path functions
{{range .Values}}{{if not .Primitive}}{{if not .MapKey -}}
func (e *Encoder) {{ .MethodNamePfx "fastpathEnc" false }}R(f *codecFnInfo, rv reflect.Value) {
if f.ti.mbs {
fastpathTV.{{ .MethodNamePfx "EncAsMap" false }}V(rv2i(rv).([]{{ .Elem }}), e)
} else {
fastpathTV.{{ .MethodNamePfx "Enc" false }}V(rv2i(rv).([]{{ .Elem }}), e)
}
}
func (fastpathT) {{ .MethodNamePfx "Enc" false }}V(v []{{ .Elem }}, e *Encoder) {
{{/* if v == nil { e.e.EncodeNil(); return } */ -}}
e.arrayStart(len(v))
for j := range v {
e.arrayElem()
{{ encmd .Elem "v[j]"}}
}
e.arrayEnd()
}
func (fastpathT) {{ .MethodNamePfx "EncAsMap" false }}V(v []{{ .Elem }}, e *Encoder) {
{{/* if v == nil { e.e.EncodeNil() } else */ -}}
if len(v)%2 == 1 {
e.errorf(fastpathMapBySliceErrMsg, len(v))
} else {
e.mapStart(len(v) / 2)
for j := range v {
if j%2 == 0 {
e.mapElemKey()
} else {
e.mapElemValue()
}
{{ encmd .Elem "v[j]"}}
}
e.mapEnd()
}
}
{{end}}{{end}}{{end -}}
{{range .Values}}{{if not .Primitive}}{{if .MapKey -}}
func (e *Encoder) {{ .MethodNamePfx "fastpathEnc" false }}R(f *codecFnInfo, rv reflect.Value) {
fastpathTV.{{ .MethodNamePfx "Enc" false }}V(rv2i(rv).(map[{{ .MapKey }}]{{ .Elem }}), e)
}
func (fastpathT) {{ .MethodNamePfx "Enc" false }}V(v map[{{ .MapKey }}]{{ .Elem }}, e *Encoder) {
{{/* if v == nil { e.e.EncodeNil(); return } */ -}}
e.mapStart(len(v))
if e.h.Canonical { {{/* need to figure out .NoCanonical */}}
{{if eq .MapKey "interface{}"}}{{/* out of band */ -}}
var mksv []byte = make([]byte, 0, len(v)*16) // temporary byte slice for the encoding
e2 := NewEncoderBytes(&mksv, e.hh)
v2 := make([]bytesIntf, len(v))
var i, l uint {{/* put loop variables outside. seems currently needed for better perf */}}
var vp *bytesIntf
for k2 := range v {
l = uint(len(mksv))
e2.MustEncode(k2)
vp = &v2[i]
vp.v = mksv[l:]
vp.i = k2
i++
}
sort.Sort(bytesIntfSlice(v2))
for j := range v2 {
e.mapElemKey()
e.asis(v2[j].v)
e.mapElemValue()
e.encode(v[v2[j].i])
} {{else}}{{ $x := sorttype .MapKey true}}v2 := make([]{{ $x }}, len(v))
var i uint
for k := range v {
v2[i] = {{if eq $x .MapKey}}k{{else}}{{ $x }}(k){{end}}
i++
}
sort.Sort({{ sorttype .MapKey false}}(v2))
for _, k2 := range v2 {
e.mapElemKey()
{{if eq .MapKey "string"}} e.e.EncodeString(k2) {{else}}{{ $y := printf "%s(k2)" .MapKey }}{{if eq $x .MapKey }}{{ $y = "k2" }}{{end}}{{ encmd .MapKey $y }}{{end}}
e.mapElemValue()
{{ $y := printf "v[%s(k2)]" .MapKey }}{{if eq $x .MapKey }}{{ $y = "v[k2]" }}{{end}}{{ encmd .Elem $y }}
} {{end}}
} else {
for k2, v2 := range v {
e.mapElemKey()
{{if eq .MapKey "string"}} e.e.EncodeString(k2) {{else}}{{ encmd .MapKey "k2"}}{{end}}
e.mapElemValue()
{{ encmd .Elem "v2"}}
}
}
e.mapEnd()
}
{{end}}{{end}}{{end -}}
// -- decode
// -- -- fast path type switch
func fastpathDecodeTypeSwitch(iv interface{}, d *Decoder) bool {
var changed bool
var containerLen int
switch v := iv.(type) {
{{range .Values}}{{if not .Primitive}}{{if not .MapKey }}{{if ne .Elem "uint8" -}}
case []{{ .Elem }}:
fastpathTV.{{ .MethodNamePfx "Dec" false }}N(v, d)
case *[]{{ .Elem }}:
var v2 []{{ .Elem }}
if v2, changed = fastpathTV.{{ .MethodNamePfx "Dec" false }}Y(*v, d); changed {
*v = v2
}
{{end}}{{end}}{{end}}{{end -}}
{{range .Values}}{{if not .Primitive}}{{if .MapKey }}{{/*
// maps only change if nil, and in that case, there's no point copying
*/ -}}
