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gob: make nested interfaces work.

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Also clean up the code, make it more regular.

Fixes #1416.

R=rsc
CC=golang-dev
https://golang.org/cl/3985047
This commit is contained in:
Rob Pike 2011-01-28 10:53:42 -08:00
parent 04a8905442
commit 9b82481a96
6 changed files with 241 additions and 143 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
src/pkg/gob/codec_test.go
View File

@ -58,7 +58,7 @@ func TestUintCodec(t *testing.T) {
t.Errorf("encodeUint: %#x encode: expected % x got % x", tt.x, tt.b, b.Bytes())
}
}
decState := newDecodeState(nil, &b)
decState := newDecodeState(nil, b)
for u := uint64(0); ; u = (u + 1) * 7 {
b.Reset()
encState.encodeUint(u)
@ -77,7 +77,7 @@ func verifyInt(i int64, t *testing.T) {
var b = new(bytes.Buffer)
encState := newEncoderState(nil, b)
encState.encodeInt(i)
decState := newDecodeState(nil, &b)
decState := newDecodeState(nil, b)
decState.buf = make([]byte, 8)
j := decState.decodeInt()
if i != j {
@ -315,7 +315,7 @@ func execDec(typ string, instr *decInstr, state *decodeState, t *testing.T, p un
func newDecodeStateFromData(data []byte) *decodeState {
b := bytes.NewBuffer(data)
state := newDecodeState(nil, &b)
state := newDecodeState(nil, b)
state.fieldnum = -1
return state
}
@ -1162,7 +1162,6 @@ func TestInterface(t *testing.T) {
}
}
}
}
// A struct with all basic types, stored in interfaces.
@ -1182,7 +1181,7 @@ func TestInterfaceBasic(t *testing.T) {
int(1), int8(1), int16(1), int32(1), int64(1),
uint(1), uint8(1), uint16(1), uint32(1), uint64(1),
float32(1), 1.0,
complex64(0i), complex128(0i),
complex64(1i), complex128(1i),
true,
"hello",
[]byte("sailor"),

