Official Go implementation of the Ethereum protocol
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go-ethereum/rlp/typecache.go

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5.8 KiB

// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package rlp
import (
"fmt"
"maps"
"reflect"
"sync"
"sync/atomic"
"github.com/ethereum/go-ethereum/rlp/internal/rlpstruct"
)
// typeinfo is an entry in the type cache.
type typeinfo struct {
decoder decoder
decoderErr error // error from makeDecoder
writer writer
writerErr error // error from makeWriter
}
// typekey is the key of a type in typeCache. It includes the struct tags because
// they might generate a different decoder.
type typekey struct {
reflect.Type
rlpstruct.Tags
}
type decoder func(*Stream, reflect.Value) error
type writer func(reflect.Value, *encBuffer) error
var theTC = newTypeCache()
type typeCache struct {
cur atomic.Value
// This lock synchronizes writers.
mu sync.Mutex
next map[typekey]*typeinfo
}
func newTypeCache() *typeCache {
c := new(typeCache)
c.cur.Store(make(map[typekey]*typeinfo))
return c
}
func cachedDecoder(typ reflect.Type) (decoder, error) {
info := theTC.info(typ)
return info.decoder, info.decoderErr
}
func cachedWriter(typ reflect.Type) (writer, error) {
info := theTC.info(typ)
return info.writer, info.writerErr
}
func (c *typeCache) info(typ reflect.Type) *typeinfo {
key := typekey{Type: typ}
if info := c.cur.Load().(map[typekey]*typeinfo)[key]; info != nil {
return info
}
// Not in the cache, need to generate info for this type.
return c.generate(typ, rlpstruct.Tags{})
}
func (c *typeCache) generate(typ reflect.Type, tags rlpstruct.Tags) *typeinfo {
c.mu.Lock()
defer c.mu.Unlock()
cur := c.cur.Load().(map[typekey]*typeinfo)
if info := cur[typekey{typ, tags}]; info != nil {
return info
}
// Copy cur to next.
c.next = maps.Clone(cur)
// Generate.
info := c.infoWhileGenerating(typ, tags)
// next -> cur
c.cur.Store(c.next)
c.next = nil
return info
}
func (c *typeCache) infoWhileGenerating(typ reflect.Type, tags rlpstruct.Tags) *typeinfo {
key := typekey{typ, tags}
if info := c.next[key]; info != nil {
return info
}
// Put a dummy value into the cache before generating.
// If the generator tries to lookup itself, it will get
// the dummy value and won't call itself recursively.
info := new(typeinfo)
c.next[key] = info
info.generate(typ, tags)
return info
}
type field struct {
index int
info *typeinfo
optional bool
}
// structFields resolves the typeinfo of all public fields in a struct type.
func structFields(typ reflect.Type) (fields []field, err error) {
// Convert fields to rlpstruct.Field.
var allStructFields []rlpstruct.Field
for i := 0; i < typ.NumField(); i++ {
rf := typ.Field(i)
allStructFields = append(allStructFields, rlpstruct.Field{
Name: rf.Name,
Index: i,
Exported: rf.PkgPath == "",
Tag: string(rf.Tag),
Type: *rtypeToStructType(rf.Type, nil),
})
}
// Filter/validate fields.
structFields, structTags, err := rlpstruct.ProcessFields(allStructFields)
if err != nil {
if tagErr, ok := err.(rlpstruct.TagError); ok {
tagErr.StructType = typ.String()
return nil, tagErr
}
return nil, err
}
// Resolve typeinfo.
for i, sf := range structFields {
typ := typ.Field(sf.Index).Type
tags := structTags[i]
info := theTC.infoWhileGenerating(typ, tags)
fields = append(fields, field{sf.Index, info, tags.Optional})
}
return fields, nil
}
// firstOptionalField returns the index of the first field with "optional" tag.
func firstOptionalField(fields []field) int {
for i, f := range fields {
if f.optional {
return i
}
}
return len(fields)
}
type structFieldError struct {
typ reflect.Type
field int
err error
}
func (e structFieldError) Error() string {
return fmt.Sprintf("%v (struct field %v.%s)", e.err, e.typ, e.typ.Field(e.field).Name)
}
func (i *typeinfo) generate(typ reflect.Type, tags rlpstruct.Tags) {
i.decoder, i.decoderErr = makeDecoder(typ, tags)
i.writer, i.writerErr = makeWriter(typ, tags)
}
// rtypeToStructType converts typ to rlpstruct.Type.
func rtypeToStructType(typ reflect.Type, rec map[reflect.Type]*rlpstruct.Type) *rlpstruct.Type {
k := typ.Kind()
if k == reflect.Invalid {
panic("invalid kind")
}
if prev := rec[typ]; prev != nil {
return prev // short-circuit for recursive types
}
if rec == nil {
rec = make(map[reflect.Type]*rlpstruct.Type)
}
t := &rlpstruct.Type{
Name: typ.String(),
Kind: k,
IsEncoder: typ.Implements(encoderInterface),
IsDecoder: typ.Implements(decoderInterface),
}
rec[typ] = t
if k == reflect.Array || k == reflect.Slice || k == reflect.Ptr {
t.Elem = rtypeToStructType(typ.Elem(), rec)
}
return t
}
// typeNilKind gives the RLP value kind for nil pointers to 'typ'.
func typeNilKind(typ reflect.Type, tags rlpstruct.Tags) Kind {
styp := rtypeToStructType(typ, nil)
var nk rlpstruct.NilKind
if tags.NilOK {
nk = tags.NilKind
} else {
nk = styp.DefaultNilValue()
}
switch nk {
case rlpstruct.NilKindString:
return String
case rlpstruct.NilKindList:
return List
default:
panic("invalid nil kind value")
}
}
func isUint(k reflect.Kind) bool {
return k >= reflect.Uint && k <= reflect.Uintptr
}
func isByte(typ reflect.Type) bool {
return typ.Kind() == reflect.Uint8 && !typ.Implements(encoderInterface)
}