case map[{{ .MapKey }}]{{ .Elem }}:
containerLen = d.mapStart()
if containerLen != decContainerLenNil {
if containerLen != 0 {
fastpathTV.{{ .MethodNamePfx "Dec" false }}L(v, containerLen, d)
}
d.mapEnd()
}
case *map[{{ .MapKey }}]{{ .Elem }}:
{{/*
containerLen = d.mapStart()
if containerLen == 0 {
d.mapEnd()
} else if containerLen == decContainerLenNil {
*v = nil
} else {
if *v == nil {
*v = make(map[{{ .MapKey }}]{{ .Elem }}, decInferLen(containerLen, d.h.MaxInitLen, {{ .Size }}))
}
fastpathTV.{{ .MethodNamePfx "Dec" false }}L(*v, containerLen, d)
}
// consider delegating fully to X - encoding *map is uncommon, so ok to pay small function call cost
*/ -}}
fastpathTV.{{ .MethodNamePfx "Dec" false }}X(v, d)
{{end}}{{end}}{{end -}}
default:
_ = v // workaround https://github.com/golang/go/issues/12927 seen in go1.4
return false
}
return true
}
func fastpathDecodeSetZeroTypeSwitch(iv interface{}) bool {
switch v := iv.(type) {
{{range .Values}}{{if not .Primitive}}{{if not .MapKey -}}
case *[]{{ .Elem }}:
*v = nil
{{end}}{{end}}{{end}}
{{range .Values}}{{if not .Primitive}}{{if .MapKey -}}
case *map[{{ .MapKey }}]{{ .Elem }}:
*v = nil
{{end}}{{end}}{{end}}
default:
_ = v // workaround https://github.com/golang/go/issues/12927 seen in go1.4
return false
}
return true
}
// -- -- fast path functions
{{range .Values}}{{if not .Primitive}}{{if not .MapKey -}}
{{/*
Slices can change if they
- did not come from an array
- are addressable (from a ptr)
- are settable (e.g. contained in an interface{})
*/}}
func (d *Decoder) {{ .MethodNamePfx "fastpathDec" false }}R(f *codecFnInfo, rv reflect.Value) {
if f.seq != seqTypeArray && rv.Kind() == reflect.Ptr {
vp := rv2i(rv).(*[]{{ .Elem }})
if v, changed := fastpathTV.{{ .MethodNamePfx "Dec" false }}Y(*vp, d); changed { *vp = v }
} else {
fastpathTV.{{ .MethodNamePfx "Dec" false }}N(rv2i(rv).([]{{ .Elem }}), d)
}
}
func (f fastpathT) {{ .MethodNamePfx "Dec" false }}X(vp *[]{{ .Elem }}, d *Decoder) {
if v, changed := f.{{ .MethodNamePfx "Dec" false }}Y(*vp, d); changed { *vp = v }
}
func (fastpathT) {{ .MethodNamePfx "Dec" false }}Y(v []{{ .Elem }}, d *Decoder) (_ []{{ .Elem }}, changed bool) {
slh, containerLenS := d.decSliceHelperStart()
if slh.IsNil {
if v == nil { return }
return nil, true
}
if containerLenS == 0 {
if v == nil { v = []{{ .Elem }}{} } else if len(v) != 0 { v = v[:0] }
slh.End()
return v, true
}
hasLen := containerLenS > 0
var xlen int
if hasLen {
if containerLenS > cap(v) {
xlen = decInferLen(containerLenS, d.h.MaxInitLen, {{ .Size }})
if xlen <= cap(v) {
v = v[:uint(xlen)]
} else {
v = make([]{{ .Elem }}, uint(xlen))
}
changed = true
} else if containerLenS != len(v) {
v = v[:containerLenS]
changed = true
}
}
var j int
for j = 0; (hasLen && j < containerLenS) || !(hasLen || d.checkBreak()); j++ {
if j == 0 && len(v) == 0 {
if hasLen {
xlen = decInferLen(containerLenS, d.h.MaxInitLen, {{ .Size }})
} else {
xlen = 8
}
v = make([]{{ .Elem }}, uint(xlen))
changed = true
}
{{/* // if indefinite, etc, then expand the slice if necessary */ -}}
if j >= len(v) {
v = append(v, {{ zerocmd .Elem }})
changed = true
}
slh.ElemContainerState(j)
{{ if eq .Elem "interface{}" }}d.decode(&v[uint(j)]){{ else }}v[uint(j)] = {{ decmd .Elem }}{{ end }}
}
if j < len(v) {
v = v[:uint(j)]
changed = true
} else if j == 0 && v == nil {
v = []{{ .Elem }}{}
changed = true
}
slh.End()