54
src/pkg/gob/decode.go
View File

@ -30,15 +30,17 @@ type decodeState struct {
dec *Decoder
// The buffer is stored with an extra indirection because it may be replaced
// if we load a type during decode (when reading an interface value).
b **bytes.Buffer
b *bytes.Buffer
fieldnum int // the last field number read.
buf []byte
}
func newDecodeState(dec *Decoder, b **bytes.Buffer) *decodeState {
// We pass the bytes.Buffer separately for easier testing of the infrastructure
// without requiring a full Decoder.
func newDecodeState(dec *Decoder, buf *bytes.Buffer) *decodeState {
d := new(decodeState)
d.dec = dec
d.b = b
d.b = buf
d.buf = make([]byte, uint64Size)
return d
}
@ -407,10 +409,10 @@ func allocate(rtyp reflect.Type, p uintptr, indir int) uintptr {
return *(*uintptr)(up)
}
func (dec *Decoder) decodeSingle(engine *decEngine, rtyp reflect.Type, b **bytes.Buffer, p uintptr, indir int) (err os.Error) {
func (dec *Decoder) decodeSingle(engine *decEngine, rtyp reflect.Type, p uintptr, indir int) (err os.Error) {
defer catchError(&err)
p = allocate(rtyp, p, indir)
state := newDecodeState(dec, b)
state := newDecodeState(dec, &dec.buf)
state.fieldnum = singletonField
basep := p
delta := int(state.decodeUint())
@ -426,10 +428,10 @@ func (dec *Decoder) decodeSingle(engine *decEngine, rtyp reflect.Type, b **bytes
return nil
}
func (dec *Decoder) decodeStruct(engine *decEngine, rtyp *reflect.StructType, b **bytes.Buffer, p uintptr, indir int) (err os.Error) {
func (dec *Decoder) decodeStruct(engine *decEngine, rtyp *reflect.StructType, p uintptr, indir int) (err os.Error) {
defer catchError(&err)
p = allocate(rtyp, p, indir)
state := newDecodeState(dec, b)
state := newDecodeState(dec, &dec.buf)
state.fieldnum = -1
basep := p
for state.b.Len() > 0 {
@ -456,9 +458,9 @@ func (dec *Decoder) decodeStruct(engine *decEngine, rtyp *reflect.StructType, b
return nil
}
func (dec *Decoder) ignoreStruct(engine *decEngine, b **bytes.Buffer) (err os.Error) {
func (dec *Decoder) ignoreStruct(engine *decEngine) (err os.Error) {
defer catchError(&err)
state := newDecodeState(dec, b)
state := newDecodeState(dec, &dec.buf)
state.fieldnum = -1
for state.b.Len() > 0 {
delta := int(state.decodeUint())
@ -614,9 +616,17 @@ func (dec *Decoder) decodeInterface(ityp *reflect.InterfaceType, state *decodeSt
if !ok {
errorf("gob: name not registered for interface: %q", name)
}
// Read the type id of the concrete value.
concreteId := dec.decodeTypeSequence(true)
if concreteId < 0 {
error(dec.err)
}
// Byte count of value is next; we don't care what it is (it's there
// in case we want to ignore the value by skipping it completely).
state.decodeUint()
// Read the concrete value.
value := reflect.MakeZero(typ)
dec.decodeValueFromBuffer(value, false, true)
dec.decodeValue(concreteId, value)
if dec.err != nil {
error(dec.err)
}
@ -639,10 +649,12 @@ func (dec *Decoder) ignoreInterface(state *decodeState) {
if err != nil {
error(err)
}
dec.decodeValueFromBuffer(nil, true, true)
if dec.err != nil {
error(err)
id := dec.decodeTypeSequence(true)
if id < 0 {
error(dec.err)
}
// At this point, the decoder buffer contains the value. Just toss it.
state.b.Reset()
}
// Index by Go types.
@ -733,7 +745,7 @@ func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string) (decOp
}
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
// indirect through enginePtr to delay evaluation for recursive structs
err = dec.decodeStruct(*enginePtr, t, state.b, uintptr(p), i.indir)
err = dec.decodeStruct(*enginePtr, t, uintptr(p), i.indir)
if err != nil {
error(err)
}
@ -798,7 +810,7 @@ func (dec *Decoder) decIgnoreOpFor(wireId typeId) decOp {
}
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
// indirect through enginePtr to delay evaluation for recursive structs
state.dec.ignoreStruct(*enginePtr, state.b)
state.dec.ignoreStruct(*enginePtr)
}
}
}
@ -907,7 +919,11 @@ func (dec *Decoder) compileDec(remoteId typeId, rt reflect.Type) (engine *decEng
if t, ok := builtinIdToType[remoteId]; ok {
wireStruct, _ = t.(*structType)
} else {
wireStruct = dec.wireType[remoteId].StructT
wire := dec.wireType[remoteId]
if wire == nil {
error(errBadType)
}
wireStruct = wire.StructT
}
if wireStruct == nil {
errorf("gob: type mismatch in decoder: want struct type %s; got non-struct", rt.String())
@ -976,7 +992,7 @@ func (dec *Decoder) getIgnoreEnginePtr(wireId typeId) (enginePtr **decEngine, er
return
}
func (dec *Decoder) decode(wireId typeId, val reflect.Value) os.Error {
func (dec *Decoder) decodeValue(wireId typeId, val reflect.Value) os.Error {
// Dereference down to the underlying struct type.
rt, indir := indirect(val.Type())
enginePtr, err := dec.getDecEnginePtr(wireId, rt)
@ -989,9 +1005,9 @@ func (dec *Decoder) decode(wireId typeId, val reflect.Value) os.Error {
name := rt.Name()
return os.ErrorString("gob: type mismatch: no fields matched compiling decoder for " + name)
}
return dec.decodeStruct(engine, st, dec.state.b, uintptr(val.Addr()), indir)
return dec.decodeStruct(engine, st, uintptr(val.Addr()), indir)
}
return dec.decodeSingle(engine, rt, dec.state.b, uintptr(val.Addr()), indir)
return dec.decodeSingle(engine, rt, uintptr(val.Addr()), indir)
}
func init() {

187
src/pkg/gob/decoder.go
View File

@ -17,14 +17,13 @@ import (
type Decoder struct {
mutex sync.Mutex // each item must be received atomically
r io.Reader // source of the data
buf bytes.Buffer // buffer for more efficient i/o from r
wireType map[typeId]*wireType // map from remote ID to local description
decoderCache map[reflect.Type]map[typeId]**decEngine // cache of compiled engines
ignorerCache map[typeId]**decEngine // ditto for ignored objects
state *decodeState // reads data from in-memory buffer
countState *decodeState // reads counts from wire
buf []byte
countBuf [9]byte // counts may be uint64s (unlikely!), require 9 bytes
byteBuffer *bytes.Buffer
countBuf []byte // used for decoding integers while parsing messages
tmp []byte // temporary storage for i/o; saves reallocating
err os.Error
}
@ -33,32 +32,123 @@ func NewDecoder(r io.Reader) *Decoder {
dec := new(Decoder)
dec.r = r
dec.wireType = make(map[typeId]*wireType)
dec.state = newDecodeState(dec, &dec.byteBuffer) // buffer set in Decode()
dec.decoderCache = make(map[reflect.Type]map[typeId]**decEngine)
dec.ignorerCache = make(map[typeId]**decEngine)
dec.countBuf = make([]byte, 9) // counts may be uint64s (unlikely!), require 9 bytes
return dec
}
// recvType loads the definition of a type and reloads the Decoder's buffer.
// recvType loads the definition of a type.
func (dec *Decoder) recvType(id typeId) {
// Have we already seen this type? That's an error
if dec.wireType[id] != nil {
if id < firstUserId || dec.wireType[id] != nil {
dec.err = os.ErrorString("gob: duplicate type received")
return
}
// Type:
wire := new(wireType)
dec.err = dec.decode(tWireType, reflect.NewValue(wire))
dec.err = dec.decodeValue(tWireType, reflect.NewValue(wire))
if dec.err != nil {
return
}
// Remember we've seen this type.
dec.wireType[id] = wire
}
// Load the next parcel.
dec.recvMessage()
// recvMessage reads the next count-delimited item from the input. It is the converse
// of Encoder.writeMessage. It returns false on EOF or other error reading the message.
func (dec *Decoder) recvMessage() bool {
// Read a count.
nbytes, _, err := decodeUintReader(dec.r, dec.countBuf)
if err != nil {
dec.err = err
return false
}
dec.readMessage(int(nbytes))
return dec.err == nil
}
// readMessage reads the next nbytes bytes from the input.
func (dec *Decoder) readMessage(nbytes int) {
// Allocate the buffer.
if cap(dec.tmp) < nbytes {
dec.tmp = make([]byte, nbytes+100) // room to grow
}
dec.tmp = dec.tmp[:nbytes]
// Read the data
_, dec.err = io.ReadFull(dec.r, dec.tmp)
if dec.err != nil {
if dec.err == os.EOF {
dec.err = io.ErrUnexpectedEOF
}
return
}
dec.buf.Write(dec.tmp)
}
// toInt turns an encoded uint64 into an int, according to the marshaling rules.
func toInt(x uint64) int64 {
i := int64(x >> 1)
if x&1 != 0 {
i = ^i
}
return i
}
func (dec *Decoder) nextInt() int64 {
n, _, err := decodeUintReader(&dec.buf, dec.countBuf)
if err != nil {
dec.err = err
}
return toInt(n)
}
func (dec *Decoder) nextUint() uint64 {
n, _, err := decodeUintReader(&dec.buf, dec.countBuf)
if err != nil {
dec.err = err
}
return n
}
// decodeTypeSequence parses:
// TypeSequence
// (TypeDefinition DelimitedTypeDefinition*)?
// and returns the type id of the next value. It returns -1 at
// EOF. Upon return, the remainder of dec.buf is the value to be