return v, changed
}
func (fastpathT) {{ .MethodNamePfx "Dec" false }}N(v []{{ .Elem }}, d *Decoder) {
slh, containerLenS := d.decSliceHelperStart()
if slh.IsNil {
return
}
if containerLenS == 0 {
slh.End()
return
}
hasLen := containerLenS > 0
for j := 0; (hasLen && j < containerLenS) || !(hasLen || d.checkBreak()); j++ {
{{/* // if indefinite, etc, then expand the slice if necessary */ -}}
if j >= len(v) {
fastpathDecArrayCannotExpand(slh, hasLen, len(v), j, containerLenS)
return
}
slh.ElemContainerState(j)
{{ if eq .Elem "interface{}" -}}
d.decode(&v[uint(j)])
{{- else -}}
v[uint(j)] = {{ decmd .Elem }}
{{- end }}
}
slh.End()
}
{{end}}{{end}}{{end -}}
func fastpathDecArrayCannotExpand(slh decSliceHelper, hasLen bool, lenv, j, containerLenS int) {
slh.d.arrayCannotExpand(lenv, j+1)
slh.ElemContainerState(j)
slh.d.swallow()
j++
for ; (hasLen && j < containerLenS) || !(hasLen || slh.d.checkBreak()); j++ {
slh.ElemContainerState(j)
slh.d.swallow()
}
slh.End()
}
{{range .Values}}{{if not .Primitive}}{{if .MapKey -}}
{{/*
Maps can change if they are
- addressable (from a ptr)
- settable (e.g. contained in an interface{})
*/ -}}
func (d *Decoder) {{ .MethodNamePfx "fastpathDec" false }}R(f *codecFnInfo, rv reflect.Value) {
containerLen := d.mapStart()
if containerLen == decContainerLenNil {
if rv.Kind() == reflect.Ptr {
*(rv2i(rv).(*map[{{ .MapKey }}]{{ .Elem }})) = nil
}
} else {
if rv.Kind() == reflect.Ptr {
vp, _ := rv2i(rv).(*map[{{ .MapKey }}]{{ .Elem }})
if *vp == nil {
*vp = make(map[{{ .MapKey }}]{{ .Elem }}, decInferLen(containerLen, d.h.MaxInitLen, {{ .Size }}))
}
if containerLen != 0 {
fastpathTV.{{ .MethodNamePfx "Dec" false }}L(*vp, containerLen, d)
}
} else if containerLen != 0 {
fastpathTV.{{ .MethodNamePfx "Dec" false }}L(rv2i(rv).(map[{{ .MapKey }}]{{ .Elem }}), containerLen, d)
}
d.mapEnd()
}
}
func (f fastpathT) {{ .MethodNamePfx "Dec" false }}X(vp *map[{{ .MapKey }}]{{ .Elem }}, d *Decoder) {
containerLen := d.mapStart()
if containerLen == decContainerLenNil {
*vp = nil
} else {
if *vp == nil {
*vp = make(map[{{ .MapKey }}]{{ .Elem }}, decInferLen(containerLen, d.h.MaxInitLen, {{ .Size }}))
}
if containerLen != 0 {
f.{{ .MethodNamePfx "Dec" false }}L(*vp, containerLen, d)
}
d.mapEnd()
}
}
func (fastpathT) {{ .MethodNamePfx "Dec" false }}L(v map[{{ .MapKey }}]{{ .Elem }}, containerLen int, d *Decoder) {
{{/* No need to check if containerLen == decContainerLenNil, as that is checked by R and L above */ -}}
{{if eq .Elem "interface{}" }}mapGet := v != nil && !d.h.MapValueReset && !d.h.InterfaceReset
{{else if eq .Elem "bytes" "[]byte" }}mapGet := v != nil && !d.h.MapValueReset
{{end -}}
var mk {{ .MapKey }}
var mv {{ .Elem }}
hasLen := containerLen > 0
for j := 0; (hasLen && j < containerLen) || !(hasLen || d.checkBreak()); j++ {
d.mapElemKey()
{{ if eq .MapKey "interface{}" }}mk = nil
d.decode(&mk)
if bv, bok := mk.([]byte); bok {
mk = d.string(bv) {{/* // maps cannot have []byte as key. switch to string. */}}
}{{ else }}mk = {{ decmd .MapKey }}{{ end }}
d.mapElemValue()
{{ if eq .Elem "interface{}" "[]byte" "bytes" -}}
if mapGet { mv = v[mk] } else { mv = nil }
{{ end -}}
{{ if eq .Elem "interface{}" -}}
d.decode(&mv)
{{ else if eq .Elem "[]byte" "bytes" -}}
mv = d.d.DecodeBytes(mv, false)
{{ else -}}
mv = {{ decmd .Elem }}
{{ end -}}
if v != nil { v[mk] = mv }
}
}
{{end}}{{end}}{{end}}