// decoded. If this is an interface value, it can be ignored by
// simply resetting that buffer.
func (dec *Decoder) decodeTypeSequence(isInterface bool) typeId {
for dec.err == nil {
if dec.buf.Len() == 0 {
if !dec.recvMessage() {
break
}
}
// Receive a type id.
id := typeId(dec.nextInt())
if id >= 0 {
// Value follows.
return id
}
// Type definition for (-id) follows.
dec.recvType(-id)
// When decoding an interface, after a type there may be a
// DelimitedValue still in the buffer. Skip its count.
// (Alternatively, the buffer is empty and the byte count
// will be absorbed by recvMessage.)
if dec.buf.Len() > 0 {
if !isInterface {
dec.err = os.ErrorString("extra data in buffer")
break
}
dec.nextUint()
}
}
return -1
}
// Decode reads the next value from the connection and stores
@ -76,75 +166,6 @@ func (dec *Decoder) Decode(e interface{}) os.Error {
return dec.DecodeValue(value)
}
// recvMessage reads the next count-delimited item from the input. It is the converse
// of Encoder.writeMessage.
func (dec *Decoder) recvMessage() {
// Read a count.
var nbytes uint64
nbytes, _, dec.err = decodeUintReader(dec.r, dec.countBuf[0:])
if dec.err != nil {
return
}
dec.readMessage(int(nbytes), dec.r)
}
// readMessage reads the next nbytes bytes from the input.
func (dec *Decoder) readMessage(nbytes int, r io.Reader) {
// Allocate the buffer.
if nbytes > len(dec.buf) {
dec.buf = make([]byte, nbytes+1000)
}
dec.byteBuffer = bytes.NewBuffer(dec.buf[0:nbytes])
// Read the data
_, dec.err = io.ReadFull(r, dec.buf[0:nbytes])
if dec.err != nil {
if dec.err == os.EOF {
dec.err = io.ErrUnexpectedEOF
}
return
}
}
// decodeValueFromBuffer grabs the next value from the input. The Decoder's
// buffer already contains data. If the next item in the buffer is a type
// descriptor, it will be necessary to reload the buffer; recvType does that.
func (dec *Decoder) decodeValueFromBuffer(value reflect.Value, ignoreInterfaceValue, countPresent bool) {
for dec.state.b.Len() > 0 {
// Receive a type id.
id := typeId(dec.state.decodeInt())
// Is it a new type?
if id < 0 { // 0 is the error state, handled above
// If the id is negative, we have a type.
dec.recvType(-id)
if dec.err != nil {
break
}
continue
}
// Make sure the type has been defined already or is a builtin type (for
// top-level singleton values).
if dec.wireType[id] == nil && builtinIdToType[id] == nil {
dec.err = errBadType
break
}
// An interface value is preceded by a byte count.
if countPresent {
count := int(dec.state.decodeUint())
if ignoreInterfaceValue {
// An interface value is preceded by a byte count. Just skip that many bytes.
dec.state.b.Next(int(count))
break
}
// Otherwise fall through and decode it.
}
dec.err = dec.decode(id, value)
break
}
}
// DecodeValue reads the next value from the connection and stores
// it in the data represented by the reflection value.
// The value must be the correct type for the next
@ -154,12 +175,12 @@ func (dec *Decoder) DecodeValue(value reflect.Value) os.Error {
dec.mutex.Lock()
defer dec.mutex.Unlock()
dec.buf.Reset() // In case data lingers from previous invocation.
dec.err = nil
dec.recvMessage()
if dec.err != nil {
return dec.err
id := dec.decodeTypeSequence(false)
if id >= 0 {
dec.err = dec.decodeValue(id, value)
}
dec.decodeValueFromBuffer(value, false, false)
return dec.err
}

16
src/pkg/gob/encode.go
View File

@ -395,17 +395,21 @@ func (enc *Encoder) encodeInterface(b *bytes.Buffer, iv *reflect.InterfaceValue)
if err != nil {
error(err)
}
// Send (and maybe first define) the type id.
enc.sendTypeDescriptor(typ)
// Encode the value into a new buffer.
// Define the type id if necessary.
enc.sendTypeDescriptor(enc.writer(), state, typ)
// Send the type id.
enc.sendTypeId(state, typ)
// Encode the value into a new buffer. Any nested type definitions
// should be written to b, before the encoded value.
enc.pushWriter(b)
data := new(bytes.Buffer)
err = enc.encode(data, iv.Elem())
if err != nil {
error(err)
}
state.encodeUint(uint64(data.Len()))
_, err = state.b.Write(data.Bytes())
if err != nil {
enc.popWriter()
enc.writeMessage(b, data)
if enc.err != nil {
error(err)
}
}

74
src/pkg/gob/encoder.go
View File

@ -16,9 +16,8 @@ import (
// other side of a connection.
type Encoder struct {
mutex sync.Mutex // each item must be sent atomically
w io.Writer // where to send the data
w []io.Writer // where to send the data
sent map[reflect.Type]typeId // which types we've already sent
state *encoderState // so we can encode integers, strings directly
countState *encoderState // stage for writing counts
buf []byte // for collecting the output.
err os.Error
@ -27,13 +26,27 @@ type Encoder struct {
// NewEncoder returns a new encoder that will transmit on the io.Writer.
func NewEncoder(w io.Writer) *Encoder {
enc := new(Encoder)
enc.w = w
enc.w = []io.Writer{w}
enc.sent = make(map[reflect.Type]typeId)
enc.state = newEncoderState(enc, new(bytes.Buffer))
enc.countState = newEncoderState(enc, new(bytes.Buffer))
return enc
}
// writer() returns the innermost writer the encoder is using
func (enc *Encoder) writer() io.Writer {
return enc.w[len(enc.w)-1]
}
// pushWriter adds a writer to the encoder.
func (enc *Encoder) pushWriter(w io.Writer) {
enc.w = append(enc.w, w)
}
// popWriter pops the innermost writer.
func (enc *Encoder) popWriter() {
enc.w = enc.w[0 : len(enc.w)-1]
}
func (enc *Encoder) badType(rt reflect.Type) {
enc.setError(os.ErrorString("gob: can't encode type " + rt.String()))
}
@ -42,16 +55,14 @@ func (enc *Encoder) setError(err os.Error) {
if enc.err == nil { // remember the first.
enc.err = err
}
enc.state.b.Reset()
}
// Send the data item preceded by a unsigned count of its length.
func (enc *Encoder) send() {
// Encode the length.
enc.countState.encodeUint(uint64(enc.state.b.Len()))
// writeMessage sends the data item preceded by a unsigned count of its length.
func (enc *Encoder) writeMessage(w io.Writer, b *bytes.Buffer) {
enc.countState.encodeUint(uint64(b.Len()))
// Build the buffer.
countLen := enc.countState.b.Len()
total := countLen + enc.state.b.Len()
total := countLen + b.Len()
if total > len(enc.buf) {
enc.buf = make([]byte, total+1000) // extra for growth
}
@ -59,15 +70,15 @@ func (enc *Encoder) send() {
// TODO(r): avoid the extra copy here.
enc.countState.b.Read(enc.buf[0:countLen])
// Now the data.
enc.state.b.Read(enc.buf[countLen:total])
b.Read(enc.buf[countLen:total])
// Write the data.
_, err := enc.w.Write(enc.buf[0:total])
_, err := w.Write(enc.buf[0:total])
if err != nil {
enc.setError(err)
}
}
func (enc *Encoder) sendType(origt reflect.Type) (sent bool) {
func (enc *Encoder) sendType(w io.Writer, state *encoderState, origt reflect.Type) (sent bool) {
// Drill down to the base type.
rt, _ := indirect(origt)
@ -112,10 +123,10 @@ func (enc *Encoder) sendType(origt reflect.Type) (sent bool) {
}
// Send the pair (-id, type)
// Id:
enc.state.encodeInt(-int64(info.id))
state.encodeInt(-int64(info.id))
// Type:
enc.encode(enc.state.b, reflect.NewValue(info.wire))
enc.send()
enc.encode(state.b, reflect.NewValue(info.wire))
enc.writeMessage(w, state.b)
if enc.err != nil {
return
}
@ -128,10 +139,10 @@ func (enc *Encoder) sendType(origt reflect.Type) (sent bool) {
switch st := rt.(type) {
case *reflect.StructType:
for i := 0; i < st.NumField(); i++ {
enc.sendType(st.Field(i).Type)
enc.sendType(w, state, st.Field(i).Type)
}
case reflect.ArrayOrSliceType:
enc.sendType(st.Elem())
enc.sendType(w, state, st.Elem())
}
return true
}
@ -144,13 +155,13 @@ func (enc *Encoder) Encode(e interface{}) os.Error {
// sendTypeId makes sure the remote side knows about this type.
// It will send a descriptor if this is the first time the type has been
// sent. Regardless, it sends the id.
func (enc *Encoder) sendTypeDescriptor(rt reflect.Type) {
// sent.
func (enc *Encoder) sendTypeDescriptor(w io.Writer, state *encoderState, rt reflect.Type) {
// Make sure the type is known to the other side.
// First, have we already sent this type?
if _, alreadySent := enc.sent[rt]; !alreadySent {
// No, so send it.
sent := enc.sendType(rt)
sent := enc.sendType(w, state, rt)
if enc.err != nil {
return
}
@ -168,9 +179,12 @@ func (enc *Encoder) sendTypeDescriptor(rt reflect.Type) {
enc.sent[rt] = info.id
}
}
}
// sendTypeId sends the id, which must have already been defined.
func (enc *Encoder) sendTypeId(state *encoderState, rt reflect.Type) {
// Identify the type of this top-level value.
enc.state.encodeInt(int64(enc.sent[rt]))
state.encodeInt(int64(enc.sent[rt]))
}
// EncodeValue transmits the data item represented by the reflection value,
@ -181,26 +195,26 @@ func (enc *Encoder) EncodeValue(value reflect.Value) os.Error {
enc.mutex.Lock()
defer enc.mutex.Unlock()
// Remove any nested writers remaining due to previous errors.
enc.w = enc.w[0:1]
enc.err = nil
rt, _ := indirect(value.Type())
// Sanity check only: encoder should never come in with data present.
if enc.state.b.Len() > 0 || enc.countState.b.Len() > 0 {
enc.err = os.ErrorString("encoder: buffer not empty")
return enc.err
}
state := newEncoderState(enc, new(bytes.Buffer))
enc.sendTypeDescriptor(rt)
enc.sendTypeDescriptor(enc.writer(), state, rt)
enc.sendTypeId(state, rt)
if enc.err != nil {
return enc.err
}
// Encode the object.
err := enc.encode(enc.state.b, value)
err := enc.encode(state.b, value)
if err != nil {
enc.setError(err)
} else {
enc.send()
enc.writeMessage(enc.writer(), state.b)
}
return enc.err

44
src/pkg/gob/encoder_test.go
View File

@ -383,3 +383,47 @@ func TestInterfaceIndirect(t *testing.T) {
t.Fatal("decode error:", err)
}
}
// Another bug from golang-nuts, involving nested interfaces.
type Bug0Outer struct {
Bug0Field interface{}
}
type Bug0Inner struct {
A int
}
func TestNestedInterfaces(t *testing.T) {
var buf bytes.Buffer
e := NewEncoder(&buf)
d := NewDecoder(&buf)
Register(new(Bug0Outer))
Register(new(Bug0Inner))
f := &Bug0Outer{&Bug0Outer{&Bug0Inner{7}}}
var v interface{} = f
err := e.Encode(&v)
if err != nil {
t.Fatal("Encode:", err)
}
Debug(bytes.NewBuffer(buf.Bytes()))
err = d.Decode(&v)
if err != nil {
t.Fatal("Decode:", err)
}
// Make sure it decoded correctly.
outer1, ok := v.(*Bug0Outer)
if !ok {
t.Fatalf("v not Bug0Outer: %T", v)
}
outer2, ok := outer1.Bug0Field.(*Bug0Outer)
if !ok {
t.Fatalf("v.Bug0Field not Bug0Outer: %T", outer1.Bug0Field)
}
inner, ok := outer2.Bug0Field.(*Bug0Inner)
if !ok {
t.Fatalf("v.Bug0Field.Bug0Field not Bug0Inner: %T", outer2.Bug0Field)
}
if inner.A != 7 {
t.Fatalf("final value %d; expected %d", inner.A, 7)
}
}